role of n2 in austenitic ss

Role of nitrogen on the corrosion behavior ofaustenitic stainless steels

H. Baba *, T. Kodama, Y. Katada

National Institute for Materials Science, 1-2-1, Sengen, Tsukuba-shi, Ibaraki-ken 305-0047, Japan

Received 13 December 2001; accepted 6 February 2002

Abstract

The role of nitrogen in the mechanisms of localized corrosion resistance and repassivation

were electrochemically investigated using a nitrogen-bearing austenitic stainless (SUS316L)

steel in 0.1 and 0.5 M Na2SO4 solutions and a 3.5% NaCl solution. Almost 100% of the ni-

trogen compounds dissolved into the bulk solution after crevice corrosion were transformed

into NH3. That is, the mole amount of ammonia in the solution was approximately equivalent

to the mole amount of nitrogen dissolved in the steel. This suggests that NH4þ consuming Hþ

in the pit controlled the local decrease of pH and promoted the repassivation. NO3–N and

NO2–N were not detected by chemical analyses in the high potential and thermodynamically

stable zone as NO�3 in the potential–pH diagram. The repassivation in nitrogen-bearing

SUS316L steel in a 0.1 M Na2SO4 solution was studied using the scratching electrode tech-

nique, which measured the partially destroyed passivation films on the steel. This technique

showed that nitrogen dissolved in the steel has a strong repassivation capacity. � 2002

Elsevier Science Ltd. All rights reserved.

Keywords: Nitrogen reaction; Crevice corrosion; Pitting corrosion; Stainless steel; Repassivation;

Scratching electrode; Transient current

1. Introduction

Although the formation of a film of chromium oxide is effective for protectingstainless steels, when localized damage on this passive film occurs, corrosion ad-vances rapidly. Generally, in most metals and alloys this passive film is difficult to

www.elsevier.com/locate/corsci

Corrosion Science 44 (2002) 2393–2407

*Corresponding author. Tel.: +81-298-59-2331; fax: +81-298-59-2301.

E-mail address: [email protected] (H. Baba).

0010-938X/02/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.

PII: S0010-938X(02 )00040-9

remove by cathodic reduction. The repassivation that takes place after mechanicaldamage of the original passivation film exposes a new surface has been studied usingdiverse methods, such as scratch [1–3], rub [4,5], erosion [6] and abrasion [7–9]. Aftera new surface is exposed, a new passivation film is formed again by dissolution re-action of the metal, cathodic reaction (Hþ discharge), and charging of the electricdouble layer. Research work on the process is crucial for studying repassivationtrends in alloys, as well as for evaluation of corrosion sensitivity.

S. Ahila [10] investigated the passivation mechanism of Cr–Mn steel, and Cr–Nisteel in a solution of Na2SO4–NaCl in the presence of nitrogen using the scratchtechnique to impart mechanical damage. Results indicated that a large amount ofnitrogen existed at the boundary between the metal and the oxidation film, and thatthe nitrogen induced effectively the re-appearance of passivation film and increasedthe localized corrosion resistance of this film.

On the other hand, although doping of austenitic stainless steel with nitrogen islimited by its solubility, it has been well known for several decades from some re-search [11,12] that nitrogen dissolved in austenitic steel increases its strength, andimproves the resistances to pitting corrosion and crevice corrosion in solutionscontaining chloride ions. The following mechanisms have been suggested to explainhow nitrogen operates: (1) nitrogen in solid solution is dissolved and producesNH4

þ, depressing oxidation inside a pit [11,13–15]; (2) concentrated nitrogen at thepassive film/alloy surface stabilizes the film, and prevents attack of anions (Cl�) [16–19]; (3) produced nitrate ions improve the resistance to pitting corrosion [20]; (4)nitrogen addition stabilizes the austenitic phase [21]; and (5) nitrogen blocks thekink, and controls the increase of electric current for pit production [22]. However,there are still many points that must be clarified.

In the present research, a nitrogen-bearing 316L austenitic stainless steel was usedto investigate the effect of nitrogen addition on the mechanisms of localized corro-sion resistance and repassivation. The capacity for repassivation was evaluated usinga cell constituted of a reference electrode and a platinum counter electrode. A newsurface was exposed by instantaneous scratching in an experimental solution using amicrogrinder diamond blade. Instantaneous natural potential variation with time, aswell as transient phenomena of electric current decay at a given potential were in-vestigated for each specimen. After controlled potential electrolysis of nitrogen-bearing stainless steel with produced crevices, the amount of nitrogen compoundsdissolved in the bulk solution at the anode side was quantitatively measured to in-vestigate the suppression mechanism.

2. Experimental

2.1. Sample preparation

The chemical composition of the samples is described in Table 1. Austeniticstainless steel (SUS316L steel) was used as a base material for all the samples. Insamples F1 to F4, the nitrogen concentration was varied to try to minimize the

2394 H. Baba et al. / Corrosion Science 44 (2002) 2393–2407

presence of intermediate elements. In samples F5 to F8, 20% manganese (Mn) wasadded to the steels to increase the solubility of nitrogen.

F1 to F8 steels were high purity materials. Slabs 2–3 mm thick were made bydissolution in high vacuum, followed by forging, hot rolling, cold rolling, and finallyby the solution-heat treatment at 1150 �C for 20 min. Nitrogen content in F4N steelwas increased by thermal treatment of F4 steel at 1200 �C for 24 h in a nitrogenatmosphere. No precipitation of chromium nitride particles was detected, indicatingthat the specimen is a mono-phase of austenitic steel. Samples of 20� 30� 2 mmand of 50� 50� 3 mm were cut from the slabs and polished using a wet emery paperof number 600. Some samples were also prepared by buff-polishing using diamondpaste, washing in water, degreasing with acetone, washing in alcohol, and drying.

2.2. Electrochemical measurements

Experiments were designed to investigate the role of nitrogen on the repassivationmechanisms and localized corrosion resistance of SUS316L steels with different ni-trogen contents, using a 0.5 and 0.1 M H2SO4 solutions and a 3.5% NaCl solution aselectrolyte solutions. All experiments were carried out at 25 �C.

The effects of nitrogen addition were evaluated by the polarization curve as well asby pitting corrosion, crevice corrosion, and repassivation experiments.

2.2.1. Repassivation mechanism caused by self-potential and current transientphenomena

How a repassivation film was formed again after the passivation film was damagedin a solution was investigated. The cell used was consisted of a reference electrode anda platinum electrode. In the cell immersed in the test solution, a microgrinder dia-mond blade was used to expose the sample surface by scratching by rotating at highspeed and completing the movement from top to bottom in approximately 1 s. In-stantaneous self-potential variations with time as well as variations with time ofelectric current decay curve at a constant potential were measured for each specimen.Scratching of the specimen was carried out after immersion for 30 min in the test

Table 1

Chemical compositions of steels, mass%

Sample

no.

C Si Mn P S Ni Cr Mo N Al

(total)

O

F1 0.004 0.01 <0.01 <0.001 0.001 14.23 16.64 2.25 0.002 0.045 0.002

F2 0.002 0.01 <0.01 <0.001 0.001 14.26 16.56 2.27 0.056 0.073 0.002

F3 0.001 0.01 0.01 0.001 0.001 14.10 16.40 2.23 0.114 0.064 0.002

F4 0.003 0.02 0.01 0.001 0.001 14.08 16.36 2.29 0.171 0.078 0.002

F4N 0.003 0.02 0.01 0.001 0.001 14.08 16.36 2.29 0.515 0.078 0.002

F5 0.007 0.01 20.3 <0.001 0.002 14.43 16.63 2.32 0.004 0.003 0.003

F6 0.003 0.01 20.1 <0.001 0.002 14.39 16.62 2.26 0.118 0.009 0.005

F7 0.002 0.01 20.1 <0.001 0.003 14.26 16.96 2.18 0.320 0.018 0.002

F8 0.002 0.01 20.0 <0.001 0.002 14.29 16.91 2.18 0.394 0.010 0.003

H. Baba et al. / Corrosion Science 44 (2002) 2393–2407 2395

solution. A saturated calomel electrode was used as a reference electrode, and thepotential values were presented according to the SCE standard.

2.2.2. Controlled potential electrolysis and quantitative analysis of the nitrogencompounds

Crevice-forming devices were made from polysulfur resin discs of 25.4 mm di-ameter. A crevice assembly was fabricated by applying an 8.5 Nm torque to setcrevice devices on both sides of a test specimen of 50� 50� 3 mm and fixing themby titanium bolts. The assembly was immersed in a 3.5% NaCl solution (260 cm3) inthe anode section of a glass electrolytic cell where the anode and the cathode wereseparated by a glass filter.

The cathodic section contained the same 3.5% NaCl solution (260 cm3) and a Ptcounter electrode. A saturated calomel electrode was used as reference electrode andcontrolled potential electrolysis was carried out at a fixed potential by a potentiostat.The current density at that time and the variation of pH with time were measured,and the velocity of crevice corrosion was calculated from the data of weight loss ofthe specimen during the controlled potential electrolysis.

Among the compounds produced by nitrogen dissolved from crevice corrosioninto the bulk solution in the anode section, quantities of ammonia based nitrogen(NH3–N), nitrous based nitrogen (NO2–N), and nitric based nitrogen (NO3–N) werequantitatively analyzed by absorptiometry using the model ASTM D1426-93 or themodel ASTM D3867-90.

2.2.3. Polarization measurementsPotentiodynamic polarization was carried out at 20 mVmin�1 in the anode di-

rection, starting from the self-potential after 10 min of cathodic reduction reaction at�0.7 V (SCE) in an argon free 0.5 M H2SO4 solution kept at 25 �C. The poten-tiodynamic polarization curves were also calculated at 20 mVmin�1 for an argon free3.5% NaCl solution. The value of potential exceeding 10�4 A cm�2 after a suddenincrease of electric current was called the pitting corrosion potential (Epit). A calomelelectrode was used as reference electrode, and potential values were exhibited ac-cording to the SCE standard.

3. Results and discussion

3.1. Polarization curve

A large number of researchers have studied the anode polarization curve of anitrogen-bearing austenitic stainless steel in sulfuric acid solutions or in its Cl�

adding solutions [11,19,23–25].Some of these researchers reported that nitrogen acted to increase the critical

passivation current density (icrit), whereas other researchers reported just the oppo-site effect, that is, nitrogen lowered the critical density (icrit). A few more have said


that the nitrogen had no effect on the critical density (icrit). The effect of nitrogen hasnot been well understood.

Fig. 1(a) shows anodic potentiodynamic polarization curves for a SUS316L steel(low Mn content) in 0.5 M H2SO4 solution with diverse amounts of nitrogen ad-dition. In this figure, it is evident that no trends of icrit nor passivation-maintainingcurrent densities varied for any specimen. From these polarization behaviors, therewas not any noticeable effect of the nitrogen addition, nor apparent differences re-garding the formation of the passivation film on the modified steels. At icrit valueshigher than 1 mAcm�2, nitrogen dissolved in solid solution lowered the icrit, whereasfor lower icrit values there were not any apparent effects of nitrogen on icrit values [22].For high values of icrit, nitrogen tended to be concentrated on the metal surface, andit was thought that this controls the dissolution process [26]. As shown in Fig. 1(a),the icrit value was much lower than 1 mAcm�2, and the nitrogen addition did notexhibit any noticeable effects on the anodic polarization curves. Fig. 1(b) shows thecurve of anodic potentiodynamic polarization of a SUS316L steel (high Mn steel) in0.5 M H2SO4 with different amounts of nitrogen additive. Regardless of the highamount of nitrogen, icrit values were higher than for low Mn steels. This behaviorcould be attributed to the high Mn content [27].

Fig. 2 shows polarization curves of high Mn and low Mn SUS316L steel withdifferent amounts of nitrogen additive in a 3.5% NaCl solution.

As has been reported before [14,15,28–30], the pitting corrosion potential (Epit) oflow and high Mn steels in a chloride-ion-containing solution increased with theamount of nitrogen additive. However, despite the high nitrogen content, high Mncontaining steel (F8) showed a Epit value much lower than the Epit value for low Mnmaterial. This phenomenon could be attributed to the presence of non-metal inter-mediates such as MnS at the grain boundary, which lowered the resistance to localcorrosion.

3.2. Evaluation of the repassivation mechanism of the new surface exposed byscratching

3.2.1. Effect of nitrogen on the time variation of self-potentialFig. 3 shows time variations of self-potential for high and low Mn specimens with

different nitrogen content, after a new surface was exposed by scratching with adiamond blade in a 0.1 M Na2SO4 solution. When a new surface was exposed byscratching, the potential dropped dramatically, but it increased in a very short timeafter scratching was stopped. After 1 h, the potential recovered to a value corre-sponding to the value before scratching. This recovery was much faster in the lowMn steel with a high nitrogen content, and the final value of potential was higherthan in the high Mn steel.

3.2.2. Effect of nitrogen on the current decayFig. 4 shows an example of a current decay curve for a steel with a newly exposed

surface kept at 0.75 V (SCE) in a 0.1 M Na2SO4 solution. When scratching of thesurface with a passivation film started, the current gradually increased. Once the


Fig. 1. Anodic polarization curves of nitrogen-bearing 316L stainless steels in 0.5 M H2SO4: (a) low Mn

steels, (b) high Mn steels.


scratching was stopped and the diamond blade was retired, there appeared a suddenjump of the current attributed to the exposure of a new surface. Afterwards, thecurrent returned to the original value because of repassivation, where the maximumcurrent was called the peak current of repassivation.

Fig. 5(a) and (b) correspond to current decay curves for high Mn and low Mnsteels respectively, with a newly exposed surface under a controlled potential of

Fig. 2. Potentiodynamic polarization curves of nitrogen-bearing 316L stainless steels in 3.5% NaCl.

Fig. 3. Variation in the rest potential with time of nitrogen-bearing 316L stainless steels in 0.1 M Na2SO4

solution after scratching.


0.75 V (SCE) in a 0.1 M Na2SO4 solution. The decay curves for high Mn and lowMn-containing SUS316L steels, differ according to the type of steel. The higher therespective amount of nitrogen addition, the steeper was the slope of decay, and thehigher the repassivation effect. Specifically, the presence of nitrogen in the steel assolid solution enhanced the repassivation process. Thus, from the present study, the

Fig. 4. Current decay curve after the new exposure surface formed.

Fig. 5. Current decay after scratching of nitrogen-bearing 316L stainless steels in 0.1 M Na2SO4 solution

under potentiostatic condition of 0.75 V (SCE): (a) high Mn steels, (b) low Mn steels.


role of the nitrogen dissolved as a solid solution in the steel was a significant effect inthe repassivation process after the original passivation film was damaged, ratherthan helping to form and to preserve the passivation film. It is well known thatnitrogen-bearing austenitic steel is dissolved by corrosion and that nitrogen is con-centrated at the interface between the passivation film and the metal from AES andXPS analyses [16–18]. Lu et al. [16] suggested that the concentrated nitrogen sup-presses further dissolution of the metal.

Fig. 6 shows repassivation peak currents for steels with newly exposed surfaces forpotential values in 0.1 M Na2SO4 solution. The repassivation peak current increasedwith increasing potential, and decreased to a low value with increasing amount ofnitrogen.

3.3. Effect of nitrogen on the crevice corrosion

The effect of nitrogen on the corrosion behavior of a sample with crevice formedwas investigated. Specimens with crevice formation were immersed in a 3.5% NaClsolution in the anodic section of a electrolytic cell. Controlled potential electrolysiswas carried out at the prescribed potential, and the resultant curves of currentdensity vs. time are shown in Fig. 7. Controlled potential electrolysis was carried outat 0.3 V (SCE), and behaviors of a steel with nitrogen addition (F4) and a steelwithout nitrogen addition (F1) were compared. The results indicated that the currentdensity was extremely low indicating formation of passivation on the surface. On theother hand, controlled potential electrolysis at 0.4 V (SCE) resulted in a gradualincrease in the current density for the nitrogen-bearing steel (F4), and it was sug-gested that the crevice corrosion proceeded.

It is of crucial importance to consider how nitrogen in steels affects the repassi-vation process of the metal surface. Specimens of nitrogen-bearing SUS316L steelwith crevice formation were immersed in a 3.5% NaCl solution in the anodic sectionof the electrolytic cell and controlled potential electrolysis was carried out at aconstant potential. Table 2 summarizes the results from quantitative analyses of the

Fig. 6. Repassivation peak current after scratching of nitrogen-bearing 316L stainless steels in 0.1 M

Na2SO4.


nitrogen compounds dissolved in the bulk solution at the anodic section as well asthe transformation rate of NH3–N to the NH3. Crevice corrosion was not observedin specimens with controlled potential electrolysis at low potential (F8 steel: 0.05 V(SCE), F4 steel: 0.3 V (SCE), and F4N steel: 0.4 V (SCE)), that is, there is no pre-cipitation of NH3–N, NO3–N, and NO2–N. When controlled potential electrolysiswas carried out at potentials that allow crevice corrosion (F8 steel: 0.1 V (SCE), F4steel: 0.4 V (SCE), and F4N steel: 0.7 V (SCE)), NH3–N was detected in the bulksolution, and the NH3 transformation rate of the nitrogen presented as solid solutionin the steel was almost 100% regardless of the amount of nitrogen in the steel.However, NO3–N and NO2–N were not detected in the bulk solution for any of thesteels. In other words, the mole content of ammonia dissolved in the solution cor-responded almost completely to the mole content of nitrogen that was contained inthe steel. There are several reports [11,14,29,30] on analyses of the nitrogen com-pounds formed from nitrogen contained in the steel and dissolved into the solution.These results were in complete agreement with the results reported by Osozawa et al.[11] who reported that nitrogen dissolved into the solution was present as NH4

þ. Theamount of Hþ forming NH4

þ in the pit detected in the solution corresponded to theamount of N in the dissolved metal. Thus, it was suggested that formed NH4

þ

controlled the local decrease of pH and promoted the repassivation.

Fig. 7. Current density vs. time curve for nitrogen-bearing 316L stainless steels in 3.5% NaCl at applied

potentials of 0.3 and 0.4 V (SCE).

Table 2

Conversion of nitrogen in stainless steel into ammonia as the result of electrochemical dissolution of

stainless steels

Steel type E (V vs. SCE) Time (h) NH3–N (ppm) NO3–N (ppm) NH3 conversion (%)a

F8 (0.394N) 0.05 3 0 0 –

0.1 3 0.15 0.04 102

F4 (0.171N) 0.3 6 0 0 –

0.4 6 0.71 0.03 116

F4N (0.515N) 0.4 24 0 0 –

0.7 6 1.61 0.03 120

aConversion efficiency of interstitial N in stainless steels to ammonia (molar ratio).


Fig. 8 shows the relationship between crevice corrosion rate and nitrogen contentfor a low Mn steel, SUS316L, with diverse nitrogen content after forming crevices.Controlled potential electrolyses were conducted for 6 h at diverse potential values ina 3.5% NaCl solution. It was found that an increase in the nitrogen content retardedthe crevice corrosion rate and that nitrogen in solid solution suppressed crevicecorrosion. Also, the crevice corrosion rate increased as the electrolysis potentialincreased.

The amount of nitrogen compounds in the bulk solution at the anode side wascalculated by controlled potential electrolysis at diverse potentials using the potentialvs. pH equilibrium diagram [31] for the NH3–H2O system.

As shown in Fig. 9, F4N steel (indicated as A on the diagram) exists in the NO�3

stable region, but almost all the time it was detected as NH3–N. Using the potential–pH equilibrium diagram for the NH3–H2O system, Jargelius-Pettersson [30] sug-gested that even in the thermodynamically stable region of NO�

3 , almost all of thenitrogen was detected in the NH4

þ form.

3.4. Reaction of nitrogen

Nitrogen dissolved in the austenitic steel exists as an interstitial atom in the cell,but if it contacts water, the following reaction takes place to form NH3:

Nþ 3H2Oþ 3e� ¼ NH3 þ 3OH�

Fig. 8. Effect of N content on crevice corrosion rate of nitrogen-bearing 316L stainless steels in 3.5%

NaCl.


where underlined N indicates the element N in solid solution. As is evident from thisequation, the ammonia production reaction is an cathodic reaction and a reversereaction of the metal anodic dissolution.

To evaluate the reaction for dissolution of the nitrogen in solid solution, it isnecessary to establish the chemical potential (l) of N in the stainless steel. Thematerial used in the present work was analyzed as a 23Cr–4Ni–2Mo–Fe–N stainlesssteel with a high nitrogen content. The nitrogen in solid solution is naturally su-persaturated at room temperature with a tendency to precipitate Cr2N.

It is assumed that the N in solid solution and Cr2N are in equilibrium, and thatthe activity of N is the standard value (l;

N).

Nþ 2Cr ¼ Cr2N

0 ¼ DG ¼ DG0 � 2:3RT logf½mass% N�a2Crg;

DG0 ¼ l0Cr2N � l;

N � 2l0Cr:

From the thermodynamic data

l0Cr2N ¼ �104:2 kJ mol�1 ð298 KÞ:

Assuming that the activity of Cr in solid solution follows Raoult’s law, l0Cr ¼ 0

according to the definition. In the case of the 23Cr–4Ni–2Mo–Fe–N system, the limitto the solubility of nitrogen can be calculated using ThermoCalc with the followingequation:

log½mass% N� ¼ �3; 661=T þ 2:59:

Fig. 9. E–pH diagram for a system consisting of ammonia, nitrite and nitrate. A, B and C indicate the

potentials at which samples F4N, F4 and F8 are processed for crevice corrosion.


When the activity of Cr in solid solution is an ideal fluid,

aCr ¼ xCr ¼ 0:23:

Assuming that this solubility limit is the standard activity at each temperature, thechemical potential of N is expressed with the following equation:

l;N ¼ l0

Cr2N � 2:3RTfð�3; 661=T þ 2:59Þ þ 2 log 0:23g:

From this equation, the chemical potential of N in solid solution of the 23Cr–4Ni–2Mo–Fe–N system is calculated from the following equation:

lN ¼ l;N þ 2:3RT logðmass% NÞ:

In the case of 23Cr–4Ni–2Mo–Fe–1.0N steel, lNð1 mass%Þ ¼ �41:6 kJmol�1.Fig. 10 shows the E–pH diagram of N in an c steel (23Cr–4Ni–2Mo–Fe–1.0N

steel) with 1.0% of nitrogen in solid solution. the E–pH diagrams of Fe and Cr arelayered in the same figure. The stable region for nitrogen N in solid solution is drawnas a shadowed area. This figure suggests that N operates as a slightly milder oxidantthan Hþ.

In the present study using a scratching electrode, it was found that the nitrogen Nin solid solution acts to increase the steel potential and to promote the repassivationprocess. On the other hand, as the above-described thermodynamic evaluationshows, N is a mild oxidant at room temperature and not strong enough to acceleratethe repassivation. As the thermodynamic values for N used in the above evaluationwere calculated from an extrapolation of values obtained in the 1000–1200 �C rangeon the solid solubility curve in the vicinity of room temperature, it was impossible to

Fig. 10. E–pH diagram for nitrogen where interstitial N (hatched zone) is presumed to be active in redox

reaction. For comparison the diagram for Fe and Cr are also given.


avoid introducing a considerable error into the calculation of lN (298 K). Therefore,it is necessary to refine the accuracy of the calculation.

If nitrogen in solid solution is a strong oxidant as a passivation agent, that is, ifthe N and NH4

þ coexisting line in Fig. 10 shifts to a higher potential zone, the strongrepassivation capacity of the high nitrogen-bearing steel would be explained withoutany contradiction, regardless of ammonia production.

4. Conclusions

Using a SUS316L steel with diverse nitrogen contents, the role of nitrogen in themechanisms of local corrosion resistance and repassivation were electrochemicallyinvestigated and the following conclusions were reached.

(1) An evaluation of the amount of nitrogen compounds dissolved into the bulksolution after crevice corrosion indicated that the transformation rate of solid so-lution nitrogen from the steel into NH3 was close to 100% regardless of the contentof nitrogen. That is, the mole amount of ammonia in the solution is approximatelyequivalent to the mole amount of nitrogen dissolved in the steel. Also, NO3–N andNO2–N were not detected by chemical analyses in the high potential and thermo-dynamically stable zone as NO�

3 in the potential–pH diagram.(2) Using the scratching electrode technique in a 0.1 M Na2SO4 solution, a new

surface was exposed in SUS316L steels with diverse nitrogen addition, and self-potential as well as decay current variation with time were measured. We obtainednotable results proving that nitrogen in solid solution of the steel facilitated therepassivation.

(3) In high and low Mn SUS316L steels with nitrogen addition, the nitrogen insolid solution increased the pitting corrosion potential (Epit) with the increase innitrogen content. On the other hand, regardless of the high nitrogen content, Epit

in high Mn steel showed lower values than in low Mn steel. This could be attributedto a high Mn additive decreasing the local corrosion resistance.

(4) Critical current density of passivation (icrit) in 0.5 M H2SO4 for nitrogen-bearing SUS316L steel was not clearly affected by the nitrogen addition.

References

[1] T.A. Adler, R.P. Walters, Corrosion 49 (1993) 399.

[2] G.T. Burstein, P.I. Marshall, Corros. Sci. 23 (1983) 125.

[3] J.C. Nelson, C. Kang, A. Bronson, Electrochem. Soc. 136 (1989) 2948.

[4] T.R. Beck, Electrochem. Acta 18 (1973) 807.

[5] D. Boomer, R. Hermann, A. Turnbull, Corros. Sci. 29 (1989) 1087.

[6] R. Oltra, C. Gabrielli, F. Heut, M. Keddam, Electrochem. Acta 31 (1986) 1501.

[7] J.R. Ambrose, J. Kruger, Corrosion 28 (1972) 30.

[8] M.B. Abuzriba, R.A. Dodd, F.J. Worzala, J.R. Conrad, Corrosion 48 (1992) 2.

[9] M. Barbosa, Corrosion 44 (1988) 149.

[10] S. Ahila, B. Reynders, H.J. Grabke, Corros. Sci. 38 (1996) 1991.


[11] K. Osozawa, N. Okato, Y. Fukase, K. Yokota, Boshoku-Gijyutsu (Corros. Eng.) 24 (1975) 1.

[12] J.E. Truman, M.J. Coleman, K.R. Pirt, Br. Corros. J. 12 (1977) 236.

[13] K. Osozawa, N. Okato, in: R.W. Stahele, H. Okada (Eds.), Passivity and its Breakdown on Iron and

Iron Base Alloys, NACE, 1976, p. 135.

[14] G.C. Palit, V. Kain, H.S. Gadiyar, Corrosion 49 (1993) 977.

[15] T. Komori, U. Nakada, in: Proceedings of the 39th Japan Corrosion Conference, JSCE, 1992, p. 353.

[16] Y.C. Lu, R. Bandy, C.R. Clayton, R.C. Newman, J. Electrochem. Soc. 130 (1983) 1774.

[17] C.-O.A. Olsson, Corros. Sci. 37 (1995) 467.

[18] I. Olefjord, L. Wergrelius, Corros. Sci. 38 (1996) 1203.

[19] A.S. Vanini, J.P. Audouard, P. Marcus, Corros. Sci. 36 (1994) 1825.

[20] H.P. Leckie, H.H. Uhlig, J. Electrochem. Soc. 113 (1966) 1262.

[21] M.A. Streicher, J. Electrochem. Soc. 103 (1956) 375.

[22] R.C. Newman, T. Shahrabi, Corros. Sci. 27 (1987) 827.

[23] A. Belfrouh, C. Masson, D. Vougner, A.M. DeBecdelievre, N.S. Prakash, J.P. Audouard, Corros. Sci.

38 (1996) 1639.

[24] S.J. Pawel, E.E. Stansbury, C.D. Lundin, Corrosion 45 (1989) 125.

[25] H. Yashiro, A. Tsuboi, K. Tanno, in: Proceeding of JSCE Corrosion’95, JSCE, 1995, p. 267.

[26] K. Osozawa, Zairyo-to-Kankyo (Corros. Eng.) 47 (1998) 561.

[27] P.R. Levey, A. van Bennekom, Corrosion 51 (1995) 911.

[28] H. Yashiro, D. Takahashi, N. Kumagai, K. Mabuchi, Zairyo-to-Kankyo (Corros. Eng.) 47 (1998)

591.

[29] H. Ohno, H. Tanabe, A. Sakai, T. Misawa, Zairyo-to-Kankyo (Corros. Eng.) 47 (1998) 584.

[30] R.F.A. Jargelius-Pattersson, Corros. Sci. 41 (1999) 1639.

[31] M. Pourbaix, in: Atlas of Electrochemical Equilibria in Aqueous Solutions, NACE, 1966, p. 493.


role of n2 in austenitic ss

Documents