dievar - home | assab · 3 23diev dievar dievar is a hot work die steel specially developed by...
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UDDEHOLMDIEVAR
DIEVAR
2
DIEVAR
ASSAB is a trademark of ASSAB Pacific Pte Ltd.
The information contained herein is based on our present state of knowledge and is intended to provide general notes on our products and their uses. It should not therefore be construed as a warranty of specific properties of the products described or a warranty for fitness for a particular purpose. Each user of ASSAB products is responsible for making its own determination as to the suitability of ASSAB products and services.
Edition D1141010
REFERENCE STANDARD
AISI WNr. JIS
ASSAB DF-2 ARNE O1 (1.2510) (SKS 3)
ASSAB DF-3 O1 (1.2510) (SKS 3)
ASSAB XW-5 SVERKER 3 D6 (D3) (1.2436) (SKD 2)
ASSAB XW-10 RIGOR A2 1.2363 SKD 12
ASSAB XW-41 SVERKER 21 D2 1.2379 SKD 11
ASSAB XW-42 D2 1.2379 SKD 11
CARMO CARMO 1.2358
CALMAX CALMAX 1.2358
CALDIE CALDIE
ASSAB 88 SLEIPNER
ASSAB PM 23 SUPERCLEAN VANADIS 23 SUPERCLEAN (M3:2) 1.3395 SKH 53
ASSAB PM 30 SUPERCLEAN VANADIS 30 SUPERCLEAN (M3:2 + Co) 1.3294 SKH 40
ASSAB PM 60 SUPERCLEAN VANADIS 60 SUPERCLEAN (1.3292)
VANADIS 4 EXTRA SUPERCLEAN VANADIS 4 EXTRA SUPERCLEAN
VANADIS 6 SUPERCLEAN VANADIS 6 SUPERCLEAN
VANADIS 10 SUPERCLEAN VANADIS 10 SUPERCLEAN
VANCRON 40 SUPERCLEAN VANCRON 40 SUPERCLEAN
ELMAX SUPERCLEAN ELMAX SUPERCLEAN
ASSAB 518 P20 1.2311
ASSAB 618 P20 Mod. 1.2738
ASSAB 618 HH P20 Mod. 1.2738
ASSAB 618 T P20 Mod. 1.2738 Mod.
ASSAB 718 SUPREME IMPAX SUPREME P20 Mod. 1.2738
ASSAB 718 HH IMPAX HH P20 Mod. 1.2738
NIMAX NIMAX
MIRRAX 40 MIRRAX 40 420 Mod.
VIDAR 1 ESR VIDAR 1 ESR H11 1.2343 SKD 6
UNIMAX UNIMAX
CORRAX CORRAX
ASSAB 2083 420 1.2083 SUS 420J2
STAVAX ESR STAVAX ESR 420 Mod. 1.2083 ESR SUS 420J2
MIRRAX ESR MIRRAX ESR 420 Mod.
POLMAX POLMAX
RAMAX HH RAMAX HH 420 F Mod.
ROYALLOY ROYALLOY
PRODAX
ASSAB PT18
ASSAB MMXL
ASSAB MM40
ALVAR 14 ALVAR 14 1.2714 SKT 4
ASSAB 2714 1.2714 SKT 4
ASSAB 8407 2M ORVAR 2M H13 1.2344 SKD 61
ASSAB 8407 SUPREME ORVAR SUPREME H13 Premium 1.2344 ESR SKD 61
DIEVAR DIEVAR
HOTVAR HOTVAR
QRO 90 SUPREME QRO 90 SUPREME
FORMVAR FORMVAR
ASSAB 705 4340 1.6582 SNCM8
ASSAB 709 4140 1.7225 SCM4
ASSAB 760 1050 1.1730 S50C
3
DIEVAR
DIEVARDievar is a hot work die steel specially developed by Uddeholm Tooling, our steel mill in Sweden, to provide the best possible performance.
The chemical composition and the very latest in production technique make the property profile outstanding. Dievar possesses a combination of excellent toughness and very good hot strength, resulting in a superior hot work die steel that have excellent resistance to heat checking and gross cracking.
Dievar is suitable for high demand hot work applications like die casting, extrusion and forging. The property profile also makes it a suitable choice in other applications such as plastic moulding (e.g., to solve chipping/cracking) and High Performance Steel.
Dievar offers the potential for significant improvements in die life, thereby improving the tooling economy.
4
DIEVAR
Applications
Type Cr-Mo-V alloyed hot work tool steel
Standard specification
None
Delivery condition
Soft annealed to approx. 160 HB
Colour code Yellow / Grey
DIE CASTING
EXTRUSION
Part Aluminium / Magnesium alloys
Dies 44-50 HRC
PartCopperalloys
Aluminium / Magnesium alloys
Dies - 46-52 HRC
Liners, dummy blocks, stems
46-52 HRC 44-52 HRC
General
Dievar is a high performance chromium-molybdenum-vanadium alloyed hot work tool steel which offers a very good resistance to heat checking, gross cracking, hot wear and plastic deformation. Dievar is characterised by:
Excellent toughness and ductility in all directions Good temper resistance Good high-temperature strength Excellent hardenability Good dimensional stability throughout heat treatment and coating operations
Dievar is a premium hot work tool steel developed by Uddeholm. It is manufactured utilising the very latest in production and refining techniques. The Dievar development has yielded a die steel with the ultimate resistance to heat checking, gross cracking, hot wear and plastic deformation. The unique properties profile of Dievar makes it the best choice for die casting, forging and extrusion.
Heat checking is one of the most common failure mechanisms, e.g., in die casting and nowadays also in forging applications. Dievar’s superior ductility yields the highest possible level of heat checking resistance. With Dievar’s outstanding toughness and hardenability, its resistance to heat checking will be further improved. If gross cracking is not a factor, then a higher workinghardness can be utilised (+2 HRC).
Regardless of the dominant failure mechanism (e.g., heat checking, gross cracking, hot wear or plastic deformation), Dievar offers the potential for significant improvements in die life as well as tooling economy.
Dievar is the material of choice for the high demand die casting, forging and extrusion industries.
HOT FORGING
Part Steel / Aluminium
Inserts 44-52 HRC
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DIEVAR
Properties
Temperature 20°C 400°C 600°C
Density kg/m3 7800 7700 7600
Modulus of elasticity MPa
210 000 180 000 145 000
Coefficient of thermal expansion per °C from 20°C
- 12.7 x 10-6 13.3 x 10-6
Thermal conductivity W/m °C
- 31 32
MECHANICAL PROPERTIES
Approximate tensile properties at room temperature, tested in the short transverse direction.
Hardness 44 HRC 48 HRC 52 HRC
Tensile strength, R
m
1480 MPa 1640 MPa 1900 MPa
Yield strength, R
P0.2
1210 MPa 1380 MPa 1560 MPa
Elongation, A5
13 % 13 % 12.5 %
Reduction ofarea, Z
55 % 55 % 52 %
The reported properties are representative of samples which have been taken from the centre of a 610 x 203 mm bar. Unless otherwise indicated, all specimens were hardened at 1025°C, quenched in oil and tempered 2 + 2 hours at 615°C to 45±1 HRC.
PHYSICAL PROPERTIES
Hardened and tempered to 44 - 46 HRC.
Approximate tensile properties at elevated temperatures
Short transverse direction, 45±1 HRC.
Charpy V-notch impact toughness at elevated temperatures
Short transverse direction.
At a hardness of approximately 45 HRC, the minimum average unnotched impact ductility is 300 J in the short transverse direction.
Temper resistance
The specimens have been hardened and tempered to 45 HRC, and then held at different temperatures from 1 to 100 hours.
100 200 300 400 500 700ºC600Testing temperature
200
400
600
800
1000
1200
1400
1600
1800
2000
Rm, Rp0.2MPa
10
20
30
40
50
60
70
80
90
100
A5, Z%
Z
Rm
Rp0.2
A5
50
Testing temperature
100 150 200 250 300 350 400 450°C
20
40
60
80
100
120
140
Impact energy, J
50 HRC
47 HRC
45 HRC
0.1 1 10 100Time, h
25
30
35
40
45
50
Hardness, HRC
500°C
550°C
600°C
650°C
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DIEVAR
Hardness, grain size and retained austenite as functions of austenitising temperature
SOFT ANNEALING
Protect the steel and heat through to 850°C. Then cool in the furnace at 10°C per hour to 650°C, then freely in air.
Tempering graph
Soaking time = time at hardening temperature after the tool is fully heated through.
Protect the tool against decarburisation and oxidation during austenitising.
Temperature °C
Soaking time minutes
Hardness before tempering
1000 30 52±2 HRC
1025 30 55±2 HRC
Heat treatment
STRESS RELIEVING
After rough machining, the tool should be heated through to 650°C, holding time 2 hours. Cool slowly to 500°C, then freely in air.
HARDENING
Preheating temperature: 600–900°C. Normally a minimum of two preheats, the first in the 600–650°C range, and the second in the 820–850°C range. When three preheats are used, the second is carried outat 820°C, and the third at 900°C.Austenitising temperature: 1000–1030°C
TEMPERING
Choose the tempering temperature according to the hardness required by reference to the tempering graph below. Temper at least three times for die casting dies, and two times for forging and extrusion tools. The tool should be cooled to room temperature between the tempers. The minimum holding time at tempering temperature is 2 hours.
Tempering in the range of 500–550°C is normally not recommended, and it will result in a lower toughness.
QUENCHING
As a general rule, quench rates should be as rapid as possible. Accelerated quench rates are required to optimise tool properties specifically with regards to toughness and resistance to gross cracking. However, risk of excessive distortion and cracking must be considered.
The quenching media should be capable of creating a fully hardened microstructure. Different quench rates for Dievar are defined by the CCT graph as shown in page 7.
High speed gas/circulating atmosphere Vacuum (high speed gas with sufficient positive pressure). An interrupted quench at 320–450°C is
recommended for distortion control, or when quench cracking is a concern.
Martempering bath, salt bath or fluidised bed at 450–550°C
Martempering bath, salt bath or fluidised bed at approx. 180–200°C
Warm oil, approx. 80°C
Note: Temper the tool as soon as its temperature reaches 50–70°C.
Austenitising temperture
990 1000 1010 1020 1030 1040 1050°C50
52
54
56
58
6010
8
6
0
2
4
GrainsizeASTM Hardness, HRC Retained austenite %
Grain size
Hardness
Retained austenite
Tempering temperature (2 + 2h)
100 200 300 400 500 600 700°C25
30
35
40
45
50
55
60Hardness, HRC Retained austenite, %
Retained austenite
Temper
1000°C
Austenitising temperature1025°C
2
4
6
7
DIEVAR
CCT graph
Austenitising temperature 1025°C. Holding time 30 minutes.
DIMENSIONAL CHANGES DURING HARDENINGAND TEMPERING
During hardening and tempering, the tool is exposed to both thermal and transformation stresses. These stresses will result in distortion. Insufficient levels of machine stock may result in slower than recommended quench rates during heat treatment. To reduce the level of distortion, a stress relief is always recommended bewteen rough and semi-finish machining, prior to hardening.
For a stress relieved Dievar tool, a minimum machining allowance of 0.3% is recommended to correct for distortion during heat treatment with a rapid quench.
Effect of tempering temperature on room temperature Charpy V-notch impact energy
Short transverse direction.
Tempering temperature (2h + 2h)
200 300 400 500 600 700°C
10
20
30
40
50
60
10
20
30
40
50
60
Impact strengthHardness HRC
Temper brittleness zone
Austenitising temperature 1025ºCHolding time 30 minutes
Carbides
Pearlite
Bainite
Martensite Mf
MS
AC1f
= 890ºC
AC1s
= 820ºC
1
98765432
681627620592566488468464405
1.515
280124832055200
104002080041600
CoolingCurve No.
HardnessHV 10
T800-500
(sec)
1 2 3 4 5 6 7 8 9
1 10 100 1000 10 000 100 000 Seconds
1 10 100 1000 Minutes
1 10 100 HoursAir cooling of
bars, Ømm60090101.50.2
1100
1000
900
800
700
600
500
400
300
200
100
°C
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DIEVAR
TURNING
Machining recommendations
MILLING
Face and square shoulder milling
Cutting data parameters
Milling with carbide
Rough milling Fine milling
Cutting speed (v
c)
m/min130 - 180 180 - 220
Feed (fz)
mm/tooth0.2 - 0.4 0.1 - 0.2
Depth of cut (ap)
mm2 - 4 ≤ 2
Carbidedesignation ISO
P20 - P40Coated carbide
P10Coated carbide
or cermet
Cutting data parameters
Turning with cabideTurning
with HSS†
Rough turning
Fine turning
Fine turning
Cutting speed (v
c)
m/min150 - 200 200 - 250 15 - 20
Feed (f) mm/r
0.2 - 0.4 0.05 - 0.2 0.05 - 0.3
Depth of cut (ap)
mm2 - 4 0.5 - 2 0.5 - 2
Carbide designation ISO
P20 - P30 Coated carbide
P10 Coated
carbide or cermet
-
Drill diameter mm
Cutting speed (vc)
m/minFeed (f) mm/r
≤ 5 15 - 20* 0.05 - 0.15
5 - 10 15 - 20* 0.15 - 0.20
10 - 15 15 - 20* 0.20 - 0.25
15 - 20 15 - 20* 0.25 - 0.35
* For coated HSS drill, vc~ 35–40 m/min
1 Drill with replaceable or brazed carbide tip2 Depending on drill diameter
Cutting data parameters
Type of drill
Indexable insert
Solid carbide
Brazed carbide1
Cutting speed (v
c)
m/min180 - 220 120 - 150 60 - 90
Feed (f) mm/r
0.05 - 0.252 0.10 - 0.252 0.15 - 0.252
End milling
1 For coated HSS end mill, vc~ 45–50 m/min
Cutting data parameters
Type of milling
Solid carbide
Carbide indexable
insert
High speed steel
Cutting speed (v
c)
m/min130 - 170 120 - 160 25 - 301
Feed (f) mm/tooth
0.03 - 0.202 0.08 - 0.202 0.05 - 0.352
Carbide designation ISO
- P20 - P30 -
The cutting data below are to be considered as guiding values and as starting points for developing your own best practice.
Condition: Soft annealed condition ~160 HB
Carbide drill
† High speed steel
DRILLING
High speed steel twist drill
Type of grinding Grinding wheel designation
Face grinding straight wheel A 46 HV
Face grinding segments A 24 GV
Cylindrical grinding A 46 LV
Internal grinding A 46 JV
Profile grinding A 100 LV
GRINDING
Wheel recommendation
9
DIEVAR
TURNING
Machining recommendations
MILLING
Face and square shoulder milling
Cutting data parameters
Milling with carbide
Rough milling Fine milling
Cutting speed (v
c)
m/min50 - 90 90 - 130
Feed (fz)
mm/tooth0.2 - 0.4 0.1 - 0.2
Depth of cut (ap)
mm2 - 4 ≤ 2
Carbidedesignation ISO
P20 - P40Coated carbide
P10Coated carbide
or cermet
Cutting data parameters
Turning with carbide
Rough turning Fine turning
Cutting speed (v
c)
m/min40 - 60 70 - 90
Feed (f) mm/r
0.2 - 0.4 0.05 - 0.2
Depth of cut (ap)
mm1 - 2 0.5 - 1
Carbide designation ISO
P20 - P30 Coated carbide
P10 Coated carbide or
cermet
Drill diameter mm
Cutting speed (vc)
m/minFeed (f) mm/r
≤ 5 4 - 6 0.05 - 0.10
5 - 10 4 - 6 0.10 - 0.15
10 - 15 4 - 6 0.15 - 0.20
15 - 20 4 - 6 0.20 - 0.30
1 Drill with replaceable or brazed carbide tip2 Depending on drill diameter
Cutting data parameters
Type of drill
Indexable insert
Solid carbide
Brazed carbide1
Cutting speed (v
c)
m/min60 - 80 60 - 80 40 - 50
Feed (f) mm/r
0.05 - 0.252 0.10 - 0.252 0.15 - 0.252
End milling
1 Depending on radial depth of cut and cutter diameter
Cutting data parameters
Type of milling
Solid carbide
Carbide indexable
insert
High speed steel
TiCN coated
Cutting speed (v
c)
m/min60 - 80 70 - 90 5 - 10
Feed (f) mm/tooth
0.03 - 0.201 0.08 - 0.201 0.05 - 0.351
Carbide designation ISO
- P10 - P20 -
Type of grinding Grinding wheel designation
Face grinding straight wheel A 46 HV
Face grinding segments A 36 GV
Cylindrical grinding A 60 KV
Internal grinding A 60 IV
Profile grinding A 120 JV
The cutting data below are to be considered as guiding values and as starting points for developing your own best practice.
Condition: Hardened and tempered to 45±1 HRC
Carbide drill
DRILLING
High speed steel twist drill (TiCN coated)
GRINDING
Wheel recommendation
10
DIEVAR
Following the EDM process, the applicable die surfaces are covered with a resolidified layer (white layer) and a rehardened and untempered layer, both of which are very brittle and hence detrimental to die performance.
If EDM is used, the white layer must be completely removed by grinding or stoning. After finish machining, the tool should be given an additional temper at approx. 25°C below the highest previous tempering temperature.
NITRIDING AND NITROCARBURISING
Nitriding and nitrocarburising result in a hard surface layer which has the potential to improve resistance to wear and soldering, as well as resistance to premature heat checking. Dievar can be nitrided using gas or plasma. It can also be nitrocarburised via gas or salt bath process. The nitriding and nitrocarburising temperature should be at least 25–50°C below the highest previous tempering temperature, depending upon the process time and temperature. Otherwise, a permanent loss of core hardness, strength, and/or dimensional tolerances may be experienced.
During nitriding and nitrocarburising, a brittle compound layer, known as the white layer, may be generated. The white layer is very brittle and may result in cracking or spalling when exposed to heavy mechanical or thermalloads. As a general rule, the white layer formationmust be avoided.
Electrical discharge machining
Nitriding in ammonia gas at 510°C, or plasma nitriding at 480°C, both result in a surface hardness of approx. 1100 HV
0.2. In general, plasma nitriding is the preferred
method because of better control over nitrogen potential. However, careful gas nitriding can give perfectly acceptable results.
The surface hardness after nitrocarburising in either gas or salt bath at 580°C is approx. 1100 HV
0.2.
Depth of nitriding
Surface treatment
* Depth of case = distance from surface where hardness is 50 HV0.2
over base hardness
ProcessTime
h
Surfacehardness
HV0.2
Depth*mm
Gas nitriding at 510°C
1030
11001100
0.160.22
Plasma nitriding at 480°C
10 1100 0.15
Nitrocarburising – in gas at 580°C
– in salt bath at 580°C
2
1
1100
1100
0.13
0.08
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DIEVAR
WeldingWelding of die components can be performed, with acceptable results, as long as proper precautions are taken during the preparation of the joint, the filler material selection, the preheating of the die, the controlled cooling of the die and the post weld heat treatment processes. The following guidelines summarise the most important welding process parameters.
Welding method
TIG MMA
Working temp.1
325 - 375ºC 325 - 375ºC
Filler material
QRO 90 TIG-WELDDIEVAR TIG-WELD
QRO 90 WELD
Maximuminterpasstemp.2
475°C 475°C
Cooling rate
20 - 40ºC/h for the first 2 to 3 hours and then freely in air
Hardness after welding
50 - 55 HRC 50 - 55 HRC
Heat treatment after welding
Hardened condition
Temper at 25°C below the original temper-ing temperature.
Soft annealed condition
Soft anneal the material at 850°C in protected atmosphere. Then cool in the furnace at 10°C per hour to 600°C, then freely in air.
1 Preheating temperature must be established throughout the die and must be maintained for the entire welding process, to prevent weld cracking2 The temperature of the tool in the weld area immediately before the second and subsequent pass of a multiple pass weld. When exceeded, there is a risk of distortion of the tool or soft zones around the weld.
Further information
For further information, i.e., steel selection, heat treatment, application and availability, please contact our ASSAB office nearest to you.
12
DIEVAR
Relative comparison of ASSAB hot work die steels
QUALITATIVE COMPARISON OF CRITICAL DIE STEEL PROPERTIES
QUALITATIVE COMPARISON OF RESISTANCE TO DIFFERENT DIE FAILURES
ASSAB gradeTemper
resistanceHot yieldstrength
Creepstrength
Coefficientof thermalexpansion
Heatconductivity
Ductility
ALVAR 14
ASSAB 8407 2M
ASSAB 8407 SUPREME
DIEVAR
HOTVAR
QRO 90 SUPREME
ASSAB gradeHeat
checkingGross
crackingHot wear /
ErosionPlastic
deformationCorrosion (Al)
ALVAR 14
ASSAB 8407 2M
ASSAB 8407 SUPREME
DIEVAR
HOTVAR
QRO 90 SUPREME
13
DIEVAR
14
DIEVAR
Product : Automotive housingWork material : A380 Aluminium alloyWork temp. : 690°CTooling size : 406 x 508 x 508 mmDie material : Premium H13 at 44-46 HRC vs DIEVAR 46-48 HRCBackground : Severe heat checking begins on Premium H13 at approximately 20,000 shots. The customer wanted better die life.
RESISTANCE TO HEAT CHECKING
Case study
Premium H13 DIEVAR
Comparison of Premium H13 and DIEVAR after 42,000 shots.
Premium H13 DIEVAR
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DIEVAR
MALAYSIA
Kuala Lumpur - Head OfficeASSAB Steels (Malaysia) Sdn. Bhd.Tel : +60 3 6189 0022Fax: +60 3 6189 0044/[email protected]
NingboASSAB Tooling Technology(Ningbo) Co., Ltd.Tel : +86 574 8680 7188Fax: +86 574 8680 [email protected]
Cikarang*PT. ASSAB Steels IndonesiaTel : +62 21 461 1314Fax: +62 21 461 1306/ +62 21 461 [email protected]
Jiangxi*ASSAB Tooling (Dong Guan) Co, Ltd., Jiangxi BranchTel : +86 769 2289 7888Fax : +86 769 2289 [email protected]
Tel : +62 21 5316 0720-1
Choosing the right steel is of vital importance. ASSAB engineers and metallurgists are always ready to assist you in your choice of the optimum steel grade and the best treatment for each application. ASSAB not only supplies steel products with superior quality, we offer state-of-the-art machining, heat treatment and surface treatment services to enhance steel properties to meet your requirement in the shortest lead time. Using a holistic approach as a one-stop solution provider, we are more than just another tool steel supplier.
ASSAB and Uddeholm are present on every continent. This ensures you that high-quality tool steels and local support are available wherever you are. Together we secure our position as the world's leading supplier of tooling materials.
For more information, please visit www.assab.com