Tooling Materials&Heat Treatment

8/3/2019 Tooling Materials&Heat Treatment

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TOOLING MATERIALS

Required Properties: Depending upon the application, tool steels requirea combination of all or some of the following properties.

1.Strength

2.Hardness

3.Wear Resistance

4.Machinability

5.Toughness

6.Hot hardness

7.Corrosion resistance

The above mentioned properties can be obtained by adding the alloying

elements like Carbon, Tungsten, Chromium, Vanadium, Molybdenum, Silicon,

Nickel, Manganese, Copper, Cobalt etc… to the base metal.




Effects of Alloying Elements:

Carbon

* >0.6% for normally alloyed steels assures hardenability.

* Up to 1.3% it increases hardness, brittleness slightly and wear

resistance considerably.

Chromium

*It improves hardenability and together with high carbon improves wear

resistance and toughness.

*High chromium percentage increases hardening temperature and affects

the grindability. It also increases corrosion resistance.

Cobalt

*It increases hot hardness.

*It doesn’t form carbide and thus provides toughness.

Silicon

*It is needed as deoxidizer and improves the hot-forming properties of

the steel and also increases machinability.

* Generally for tooling steels, it is kept below 0.3%.

Tungsten

*It improves Hot hardness.

*It forms hard abrasion resistance carbides, thus improving the wear

resistance.




Vanadium

*It refines the carbide structure and thus improves forgeability.

*It has a very strong tendency to form a hard carbide, thus improves

hardness, and wear properties.

* Large amount of vanadium carbide causes low grindability. Hence itis kept not usually more than 1%.

Nickel

Generally in combination with other alloying elements, particularly

chromium, nickel is used to improve the toughness, corrosion

resistance and to some extent, the wear resistance of tool steels.

Manganese

*To about 0.60%, manganese is added for reducing brittleness and to

improve forgeability by nullifying the effects of sulpher. It also

provides very good machinability.

*Larger amounts of manganese improve hardenability, thus reducing

deformation.

Molybdenum

*In small amounts, it improves deep hardening and toughness.

*It is used often in larger amounts in certain high-speed tool steels to

replace tungsten.




Chemical composition of Commonly used Tooling materials:

C Cr V Ni Co Mo Mn Si Cu P S

A2 0.95-1.05 4.75-5.5 0.15-

0.5

0.30 - 0.90-

1.40

1.00 0.50 0.25 0.03 0.03

D2 1.40-1.60 11.00-13.00

1.10 0.30 1.00 0.70-1.20

0.60 0.60 0.25 0.03 0.03

O1 0.85-1.00 0.40-

0.60

0.30 0.30 - (W=0.40

-0.60)

1.00-

1.40

0.50 0.25 0.03 0.03

S7 0.45-0.55 3.00-

3.50

0.20-

0.30

- - 1.30-

1.80

0.20-

0.80

0.20-

1.00

0.25 0.03 0.03

4140 0.38-0.43 0.80-1.10

- - - 0.15-0.25

0.75-1.00

0.15-0.30

- 0.035 0.04

4150 0.48-0.53 0.80-

1.10

- - - 0.15-

0.25

0.75-

1.00

0.15-

0.30

- 0.035 0.04

P 20 0.28-0.40 1.40-

2.00

- - - 0.30-

0.50

0.60-

1.00

0.20-

0.80

0.25 0.003 0.003

8620 0.18-0.23 0.40-0.60

- 0.40-0.70

- 0.15-0.25

0.70-0.90

0.15-0.30

- 0.035 0.04

1060 0.55-0.65 - - - - - 0.60-

0.90

- - 0.04 0.05

6150 0.48-0.53 0.80-

1.10

0.15

min

- - - 0.70-

0.90

0.15-

0.30

- 0.035 0.04




Applications:A2 - Trim steels, Lance steels

D2 - Trim steels, Form steels

O1 - Wear plates, Pilots, Cam key, Heel Block(O1DCF)4140 - Punch Retainer, Cam Gib, Slug deflector,

4140DCF - Stock guide, Trim retainer, Lifter bar, Bottoming block,

Form pad, Pad window, Binder pad, Gage, Lifter.

4150PHT - Lifter Depressor, Transfer pin, Stock Guide, Lift rail,

Cam push block, Gage, Standoff, Window6150 - Clamp plate, Anvil,

CRS - Key, Pad balancer, Sensor Block, Cam stop, Nitro plate,

Heel retainer, Bottoming Block, Cam pusher, Filler block,

Stop block, Keeper, Nitro cap, Anti rotation pin, Stand off,

Lifter pin, Coil feed plate, Riser, Cap, Lifter keeper,

Pilot block, Lifter bushing retainer, Die steel (Pilot receiving)

HRS - Parallels 1060 - Strippers or any other plate requiring flame hardening

Note: DCF – Decarburization Free PHT – Pre Heat Treated




Equivalence of materials:

AISI/

SAE

(US)

BS

(UK)

DIN

(Germany)

JIS

(Japan)

IS

(INDIA)

Common Names

A2 BA2 1.2363

X100CrMoV5-1SKD12 - Air-hardening medium-alloy

cold work steel

D2 BD2 1.2379

X155CrVMo12-1SKD11 - High Carbon, High Chromium

Cold work steels

O1 BO1 1.2510100MnCrW4

SKS3 - Oil hardening

cold work steels

S7 - - - - Shock Resisting Steels

4150 - 1.7228 SCM 5 - Chromium-Molybdenum steels

P 20 BP20 1.2311

40CrMnMo7- - General Mold Steel

8620 - 1.6523 SNCM21 - Nickel-Chromium-Molybdenum steel

4140 En 19 1.7225 SCM 4 - Chromium-Molybdenum steels

1060 1.0601 - - Carbon steel

6150 En 47 1.8159 SUP 10 T50Cr4V2 Chromium-vanadium steel


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HEAT TREATMENT OF TOOL STEELS:

*What Is Heat Treatment as Applied to Steel?

Heat treatment - as applied to steel - can be defined as the application of heat to change a

characteristic or condition of the steel. The amount of heat can be measured by the temperature of

the steel being treated.

Heat treatment is the process of heating an alloy to a high temperature, soaking at that

temperature and then cooling it at a particular rate in order to obtain a desired properties.

*Why Do We Heat Treat Steel?

Steel can be categorized in a variety of manners. The principle alloying element is

carbon, which influences the steel's hardness and its mechanical properties. It is necessary to apply

heat to steel to enable its condition and mechanical properties to be changed to allow the steel to

function either during manufacture or its operating life cycle.



*What happens to steel when Heat Treated? (See Figure)

*Heat treatment depends to a great extent on the structure of the metal and on the manner in which

the structure changes when the metal is heated and cooled. A pure metal cannot be hardened by heat

treatment because there is little change in its structure when heated. On the other hand, most alloys

respond to heat treatment since their structures change with heating and cooling. 1. At room temp – Structure is BCC.

2. Lower transformation temperature (1333°F) – (a) The start of phase change from ferrite to

austenite (b) Structure changes from BCC to FCC. (c) Magnetic to Non magnetic change occurs.

3.Upper transformation temperature – Complete phase change from ferrite to austenite.



Heat Treatment Processes:

Depending on the Heating temperature, soaking time and cooling rate for a particular

alloy, the structure changes and accordingly the mechanical properties.

In order to have required mechanical properties, the following major heat treatment

processes will be carried.

1.Annealing

2.Normalizing

3.Hardening

4.Tempering

5.Case Hardening

Hardening and Tempering of Tool steels:

*Hardening of steels is done to increase the strength and wear properties. *One of the pre-requisites for hardening is sufficient carbon and alloy content. If there is sufficient

Carbon content then the steel can be directly hardened. Otherwise the surface of the part has to be

carbon enriched using some diffusion treatment hardening techniques.*Hardening of steel requires a change in structure from the BCC found at room temperature to the

FCC found in the Austenitic region. The steel is heated to Austenitic region. When suddenly

quenched, the Martensite is formed. This is a very strong and brittle structure.

*In order to reduce the brittleness due to sudden cooling, hardening will be followed by tempering

process.



Heat treatment of D2:

1.ANNEAL: Heat to 1650ºF, soak 1 -1/2 hr/inch of thickness, cool 20ºF/hr to 900ºF. Cool down with

furnace to room temp. Annealed hardness 220 max. Brinell.

2.STRESS RELIEF: heat slowly to 1200-1250ºF, soak 2hrs/inch of thickness, slow cool (furnace if

possible) to room temp.

3.PREHEAT: Heat to 1250ºF, hold at this temp until thoroughly soaked.

4.HARDEN: Heat to 1850ºF, soak for 45-60 min/inch of thickness (minimum)

5.QUENCH: Air quench to 150ºF. Temper immediately.

6.TEMPER: Double temper is mandatory, three tempers is preferred. Soak for 2hrs/inch of thickness,

Air cool to room temp. (Between tempers, Double temper at the range of secondary hardness, 900-

960ºF strongly recommended)

7.OPTIONAL SUB-ZERO TREATMENT

8. STRESS RELIEF TEMPER: It is strongly recommended after significant grinding, welding or

EDM. (Select temp that is 25 or 50ºF lower than last tempering temp used)



Heat Treatment of A2:

1.ANNEAL: Heat to 1650ºF, soak 2 hr/inch of thickness, cool 40ºF/hr to 900ºF. Air cool to room

temp. Annealed hardness 235 max. Brinell.

2.STRESS RELIEF: heat slowly to 1200-1250ºF, soak 2hrs/inch of thickness, slow cool (furnace if

possible) to room temp.

3.PREHEAT: Heat to 1200ºF, hold at this temp until thoroughly soaked.

4.HARDEN: Heat to 1750-1850ºF, soak for 45-60 min/inch of greatest thickness (minimum)

5.QUENCH: Air quench to 150ºF. Temper immediately.

6.TEMPER: Double temper is mandatory, three tempers is preferred. Soak for 2hrs/inch of

thickness, Air cool to room temp between tempers.

7.OPTIONAL SUB-ZERO TREATMENT

8. STRESS RELIEF TEMPER: It is strongly recommended after significant grinding, welding or

EDM. (Select temp that is 25 or 50ºF lower than last tempering temp used)



Heat Treatment of 6150:Annealing: Heat to 1500F (815C), hold 2 hours, slow cool 50F(28C)/ hr max. to 1200F (650C),

then air or furnace cool. Hardness BHN 170/201.

Stress Relieving

Annealed Material: 1100-1300F (595-740C), hold 2 hrs, air cool.Hardened Material: 50-100F (30-55C) below last tempering temperature, hold 2 hrs, air cool.

Hardening: (Atmosphere or Vacuum Furnace).

Preheat: 1200-1250F (650-675C), equalize.

Hardening: 1550-1650F (845-900C), soak 10 to 30 minutes. For vacuum hardening, use the high

side of the high heat range and soak times.

Quench: Oil quench to hand warm, 150F (65C). Temper immediately. Note vacuum furnaces must

have oil quench capability.

Temper: Tempering at 400-1200F (205-650C) for 1 hr/inch of thickness thickness(2 hrs min.). Air

cool to room temperature.



Recommended Heat Treatment temperatures for Tool steels:

Material Preheat Temp ºF Hardening Temp ºF Tempering Temp ºF Quenching Media

O1 1247-1346 1454/1499 347/599 Oil at 149F

4140 1247-1301 1508/1598 806/1292 Oil

S7 1301Approx 1751 392-995 Air/oil for sections above

3”

P20 1508/1544 392-1112 Oil/Air

D2 1250 1850 900-960(Doubletempering is mandatory,

triple temper is preferred.)

Air quench to 150F

A2 1200 1750-1850 500 (Double tempering is

mandatory, triple temper is

preferred.)

Air quench to 150F

6150 1200-1250 1550-1650 400-1200 Oil quench to 150F

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Tooling Materials&Heat Treatment