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

5

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

6

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

8

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

11

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

15

DIEVAR

MALAYSIA

Kuala Lumpur - Head OfficeASSAB Steels (Malaysia) Sdn. Bhd.Tel : +60 3 6189 0022Fax: +60 3 6189 0044/55info.kualalumpur@assab.com

NingboASSAB Tooling Technology(Ningbo) Co., Ltd.Tel : +86 574 8680 7188Fax: +86 574 8680 7166info.ningbo@assab.com

Cikarang*PT. ASSAB Steels IndonesiaTel : +62 21 461 1314Fax: +62 21 461 1306/ +62 21 461 1309info.cikarang@assab.com

Jiangxi*ASSAB Tooling (Dong Guan) Co, Ltd., Jiangxi BranchTel : +86 769 2289 7888Fax : +86 769 2289 9312info.jiangxi@assab.com

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