pubs_121675610 - edicao 30 anos da acom outokumpu
TRANSCRIPT
www.outokumpu.com
acom4 - 2010A corrosion management and applications engineering magazine from Outokumpu
30 y
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acom chronicle 1980–2010 page 2
superaustenitic stainless steels in demanding environments page 4
Lean duplex – the first decade of service experience page 17
80 years with duplex steels – a historic review and prospects for the future page 28
30 years with acom – in order page 35
– by subject page 42
Jubilee issue:30 years with acom1980–2010
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acom chronicle 1980–2010Acom has, over the years, published close to 150 articles in almost 100 issues. Many authors have contributed: Outokumpu employees as well as authors representing customers and research institutes. The number of subscribers has varied during the years, with a maximum of almost 2000 at the time when it existed in its paper form, sent out by ordinary post. Today it is available free at the Outokumpu webpage (www.outokumpu.com) but also distributed to almost 800 subscribers via e-mail. The subscribers include persons in the academic world such as students, teachers and professors but the majority are employed in the industry as researchers, engineers and technical staff. During the years, six editors have worked with acom, all of them listed in Table 1.
Acom continues to provide its readers with relevant technological research information. It has survived a number of structural changes, company-wise, and will hopefully continue to prosper and flourish for at least another 30 years. Outokumpu is proud to present this issue of acom, which contains articles on superaustenitics and duplexes with a somewhat historical view, to celebrate the 30th year of acom. An index is found in the end of this issue with all published titles and a subject index that hopefully will be very useful for all interested in the wide field of stainless steel.
Enjoy your reading and please do not hesitate to contact us if you have any questions, comments or suggestions on acom, its content or future!
Jesper GunnarssonEditor of [email protected]
history of acomIt all started when Nyby-Uddeholm AB was formed in 1979 from two merging companies. This was the result of an early reorganization due to an overcapacity in the stainless steel production in the Swedish steel industry. This new company launched a new way of communicating technical information: NUCCI – Nyby Uddeholm Corrosion Control Information. The first issue, in 1980, see Figure 1, was mastered by Sten Nordin, who became the first editor of NUCCI. In 1984, the major reorganization of the Swedish stainless steel industry occurred, forming Avesta AB. The new company liked the concept of NUCCI and continued the publishing activity, but under a new name – acom – Avesta Corrosion Management. The first issue is seen in Figure 2. The first decade of the
Editor: Year:
Sten Nordin 1980 – 1983 1984 – 1986
Gary Coates 1983 – 1984
Sten von Matérn 1986 – 1994
Jan Olsson 1995 – 2006
Claes Olsson 2007 – 2008
Jesper Gunnarsson 2009 –
editors Table 1
Fig. 1 Fig. 2
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Fig. 4 Fig. 5 Fig. 3
technical magazine contained a number of articles on desalination and offshore applications, often written by or in co-operation with Norwegian engineers. During this time technical improvements in manufacturing processes allowed the production of higher-alloyed austenitics, materials ideally suited to these fields.
Although the superaustenitic stainless steel 254 SMO® had appeared for the first time in NUCCI in 1984, it was not until the end of the 1980’s this material started to appear regularly in the magazine. In the following decade, many articles covered different aspects of the properties of the higher alloyed austenitics with 654 SMO® appearing in the first half of 1992.
During 1992, Avesta AB and the stainless steel division of British Steel plc, formerly the British Steel Corporation, merged, forming Avesta Sheffield AB. Two major changes were made to acom two years later, in the first number of 1994, see Figure 3. The first change was visual and the second affected the contents of acom. Instead of being officially corrosion-orientated, it was given a wider scope and called acom – Avesta Sheffield Corrosion Management and Application Engineering.
In 2001, Avesta Sheffield AB merged with the Finnish Outokumpu, forming Avesta Polarit AB. A new design of acom was presented to the readers, see Figure 4. In the beginning of the 2000’s, the transformation of the printed version to a digital acom started. During 2004, some structural changes were made when Outokumpu took over the full ownership. A new acom design was launched and is seen in Figure 5.
If the acoms during the 1990’s focused on superaustenitics, then the 2000’s emphasized the duplex stainless steels and their development. Especially the new lean duplex grade LDX 2101® attracted a lot of attention. This grade was lean in terms of nickel content, an interesting feature in times of large nickel price fluctuations. The launch of this stainless steel grade came at the right time with sky-high nickel prices, giving a boost to its marketing and production. In addition to new grades, other fields were covered by acom, more and more belonging to the field of “application engineering”.
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superaustenitic stainless steels in demanding environments
mats Liljas, carolina canderyd, rachel Pettersson and mikael willför,
outokumpu stainless aB, sweden
abstractAs a result of their high alloy content, superaustenitic stainless steels demonstrate good resistance to pitting, crevice corrosion and stress corrosion cracking in chloride environments, including seawater. The resistance to acid corrosion means that they also find use in applications such as chemical process equipment, hydrometallurgy and flue gas cleaning. Although mechanical properties are not the primary reason for selecting superaustenitics, advantages can be gained from the fact that they have yield strengths up to twice that of the standard austenitic grades. Compared to superduplex stainless steels, superaustenitics have the advantages of a wider application temperature range and superior ductility.
This paper presents results of laboratory tests to compare the three superaustenitic steels 254 SMO®, 4565 and 654 SMO®. Data are compared to standard austenitic grades to give perspective, and a number of successful application examples are summarised.
Keywords: superaustenitic, corrosion, welding, seawater, FGD, offshore
1. history of superaustenitics developmentFrom the first commercial austenitic stainless steel, developed in Germany almost 100 years ago, the evolution of austenitic stainless has followed different paths depending on technological requirements and manufacturing capabilities. An important driving force has been the need from end users for materials that are resistant to increasingly harsh environments. Additions of Mo and Si were used at an early stage to improve the corrosion resistance to acids, important industries being chemical and pulp and paper industry (sulphite industry). The need for materials to withstand sulfuric acid also gave rise to development of special stainless steel alloys in the 1930’s. In Europe (France) Uranus B6, with approximately 20Cr-25Ni-4.5Mo-1.5Cu was developed and during the same époque, Alloy 20, containing 20Cr-30Ni-2.5Mo-3.5Cu, was developed in USA and later marketed as Alloy 20Cb-3. Uranus B6, generally known today as 904L, came into a very widespread use starting from the 1970’s in applications such as pulp and paper and the chemical industry. One reason for the increased use was improved production capability through the introduction of new refining technologies, such as AOD (Argon Oxygen Decarburization) in the early 1970’s. These technologies allowed much better control of alloy additions, improved removal of detrimental tramp elements and facilitated the possibility to produce extra low carbon (ELC) steels.
Alloy 20 and 904L formed a base for further development of superaustenitic steels. Allegheny Ludlum introduced AL-6X (20Cr-25Ni-6Mo) in the early 1970’s. This material was mainly used in thin-walled condenser tubing for seawater cooled power plants. The high alloy content made the steel prone to precipitation of intermetallic phases preventing fabrication in heavier sections. In 1976 Avesta Jernverk introduced 254 SMO®, a 6Mo superaustenitic stainless steel with a balanced composition containing 20%Cr, 18%Ni, 6%Mo, 0.7%Cu and 0.2% N [1]. The addition of nitrogen slowed the precipitation of intermetallic phases, facilitating production of heavier gauges. It also improved the mechanical and corrosion properties. The addition of some copper was made to enhance the corrosion resistance in certain acids without jeopardizing the resistance to pitting and crevice corrosion. Later, other 6% Mo steels followed this nitrogen-alloying approach. Examples include AL-6XN
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Fig. 1 Thermo-Calc modeling (TCFE5 database) of equilibria in superaustenitic grades (top row) and the same grades without nitrogen showing how the fully austenitic “window” is achieved by nitrogen alloying and the maximum temperature for sigma phase is decreased.
(N08367) and Cronifer 1925hMo (N08926). A common feature of this family of so-called 6Mo superaustenitic steels is a very high resistance to pitting and crevice corrosion. Therefore, they have been used extensively in the offshore and desalination industries for seawater handling, in chlorine and chlorine dioxide stages in bleach plants, and in flue gas desulphurization.
The concept of nitrogen alloying had been used for decades in other types of austenitic alloys. Well-known commercial grades were for example the Nitronic series from Armco where an improved strength was achieved with this addition. In the late 1960’s it was shown that the nitrogen alloying retards both carbide and intermetallic phase precipitation in austenitic steels [2]. The German grade 1.4439 (~317 LMN) with minimum 4%Mo and 0.15%N was an example of a steel where this knowledge was used. This grade has since been used in many applications with severe corrosion environments such as heat exchangers, flue gas desulphurization (FGD) and pulp and paper bleach plants.
To attain higher nitrogen solubility and thereby even higher nitrogen levels, manganese alloying was employed, higher levels of chromium and molybdenum also contributed in this respect. An example of this strategy is Alloy 4565, developed in the 1980’s and with close to 0.5%N [3] as listed in Table 1. Because of its high alloy content, still with a stable austenitic structure, it shows improved corrosion resistance and strength compared to the 6Mo steels. The use of thermodynamic databases to predict the nitrogen solubility and phase stability in high alloy austenitic steels is an important tool in this type of development work and is illustrated in Figure 1. Important factors to consider are the nitrogen solubility and the availability of a fully austenitic “window”, without the precipitation of intermetallic phases or the precipitation of high temperature ferrite which easily decomposes to austenite+sigma phase.
If the alloying levels of chromium and molybdenum are further increased, high nitrogen contents can be reached yet with quite low manganese addition. This was utilized in the development of 654 SMO®, with just 3%Mn but still 0.5%N [4], Table 1. 654 SMO® is one of the most highly alloyed superaustenitic stainless steels produced to date and as a consequence, it has a corrosion resistance at a similar level to many nickel-base alloys.
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254 SMO® 4565 654 SMO®
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2. Grades and mechanical propertiesIn Table 1 typical compositions of some austenitic stainless steels are listed. 316L and 904L are included for comparison. The superaustenitic grades 254 SMO® and 654 SMO® are Outokumpu trademarks and 4565 is also produced by Outokumpu.
Minimum strength levels are listed in Table 2. The superaustenitic grades, particularly those with high nitrogen contents, exhibit clearly higher strengths than standard austenitics, still with good ductility.
Grade designations and typical compositions in weight percent steel grade. Table 1
Steel grade UNS EN C N Cr Ni Mo Other PRE*
316L S31603 1.4404 0.02 17.2 10.1 2.1 24
904L N08904 1.4539 0.01 20 25 4.3 1.5Cu 34
254 SMO® S31254 1.4547 0.01 0.20 20 18 6.1 0.7Cu 43
4565 S34565 1.4565 0.02 0.45 24 17 4.5 5.5Mn 46
654 SMO® S32654 1.4652 0.01 0.5 24 22 7.3 3Mn 0.5Cu 56
*PRE = (%Cr) + 3.3x(%Mo) + 16x(%N)
mechanical properties at rt, minimum values according to standards. Table 2
Rp0.2 Rp1.0 Rm A5 KV Steel grade EN (MPa) (MPa) (MPa) (%) (J)
316L 1.4404 220 260 520 45 60
316L 1.4539 220 260 520 35 60
254 SMO® 1.4547 300 340 650 35 60
4565 1.4565 420 460 800 30 90
654 SMO® 1.4652 430 470 750 40 60
Yield strength Tensile strength Elongation MaxSteel grade UNS (ksi) (MPa) (ksi) (MPa) (%) RB
316L S31603 25 205 70 515 40 95
904L N08904 31 220 71 490 35 90
254 SMO® S31254 45 310 100 690 35 96
4565 S34565 60 415 115 795 35 100
654 SMO® S32654 62 430 109 750 40 –
ASTM A240
EN 10088 (sheet/plate and strip)
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3. corrosion resistance3.1 Pitting and crevice corrosion
The pitting corrosion resistance of a stainless steel is mainly dependent on the chemical composition, which is the reason why the concept of the Pitting Resistance Equivalent (PRE, Table 1) has found such wide acceptance as a simple predictor of localized corrosion resistance. Good agreement is seen with the critical pitting temperatures according to both ASTM G150 and ASTM G 48 method E, shown in Figure 2 and Figure 3 respectively. A common feature for the two tests is that they both use temperature as the critical evaluation parameter, showing at what temperature pitting corrosion occurs in respective test solution. However, the tests are very different: ASTM G150 is an electrochemical measurement in 1M NaCl, while G 48 method E involves immersion testing in FeCl3 solution, so the CPT-values from the two methods should not be inter-changed. ASTM G150 is the less aggressive method and does not differentiate between 4565 and 654 SMO® since the critical temperatures for both alloys lie above the upper attainable temperature limit. However, the results from ASTM G48 method E show that pitting corrosion occur for 4565 at 90°C but not for 654 SMO® or for the nickel-base alloy C-276. ASTM G 48 method F is used to compare the crevice corrosion resistance by evaluating a critical temperature for corrosion under Teflon crevice-formers. Crevice corrosion occurs at lower temperatures than pitting, so the method allows even very corrosion resistant materials to be ranked. The results in Figure 4 show that 654 SMO® has much better resistance to crevice corrosion than the other grades, even the nickel-base alloy C-276. 4565 has a higher CPT than 254 SMO® but the critical crevice corrosion temperature of the two alloys is similar.
3.2 chloride-induced stress corrosion cracking
Chloride-induced stress corrosion cracking (SCC) of stainless steels may be a cause for failure in process environments and seawater, or even under relatively benign conditions with relatively low levels of chlorides – if these become concentrated by evaporation. Immersion tests to rank SCC resistance are of rather limited usefulness. The widely-prevalent sodium chloride can in practice be used for testing up to a concentration of 25 weight percent, which boils at 107°C (225°F), as specified in ASTM G123. This is appropriate and useful for testing lower-alloyed standard grades but not sufficiently aggressive for ranking superaustenitic steels.
At the other end of the spectrum, magnesium chloride solution has long been established as a stress corrosion cracking test because of the high temperatures attainable in saturated solutions. Table 3 shows results from testing in a 45% MgCl2 solution boiling at 155°C, as specified by both MTI-3 [6] and ASTM G36. In this case the test is too aggressive to give differentiation since all specimens of 316L, 254 SMO® and
Fig. 2 CPT-values for ground surfaces (wet 320 grit) evaluated with ASTM G150. [5]
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Fig. 3 CPT-values for ground surfaces (dry 120 grit) evaluated with ASTM G48 method E. [5]
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Fig. 4 Critical crevice corrosion temperatures, CCT, for ground surfaces (dry 120 grit) evaluated with ASTM G48 method F. [5]
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654 SMO® failed in the 24 hour test period. The only difference in performance is the slightly longer time to failure for 904L, which may be related to the lower molybdenum level in this alloy compared to the superaustenitic grades. The test environment has long been recognised as giving such unusual ranking effects, which disagree with practical experience and other test environments. The test has largely fallen out of favour for this reason.
More useful are standardised tests designed to simulate stress corrosion cracking in evaporative conditions, for example under wetted insulation or at waterlines. The ASTM C692 standard is designed for evaluation of the tendency for insulation materials to cause stress corrosion cracking, but by using a chloride-free insulation and allowing this to soak up a chloride solution of controlled concentration, it can instead become a test for stainless steels. However, as shown in Table 4, this test is not severe enough to cause cracking in super-austenitic grades, since no failure is observed for 254 SMO®.
The drop evaporation test [7, 8] simulates the situation which can occur on heat transfer surfaces, where material is repeatedly wetted and dried, leading to a build-up of chloride. A dilute (0.1M) sodium chloride solution is dripped onto uniaxially loaded, electrically heated specimens and the drop rate adjusted to 6 drops per minute, which means that one drop is evaporated just before the next one falls on the specimen. This gives a specimen temperature which fluctuates in the range 80–120°C (176–248°F). Specimens are electropolished to eliminate residual stresses and the threshold stress is defined as the maximum percentage of the 200°C (392°F) yield stress which does not cause cracking in 500 hours. Results in Table 5 show very good differentiation between the austenitic grades and demonstrate the superior stress corrosion cracking of the superaustenitic grades compared to both 316L and 904L. The threshold stress for 254 SMO® is 80% of the yield stress while no cracking occurs for 654 SMO® even at the yield stress. The actual stresses involved are also higher for the superaustenitic grades by virtue of their higher yield stress. The common notion that austenitic stainless steels are very susceptible to stress corrosion cracking is clearly relevant to low alloyed standard grades but is strongly disproved by the superaustenites.
Number of failed U-bend specimens after testing in 45% mgcl2
boiling at 155ºc (311ºF) [5] Table 3
Duration 316L 904L 254 SMO® 654 SMO®
24 hours 3/3 0/3 3/3 3/3
96 hours – 3/3 – –
Number of failed U-bend specimens after testing according
to modified astm c 692 for 672 hours. Table 4
Grade: 316L 904L 254 SMO® 4565 654 SMO®
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threshold stress as a percentage of the yield stress at 200ºc (392ºF)
for stress corrosion cracking in the Drop evaporation test.9 Table 5
Grade: 316L 904L 254 SMO® 4565 654 SMO®
<10% 60% 80% >80% >100%
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3.3 sulfide stress crackingFor service in sour environments in the oil and gas industry, sulfide stress cracking (SSC) can be a serious damage mechanism. Qualification procedures are rigorous and involve testing with a number of variables such as partial pressure of H2S, the pH, chloride concentration and temperature.
NACE MR0175 / ISO 15156-3 [10] groups alloys into classes and defines environmental working limits. 304L falls into the category of “austenitic stainless steels” with relatively low limitation on use, Table 6. 904L falls into category A3a within “highly-alloyed austentic stainless steels” because it has PRE<40, while 254 SMO® and 654 SMO® both belong to the highest stainless category A3b. The latter allows the use of both solution annealed and cold-worked material at temperatures up to 171°C (340°F) in sour environments, if the partial pressure of hydrogen sulphide does not exceed 15 psi (1 bar), the chloride content does not exceed 5000 ppm and the hardness is not greater than HRB 95 for solution annealed material and HRC 35 for cold-worked material. 4565 was included in NACE MR0175-2001 but is no longer represented in the joint NACE-ISO document.
Table 7 shows results from some of the qualification SSC testing of 254 SMO® and 654 SMO® in NACE solution (5% NaCl, pH 3, 1 bar pH2S) and at 25°C and 90°C. Under these conditions neither grade exhibited any cracking after 720 hours, even when cold worked up to 80%. As a comparison, extensive cracking was observed for 2205 material tested at 90°C at a lower H2S level of 0.1bar.
Limiting conditions for use of different austenitic grades
according to Nace mr0175 / iso 15156-3 Table 6
Temperature. Max H2S partial ChlorideGrade Class (°C/°F) pressure (kPa/psi) (mg.l-1)
304L A2 60 / 140 60 / 50 < 50
904L A3a 60 / 140 350 / 50 < 50
254 SMO® A3b 120 / 250 700 / 100 5000 654 SMO® 171 / 340 100 / 15 5000
ssc testing of 4-PB specimens in Nace solution
(5% Nacl, ph 3, 1 bar ph2s) for 720 hours [11] Table 7
Cold work Stress Temp. Grade (%) (percent of yield stress) (°C/°F) Result
254 SMO® 0 100 90 / 194 No cracking 40 – 80 90 25 / 77 No cracking
654 SMO® 0 100 90 / 194 No cracking 0 – 80 100 25 / 77 No cracking
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3.4 Uniform corrosion
Uniform corrosion tests in different environments have been carried out for many years and a large amount of data for different concentrations and temperatures can be found [5]. The test method involves a test period of 24h + 72h + 72h and has previously been described in detail [12]. One way of presenting the results is as iso-corrosion diagrams in which the line for each steel grade represents a corrosion rate of 0.1 mm . y-1 (~4 mpy). The iso-corrosion diagrams for sulphuric acid and sulphuric acid with an addition of 2000 ppm chlorides are shown in Figure 5 and Figure 6 respectively. 654 SMO® shows the best performance at concentrations up to about 60% while in very concentrated sulphuric acid 316 and 904L actually show lower corrosion rates than the superaustenitic grades. The addition of 2000 ppm chlorides displaces the curves to lower concentrations and temperatures and the performance of 654 SMO® is outstanding in the concentration range up to 90%. All steels except 316 show an interesting region of somewhat lower corrosion rates at ~ 70 – 80% in the presence of 2000 ppm chlorides, the same trend can be seen with addition of 200 ppm chlorides [5]. Concentrations around 50% sulphuric acid are thus more corrosive when contaminated with chlorides than higher concentrations.
The iso-corrosion curves for hydrochloric acid are shown in Figure 7 and show a strong dependence on the alloy content, with the highest corrosion resistance for 654 SMO® followed by 254 SMO®. The relative performance of the alloys in this environment shows the same general trend as the PRE values, which is unsurprising since both reflect the resistance to chloride environments, albeit in rather different pH regimes.
A widely-accepted method for evaluating uniform corrosion resistance in a number of standardized environments is that specified in ASTM G157 and MTI-1 [13].The critical temperature is the lowest temperature where the corrosion rate exceeds 0.127 mm . y-1 (5 mpy), the corrosion rate is calculated on sample weight loss over a 96 hour test period.
A comparison between the steel grades resistance in the prescribed 85% phosphoric acid and 50% sodium hydroxide environments, plus results from two additional test solutions simulating wet-process phosphoric acid, WPA 1 and WPA 2,
Fig. 5 Iso-corrosion diagram for sulphuric acid – the line represent a corrosion rate of 0.1 mm . y-1 (~4 mpy). [5]
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Fig. 6 Iso-corrosion diagram for sulphuric acid with addition of 2000 ppm chlorides – the line represent a corrosion rate of 0.1 mm . y-1 (~4 mpy). [5]
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Fig. 7 Iso-corrosion diagram for hydrochloric acid – the line represent a corrosion rate of 0.1 mm . y-1
(~4 mpy). [5]
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is shown in Table 8. The detailed chemistry of the latter two environments is given in Table 9. In the pure 85% phosphoric acid there is only a relatively small difference between the performance of the superaustenitic grades and the standard 316L, with the best performance being shown by 254 SMO®. However, the addition of impurities such as chlorides, fluorides, sulfuric acid in the WPA 1 and WPA 2 environments causes a drastic drop in the corrosion resistance of 316L. On the other hand 654 SMO® is barely affected. In the caustic environment, 50% NaOH there is a clear differentiation between the performance of the different alloy grades, with successively higher critical temperatures being measured for 254 SMO®, 4565 and 654 SMO®.
4. weldingAustenitic stainless steels are usually considered as having very good weldability. This is in general valid also for superaustenitic steels although the high alloy contents mean that certain precautions must be taken. High alloy contents favour precipitation of intermetallic phase in the weld metal and heat-affected zone, but smaller amounts of precipitates do not usually affect weldment properties, e.g. corrosion resistance. However, it is advisable to weld with moderate heat input and the lowest possible dilution of the parent metal. The pitting corrosion resistance of the weld metal can be reduced due to microsegregation of mainly molybdenum during solidification. Therefore filler metals are, in most cases, over-alloyed with chromium, nickel and molybdenum to make the weld metal richer in elements enhancing the corrosion resistance. The most common welding consumables are nickel-base alloys as shown in Table 10.
Another way to reduce segregation is to carry out post weld heat treatment, which is usually done for mill-welded tubes and pipes. Very rapid solidification, such as in laser welding, results in considerably less segregation and autogenous laser welding can be applied with minimum loss in pitting corrosion resistance.
the critical temperatures for the steel grades in different acids
and in sodium hydroxide [5]. Table 8
85% H3PO4 WPA 1 WPA 2 50% NaOH
316L 95 <10 <10 90
254 SMO® 110 80 60 115
4565 95 65 70 120
654 SMO® 90 95 80 135
compositions in weight percent of the simulated wet-process phosphoric acid solution used in table 8 [5]. Table 9
H3PO4 Cl- F- H2SO4 Fe2O3 Al2O3 SiO2 CaO MgO
WPA 1 75 0.2 0.5 4.0 0.3 0.2 0.1 0.2 0.7
WPA 2 75 0.02 2.0 4.0 0.3 0.2 0.1 0.2 0.7
Filler metals for superaustenitics, typical compositions. Table 10
Base material EN ISO 18274 AWS A5.14 C Cr Ni Mo Other
254 SMO® WNiCr22Mo9Nb ERNiCrMo-3 0.01 22 65 9 3.5Nb
4565 WNiCr25Mo16 ERNiCrMo-13 0.01 25 60 15 –
654 SMO® WNiCr25Mo16 ERNiCrMo-13 0.01 25 60 15 –
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5. competing stainless steels 5.1 alternative superaustenitic grades
During the long existence of superaustenitic grades there have emerged several alloys under different trade names and different UNS numbers which are very similar in properties. Some of these were mentioned in the history chapter. Particularly among the 6Mo super-austenitic grades there has been a debate about whether one alloy is superior to the other or not. Mechanical data is fairly straightforward since the design levels are listed in the standards. Ranking of the alloys regarding pitting corrosion can be made using the pitting index, PRE, showing that one alloy is potentially slightly better than the other. Several field exposures of similar alloys have been executed with very varying results, in one test one alloy is better and in the next test another alloy performs best. Certainly, it is very difficult, if not impossible, to make a fair judgment of the exact corrosion resistance of each alloy as many factors concerning the material and environmental condition affect the outcome. Instead service performance in different applications gives more reliable information. The standard used by Norwegian offshore, NORSOK, has selected a realistic approach and included the three most common 6Mo grades (S31254, N08926 and N08367) in one datasheet making all grades fully interchangeable. However, the lower nickel content in 254 SMO® (S31254) represents a cost advantage.
5.2 superaustenitics vs. superduplex
Superduplex steels were introduced during the 1980’s and were naturally compared with superaustenitic 6Mo steels as they have the same level of the PRE pitting index. In most environments superduplex steels showed very similar corrosion performance to the 6Mo grades. With the inherent high strength and lower raw material costs superduplex steels offer excellent alternatives for many applications and today there are areas where super-duplex steel is the dominating construction material. Numerous comparisons have been made between the two groups of steels. Superduplex steels have been reported to show better crevice corrosion resistance than superaustenitic steels. On the other hand super-austenitic steels exhibit better uniform corrosion resistance in active conditions.
The largest difference is related to the microstructure and its stability. Being highly alloyed both types of steels are susceptible to precipitation of intermetallic phases. This process is more rapid in duplex steels as reactions are much faster in the ferrite phase. Hence, pitting corrosion resistance and impact toughness of superduplex steels deteriorate faster than in superaustenitic grades, which is important to take into account during, e.g., heat treatment. Also the welding parameter window for optimum corrosion resistance and toughness is smaller for superduplex steels than for superaustenitic steels.
It is well known that the duplex microstructure presents higher strength levels than that of superaustenitic materials. With increased nitrogen additions to superaustenitic steels an increased strength is coupled with improved ductility, which can be utilized for advanced forming operations such as pressing of heat exchanger plates.
An important difference between duplex steels and austenitic steels in general is the practical temperature range for the use. While most austenitic steels, including superaustenitics, can be used in cryogenic conditions down to -196°C, duplex steels have a minimum usage temperature of -40 to -50°C as a result of a ductile-to-brittle transition of the impact toughness. Likewise, the upper temperature of superduplex is maximized to about 250°C due to spinodal decomposition which embrittles the ferrite phase. Superaustenitic steels can be exposed to temperatures up to 400°C without adverse effects.
In recent years some hyper duplex steels have appeared that are clearly more alloyed than superduplex steels and show superior corrosion performance. Although they do not reach the PRE level of the highest alloyed superaustenitic steels they provide interesting alternatives in some applications. However, as discussed above, the very high levels of chromium and molybdenum make the hyper duplex steels more sensitive to precipitation effects.
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Fig. 9 Complex superaustenitic piping system in pharmaceutical manufacture.
Fig. 10 Oseberg platform, main seawater piping in 254 SMO®, 1997.
Fig. 8 Filter washers of 254 SMO® in a Swedish bleach plant, still showing good performance after 30 years in service.
6. applications Superaustenitic steels have been used in a very wide range of applications due to their high resistance to both general and localised corrosion. Below some important areas are described.
6.1 Pulp & paper industry
Pulp & paper production was an early industrial area where highly corrosion resistant materials were required for safe and effective production. One application was sulphite digesters using corrosive cooking acids. Another area of concern has been the flue gas treatment from the recovery boiler where quite corrosive conditions appear in the scrubber. 254 SMO® has been employed with good results in this application [14]. The most aggressive aqueous environment was encountered in bleach plants using chlorine and chlorine dioxide as bleaching agents. Together with high chloride levels these agents produced very high corrosion potentials resulting in great risk of pitting and crevice corrosion. In the late 1970’s 254 SMO® replaced other austenitic grades such as 316L and 317L, which often suffered from heavy corrosion, giving short service life. More than a hundred filter washers have since been fabricated from 254 SMO® globally [15]. Chlorine and chlorine dioxide bleaching are nowadays replaced by more environmental friendly processes, resulting in less aggressive corrosion conditions for the construction materials, but on the other hand increasing recirculation leads to increased aggressivity. Numerous mills still are running the equipment in 254 SMO® with very good performance records, Figure 8 [15].
6.2 chemical and pharmaceutical industry
These industries comprise a large variety of corrosive conditions with very different requirement on materials. Materials selections range from type 304 to very expensive nickel-base materials. Superaustenitic steels have found extensive use for environments with particularly aggressive acids or halides. Examples of applications for 254 SMO® are production of amines, aluminium fluoride, chlorate and soda ash [16]. Both 254 SMO® and 654 SMO® have been used successfully in the recovery of solvents, mainly chlorinated hydrocarbons.
6.3 offshore applications
Due to excellent corrosion resistance, including H2S containing environments as detailed in section 3.3, 6Mo superaustenitic grades such as 254 SMO® as well as grade 4565 are used in both process streams and in seawater handling in the offshore industry. Large quantities of pipes and fittings in 254 SMO® are installed in a variety of platforms and sites in the North Sea and the Arabian Gulf region with very good results [16]. The main application has been seawater piping for service water, fire water and ballast water [17]. Figure 10 shows an example from the North Sea. Grade 4565 has also been employed for different North Sea projects in similar applications [18]. Even though duplex grades are commonly used for the so-called carcass for flexible pipes, the higher resistance of the superaustenitics in general, and 654 SMO® in particular, to H2S environments can make them attractive alternatives when exploring more sour wells.
6.4 Desalination
Saline waters include a wide range of salinity, ranging from ground water and brackish water to seawater and brine. To be potable or usable industrial waters, salt must be removed. There are several technologies for desalination with different demands on the construction materials. While in the past standard austenitic grades were used, duplex stainless steels today provide a cost-effective alternative in the stages with moderate demands regarding corrosion resistance. Highly alloyed stainless steels are used in reverse osmosis (RO) plants. They can also constitute a competitive alternative to copper alloys and titanium for condenser tubing in multi-stage flash (MSF) and multiple-effect distillation (MED) evaporators.
254 SMO® has a long record of successful installations and is probably the grade with the best reputation in desalination. It has been used since the beginning of the 1980’s and there are at least fifty RO plants with high-pressure piping of 254 SMO®, with no reported
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failures. In Figure 11 an installation in Gran Canaria is shown. In thermal desalination, this grade has been selected for once-through MSF plants using air-saturated feed, e.g. Methannex plants in Chile, and also for MED plants, e.g. Ras Tanura in Saudi Arabia. For the latter case both practical experience and field tests [19] showed that 254 SMO® is probably over-specified and lower alloyed duplex alternatives could be more cost efficient. However, it might be justified to use 254 SMO® for creviced areas where conditions are more aggressive.
For the MED technology there is one plant in service where 4565 has been installed as thin-walled condenser tubes (AVR’s Demi Water Plant in the Netherlands, 1.4 million meters of OD 30 x 0.3 mm tubes) [18].
6.5 seawater
Besides the examples given above there are various applications (such as power plants) where seawater or brackish water is used as a coolant. Natural seawater is aggressive to stainless steels partly because biofouling increases the corrosion potential. Removal of the biofilm is usually done with chlorine that also raises the potential and hence the risk of localized corrosion. For the combination of high temperatures and full chlorination the only resistant material choice is titanium. However, restricted chlorination and moderate temperatures allow the use of some stainless steels. For adequate corrosion performance in seawater at ambient temperature up to +35°C at least 6Mo superaustenitic steel such as 254 SMO® is required [20]. Tests have shown that the higher alloyed superaustenitic steel 654 SMO® can be used up to +70°C in such environments without crevice corrosion [21]. Grade 4565 has its limit somewhere in between the two.
Service water piping: 254 SMO® has been used for this purpose in Swedish nuclear power plants with very good performance [22].
Condensers: Welded tubing of 254 SMO® has been used successfully in many seawater-cooled condensers in different parts of the world. The material has been used in Finnish nuclear power plants since the early 1980’s [22]. This material was also selected as tubesheet material in a Swedish nuclear plant using titanium tubing rolled into the tubesheets.
654 SMO® was employed to replace titanium tubes in nuclear condensers in Sweden and Finland [23]. The titanium tubing suffered from erosion from condensed water droplets, resulting in rapid reduction of wall thickness [24]. More than 200km of condenser tubing in grade 654 SMO® was installed during 1990’s [23]. One example is shown in Figure 12.
Heat exchangers: 254 SMO® has been used extensively in shell and tube type heat exchangers cooled with brackish and seawater in different industrial plants. Alloys 4565 and 654 SMO® have also been used to some extent.
Being very effective thermally, plate heat exchangers (PHE) can be considered one of the most demanding constructions for stainless steels, both in terms of corrosion and fabrication. 254 SMO® has been used for more than 25 years in different PHE applications [20]. However, the severe crevices between the sheets restrict the use of stainless steels to quite low temperatures to avoid crevice corrosion in chlorinated ocean water. The primary materials choice for PHE in seawater is titanium, when it is available and as long as the process side is not too aggressive to titanium. Nickel-base alloys can be a second alternative but some results [20, 21] also indicate that superaustenitic steels such as 654 SMO® may be expected to out-perform some nickel-base alloys in chlorinated seawater and even be an alternative to titanium.
The forming of PHE plates is complex, which limits the applicability of duplex steels for this application. Instead, the high nitrogen superaustenitic steels such as 654 SMO®, with high elongation and good formability, are eminently suitable for this application. This steel has also been selected for various critical applications such as cooling of sulphuric acid, FGD and in ships.
6.6 Flue gas desulphurization – waste incineration
A flue gas desulphurization plant (FGD) is effectively a chemical plant incorporated into a power station with the purpose to separate noxious materials – primarily sulphur – from the flue gases. Corrosion conditions in a FGD plant utilizing the wet scrubbing process technology are a complex combination of chlorides and fluorides, acidity, temperature and
Fig. 11 SWRO desalination plant. HP pipes in 254 SMO®, Gran Canaria 1992.
Fig. 12 Installation of condenser tubing in grade 654 SMO® as replace- ment of titanium tubes at Forsmark nuclear power station, Sweden.
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construction details (deposits, crevices), depending on the fossil fuel used. It may be appropriate to use engineering diagrams summarizing laboratory data and service experience indicating guidelines for material selection, see Figure 13.
As shown in Figure 13 superaustenitic grades can be utilized up to high severity of the environment. The most resistant superaustenitic grade, 654 SMO®, is positioned in the most aggressive area along with some nickel-base alloys although it does not meet the resistance of the best nickel-base alloys. 254 SMO® and 654 SMO® are being used to some extent in FGD systems. Due to its high corrosion resistance combined with high mechanical strength, 4565 has in recent years also been selected for numerous components for FGD plants, mainly in Europe. Examples of equipment are absorber vessels, spray lances, demisters, piping systems and ducts, dampers, and fans [18]. Figure 14 shows an absorber under erection in Italy.
Flue gas from incineration of waste containing plastics may contain hydrogen chloride and hydrogen fluoride, resulting in very aggressive conditions in wet cleaning stages. The high alloy grade 654 SMO® has been selected for the most critical parts in such a plant due to its high corrosion resistance [26].
6.7 hydrometallurgy
Hydrometallurgy is part of the field of extractive metallurgy involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials. Hydrometallurgy is typically divided into three general areas; leaching, solution concentration and purification, and metal recovery. Important metals include copper, nickel and zinc. Leaching is the most demanding stage as the solution is strong acid (predominantly sulphuric acid) and containing chlorides. Several field tests have shown that steels resisting sulphuric acid with chlorides also perform well in practice. 254 SMO® has been used with good service performance in several plants [5].
7. concluding remarksSuperaustenitic stainless steels have existed for more than thirty years and in this paper the properties and numerous successful service records for some of the grades are given. This family of stainless steels plays an important role in bridging the gap between standard stainless steels and nickel-base alloys, and in some environments can even out-perform the latter. A stable austenitic structure and high ductility are reasons for superaustenitic steels being chosen for difficult components and for a wide range of temperatures.
Fig. 13 Guideline for material selection in wet scrubber applications [25].
Fig. 14 FGD absorber during erection, La Spezia, Italy, 2001. Source:StainlessSteelWorld
ppmHalogen-lons (Cl+F)
< 100
< 500
< 1000
< 5000
< 10000
< 50000
< 100000
< 500000
neutral to slighly acidic
6.5 4.5 3.0 2.0 1.5 1.0
acidic strongly acidic
temperature range 50 – 70°C
very
hig
hm
ediu
mlo
whi
gh
AcidiypH
317LMN
904L
2205
254 SMO®
654 SMO®
2507
4565
Alloy 31
Alloy 625
Alloy C-276
Alloy 59
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8. references[1] Swedish Patent no SE7601070-1 (1985)[2] H. Thier, A. Baumel, E. Schmidtmann: ”Einfluss von Stickstoff auf das
Ausscheidungsverjalten des Stahles X5 CrNiMo 17 13“. Archiv für das Eisenhüttenwesen 40:4 (1969) 333–389
[3] German Patent no DE 3729577 C1 (1988) [4] Swedish Patent no 9000129-8, (1992)[5] Outokumpu Corrosion Handbook, 10th Edition, 2009[6] R. S. Treseder: MTI Manual No 3 “Guideline information on new wrought iron
and nickel-base corrosion resistant alloys – Phase 1 Corrosion Test Methods”. Materials Technology Institute of the Chemical Process Industries Inc, May 1980, Appendix C, “Method MTI-3 for laboratory testing of wrought iron and nickel-base alloys for relative resistance to stress corrosion cracking in a boiling magnesium chloride solution.
[7] S. Henrikson, S. M. Åsberg “A new accelerated tests for studying the susceptibility of stainless steels to chloride stress corrosion cracking “ Corrosion 35:9 (1979) 429–431
[8] As [6], Appendix E Method MTI-5 for laboratory testing of wrought iron- and nickel base alloys for relative resistance to stress corrosion cracking in a sodium chloride drop evaporation system.
[9] H. Andersen, P.-E. Arnvig, W. Wasielewska, L. Wegrelius: SCC of stainless steel under evaporative conditions ACOM 3-1998
[10] NACE MR0175 / ISO 15156-3:2003 (E) Petroleum and natural gas industries – Materials for use in H2S-containing environments in oil and gas production – Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys
[11] C. Wolfe, P.-E. Arnvig, W. Wasielewska, R. Pettersson: “Hydrogen sulphide resistance of highly-alloyed austenitic stainless steels”. ACOM 2-1997
[12] C. Canderyd, A. Bergquist, R. Pettersson: Uniform Corrosion of Lean Duplex Stainless Steel Compared to Standard Austenitic Grades. Eurocorr 2009
[13] As [6] Appendix A Method MTI-1 for laboratory testing of wrought iron- and nickel-base alloys for relative resistance to corrosion in selected media.
[14] B. Wallén et al, “Performance of a high molybdenum stainless steel in gas cleaning systems with particular reference to pulp and paper industry” NACE Corrosion 1983, paper No. 83
[15] M. Liljas, R. Pettersson, L. Wegrelius, R.M. Davison: “UNS S31254-A bleach plant success story”, NACE Corrosion 2010, paper No. 10083
[16] J. Olsson, H. Grützner, ”Experiences with a high alloyed stainless steel under highly corrosive conditions”, Werkstoffe und Korrsion, 40, (1989), p. 279
[17] B. Wallén et al, ”Stainless steel for seawater piping”, 1993[18] B. Beckers et al, “Outokumpu 4565, a High Performance Superaustenitic Stainless
Steel”, Stainless Steel World 2007, paper No. 7031[19] M. Snis et al, “Stainless steel for LT-MED plants”, IDA World Congress,
Mas Palomas, Gran Canaria, (2007)[20] O. Persson et al, ”The use of corrosion resistant alloys (CRAs) in compact plate
heat exchangers in seawater”, NACE Corrosion, (2007), Paper No. 07249[21] B. Wallén et al, ”Performance of a High-alloy Stainless Steel in Sea Water Cooled
Plate Heat Exchangers”, Marine Corrosion of Stainless Steels, European Federation of Corrosion Publications, Number 33, 2001
[22] J. Olsson, J.D. Redmond, “Application of Avesta 254 SMO® (UNS S31254) austenitic stainless steel in power plants” NACE Corrosion 91, (1991), Paper No. 505
[23] J. Olsson, W. Wasielewska, “Applications and experience with a superaustenitic 7Mo stainless steel in hostile environments”, Materials and Corrosion, 48, (1997), p. 791
[24] J. Tavast, “Steam side droplet erosion in titanium-tubed condensers – experiences and remedies”, Joint Power Generation Conference, Houston, Tx, Oct., 1996
[25] P. Vangeli, G.M. Carcini, “FGD plants: stainless steel makes the grade”, Power Engineering, Nov. 2009, p. 78
[26] B. Wallén et al, “Corrosion testing in the flue gas cleaning and condensation systems in Swedish waste incineration plants”, NACE Corrosion 94, (1994), Paper no. 410
Reproduced with permission from Stainless Steel World.This paper was originally presented at the Stainless Steel World America Conference, 5–7 th October, 2010, Houston, Texas, USA.
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Lean duplex – the first decade of service experience
elisabet alfonsson, outokumpu stainless aB, sweden
abstractThe lean duplex grade LDX 2101® was developed in order to offer the market a stainless steel for light-weight constructions, suitable for use in environments where 2205 would be over-specified from a corrosivity perspective. The grade has now been on the market for almost a decade and is used in a large variety of applications. Other suppliers have followed with lean duplex grades with a similar property profile as LDX 2101®. A number of case stories showing how the properties of LDX 2101® can be utilized were selected to illustrate the applicability of lean duplex grades. These include: – Civil engineering applications such as bridges – Pipe lines– Flexible pipes in oil and gas industry– Water heaters for domestic as well as industrial use– Tanks for storage and transportation
The philosophy behind the development of the multi-purpose duplex grade LDX 2101® is briefly discussed and future possibilities is illustrated by the recently developed grade LDX 2404®.
Keywords: Lean duplex stainless steel, application, reinforcement bar, pipe, tank, bridge
1. why lean duplex stainless steel?Outokumpu started development of LDX 2101® in the late 90’s in order to offer the market a stainless steel which combined the high mechanical strength of duplex grades with, at least, the basic level of corrosion resistance offered by the dominating grades typified by AISI 304/EN1.4301 [1]. 2205 which was, and still is, the dominating duplex grade on the market was considered mainly for upgrading in situations when AISI 316 and similar austenitic grades did not offer sufficient corrosion resistance. The high mechanical strength, allowing weight reduction, was seen as an additional benefit but often not as the main rea-son for selecting 2205. For those who made the switch to 2205 and realized the potential to make lighter constructions, the mechanical strength was highly appreciated, not the least in the chemical tanker segment, where cargo tanks in grade 2205 made it possible to increase the payload of the ships. The main driver for the development of LDX 2101® was to make light-weight construction with duplex stainless steel an option also for the dominating volume of stainless steel applications which do not require the corrosion resistance of 2205.
Grade 2304, intended as a duplex substitute to type AISI 316 had been on the market since the late 80’s but had not gained the same popularity as 2205. It was rather considered as a niche grade, used in a few applications. The yield strength of 2304 is significantly higher than for standard austenitic grades but somewhat lower than for 2205. The development of LDX 2101® aimed at achieving a grade which combined the mechanical strength of 2205 with a corrosion resistance appropriate for a majority of moderately corrosive conditions while using alloying elements in a more cost efficient way than in the past. The most important features of the alloy concept are a high nitrogen content which stabilizes austenite and improves the mechanical strength of the austenitic phase and a low nickel content to achieve a better long-term predictability of raw material costs.
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LDX 2101® was established on the market in time to meet the demand for grades with a better price stability than standard austentic grades that occurred as a consequence of the nickel price peak in 2006 – 2008. Some users switched from 304 to LDX 2101® merely on grounds of the difference in price per kg, while many others also utilized the superior technical properties, in particular the mechanical strength, to achieve more competitive constructions. The market pull resulted in a fast volume growth and LDX 2101® (EN 1.4162, UNS S32101) is today an established member of the duplex family with a market demand of several 10,000 tonnes per year. Recently other suppliers have offered lean duplex grades (e.g. UNS S82011 and EN1.4062/UNS S32202, see compositions and properties in Table 1 and Table 2) with a similar profile as LDX 2101®. The grade UNS S32001, built on a patent published in 1989 and previously marketed mainly towards some niche-applications in automotive and oil and gas industries, has also been more actively marketed.
In the following sections technical properties of LDX 2101® as well as a selection of application cases will be highlighted.
2. chemical compositions and propertiesLDX 2101® (UNS S32101) as well as the lean duplex grades UNS S32001 (promoted by e.g. AK Steel and Acerinox), S82011 (AL2102 by ATI) and S32202 (UR/DX2202 by Arcelor Mittal) are all mainly aimed to be used as substitutes for 304 types and carbon steel. They all contain low contents of nickel and all but UNS S32001 have a maximum nitrogen content exceeding than of 2205 (UNS S31803/S32205). UNS S32003 (AL 2003 by ATI) has a higher alloy element content, and aims primarily to replace 316 types. Compared to the previously existing 2304 (UNS S32304) it contains less chromium, has a lower maximum content of nickel and a higher maximum content of nitrogen.
chemical composition of lean duplex, duplex and standard austenitic grades, astm a240 Table 1
EN UNS C Cr Ni Mo Mn Cu N
1.4307 S30403 ≤ 0.030 17.5 – 19.5 8.0 – 12.0 – ≤ 2.00 – ≤ 0.10
– S32001 ≤ 0.030 19.5 – 21.5 1.00 – 3.00 ≤ 0.60 4.0 – 6.0 1.00 0.05 – 0.17
1.4162 S32101 ≤ 0.040 21.0 – 22.0 1.35 – 1.70 0.10 – 0.80 4.0 – 6.0 0.10 – 0.80 0.20 – 0.25
– S82011 ≤ 0.030 20.5 – 23.5 1.0 – 2.0 0.10 – 1.00 2.0 – 3.0 ≤ 0.50 0.15 – 0.27
1.4062 S32202 ≤ 0.030 21.5 – 24.0 1.00 – 2.80 ≤ 0.45 ≤ 2.00 – 0.18 – 0.26
1.4404 S31603 ≤ 0.030 16.0 – 18.0 10.0 – 14.0 2.00 – 3.00 ≤ 2.00 – ≤ 0.10
1.4362 S32304 ≤ 0.030 21.5 – 24.5 3.0 – 5.5 0.05 – 0.60 ≤ 2.50 0.05 – 0.60 0.05 – 0.20
– S32003 ≤ 0.030 19.5 – 22.5 3.0 – 4.0 1.50 – 2.00 ≤ 2.00 – 0.14 – 0.20
1.4462 S31803 ≤ 0.030 21.0 – 23.0 4.5 – 6.5 2.5 – 3.5 ≤ 2.00 – 0.08 – 0.20
1.4462 S32205 ≤ 0.030 22.0 – 23.0 4.5 – 6.5 3.0 – 3.5 ≤ 2.00 – 0.14 – 0.20
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As shown in Table 2, all the lean duplex grades intended to substitute 304 types, as well as UNS S82011, have a minimum yield strength in ASTM A240 which is on a par with 2205 (UNS S31803, S32205) and exceeds that of 2304 (UNS S32304). LDX 2101® as well as S82011 both have significantly higher minimum yield strengths for gauges thinner than 5 mm.
A low nickel content does not contribute to high impact toughness at lower temperatures and the lean duplex grades may show lower impact strength than 2205 at sub-zero temperatures. Minimum values for flat products are shown in Table 3. It should be emphasised that weldments, in particular for larger gauges, typically show lower impact strength than the base material.
mechanical properties of lean duplex, duplex and standard
austenitic grades, astm a240 Table 2
EN UNS Thickness Rp0.2 (MPa) Rm (MPa) A5 (%)
1.4307 S30403 170 485 40
– S32001 450 620 25
1.4162 S32101 ≤5.00 530 700 30 >5.00 450 650 30
– S82011 ≤5.00 515 700 30 >5.00 450 655 30
– S32202 450 650 30
1.4404 S31603 170 485 40
1.4362 S32304 400 600 25
– S32003 485 690 25
1.4462 S31803 450 620 25
1.4462 S32205 450 655 25
impact toughness, minimum values according to eN 10028,
transverse direction, J Table 3
Temperature (°C) LDX 2101®* 2304 2205
20 60 60 60
-40 27 40 40
*Values from internal specification, AM611
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2.3 corrosion resistance2.3.1 Uniform corrosionThe uniform corrosion resistance of LDX 2101® has been tested in accordance with the MTI-1 test programme, which includes a large number of inorganic and organic acid solutions and one alkaline solution. LDX 2101® performed on a par with or significantly better than 4301 (304) in all test solutions with the exception of an almost water-free mixture of acetic acid and acetic anhydride, in which all austentic grades tested performed better than duplex or ferritic grades. [2]
2.3.2 Pitting corrosionThere are several standardized test methods for a fast ranking of resistance to pitting corrosion. One of these is determination of the critical pitting temperature (CPT) in acidified 6% ferric chloride solution according to the test procedure ASTM G48 Method E. Typical CPT values are presented in Table 4.
2.3.3. Stress corrosion crackingDuplex stainless steels in general show much higher resistance than standard austenitic types AISI 304 and 316 to chloride-induced stress corrosion cracking (SCC). LDX 2101® is no exception. Results from immersion tests in a concentrated chloride solution as well as under evaporative conditions are presented in Table 5. [3]
typical cPt values determined according to astm G48 method e Table 4
Steel grade CPT (°C)
Outokumpu EN ASTM
LDX 2101® 1.4162 S32101 15
2304 1.4362 S32304 25
2205 1.4462 S32205 40
4307 1.4307 304L 10
4404 1.4404 316L 20
4432 1.4436 316L 25
results of stress corrosion cracking tests in chloride solutions Table 5
Outokumpu 40% CaCl2, 500h, 40% CaCl2, 500h, steel grade U-bends 4-point bends Wick test
LDX 2101® 0(6)* 0(2) 0(6)
2304 0(6) 0(2) 0(6)
2205 0(6) 0(2) 1(6)
4307 6(6) 4(4) 5(5)
*0(6) = no specimens showed stress corrosion cracks, in total 6 specimens tested.
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3. application cases3.1 hot water tanks
Most commonly, domestic hot water systems include a hot water tank. The inner shell of these water tanks could be of carbon steel, with an internal enamel coating or copper lining for corrosion protection, or they can be solid stainless steel, as seen in Figure 7. With the entirely stainless solution, one single material provides the combined function of load bearing and corrosion protection. Sacrificial anodes, as typically installed in enamelled steel tanks, are not necessary. Stainless steel grades that have traditionally been used in hot water tanks are 316L, 316Ti and 444.
The main corrosion risks for stainless steel used in hot water tanks are pitting, crevice corrosion and stress corrosion cracking (SCC). The risk of SCC increases with higher metal skin temperature. The largest SCC risk thus occurs in hot water tanks, which are externally heated by either a heating jacket or a gas flame. LDX 2101®, as well as ferritic grades and other duplexes, provide much higher resistance to SCC than standard austenitic grades. When pitting and crevice corrosion is the main concern it should be noted that the pitting resistance of LDX 2101® is not entirely on the level of 1.4404/316L. If chloride levels are so high that 1.4404 cannot be considered over specified, 2304 and even 2205 might be the preferred duplex options.
Duplex stainless steel for domestic water heaters was introduced more than 15 years ago. The grade 2304 came to replace 444 due to a combination of better weldability and availability and the volume of 2304 supplied to this application has steadily increased. In recent years many manufacturers of hot water tanks have chosen LDX 2101® as a substitute for ferritic as well as the common austenitic grades. One advantage of stainless water tanks in general is their lower weight compared to carbon steel tanks with corrosion protection. Water tank inner shells are pressure vessels and due to the higher yield strength, duplex stainless grades offer the possibility of further weight reduction compared to austenitic and ferritic stainless steels [4,9]. Less weight to handle per tank is an advantage during manufacturing, transport, and not the least during final assembly.
Due to differences in properties between the different groups of stainless steels, the change from austenitic or ferritic stainless steels to duplex typically calls for some adjustment of manufacturing equipment and procedures. Due to the higher yield strength of duplex grades, higher forces need to be applied in forming operations. In cases when the higher strength is utilised in terms of reduced wall thickness this effect is however less pronounced. The duplex grades show a significantly higher spring-back during forming, which means that a duplex tank body shell has to be roll-bended to a smaller radius in order to get the same final shape as a corresponding austenitic shell.
When using automatic TIG-welding, the travel speed of the welding torch might have to be reduced when changing from austenitic to duplex stainless steels, while the welding of duplex is generally considered easier compared to welding ferritics.
3.2 adBlue tanks (NoX emission reduction)
Emissions from cars, trucks and other vehicles are a concern all over the world. European emission standards define the acceptable limits for exhaust emissions of new vehicles sold in EU member states. The Euro V emission standard, which has been in force since October 1st 2009 implied a 20% reduction of permitted NOX emissions from diesel vehicles, compared to the previous Euro IV standard. The maximum NOX emissions allowed according to EuroV is 180 mg.km-1 [4,5]. The permitted limits for particulate matters were reduced simultaneously. One method to reduce the NOX emissions is to treat the exhaust gases by a so-called selective catalytic reduction process, by which the NOX gases are converted to nitrogen and water. This process uses AdBlue, a solution of urea and demineralised water, which is injected into the emission gas before it enters the catalytic converter. Trucks using this NOX reduction method carry the urea solution in tanks made of metal or polymer.
A Swedish company produces the AdBlue tanks for some well-known truck brands. They originally manufactured aluminium tanks, but one problem experienced was manganese rich precipitates, which clogged the particulate filters. The precipitates were tracked back to the aluminium tanks. A test programme started to evaluate various austenitic, ferritic
Fig. 1 Water tank inner shell in stainless steel.
Fig. 2 AdBlue tank in LDX 2101® on a truck (the middle tank on the photo). Photo Courtesy of Fueltech.
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and duplex stainless steels as alternatives to aluminium. For stainless steels the corrosivity of the AdBlue solution is not too severe, hence the highest alloyed grades could be excluded for cost reasons. Among the remaining grades, 2205 was excluded due to long pickling times after welding and ferritic EN 1.4521 due to welding difficulties. Austenitic EN1.4404 and LDX 2101® were the remaining candidates. LDX 2101® was chosen, one tank is seen in Figure 2, with one advantage over 1.4404 being that separating/stabilising barriers inside the tanks could be eliminated when LDX 2101® was used. LDX 2101® also passed vibration tests at the truck manufacturer without any problems. A gauge of 2 mm is used and the maximum tank volume is 125 litres. [4]
3.3 carcass for flexible pipe
Flexible pipes are used in flow lines and risers in the oil and gas industry. The pipe walls are typically unbonded composite structures, consisting of several polymer and steel layers. One of the inner layers is typically a so-called carcass, which is an interlocking structure manufactured from metal strip. The purpose of the carcass is to ensure integrity against collapse of an inner polymer lining and to protect the lining from mechanical wear from e.g. pigging tools and abrasive particles in the product flow. The carcass is typically made of a corrosion resistant alloy in order to withstand the environment present in the bore hole. The conditions during service are usually not so acidic as to induce uniform corrosion on stainless steel. Various forms of localised corrosion are the main concern, due to potential presence of chloride ions, hydrogen sulphide and often high temperatures. Conventional austenitic grades such as AISI 316L and even 304L have been used in many projects and are still used. The duplex grades 2304 and LDX 2101® offer at least the same resistance to pitting corrosion as 316L and 304L respectively, together with a much higher resistance to stress corrosion cracking. Other advantages of the duplex grades are their higher yield strength and hardness. The latter is an advantage with respect to erosion/abrasion. Manufacturers of flexible pipe work with a range of duplex grades for carcasses, e.g. LDX 2101®, 2304 or 2205, as well as standard austenitic grades. The choice of grade depends on the expected service conditions as well as on the preference of the end-user. The stainless steel strip formed into the interlocking structure is typically in the thickness range 1–2 mm. Images of flexible pipes are seen in Figure 3. [4]
3.4 Bridges
Duplex stainless steel has been increasingly utilized in bridges during the last decade and that includes LDX 2101®. The corrosion resistance of LDX 2101® is adequate for moderately corrosive conditions and the grade was chosen for foot bridges in the city of Siena, located in the inland of Italy and having low pollution levels, and in Gaularfjellet mountains on the Norwegian west coast, see Figure 5. [6, 9] For the footbridge projects the main reasons to select LDX 2101® are the corrosion resistance, which results in attractive esthetics with very little maintenance, and the high yield strength, which could be utilized to give lighter weight constructions than in traditional bridge design. In the Norwegian case the low weight was of large importance since the bridge was pre-assembled and flown-in by helicopter to the site at the creek Likholefossen. The Siena bridge was assembled on site, but of pre-manufactured components which helped minimizing the impact of the constructions on the surroundings – the footbridge crosses a four-lane motorway. The low weight of the lean duplex stainless components is beneficial during transport as well as during the final assembly.
Although all-steel bridges are gaining in popularity, reinforced concrete is dominating in bridge-building. These kinds of bridges also offer a market for lean duplex stainless steel, namely in reinforcement bars (rebar). For concrete constructions exposed in marine environments permeating seawater could result in corrosion and swelling of carbon steel rebar and as a consequence cracking in the concrete. Such failures can be avoided by selective use of stainless steel reinforcement in those areas of a construction where it is likely that high chloride concentrations in the concrete will develop with time. One example where selective use of stainless rebar is applied is an on-going project in Brisbane, Australia, where the six-lane Gateway Bridge over the Brisbane River will be duplicated in order to meet the region´s future traffic demand. The new bridge will have a design life of 300 years and to ensure such a
Fig. 3 A drawing (top) and a cut samples of a flexible pipe (below) showing the non- bonded composite structure. The stainless steel carcass is the innermost interlocking layer. Picture courtesy of NKT.
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long life span the bridge design specifies stainless steel rebar in the most critical structures, the splash zones of the two main river pylons. LDX 2101® was selected over AISI 316L due to a favorable and stable price and after laboratory corrosion tests. Several research groups have tested stainless and carbon steel reinforcement bar in simulated concrete-pore solutions. These tests show that stainless reinforcement; LDX 2101® as well as 316 types, typically tolerate about 10 times higher chloride concentrations than carbon steel [7].
3.5 road tankers
The high mechanical strength of duplex stainless steel enables light weight design, which is particularly attractive for road tankers and other transportable vessels where either the payload can be increased or the fuel consumption reduced as a consequence of lower tank weight. However, with current codes for transport of dangerous goods, the higher mechanical strength of duplex grades can only be utilised for pressurised tanks. For non-pressurised tanks there currently is no benefit in terms of wall thickness compared to austenitic stainless steel.
Carbon dioxide is a substance which is typically transported and stored as a liquid and as such classified as dangerous goods. Liquid carbon dioxide is transported at low temperature and elevated pressure in specially designed road tankers. An Italian fabricator of road tankers had experience of using duplex 2205 in the inner layer of the road tankers’ double hull. They recently investigated the possibility to manufacture the tank inner hull from LDX 2101®. There is no standard for LDX 2101®, so a Particular Material Appraisal (PMA) was necessary. The appraisal involved microstructure examinations and extensive mechanical testing particularly of weldments. Based on the test results the Italian Register of Shipping (RINA) approved the use of LDX 2101® in accordance with IMO 8. The high internal pressure of the road tanker allows the high strength of LDX 2101® to be utilized and
a 30-percent weight saving can be achieved compared to tankers fabricated from conventional steels. This is a case where the service temperature approaches the range where the impact toughness of LDX 2101® needs to be considered. The sub-zero impact toughness is typically lower for duplex grades with low Ni content than for 2205. Especially weldments have to be considered. The thickness of the base material as well as welding method and weld joint geometry affects the impact toughness. A thorough qualification of the different kinds of weldments, which will occur in the construction, should precede the selection of LDX 2101® for use at sub-zero temperatures. In Figure 6 is a self-supporting road tanker seen.
Fig. 6 Self-supporting road tanker. Photo courtesy of OMSP Macola, Italy.
Fig. 5 Footbridges in LDX 2101®, left Ruffolo bridge, Siena, Italy during construction, right the bridge over Likholefossen, Norway.
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3.6 tanks and silos
Large storage tanks and silos have become a major application area for LDX 2101®. Applicable design codes include safety factors which mean that the high mechanical strength of duplex steels cannot be fully utilized in small tanks and in the upper part of large tanks. However, by selecting duplex steels over standard austenitic grades, remarkably thinner gauges can be used in the lower parts of large tanks and the total weight reduction is significant. The benefits of using thinner gauge plate and sheet are several; easier erection because sections become lighter, less time required for edge preparation before welding and less consumption of filler material. LDX 2101® has substituted not only standard austentic grades in large storage tanks but also carbon steel. The main arguments for substitution of carbon steel is related to the fact that carbon steel normally requires coating, which extends the lead time at the initial investment and requires maintenance during the service life of the tank.
Storage tanks in LDX 2101® have been installed in many different industries. The reference list includes tanks for storage and processing of such different cargos as white liquor and marble slurry used in the pulp and paper industry, atomized clay for ceramic industry, bioethanol, palm oil, wine and wheat flour, see Figure 7 and Figure 8. The weight saving compared to an entire construction in grade 1.4301/304 has typically been in the range 15–30%. In some cases LDX 2101® has been a part of a multi-grade solution and used for some sections of the construction while e.g. 1.4301 (304) or 2304 was used for other parts. In cases like marble slurry tanks and clay silos, where the cargo contain hard particles, the high hardness resulting in good abrasion resistance is an additional benefit of LDX 2101®.
3.7. Desalination
The demand for clean water is increasing in many areas of the world and desalination is a growing industry, consuming significant volumes of stainless steel. The family of duplex stainless steels is used in all the three major desalination processes, reverse osmosis (RO), multi-stage flash (MSF) and multi effect distillation (MED). The main application area of LDX 2101® in desalination is in the upper part of MSF flash chambers. Together with partners in the desalination industry, Outokumpu has introduced a DualDuplexTM concept where LDX 2101® is used in sectors of the flash chambers which mainly see vapour and condensate while 2205 is used in the lower sectors which are exposed to the brine. [8] At least three existing plants use a DualDuplex concept including LDX 2101® and a fourth one will be commissioned in 2011.
3.8 Pipelines
In comparion to standard austentic grades, LDX 2101® offers a potential of significant reduction of wall thicknesses in pressurized process pipe systems. Outokumpu Stainless Tubular Products (OSTP) recently booked a contract for a pipeline for reception of anhydrous ammonia and cyclohexane. By selecting LDX 2101® and changing the design a remarkable weight reduction could be achieved and as a consequence significant reduction of welding time and filler metal consumption. Some details of the case are presented in Table 6.
Fig. 8 Silo in LDX 2101® for storage of wheat flour under construction. Photo courtesy of Metal Alimentaria.
Fig. 7 Wine storage tank farm in duplex grades 2304 and LDX 2101®, Garcia Carrion, Spain.
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4. standardisation A general purpose stainless steel will hardly grow successfully if not listed in internation-ally accepted standards. The dominant standards differ between countries and regions. However, ASTM / ASME standard specifications are accepted not only in the US but also in many other regions all over the world and EN standards are dominating in EU and sometimes also specified in other regions. Several ISO standards are established for stainless steels and development of ISO standards will most likely be of increasing importance in a more global market. Standardisation work started early for LDX 2101® and the grade is listed in several ASTM-standards for flat, long and tubular products and also covered by the ASME code case 2418. EN standards are revised less frequently than ASTM and ASME. Today LDX 2101® is listed in the standards EN 10088-4 and -5.
The high mechanical strength of LDX 2101® makes it a very interesting grade for applications such as pressure vessels and large storage tanks. The European Pressure Equipment Directive (PED) requires that materials used for pressure equipment, and which are not listed in a harmonized standard, should either be covered by a European Approval of Material (EAM) or undergo a Particular Material Appraisal (PMA). The PMA requirement is in some cases a barrier that prevents use of new grades to substitute established materials. The process to obtain an EAM for LDX 2101® is on-going but from a producer perspective it has not been as straight-forward and predictable as would have been desirable. This is natural since no other stainless steel grade has obtained an EAM and the process is new to all parties involved. Guiding principles for EAM have been reviewed and clarified along the way and future cases will most likely run more smoothly than this pioneer one. Efficient and well defined processes for standardisation are crucial for achieving market growth of lean duplex and other new stainless grades and this requires a strong engagement in standardisation work from suppliers, users, notified bodies and standard organisations.
re-design of a chemical pipeline. Table 6
Original design New design
Design Code ASME B31.3 (weld factor z=0.8) EN 13480-3 (weld factor z=1)
Design requirements 35 bar at 150°C 35 bar at 150°C
Dimensions ANSI 14”nb x Sch40S (OD 355.6 x 9.53 mm) ISO OD 355.6 x 4 mm ANSI 10”nb x Sch40S (OD273 x 9.27 mm) ISO OD 273 x 4 mm
Steel grade 304L LDX 2101@
Max operating pressure with 14”nb x Sch40S: 56 bar 355.6 x 4 mm: 48 bardimensions specified 10”nb x Sch40S: 44 bar 273 x 4 mm: 62 bar
Total weight 446 ton 193 ton
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6. concluding remarksAfter almost a decade on the market LDX 2101® is an established multipurpose stainless construction steel. It is used in many different industries and in applications for flat as well as tubular and long products. It offers a corrosion resistance at least on a par with 304 types in combination with high yield strength, high wear resistance and excellent resistance to stress corrosion cracking. As other duplexes, LDX 2101® offers light-weight design possibilities. That potential is particularly obvious in pressure vessels and large storage tanks. The possibility of combining LDX 2101® with duplex grades with higher corrosion resistance has enabled cost efficient DualDuplexTM and even multiduplex concepts in several industries.
The low nickel content of lean duplex grades results in lower impact toughness at sub-zero temperatures than for 2205 and other duplex grades containing more nickel. A thorough qualification of weldment properties should be carried out before selecting lean duplex grades, particularly in heavy gauges, for service at sub-zero temperatures.
The new duplex grade LDX 2404®, which combines a pitting resistance well exceeding that of 316 types with a higher minimum yield strength than for 2205, shows the potential of further developing the concept of cost efficient use of alloying elements in duplex grades.
In order to facilitate a cost efficient use of the entire duplex family, steel manufacturers, users, notified bodies and standardization organizations need to cooperate actively in standardization work.
5. Future developmentLDX 2101® is today acknowledged as a general, (multi)purpose stainless steel and the grade is well established in many different industries and continuously evaluated and selected for new applications. Other suppliers have introduced grades with a similar profile.
Even when taking these new lean duplex grades into account, the duplex family contains relatively few grades compared with both the austentic and ferritic families. Since duplex is showing the fastest market growth of stainless steel families and finding use in many new applications it is logical to expect the market to require a further development of the duplex family. Outokumpu’s latest development is LDX 2404®, a grade that fills a gap between 2304 and 2205 with respect to pitting resistance and provides a mechanical strength which exceeds that of 2205 [9]. The alloy chemistry is a further development of the cost effi-cient LDX® concept including high nitrogen content and moderate levels of nickel and molyb-denum. LDX 2404® will offer new possibilities for light weight construction when corrosion conditions are demanding for the traditional austenitic grades. Together with the existing members of the duplex family LDX 2404® will also make new Dual- or MultiDuplex solu-tions possible.
chemical composition and characteristic properties
of outokumpu LDX 2404® (eN 1.4662, UNs s82441). Table 7
Mechanical properties, minimum values
Product Rp0.2 (MPa) Rm (MPa) A5 (A80)
P 480 680 25 H 550 750 25 C 550 750 25 (20)
*PRE = %Cr + 3.3% Mo + 16% N
Typical chemical composition (weight percent) and PRE
N Cr Ni Mo Mn PRE*
0.27 24 3.6 1.6 3 33
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7. references[1] P. Johansson, M. Liljas, 4th European Stainless Steel Science and
Market Congress (2002)[2] Outokumpu Corrosion Handbook, Uniform corrosion testing of stainless
steels using the MTI-1 procedure (2009) p.I:29 –I36[3] E. Johansson, T. Prosek, NACE Corrosion 2007, paper no 07475[4] M. Paijkull, E. Alfonsson, P. Johansson, Corrosion Control 007 (2007)[5] http://europa.eu/legislation_summaries/index_en.htm, Euro 5 and Euro 6
standards: reduction of pollutant emissions from light vehicles, September 10 th 2010
[6] M. Benson, Stainless Steel World, p5038 (2005)[7] Outokumpu Corrosion Handbook, Stainless steel as reinforcement
in concrete constructions (2009) p.I:96-I99[8] Outokumpu Corrosion Handbook, Stainless steel for the desalination
industry (2009) p I84–I90[9] J-O. Andersson, E. Alfonsson, C. Canderyd, H.L. Groth, Stainless Steel
World America (2010)
Reproduced with permission from Stainless Steel World.This paper was originally presented at the Duplex World Conference, 13–15th October, 2010, Beaune, France.
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80 years with duplex steels – a historic review and prospects for the future
mats Liljas, outokumpu stainless aB, sweden
introductionDuplex or ferritic-austenitic stainless steels have a history almost as long as stainless steels. They attract a large interest from the industry although they constitute less than one percent of the total volume of stainless steel. The intention with this paper is to describe the historic development of this family of steels, show their merits and main application areas and try to analyse why the market share is still limited.
Keywords: Duplex stainless steel, history, development, phase balance, ThermoCalc, applications
First generation of duplex stainless steels (Dss)Stainless steels were developed almost hundred years ago. The first grades were ferritic (martensitic) and austenitic steels. At an early stage it was found that introduction of some ferrite into austenitic stainless castings resulted in better castability and also increased the resistance to sensitisation and improved the proof strength. This development of austenitic castings was most probably the start of duplex stainless steels.
By 1930 two duplex grades were commercially available from Avesta Steelworks where stainless production started in 1924 [1]. Figure 1 shows the type of steel furnace that was used at this time and Figure 2 is a record of corrosion tests in seawater with the first duplex grades. Grade 453E (26Cr-5Ni) was essentially alloyed with chromium and nickel and was intended for heat resistance, while grade 453S (26Cr-5Ni-1Mo) also had an addition of molybdenum to obtain improved aqueous corrosion resistance. This basic composition was later standardised in many countries (type 329) and has been used for further development of 25Cr duplex grades by many producers. Duplex castings were developed in Finland roughly in the same period. In the mid 1930’s a French patent was granted to J. Holtzer Steelworks of a duplex alloy (21Cr-7Ni-2.5Mo), which originated from a mistake in the melt shop in adding too much chromium to an austenitic steel [2, 3]. Typical compositions of the first generation DSS are listed in Table 1.
Characteristic for the first duplex grades were relatively high carbon contents, since efficient process techniques for decarburization were not available. Intentional nitrogen
Fig. 1 Electric arc furnace for stainless steel, 1928. Fig. 2 Result of corrosion test of first duplex grades.
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typical compositions (in weight percent) of the first generation Dss. Table 1
Judging from these differences, various effects on steel performance could be expected. Due to its high ferrite level grade 453S was sensitive to full ferritization during thermal cycles such as in welding. UR50 tended to show limited ductility as result of improper phase balance at hot working temperatures.
In the1950’s it was reported that DSS showed good resistance to chloride stress corrosion cracking (SCC). One alloy specifically developed to combat SCC was 3RE60 developed by Sandvik [4]. This was a low carbon steel with a relatively high level of Si and no nitrogen deliberately added.
The first duplex alloy with intentional addition of nitrogen was Ferralium, which in turn was developed from Grade 26-5-1 castings but intended for both cast and wrought forms. It was claimed that addition of nitrogen reduced the problems both with cracking during casting and with welding, by producing more ductile welds [5]. Having about 25%Cr and appreciable amounts of molybdenum and copper this steel exhibited a high strength and high corrosion resistance. This steel was the forerunner to many so-called 25Cr DSS and to superduplex grades described later in this paper.
With increased use in welded constructions it became clear that many DSS could suffer from intergranular corrosion (IGC) in the heat affected zone (HAZ) due to transformation to more or less 100% ferritic microstructure, which is much more prone to carbide precipitation than austenite. An alloy was developed in the 1970’s that was claimed to be resistant to this form of corrosion [6]. This was mainly because of a more austenitic composition able to resist full ferritization in HAZ, but also the addition of nitrogen that improved the austenite reformation upon cooling. The steel grade in question was 1.4462, originally with quite a wide nitrogen range, 0.08-0.20%N.
Fig. 3 Equilibrium diagrams for early duplex grades using ThermoCalc TCFE5 database.
Used compositions: 453S: 0.09C, 0.4Si, 1.5Mn, 26Cr, 5Ni, 1.5Mo, 0,04N
UR50: 0.09C, 0.4Si, 2Mn, 21Cr, 6.5Ni, 2.5Mo, 0.04N.
1.0
0.9
0.7
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0600 9000 1200 1500
Vo
lum
e (f
ract
ion
of
ph
ases
)
Temperatue (°C)
SigmaAusteniteFerrite
453 S1.0
0.9
0.7
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0600 9000 1200 1500
Vo
lum
e (f
ract
ion
of
ph
ases
)
Temperatue (°C)
SigmaAusteniteFerrite
UR 50
Grade ASTM C Cr Ni Mo Cu Other PRE
453S AISI 329 0.09 26 6 1.5 – – 31
UR50 S32404 0.09 21 6.5 2.5 1.5 – 30
3RE60 S31500 0.03 18.5 5 2.5 – 1.7Si 27
additions were not practiced and this element was hardly mentioned. Further, the phase balance was not optimised to present standards. Calculations of the phase fractions for two of the first duplex grades show great deviation from today’s DSS. This is illustrated in Figure 3 where grade 453S has a highly ferritic composition with more than 70% ferrite at 1050°C while grade UR50 only contains about 33% ferrite at this temperature.
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second generation DssThe remedy to IGC was the addition of nitrogen, which had the power to restore the HAZ microstructure. It was also shown that nitrogen was an important element for increasing the pitting corrosion resistance. This positive effect of nitrogen on weld microstructure and corrosion resistance was further optimised and thus a second generation of DSS was born. One important feature with nitrogen alloying in duplex steels is to move the phase balance to a more austenitic one and to enhance the austenite reformation from ferrite on cooling from high temperatures due to its high diffusion rate. By this para-equilibrium condition the paradox of increasing nitrogen content to avoid nitride precipitation was achieved. There is a general agreement that “equal” proportions of ferrite and austenite offer optimum properties of duplex steel. Just how large deviations from this balance can be accepted is a never-ending but hardly constructive discussion. Instead, requirements on product properties reflected by the phase balance should be specified.
Along with the increased knowledge of utilizing nitrogen as alloying element the process techniques in steel mills were improved. With AOD, a converter is seen in Figure 4, and similar refining vessels it was possible to add nitrogen in an inexpensive way and to reduce the levels of harmful impurities. A pioneer alloy belonging to the second generation DSS is the modern version of 1.4462 often designated 2205 or 22Cr, which is still the DSS with the highest yearly produced tonnage. However, several new developments emerged during the 1980’s both in the direction of higher and leaner compositions.
As mentioned above, several 25Cr duplex grades have been used since the start in 1930’s and many of them have increasing alloying content. As mentioned earlier
Ferralium was the first higher alloyed grade with intentional nitrogen addition but there were several more 25Cr grades with similar compositions, some of which are listed in Table 2. Copper additions were made to improve corrosion resistance in reducing acids and alloying with tungsten was used to further improve the pitting resistance.
In mid 1980’s higher alloyed 25Cr DSS were introduced under the collective description superduplex steels. Zeron 100 was alloyed with molybdenum and tungsten as well as copper while for SAF 2507 the molybdenum and nitrogen were the main elements to increase corrosion performance. One of the features with SAF 2507 was that an optimum solution annealing treatment resulted in equal pitting corrosion
resistance of austenite and ferrite. This was predicted by thermodynamic equilibrium calculations using the ThermoCalc database [7].
Due to the high levels of Cr, Mo, W and N these steels showed very high pitting corrosion resistance. With the frequently used ranking equation for pitting corrosion resistance; Pitting Resistance Equivalent,
PRE = Cr + 3.3(Mo + ½W) +16N
they reached the level of 40, which is often used as a definition of a superduplex steel. An alternative way to improve corrosion resistance is to augment the Cr level further.
This was done with SAF 2906, which shows superior performance in oxidizing acids present in the urea industry. The increasing alloying content makes the microstructure more prone to precipitation of intermetallic phases with an adverse effect on corrosion resistance and ductility. There has been a vivid discussion concerning the individual effect of molybdenum and tungsten and the conclusion is that replacement of Mo by some W has a negligible effect on phase stability as well as corrosion resistance [8]. Naturally,
Fig. 4 Charging of AOD converter in 1970’s
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further upgrading of the alloy content will decrease the two-phase stability. However, a recent development of a hyperduplex grade, SAF 2707HD, with a PRE of about 49 due to very high Cr, Mo and N levels can be manufactured and welded without precipitation of intermetallic phases [9].
It has been claimed that nitrogen delays the formation of intermetallic phases in DSS in a similar way as in austenitic grades. However for DSS there is only a small effect of nitrogen on the driving force for sigma-phase formation, because nitrogen does not change the chromium activity as result of a simultaneous change in phase fraction [10]. For lower alloyed duplex steels the risk of intermetallic phase formation is naturally smaller and lean duplex grades have received much interest in recent years. Already in the mid 1980’s Sandvik introduced SAF 2304, now an established grade. To minimize raw material cost lean DSS alloys with low nickel contents compensated with manganese and nitrogen have been launched. Outokumpu LDX 2101®, with high manganese and nitrogen contents shows high strength and good corrosion performance even in the as-welded condition. The stability to intermetallic phase formation is high and the dominating phases precipitating after shorter times are carbides and nitrides that are less harmful to properties. With low nickel contents the impact toughness is slightly reduced, but fracture mechanics testing show that the material still has a low transition temperature to brittle behaviour.
Grade EN ASTM Cr Ni Mo Cu W N PRE
2205 1.4462 S31803 22.5 5 3.2 – 0.17 36AL2003 – S32003 21 3.6 1.7 0.17 29
S32900 26 5 1.5 0.04 3244LN 1.4460 S31200 25 5 2 0.15 34Carpenter 7Mo S32950 25 5 2 0.15 34Ferralium 225 – S32550 26 5.5 3 1.7 0.17 39Uranus 47N S32550 25 6.5 3 0.18 38Sumitomo DP3 – S31260 25 6.5 3 0.3 0.3 0.16 38
Zeron 100 1.4501 S32760 25 7 3.5 0.5 0.6 0.25 42SAF 2507 1.4410 S32750 25 7 4 0.27 43UR52N+ 1.4507 S32520 25 6 3.5 1.5 0.25 41DP3W – S39274 25 7 3 2 0.25 42SAF 2906 1.4477 S32906 29 7 2.2 0.35 42DP28W – S32808 27.5 7.7 1 2 0.35 40SAF 2707 – S32707 27 6.5 4.8 0.40 49
2304 1.4362 S32304 23 4 0.3 – 0.10 2619D – S32100 20 1.6 0.3 0.3 0.13 23LDX 2101 1.4162 S32101 21.5 1.5 0.3 0.3 0.22 26UR2202 1.4062 S32202 22 2 0.3 0.3 0.20 26
22C
r25
Cr
DS
SS
up
er D
SS
Lean
DS
S
typical compositions (in weight percent) of different groups of Dss. Table 2
Prospects for further development of DssThere is an active development of new duplex alloys both in the direction of high and low alloy regimes. This has resulted in several proprietary grades that show very similar property profiles and it could be argued that they should be listed in the same standard. Consequently, it is very plausible that new duplex grades will be introduced in the near future as there may be application areas lacking suitable DSS alternatives. An important alloy design tool is the thermodynamic database ThermoCalc that is frequently used to predict phase equilibria.
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Fig. 6 Cast valve bodies made of the duplex 453S grade. Fig. 5 Equipment in duplex grade 453S for sulphite digesters, Brobeck cooler.
There is probably a limit in PRE value of about 50 due to the increased risk of intermetallic phase formation when exceeding that level. Replacement of Mo with W would not offer any increased margin in this respect. As the high levels of Cr and Mo result in high solubility of nitrogen, superduplex grades can be made with nitrogen levels of 0.4% without problems with pore or nitride formation in welding. Further development of superduplex and hyperduplex grades is expected with this upper alloying level.
Naturally there is room for new DSS with tailor-made property profiles, e.g., high corrosion resistance in certain environments and specific mechanical or fabrication properties. This can be made with variants of existing grades or with new alloys. One example is addition of copper to improve corrosion resistance in certain acids.
historical application reviewThe two first duplex grades developed at Avesta Steelworks in 1930 were mainly produced as castings and rolled bars but to some extents also as plate. The heat resistant grade 453E was used as castings, e.g., for molten lead equipment and for pyrite kiln inserts. The acid resistant grade 453S was used in the sulphite pulp industry for pumps, valves and circulation systems, examples are seen in Figure 5 and Figure 6.
The interesting properties of the ferritic austenitic grades resulted in substantial tonnages of duplex material. Thus, in 1932, the duplex grades amounted to more than 6% of the total stainless steel production of Avesta Steelworks, which then was 5500 metric tonnes. It was not until 1947 that grade 453S was included in the Swedish standard as SIS 2324. Later, this steel also was listed in USA as AISI 329 and many 25Cr duplex alloys have been developed with this alloy as a base. The French grade Uranus 50 produced by J. Holtzer Steelworks was used with similar products and applications as 453S. Examples that have been reported are cast propellers, dying machines as well as vessels for petrochemical and chemical, food and pulp & paper industries [11]. J. Holtzer Steelworks also offered heat resistant duplex grades. In the 1960’s Sandvik introduced 3RE60, which found applications in tube heat exchangers in process industry.
A more widespread use of duplex steels was associated with the introduction of the second generation of DSS. An important commercial break-through was the selection of the 22Cr duplex grade for natural gas pipelines in oil and gas industry in late 1970’s. Since then, DSS have been used extensively for such applications. Inclusion of the modern duplex grades in pressure vessel standards, also in the late 1970’s, made it possible to use DSS in pressurized systems such as pulp digesters where the high strength could be utilized. The excellent corrosion resistance in acids of DSS made them ideal for chemical tankers and large tonnages of DSS material started to be used for this application in the 1980’s.
In the expanding offshore oil and gas industry there was a need for high performance materials and 6Mo austenitic steels were selected due their high resistance to seawater.
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However, superduplex grades such as Zeron 100 and SAF 2507 were developed to compete with the superaustenitic grades with good success. Today, large quantities of superduplex tubing are used in umbilicals for the control of sub-sea systems. Also in the offshore industry, lean duplex steel has been used for blast walls on oil platforms based on the high strength combined with sufficient corrosion resistance.
Other areas where DSS have partly replaced austenitic alloys are flue gas cleaning systems and seawater desalination plants. In the latter case a combination of duplex grades is used to meet different aggressive environments.
In more recent years lean duplex grades have emerged as an alternative to type 304 and 316 austenitic grades. This development has been very successful. The aim with these grades is also to replace construction steels, deriving on advantages of high strength and low maintenance costs. Increased use of such steels is now seen in bridges, storage tanks and other construction work. Lean DSS are also used for construction of transport vehicles.
The launching of the hyperduplex steel SAF 2707HD means a further expansion of the applications for DSS. With its high PRE this steel will resist seawater at high temperatures and will be used in very aggressive refinery environments, competing with nickel base alloys.
Prospects for commercial developmentDSS have now been available for almost 80 years on the market and yet they only represent about one percent of the total stainless volume. This cannot be attributed solely to conservatism in the user segment but also to various obstacles at suppliers and fabricators. No doubt there is a great potential for further volume increase considering the numerous advantages DSS offer compared to austenitic and ferritic stainless steels. Numerous articles have shown the technical benefits and cost saving in replacing austenitic grades. In recent years lean duplex grades, competing with austenitic commodity grades, have shown a large volume increase partly due the high nickel prices. It is therefore natural to anticipate further increase in application areas where austenitic commodity grades are used. ISSF data show that type 2205, competing with comparatively high alloy austenitics, has been and is still the dominating grade [12]. It has also been pointed out that hot rolled plate, which represents a small volume of the total stainless consumption, is the dominating duplex product. Development of coil products is therefore likely to be a prerequisite for larger expansion of DSS use. However, there are many applications where the ease of fabrication (forming and welding) is a governing reason for the selection of austenitic steels. Here, it can be difficult to convince the user to accept a material with high strength and different welding procedures. Also for many thin gauge applications the increased strength of DSS cannot be utilized to reduce thickness, thereby missing the cost advantage with duplex grades. Further, the limitations in surface finishes for DSS compared to austenitic grades are also claimed as a limiting factor for growth.
Therefore skilled technical support and inventive design ideas are required to widen the application areas for DSS. It is also of great importance to have duplex steels readily available to fabricators and end users. Finally, environmental reasons for using DSS as construction material; low maintenance costs and very high material circulation, will be further important arguments to enhance the selection of DSS.
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references[1] J. Olsson, M. Liljas, NACE Corrosion/94, 1994, paper no. 395[2] P. Soulignac, F. Dupoiron, Stainless Steel Europe, June 1990, p. 18[3] French patent No 803361, 1936[4] Swedish patent No 312240, 1965[5] US patent No 3567434, 1971[6] German patent No 2255673, 1974[7] Swedish patent No 8504137-7, 1985[8] S. Hertzman et al, Duplex 94, Glasgow, Nov 1994, Vol.1, paper 1[9] P. Stenvall, M. Holmquist, DSS 2007, Grado, June 2007[10] S. Hertzman et al, Duplex 2000, Venezia, Oct 2000, p. 347[11] J. Hochman, Revue du Nickel, Juillet-aout-septembre, 1950, p. 53[12] J. Charles, Duplex 2007, Grado June 2007, opening lecture
Reproduced with permission from Jernkontoret. This paper was originally presented at the 6 th European Stainless Steel Conference – Science and market, Helsinki, Finland. June 10–13, 2008.
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2010 1 Duplex stainless steels in the hydrometallurgy industry S. Ekman, R. Pettersson
1 corrosion testing of stainless steel for metal leaching applications S. Ekman, A. Bergquist, E. Torsner
2 materials performance in simulated waste combustion environments R. Pettersson, J. Flyg, P. Viklund
2 high temperature corrosion under simulated biomass deposit conditions R. Pettersson, J. Flyg, P. Viklund
2 stainless steels in waste and biomass power plant applications R. Pettersson, A. Bergquist, J. Flyg, B. Beckers
3 summary of corrosion fatigue test data for duplex suction roll shell material H. Groth, A. Kähönen, C. Tigerstrand, S. Ekman, M. Andersson, D. Eyzop
3 Fatigue properties of thin sheet stainless steel lap joints H. Nordberg, H. Groth
4 acom chronicle 1980 – 2010 J. Gunnarsson
4 superaustenitic stainless steels in demanding environments C. Canderyd, M. Liljas, R. Pettersson, M. Willför
4 Lean duplex – the first decade of service experience E. Alfonsson
4 80 years with duplex steels – a historic review and prospects for the future M. Liljas
2009 1 the welding consequences of replacing austenitic with duplex stainless steel B. Holmberg, M. Liljas, F. Hägg
1 Fracture toughness of welded commercial lean duplex stainless steels H. Sieurin, E. M. Westin, M. Liljas, R. Sandström
2 critical chloride threshold levels for stainless steel reinforcement in pore solutions S. Randström, M. Adair
2 corrosion properties of stainless steels as reinforcement in concrete in swedish outdoor environment B. Sederholm, J. Almqvist, S. Randström
2008 1 the suitability of stainless steels for road constructions J. Olsson, A. Bergquist, A. Olsson, B. Sederholm
2007 1 the use of a lean duplex stainless steel UNs s32101: thermal dimple jackets on vessels for high purity applications B. J. Uhlenkamp, J. D. Fritz
2 stress corrosion cracking properties of UNs 32101 – a new duplex stainless steel with low nickel content E. Johansson, T. Prošek
3 stainless steel for hydrometallurgy plants J. Olsson
4 stainless steels for flue gas cleaning – laboratory trials, field tests and service experience B. Beckers, A. Bergquist, C.-O. A. Olsson, M. Snis, E. Torsner
30 years with acom – in order
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2006 1 Lean duplex grades as longitudinally welded pipes for linepipes in the oil and gas business I. Rommerskirchen, S. Lemken, R. Hoffmann
1 effect of cathodic current densities and strain rates on ssrt fracture behaviour of lean duplex stainless steels and a 13%cr supermartensitic stainless steel in synthetic formation water H. Hoffmeister, C. Jonas, J. Neuss, I. Rommerskirchen, S. Lemken
1 the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments L. C. Jordan, J. W. McEnerney, J. W. McManus
2 oxidation of s35315 in water vapor containing atmospheres under cyclic and isothermal conditions P. Vangeli
2 Passive films on stainless steels - recent nano-range research C.-O. A. Olsson, G. Herting, I. Odnevall Wallinder
3 austenitic and duplex stainless steels used as construction materials B. Holmberg, A. Kähönen
4 LDX 2101®, a new stainless steel with excellent machining properties C. Bergquist, J. Olsson
2005 1 why clad when there is duplex? J. Olsson
2 corrosion properties of UNs s32101 – a new duplex stainless steel with a low nickel content tested for use as reinforcement in concrete A. Bergqvist, A. Iversen, R. Qvarfort
3 Utilization of the material strength for lower weight and cost with LDX 2101® M. Benson
2004 1 mic on stainless steels in wastewater treatment plants – field tests and a risk assessment A. Iversen
1 service experience with high performance stainless steels in aggressive fresh waters C. W. Kovach, N. Kinsman, A. Iversen
2 release rates of chromium, nickel and iron from pure samples of the metals and 304 and 316 stainless steel induced by atmospheric corrosion – a combined field and laboratory study I. Odnevall Wallinder, S. Bertling, G. Herting, C. Leygraf
3 electrochemical evaluation of pitting and crevice corrosion resistance of stainless steels in Nacl and NaBr R. F. A. Pettersson, J. Flyg
4 Passivation treatment of stainless steel L. Wegrelius, B. Sjödén
2003 1 in-plant corrosion testing in ozone bleaching environments P. Pohjanne, M. Siltala
2 Utilizing high strength stainless steel for storage tanks A. Olsson
3 effects of gas atmosphere and surface quality on rouging of three stainless steels in wFi J. E. Frantsen, T. Mathiesen, J. Rau, P. Björnstedt, J. Terävä, B. Henkel
4 stainless steels for swro plants high pressure piping, properties and experience J. Olsson, K. Cosic
4 msF chambers of solid duplex stainless steel J. Olsson, V. Jägerström, I. Resini
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2002 1–2 Fatigue behaviour of stainless steel welds M. Liljas, C. Ericsson
1–2 a new lean duplex stainless steel for construction purposes P. Johansson, M. Liljas
3–4 hytens creates new opportunities for high strength stainless steel applications J. Kemppainen, E. Schedin, E. Sörqvist
3–4 the applicability of stainless steels for crash absorbing components R. Andersson, E. Schedin, C. Magnusson, J. Ocklund, A. Persson
2001 1–2 a comparison between two high molybdenum superaustenitic stainless steel grades J. Y. Jonsson, L. Wegrelius
1-2 electrochemical studies of 254 smo stainless steel in comparison with 316L stainless steel and hastelloy c276 in phosphoric acid media in absence and presence of chloride ions L. de Micheli, A. H. P. Andrade, C. A. Barbosa, S. M. L. Agostinho
3–4 the influence of drinking water quality on the corrosion of stainless steel eN 1.4401 (ss 2347, aisi 316) A. Elfström Broo, B. Berghult, T. Hedberg
3–4 stainless steels in sewage treatment plants A. Iversen, J. Olsson
2000 1 stainless steel design stresses in eN and asme pressure vessel codes J. Jonson
2 corrosion testing in flash tanks S. J. Clarke, N. J. Stead
3 causes and remediation of corrosion failure of duplex stainless steel equipment in a PVc plant M. Davies, G. Potgieter
4 choice of specifications and design codes for duplex stainless steels M. Liljas, G. Gemmel
1998 1 corrosion of duplex stainless steels in seawater B. Wallén
2 applications and experience with a superaustenitic 7mo stainless steel in hostile environments J. Olsson, W. Wasielewska
3 scc of stainless steel under evaporative conditions H. Andersen, P.-E. Arnvig, W. Wasielewska, L. Wegrelius, C. Wolfe
4 assessment of susceptibility to chloride stress corrosion cracking of highly alloyed stainless steels. Part ii: a new immersion test method J. M. Drugli, U. Steinsmo
1997 8 high performance stainless steels and microbiologically influenced corrosion C. W. Kovach, J. D. Redmond
2 hydrogen sulphide resistance of highly-alloyed austenitic stainless steels C. Wolfe, P.-E. Arnvig, W. Wasielewska, R. F. A. Jargelius-Pettersson
3 how to perform welding in duplex stainless steels to obtain optimum weld metal properties B. Holmberg
4 the seawater resistance of a superaustenitic 7mo stainless steel B. Wallén, A. Bergqvist
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1996 1 corrosion testing in the flue gas cleaning and condensation systems in swedish waste incineration plants B. Wallén, A. Bergqvist, J. Nordström
1 seawater resistance of a second generation superaustenitic stainless steel B. Wallén, E. Alfonsson
2 machinability, corrosion resistance and weldability of an inclusion modified 2205 duplex stainless steels P.-E. Arnvig, B. Leffler, E. Alfonsson, A. Brorson
2 the lateral homogeneity of passive films formed on the duplex stainless steel 2205 investigated with aes and XPs C.-O. A. Olsson, S. E. Hörnström
2 60 years of duplex stainless steel applications J. Olsson, M. Liljas
3 Determining the potential independent critical pitting temperature (cPt) by a potentiostatic method using the avesta cell P.-E. Arnvig, A. D. Bisgård
3 intergranular corrosion testing by etching at a constant potential R. Qvarfort
3 evaluation of hcl and Na-eDta additions for ferric chloride testing using auger electron spectroscopy C.-O. A. Olsson, P.-E. Arnvig
4 steam side droplet erosion in titanium tubed condensers – experiences and remedies J. O. Tavast
1995 1 UNs s32654, a new superaustenitic stainless steel for harsh environments J. Olsson
2 Development of superaustenitic stainless steels M. Liljas
3 Desalination of seawater by reverse osmosis – the malta experience M. F. Lamendola, A. Tua
3 stainless steel for high pressure piping in swro plants. are there any options? J. Nordström, J. Olsson
4 avesta sheffield 353ma – a material for very high temperatures and harsh environments M. Segerbäck, B. Ivarsson, R. Johansson
1994 1 Design ideas and case studies utilising duplex stainless steels H. L. Groth, M. L. Erbing, J. Olsson
2 the role of nitrogen in longitudinal welding of tubing in duplex stainless steels O. Jonsson, M. Liljas, P. Stenvall
3 Digesters and pulp storage towers of duplex stainless steels – saving weight and costs J. Nordström, B. Rung
4 welding of UNs s32654 – corrosion properties and metallurgical aspects M. Liljas, P. Stenvall
1993 1 Fatigue performance of nine bolt materials in air and in seawater with cathodic protection T. Slind, T. G. Eggen, E. Bardal, P. J. Haagensen
2 corrosion problems in low-temperature desalination units S. Narain, S. H. Asad
3 stress corrosion behaviour of highly alloyed stainless steels under severe evaporative conditions P.-E. Arnvig, W. Wasielewska
4 corrosion in chloride dioxide bleach environments – experiences with stainless steels and nickel-base alloys E. Alfonsson, L. Tuveson-Carlström, B. Wallén
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1992 1 investigation of the applicability of some Pre expressions for austenitic stainless steels E. Alfonsson, R. Qvarfort
2 avesta 654 smo™ – a new high molybdenum, high nitrogen stainless steel B. Wallén, M. Liljas, P. Stenvall
3 Duplex stainless steels of yesterday and of today – a pitting corrosion investigation E. Alfonsson, R. Qvarfort
4 application of UNs s31254 (254 smo®) austenitic stainless steel in power plants J. Olsson, J. D. Redmond
1991 1–2 reverse osmosis – which stainless steel to use? B. Todd, J. W. Oldfield
1–2 experiences with a highly alloyed stainless steel in desalination plants and other arabian Gulf industrial plants J. Olsson, M. L. Erbing
3 high temperature corrosion of heat resistant alloys K. Tjokro, D. J. Young, R. Johansson, J. D. Redmond
4 testing of three highly alloyed stainless steels according to the mti corrosion tests B. Wallén, A. Bergqvist, J. Olsson
1990 1 corrosion of stainless austenitic steels in nearly anhydrous acetic acid L. Leontaritis, E.-M. Horn
2 Duplex stainless steels in chemical tankers – properties and practical experience B. Leffler
3 experiences with a high-alloys stainless steel under highly corrosive conditions J. Olsson, H. Grützner
4 some factors affecting stainless steel corrosion in seawater B. Wallén
1989 1 influence of carbon and nitrogen content on the creep properties of the austenitic stainless steel 253ma M. Yu, R. Sandström
2 corrosion and corrosion testing of high-alloy stainless steel weldments J. M. Drugli
3 corrosion problems in the oil industry R. Johnsen
4 effect of chlorination on stainless steels in sea water B. Wallén, S. Henrikson
1988 1 crevice corrosion of stainless steels in seawater J. W. Oldfield
2–3 the avesta cell – a new tool for studying pitting R. Qvarfort
2–3 electrochemical intergranular corrosion test method for acceptance test of special grade stainless steels R. Qvarfort
4 corrosion behaviour and cathodic protection of stainless steels for offshore hot risers N. Nilsen, B. Espelid
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1987 1 corrosion engineering of high pressure piping in ro-plants S. Nordin, J. Olsson
2 Galvanic corrosion of copper alloys in contact with highly alloyed stainless steel in seawater B. Wallén, T. Andersson
3–4 Performance of a high molybdenum stainless steel in the pulp and paper industry M. Liljas, R. Qvarfort, B. Wallén
3–4 Field tests with metallic materials in Finnish, Norwegian and swedish bleach plants S. Henrikson
3–4 Field experience in the application of 254 smo (UNs s31254) in the scandinavian pulp and paper industry R. M. Davison, J. Olsson, D. W. Rahoi
1986 1–2 influence of nitrogen on weldments in UNs31803 M. Liljas, R. Qvarfort
1–2 textures and anisotropy in duplex stainless steel ss2377 (2205) W. B. Hutchinson, U. von Schlippenbach, J. Jonson
1–2 applications and uses of duplex stainless steels J. Olsson, S. Nordin
3–4 sea water handling systems: past, present and future P. Gallagher, R. E. Malpas, E. B. Shone
3–4 an accelerated test method for crevice corrosion J. M. Krougman
3–4 selection of high-alloyed steels for seawater-cooled condensors L. M. Butter, A. H. M. Keller, H. B. J. Klein Avink, W. M. M. Huijbregts
1985 1 weight optimisation in offshore construction T. Eriksen
2 oxidation kinetics of heat resistant alloys part 1 G. R. Rundell
2 oxidation kinetics of heat resistant alloys part 2 G. R. Rundell
3 optimization of high-pressure piping in reverse osmosis plants S. Nordin, B. Wallén, B. Eriksson
4 high temperature behaviour of the austenitic stainless steel astm UNs30815 (253ma) and weldments A. Dhooge, W. Hoek, W. Provost, M. Steen
1984 1 electrochemical studies of crevice corrosion rates on stainless steels D. Tromans, L. Frederick
1 influence of copper on the resistance of 20cr25Nimo stainless steels to pitting and crevice corrosion J. Pleva
2 corrosion control in the offshore industry S. Nordin
2 advanced steels and metal alloys offshore – a summary P. Løvland
3 Performance of a high molybdenum stainless steel in gas cleaning systems B. Wallén, M. Liljas, J. Olsson
4 the use of stainless steels and related alloys in reverse osmosis desalination plants B. Todd, J. Oldfield
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1983 1 influence of molybdenum on stress corrosion cracking of austenitic stainless steels J. Pleva
2 the effect of nitrogen on microstructure, mechanical properties and welding of nitrogen alloyed austenitic stainless steels B. Leffler, B. Johansson
2 on the influence of nitrogen on the corrosion properties of austenitic and duplex stainless steels I. Bernhardsson
2 stainless steel X 3 crNimoN17 13 5 – a successful compromise between materials, costs and performance properties E.-M. Horn, U. Gramberg
3 stainless steels in the hydrometallurgical industry G. Steintveit
3 corrosion of stainless steels in weak sulfuric acid solutions G. Coates
1982 1 a user’s view of the need for quality assurance in welded stainless steel pipe manufacture J. Metcalf
1 the corrosion behavior of welded stainless pipe Uddeholm Steel Research Department
2 on the corrosion behavior of a ferritic 18cr-2mo steel K. Fässler, H. Spähn
2 experience with an 18cr-2mo alloy in the chemical and petrochemical industries G. Coates, G. Gemmel, F. N. Smith
3 crevice corrosion tests in seawater in the arabic Gulf
3 Preventing corrosion in air ejector condenser systems
4 materials of construction for metallurgical sulphuric acid plants P. D. Nolan
1981 1 stainless steels in desalination plants S. Nordin
1 a new approach to scale control S. Nordin
2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel S. Evant
2 corrosion resistance of stainless steels to chlorinated hydrocarbons S. Nordin
3 a laboratory study of the sulfuric acid dew-point corrosion on ss2343 stainless steel, Uddeholm 904L, and on carbon steel (ss1311) G. Johansson
3 what alloys are winning in the scrubber market? R. R. Irving
4 corrosion properties of steels for urea synthesis V. Čihal, G. V. Akimov
4 stainless steels for production of urea G. Coates
4 stainless steel for saline cooling water in the fertilizer industry G. Gemmel
SI technico-economical aspects on the design, fabrication, and operational reliability of thermal desalination plants S. Nordin
1980 1 stainless steels and saline environments – problems or opportunities S. Nordin
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corrosion
2009:2 corrosion properties of stainless steels as reinforcement in concrete in swedish outdoor environment
2007:4 stainless steels for flue gas cleaning – laboratory trials, field tests and service experience
2005:2 corrosion properties of UNs s32101 – a new duplex stainless steel with a low nickel content tested for use as reinforcement in concrete
2001:1-2 electrochemical studies of 254 smo stainless steel in comparison with 316L stainless steel and hastelloy c276 in phosphoric acid media in absence and presence of chloride ions
2000:2 corrosion testing in flash tanks
1998:1 corrosion of duplex stainless steels in seawater
1993:4 corrosion in chloride dioxide bleach environments – experiences with stainless steels and nickel-base alloys
1991:4 testing of three highly alloyed stainless steels according to the mti corrosion tests
1990:1 corrosion of stainless austenitic steels in nearly anhydrous acetic acid
1990:2 Duplex stainless steels in chemical tankers – properties and practical experience
1990:3 experiences with a high-alloys stainless steel under highly corrosive conditions
1989:2 corrosion and corrosion testing of high-alloy stainless steel weldments
1989:3 corrosion problems in the oil industry
1983:2 on the influence of nitrogen on the corrosion properties of austenitic and duplex stainless steels
1983:3 corrosion of stainless steels in weak sulfuric acid solutions
1982:1 the corrosion behavior of welded stainless pipe
1982:2 on the corrosion behavior of a ferritic 18cr-2mo steel
1982:3 Preventing corrosion in air ejector condenser systems
1981:2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel
1981:2 corrosion resistance of stainless steels to chlorinated hydrocarbons
1981:3 a laboratory study of the sulfuric acid dew-point corrosion on ss2343 stainless steel, Uddeholm 904L, and on carbon steel (ss1311)
1981:4 corrosion properties of steels for urea synthesis
1981:4 stainless steels for production of urea
1980:1 stainless steels and saline environments - problems or opportunities
atmospheric corrosion
2008:1 the suitability of stainless steels for road constructions
2004:2 release rates of chromium, nickel and iron from pure samples of the metals and 304 and 316 stainless steel induced by atmospheric corrosion – a combined field and laboratory study
cathodic protection 1993:1 Fatigue performance of nine bolt materials in air and in seawater with
cathodic protection
30 years with acom – by subject
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1990:4 some factors affecting stainless steel corrosion in seawater
1988:4 corrosion behaviour and cathodic protection of stainless steels for offshore hot risers
corrosion fatigue
2010:3 summary of corrosion fatigue test data for duplex suction roll shell material
corrosive wear 1996:4 steam side droplet erosion in titanium tubed condensers
– experiences and remedies
1993:2 corrosion problems in low-temperature desalination units
crevice corrosion 2004:3 electrochemical evaluation of pitting and crevice corrosion resistance
of stainless steels in Nacl and NaBr
1988:1 crevice corrosion of stainless steels in seawater
1986:3-4 an accelerated test method for crevice corrosion
1984:1 electrochemical studies of crevice corrosion rates on stainless steels
1984:1 influence of copper on the resistance of 20cr25Nimo stainless steels to pitting and crevice corrosion
1982:3 crevice corrosion tests in seawater in the arabic Gulf
environmentally-induced cracking 2007:2 stress corrosion cracking properties of UNs 32101
– a new duplex stainless steel with low nickel content
2006:1 the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments
1998:1 corrosion of duplex stainless steels in seawater
1998:3 scc of stainless steel under evaporative conditions
1998:4 assessment of susceptibility to chloride stress corrosion cracking of highly alloyed stainless steels. Part ii: a new immersion test method
1997:2 hydrogen sulphide resistance of highly-alloyed austenitic stainless steels
1993:3 stress corrosion behaviour of highly alloyed stainless steels under severe evaporative conditions
1983:1 influence of molybdenum on stress corrosion cracking of austenitic stainless steels
Galvanic corrosion
1987:2 Galvanic corrosion of copper alloys in contact with highly alloyed stainless steel in seawater
intergranular corrosion
1996:3 intergranular corrosion testing by etching at a constant potential
1988:2–3 electrochemical intergranular corrosion test method for acceptance test of special grade stainless steels
methods/methodology
2009:2 critical chloride threshold levels for stainless steel reinforcement in pore solutions
1998:4 assessment of susceptibility to chloride stress corrosion cracking of highly alloyed stainless steels. Part ii: a new immersion test method
1996:3 Determining the potential independent critical pitting temperature (cPt) by a potentiostatic method using the avesta cell
1996:3 intergranular corrosion testing by etching at a constant potential
1996:3 evaluation of hcl and Na-eDta additions for ferric chloride testing using auger electron spectroscopy
1992:1 investigation of the applicability of some Pre expressions for austenitic stainless steels
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1988:2–3 the avesta cell – a new tool for studying pitting
1988:2–3 electrochemical intergranular corrosion test method for acceptance test of special grade stainless steels
1986:3-4 an accelerated test method for crevice corrosion
microbiologically induced corrosion (mic)
2004:1 mic on stainless steels in wastewater treatment plants – field tests and a risk assessment
2004:1 service experience with high performance stainless steels in aggressive fresh waters
1997:1 high performance stainless steels and microbiologically influenced corrosion
Pitting corrosion 2004:3 electrochemical evaluation of pitting and crevice corrosion resistance
of stainless steels in Nacl and NaBr
1996:3 Determining the potential independent critical pitting temperature (cPt) by a potentiostatic method using the avesta cell
1992:3 Duplex stainless steels of yesterday and of today – a pitting corrosion investigation
1988:2-3 the avesta cell – a new tool for studying pitting
1984:1 influence of copper on the resistance of 20cr25Nimo stainless steels to pitting and crevice corrosion
high temperature
heat and creep resistant steels 1995:4 avesta sheffield 353ma – a material for very high temperatures and
harsh environments
1985:4 high temperature behaviour of the austenitic stainless steel astm UNs30815 (253ma) and weldments
Properties Corrosion 2010:2 materials performance in simulated waste combustion environments
2010:2 high temperature corrosion under simulated biomass deposit conditions
2010:2 stainless steels in waste and biomass power plant applications
2007:4 stainless steels for flue gas cleaning – laboratory trials, field tests and service experience
1996:1 corrosion testing in the flue gas cleaning and condensation systems in swedish waste incineration plants
1991:3 high temperature corrosion of heat resistant alloys
Creep 1989:1 influence of carbon and nitrogen content on the creep properties
of the austenitic stainless steel 253ma
Oxidation
2006:2 oxidation of s35315 in water vapor containing atmospheres under cyclic and isothermal conditions
1985:2 oxidation kinetics of heat resistant alloys part 1
1985:2 oxidation kinetics of heat resistant alloys part 2
applications Combustion 2010:2 materials performance in simulated waste combustion environments
2010:2 stainless steels in waste and biomass power plant applications
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Flue gas cleaning 2010:2 stainless steels in waste and biomass power plant applications
2007:4 stainless steels for flue gas cleaning – laboratory trials, field tests and service experience
1996:1 corrosion testing in the flue gas cleaning and condensation systems in swedish waste incineration plants
1984:3 Performance of a high molybdenum stainless steel in gas cleaning systems
1982:4 materials of construction for metallurgical sulphuric acid plants
1981:3 what alloys are winning in the scrubber market?
mechanical properties Design and design rules 2005:3 Utilization of the material strength for lower weight and cost with LDX 2101®
2003:2 Utilizing high strength stainless steel for storage tanks
2003:4 msF chambers of solid duplex stainless steel
2000:1 stainless steel design stresses in eN and asme pressure vessel codes
2000:4 choice of specifications and design codes for duplex stainless steels
1994:1 Design ideas and case studies utilising duplex stainless steels
1982:4 materials of construction for metallurgical sulphuric acid plants
1981:1 stainless steels in desalination plants
Fatigue 2010:3 Fatigue properties of thin sheet stainless steel lap joints
2006:3 austenitic and duplex stainless steels used as construction materials
2002:1–2 Fatigue behaviour of stainless steel welds
1993:1 Fatigue performance of nine bolt materials in air and in seawater with cathodic protection
Fracture toughness 2009:1 Fracture toughness of welded commercial lean duplex stainless steels
machining 2006:4 LDX 2101®, a new stainless steel with excellent machining properties
1996:2 machinability, corrosion resistance and weldability of an inclusion modified 2205 duplex stainless steel
miscellaneuos
cladding 2005:1 why clad when there is duplex?
1981:2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel
1981:SI technico-economical aspects on the design, fabrication, and operational reliability of thermal desalination plants
chronicles 2010:4 acom chronicle 1980 – 2010
2010:4 80 years with duplex steels – a historic review and prospects for the future
1996:2 60 years of duplex stainless steel applications
1995:2 Development of superaustenitic stainless steels
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Passive film/passivation
2006:2 Passive films on stainless steels – recent nano-range research
2004:4 Passivation treatment of stainless steel
1996:2 the lateral homogeneity of passive films formed on the duplex stainless steel 2205 investigated with aes and XPs
1981:2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel
industrial segments architecture, building and construction (aB&c) 2009:2 critical chloride threshold levels for stainless steel reinforcement
in pore solutions
2009:2 corrosion properties of stainless steels as reinforcement in concrete in swedish outdoor environment
2008:1 the suitability of stainless steels for road constructions
2006:3 austenitic and duplex stainless steels used as construction materials
2005:2 corrosion properties of UNs s32101 – a new duplex stainless steel with a low nickel content tested for use as reinforcement in concrete
2005:3 Utilization of the material strength for lower weight and cost with LDX 2101®
2002:1-2 a new lean duplex stainless steel for construction purposes
1985:1 weight optimisation in offshore construction
1982:4 materials of construction for metallurgical sulphuric acid plants
chemical, petrochemical and energy (cPe)
2010:2 materials performance in simulated waste combustion environments
2010:2 high temperature corrosion under simulated biomass deposit conditions
2010:2 stainless steels in waste and biomass power plant applications
2007:1 the use of a lean duplex stainless steel UNs s32101: thermal dimple jackets on vessels for high purity applications
2006:1 Lean duplex grades as longitudinally welded pipes for linepipes in the oil and gas business
2006:1 the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments
2003:3 effects of gas atmosphere and surface quality on rouging of three stainless steels in wFi
2000:3 causes and remediation of corrosion failure of duplex stainless steel equipment in a PVc plant
1992:4 application of UNs s31254 (254 smo®) austenitic stainless steel in power plants
1990:2 Duplex stainless steels in chemical tankers – properties and practical experience
1990:3 experiences with a high-alloys stainless steel under highly corrosive conditions
1989:3 corrosion problems in the oil industry
1982:4 materials of construction for metallurgical sulphuric acid plants
1982:2 experience with an 18cr-2mo alloy in the chemical and petrochemical industries
hydrometallurgy 2010:1 Duplex stainless steels in the hydrometallurgy industry
2010:1 corrosion testing of stainless steel for metal leaching applications
2007:3 stainless steel for hydrometallurgy plants
1983:3 stainless steels in the hydrometallurgical industry
1983:3 corrosion of stainless steels in weak sulfuric acid solutions
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offshore 1989:3 corrosion problems in the oil industry
1988:4 corrosion behaviour and cathodic protection of stainless steels for offshore hot risers
1985:1 weight optimisation in offshore construction
1984:2 corrosion control in the offshore industry
1984:2 advanced steels and metal alloys offshore – a summary
Pulp & Paper 2005:1 why clad when there is duplex?
2003:1 in-plant corrosion testing in ozone bleaching environments
2000:2 corrosion testing in flash tanks
1994:3 Digesters and pulp storage towers of duplex stainless steels – saving weight and costs
1993:4 corrosion in chloride dioxide bleach environments – experiences with stainless steels and nickel-base alloys
1987:3-4 Performance of a high molybdenum stainless steel in the pulp and paper industry
1987:3-4 Field tests with metallic materials in Finnish, Norwegian and swedish bleach plants
1987:3-4 Field experience in the application of 254 smo (UNs s31254) in the scandinavian pulp and paper industry
transportation 2008:1 the suitability of stainless steels for road constructions
2005:1 why clad when there is duplex?
2002:3-4 the applicability of stainless steels for crash absorbing components
1990:2 Duplex stainless steels in chemical tankers – properties and practical experience
1981:2 corrosion resistance of stainless steels to chlorinated hydrocarbons
stainless steels
Duplex stainless steels 2010:1 Duplex stainless steel in the hydrometallurgy industry
2010:3 summary of corrosion fatigue test data for duplex suction roll shell material
2010:4 80 years with duplex steels – a historic review and prospects for the future
2009:1 the welding consequences of replacing austenitic with duplex stainless steel
2006:3 austenitic and duplex stainless steels used as construction materials
2005:1 why clad when there is duplex?
2005:3 Utilization of the material strength for lower weight and cost with LDX 2101®
2000:3 causes and remediation of corrosion failure of duplex stainless steel equipment in a PVc plant
2000:4 choice of specifications and design codes for duplex stainless steels
1998:1 corrosion of duplex stainless steels in seawater
1997:3 how to perform welding in duplex stainless steels to obtain optimum weld metal properties
1996:2 60 years of duplex stainless steel applications
1994:1 Design ideas and case studies utilising duplex stainless steels
1994:2 the role of nitrogen in longitudinal welding of tubing in duplex stainless steels
1994:3 Digesters and pulp storage towers of duplex stainless steels – saving weight and costs
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1992:3 Duplex stainless steels of yesterday and of today – a pitting corrosion investigation
1990:2 Duplex stainless steels in chemical tankers – properties and practical experience
1989:2 corrosion and corrosion testing of high-alloy stainless steel weldments
1986:1–2 influence of nitrogen on weldments in UNs31803
1986:1–2 textures and anisotropy in duplex stainless steel ss2377 (2205)
1986:1–2 applications and uses of duplex stainless steels
1983:2 on the influence of nitrogen on the corrosion properties of austenitic and duplex stainless steels
Lean duplex stainless steel
2010:4 Lean duplex – the first decade of service experience
2009:1 Fracture toughness of welded commercial lean duplex stainless steels
2007:2 stress corrosion cracking properties of UNs 32101 – a new duplex stainless steel with low nickel content
2006:1 Lean duplex grades as longitudinally welded pipes for linepipes in the oil and gas business
2006:1 effect of cathodic current densities and strain rates on ssrt fracture behaviour of lean duplex stainless steels and a 13%cr supermartensitic stainless steel in synthetic formation water
2006:1 the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments
2006:4 LDX 2101®, a new stainless steel with excellent machining properties
2005:2 corrosion properties of UNs s32101 – a new duplex stainless steel with a low nickel content tested for use as reinforcement in concrete
2002:1-2 a new lean duplex stainless steel for construction purposes
high strength steel 2003:2 Utilizing high strength stainless steel for storage tanks
2002:3-4 hytens creates new opportunities for high strength stainless steel applications
1994:1 Design ideas and case studies utilising duplex stainless steels
specific steel grades 2010:4 LDX 2101® Lean duplex – the first decade of service experience
2007:1 LDX 2101® the use of a lean duplex stainless steel UNs s32101: thermal dimple jackets on vessels for high purity applications
2006:1 LDX 2101® the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments
2006:2 353 ma® oxidation of s35315 in water vapor containing atmospheres under cyclic and isothermal conditions
2006:4 LDX 2101® LDX 2101®, a new stainless steel with excellent machining properties®
2005:2 LDX 2101® corrosion properties of UNs s32101 – a new duplex stainless steel with a low nickel content tested for use as reinforcement in concrete
2005:3 LDX 2101® Utilization of the material strength for lower weight and cost with LDX 2101®
2002:1–2 LDX 2101® a new lean duplex stainless steel for construction purposes
2002:3–4 hytens® hytens creates new opportunities for high strength stainless steel applications
2001:1–2 654 smo® a comparison between two high molybdenum superaustenitic stainless steel grades
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2001:1–2 254 smo® electrochemical studies of 254 smo stainless steel in comparison with 316L stainless steel and hastelloy c276 in phosphoric acid media in absence and presence of chloride ions
2001:3-4 4401 the influence of drinking water quality on the corrosion of stainless steel eN 1.4401 (ss 2347, aisi 316)
1998:2 654 smo® applications and experience with a superaustenitic 7mo stainless steel in hostile environments
1997:4 654 smo® the seawater resistance of a superaustenitic 7mo stainless steel
1996:1 654 smo® seawater resistance of a second generation superaustenitic stainless steel
1996:2 2205 machinability, corrosion resistance and weldability of an inclusion modified 2205 duplex stainless steel
1996:2 2205 the lateral homogeneity of passive films formed on the duplex stainless steel 2205 investigated with aes and XPs
1995:1 654 smo® UNs s32654, a new superaustenitic stainless steel for harsh environments
1995:4 353 ma® avesta sheffield 353ma – a material for very high temperatures and harsh environments
1994:4 654 smo® welding of UNs s32654 – corrosion properties and metallurgical aspects
1992:2 654 smo® avesta 654 smo™ – a new high molybdenum, high nitrogen stainless steel
1992:4 254 smo® application of UNs s31254 (254 smo®) austenitic stainless steel in power plants
1991:1–2 254 smo® experiences with a highly alloyed stainless steel in desalination plants and other arabian Gulf industrial plants
1990:3 254 smo® experiences with a high-alloys stainless steel under highly corrosive conditions
1989:1 253 ma® influence of carbon and nitrogen content on the creep properties of the austenitic stainless steel 253ma
1987:3–4 254 smo® Performance of a high molybdenum stainless steel in the pulp and paper industry
1987:3–4 254 smo® Field experience in the application of 254 smo (UNs s31254) in the scandinavian pulp and paper industry
1986:1–2 2205 influence of nitrogen on weldments in UNs31803
1986:1–2 2205 textures and anisotropy in duplex stainless steel ss2377 (2205)
1985:4 253 ma® high temperature behaviour of the austenitic stainless steel astm UNs30815 (253ma) and weldments
1984:1 904L influence of copper on the resistance of 20cr25Nimo stainless steels to pitting and crevice corrosion
1984:3 254 smo® Performance of a high molybdenum stainless steel in gas cleaning systems
1983:2 4439 stainless steel X 3 crNimoN17 13 5 – a successful compromise between materials, costs and performance properties
1982:2 4521 on the corrosion behavior of a ferritic 18cr-2mo steel
1982:2 4521 experience with an 18cr-2mo alloy in the chemical and petrochemical industries
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superaustenitics 2010:4 superaustenitic stainless steels in demanding environments
2001:1-2 a comparison between two high molybdenum superaustenitic stainless steel grades
2001:1-2 electrochemical studies of 254 smo stainless steel in comparison with 316L stainless steel and hastelloy c276 in phosphoric acid media in absence and presence of chloride ions
1998:2 applications and experience with a superaustenitic 7mo stainless steel in hostile environments
1997:4 the seawater resistance of a superaustenitic 7mo stainless steel
1996:1 seawater resistance of a second generation superaustenitic stainless steel
1995:1 UNs s32654, a new superaustenitic stainless steel for harsh environments
1995:2 Development of superaustenitic stainless steels
1994:4 welding of UNs s32654 – corrosion properties and metallurgical aspects
1992:2 avesta 654 smo™ – a new high molybdenum, high nitrogen stainless steel
1992:4 application of UNs s31254 (254 smo®) austenitic stainless steel in power plants
1991:1-2 experiences with a highly alloyed stainless steel in desalination plants and other arabian Gulf industrial plants
1990:3 experiences with a high-alloys stainless steel under highly corrosive conditions
1989:2 corrosion and corrosion testing of high-alloy stainless steel weldments
1987:3-4 Performance of a high molybdenum stainless steel in the pulp and paper industry
1987:3-4 Field experience in the application of 254 smo (UNs s31254) in the scandinavian pulp and paper industry
1984:3 Performance of a high molybdenum stainless steel in gas cleaning systems
tubing
2006:1 Lean duplex grades as longitudinally welded pipes for linepipes in the oil and gas business
2006:1 effect of cathodic current densities and strain rates on ssrt fracture behaviour of lean duplex stainless steels and a 13%cr supermartensitic stainless steel in synthetic formation water
2006:1 the introduction of alloy 2101 for use as zinc-clad umbilical tubing for deepwater subsea oil and gas developments
2003:4 stainless steels for swro plants high pressure piping, properties and experience
2003:3 effects of gas atmosphere and surface quality on rouging of three stainless steels in wFi
1996:4 steam side droplet erosion in titanium tubed condensers – experiences and remedies
1995:3 stainless steel for high pressure piping in swro plants. are there any options?
1994:2 the role of nitrogen in longitudinal welding of tubing in duplex stainless steels
1987:1 corrosion engineering of high pressure piping in ro-plants
1985:3 optimization of high-pressure piping in reverse osmosis plants
1982:1 a user’s view of the need for quality assurance in welded stainless steel pipe manufacture
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1982:1 the corrosion behavior of welded stainless pipe
1982:2 on the corrosion behavior of a ferritic 18cr-2mo steel
1982:2 experience with an 18cr-2mo alloy in the chemical and petrochemical industries
1981:4 stainless steel for saline cooling water in the fertilizer industry
1981:2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel
1981:1 a new approach to scale control
water and water treatment
chlorination 2004:1 service experience with high performance stainless steels in
aggressive fresh waters
1998:1 corrosion of duplex stainless steels in seawater
1990:4 some factors affecting stainless steel corrosion in seawater
1989:4 effect of chlorination on stainless steels in sea water
Desalination 2005:1 why clad when there is duplex?
2003:4 stainless steels for swro plants high pressure piping, properties and experience
2003:4 msF chambers of solid duplex stainless steel
1995:3 Desalination of seawater by reverse osmosis – the malta experience
1995:3 stainless steel for high pressure piping in swro plants. are there any options?
1993:2 corrosion problems in low-temperature desalination units
1991:1-2 reverse osmosis – which stainless steel to use?
1991:1-2 experiences with a highly alloyed stainless steel in desalination plants and other arabian Gulf industrial plants
1987:1 corrosion engineering of high pressure piping in ro-plants
1985:3 optimization of high-pressure piping in reverse osmosis plants
1984:4 the use of stainless steels and related alloys in reverse osmosis desalination plants
1982:3 crevice corrosion tests in seawater in the arabic Gulf
1982:3 Preventing corrosion in air ejector condenser systems
1981:1 stainless steels in desalination plants
1981:SI technico-economical aspects on the design, fabrication, and operational reliability of thermal desalination plants
Drinking water 2001:3-4 the influence of drinking water quality on the corrosion of stainless
steel eN 1.4401 (ss 2347, aisi 316)
Fresh water
2004:1 service experience with high performance stainless steels in aggressive fresh waters
seawater 2003:4 stainless steels for swro plants high pressure piping,
properties and experience
2003:4 msF chambers of solid duplex stainless steel
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1998:1 corrosion of duplex stainless steels in seawater
1997:4 the seawater resistance of a superaustenitic 7mo stainless steel
1996:1 seawater resistance of a second generation superaustenitic stainless steel
1995:3 Desalination of seawater by reverse osmosis – the malta experience
1995:3 stainless steel for high pressure piping in swro plants. are there any options?
1993:1 Fatigue performance of nine bolt materials in air and in seawater with cathodic protection
1993:2 corrosion problems in low-temperature desalination units
1991:1–2 reverse osmosis – which stainless steel to use?
1990:4 some factors affecting stainless steel corrosion in seawater
1989:4 effect of chlorination on stainless steels in sea water
1988:1 crevice corrosion of stainless steels in seawater
1987:2 Galvanic corrosion of copper alloys in contact with highly alloyed stainless steel in seawater
1986:3-4 sea water handling systems: past, present and future
1986:3-4 selection of high-alloyed steels for seawater-cooled condensors
1985:3 optimization of high-pressure piping in reverse osmosis plants
1984:2 corrosion control in the offshore industry
1984:2 advanced steels and metal alloys offshore – a summary
1984:4 the use of stainless steels and related alloys in reverse osmosis desalination plants
1982:3 crevice corrosion tests in seawater in the arabic Gulf
1981:1 stainless steels in desalination plants
1981:4 stainless steel for saline cooling water in the fertilizer industry
wastewater 2004:1 mic on stainless steels in wastewater treatment plants
– field tests and a risk assessment
2001:3-4 stainless steels in sewage treatment plants
welding
2010:3 Fatigue properties of thin sheet stainless steel lap joints
2009:1 the welding consequences of replacing austenitic with duplex stainless steel
2009:1 Fracture toughness of welded commercial lean duplex stainless steels
2006:1 Lean duplex grades as longitudinally welded pipes for linepipes in the oil and gas business
2006:3 austenitic and duplex stainless steels used as construction materials
2002:1–2 Fatigue behaviour of stainless steel welds
1997:3 how to perform welding in duplex stainless steels to obtain optimum weld metal properties
1996:2 machinability, corrosion resistance and weldability of an inclusion modified 2205 duplex stainless steel
1994:2 the role of nitrogen in longitudinal welding of tubing in duplex stainless steels
1994:4 welding of UNs s32654 – corrosion properties and metallurgical aspects
1990:2 Duplex stainless steels in chemical tankers – properties and practical experience
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1989:2 corrosion and corrosion testing of high-alloy stainless steel weldments
1986:1–2 influence of nitrogen on weldments in UNs31803
1985:4 high temperature behaviour of the austenitic stainless steel astm UNs30815 (253ma) and weldments
1982:1 a user’s view of the need for quality assurance in welded stainless steel pipe manufacture
1982:1 the corrosion behavior of welded stainless pipe
1982:2 on the corrosion behavior of a ferritic 18cr-2mo steel
1981:2 a survey of some failures typical for tanks and piping systems in austenitic stainless steel
1981:SI technico-economical aspects on the design, fabrication, and operational reliability of thermal desalination plants
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Comments on acom and its articles or suggestions on future articles are appreciated and should be sent to the editor Jesper Gunnarsson at [email protected]
This document is for information only and seeks to provide professionals with the best possible information to enable them to make appropriate choices. Although every effort has been made to ensure the accuracy of the information provided in this document, Outokumpu can not accept any responsibility for any loss, damage or other consequence resulting from the use of this publication. The information provided herein may be subject to alterations without notice.
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