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D2 steel is an air hardening, high-carbon, high-chromium tool steel. It has high wear and abrasion resistant properties. It is heat treatable and will offer a hardness in the range 55-62 HRC, and is machinable in the annealed condition. D2 steel shows little distortion on correct hardening. D2 steel’s high chromium content gives it mild corrosion resisting properties in the hardened condition.Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. As a result, tools made with type D3 steel tends to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.

Chemical Composition Physical Properties Mechanical Properties Thermal Properties Other Designations

Equivalent materials to D2 tool steels are:

• DIN 1.2379
• NI KU
• B.S. BD 2
• ASTM A681
• FED QQ-T-570
• SAE J437
• SAE J438
• UNS T30402

Heat Treatment

D2 steels should be preheated very slowly to 815ºC (1500ºF) and then temperature can be increased to 1010ºC (1850ºF). They are then held at 1010ºC (1850ºF) for 20 to 45 minutes and air cooled (air quenched).

Forging

• Forging of D2 steels can be done from 1065ºC (1950ºF) down to 954ºC (1750ºF). Do not forge below 926ºC (1700ºF).

Soaking time = time at austenitlzIng temperature after the tool is fully heated through.

Annealing

D2 is supplied in the annealed and machineable condition. Re-annealing will only be necessary if the steel has been forged or hardened by the toolmaker. To anneal, heat slowly and uniformly to 900°C. Soak for three to four hours and allow to cool in the furnace to room temperature. Re-heat to 800-1040°C and again soak for three to four hours. Allow to cool in the furnace to room temperature.

Tempering

D2 steels can be tempered at 204ºC (400ºF) for achieving Rockwell C hardness of 61 and at 537ºC (1000ºF) for a Rockwell C hardness of 54.

Cold-work tool steels which include D2, D3, D4, D5, and D7 steels are high-carbon, high-chromium steels. Apart from D3 steel all group D steels have 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. As a result, tools made with type D3 steel tend to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels. The D3 steels contain 1.5 to 2.35% of carbon and 12% of chromium.

Chemical Composition Physical Properties

Physical properties of D3 tool steels are given below:

Mechanical Properties

The mechanical properties of D3 steels are tabulated below:

Thermal Properties

The following table shows the thermal properties of D3 steels.

Other Designations

Equivalent metals of D3 steel are:

• AFNOR Z 200 C 12
• DIN 1.2080
• UNI X 21O Cr 13 KU
• JIS SKD1
• B.S. BD 3
• ASTM A681
• FED QQ-T-570
• SAE J437
• SAE J438
• UNS T30403

Annealing

Annealing of D3 tool steel needs to be done in a controlled atmosphere furnace. D3 tool steels should be heated thoroughly to 871°C (1600°F) and cooled slowly at a rate of not more than -6°C (20°F) per hour, until the furnace is black. Then the material should be removed and air cooled.

Heat Treatment

D3 tool steel requires hardening and tempering to achieve maximum properties. For maximum accuracy, the parts of D3 tool steel should be stress relieved after roughing operations. Stress should be relieved at 648°C (1200°F) for one hour and cooled slowly.

Tempering

The D3 tool steel should be cooled to room temperature and should be tempered immediately. The parts should be placed in the tempering furnace and increased slowly to the desired tempering temperature. Tempering for 1 hour per inch of thickness is required.

Hardening

D3 tool steel should be heated properly since it is very sensitive to overheating and if not heated maximum hardness cannot be achieved. The work should be directly placed in a furnace preheated to 954°C (1750°F) and soaked for 20-25 minutes, plus 5 minutes per inch of thickness, and then oil-quenched to harden it.

SKD11 Tool Steel is a high- carbon and high- chromium alloy tool steel. It has good wear resistance and size ability after heat treatment and is suitable for making long-life high-precision cold-work dies.

 

SKD11 Tool Steel of Applications:
1) Making knife-edge mold, scissors, circular saw blades, metal stamping mold.
2) Making cold work or hot work dressing dies, sides of rollers, screw lines, lines dies, transformer core stamping dies, rolled knives, steel tube forming rollers, special molding rollers, screw heading molds, etc.
3) Making blanking dies, stamping dies, pressing dies with a thickness ≤ 6mm
4) Making kinds of scissors, inlaid blades, thread rolling dies.
5) Making wear-resistant slider cold heading dies, deep drawing molding dies, cold extrusion dies.
6) Making thermosetting resin molding dies, common plastic dies

Chemical Composition Mechanical Properties Applications

• 1) Making knife-edge mold, scissors, circular saw blades, metal stamping mold.
• 2) Making cold work or hot work dressing dies, sides of rollers, screw lines, lines dies, transformer corestamping dies, rolled knives, steel tube forming rollers, special molding rollers, screw heading molds, etc.
• 3) Making blanking dies, stamping dies, pressing dies with a thickness ≤ 6mm
• 4) Making kinds of scissors, inlaid blades, thread rolling dies.
• 5) Making wear-resistant slider cold heading dies, deep drawing molding dies, cold extrusion dies.
• 6) Making thermosetting resin molding dies, common plastic dies

• SKD11 Tool Steel of Applications:

Heat TreatmentSOFT ANNEALING

Protect the steel and heat through to 1560°F (850°C). Then cool in the furnace at 20°F (10°C) per hour to 1200°F (650°C), then freely in air.

HARDENING

• Preheating temperature: 1110-1290°F (650-750°C).
• Austenitizing temperature: 1810-1920°F (990¬1050°C) but usually 1830-1905°F (1000-1040°C).

Soaking time = time at austenitlzIng temperature after the tool is fully heated through.

Thread rolling dies, Hobs, Cold extrusion tools and dies, Punches, Draw plates and dies, Cutters, Measuring tools, Pressure casting moulds, Blanking, Reamer, Finishing rolls for tyre mills.

This type of steel has high dimensional stability with added wear resistance coupled with excellent edge holding qualities.

Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. This makes tools made with type D3 steel brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.

Chemical Composition Physical Properties Mechanical Properties Other Designations

The other designations of D5 tool steels are:

• ASTM A681
• SAE J437
• SAE J438
• UNS T30405
• FED QQ-T-570

Heat Treatment

D5 steels should be preheated very slowly up to 815°C (1500°F), then temperature should be increased to 1009°C (1850°F) and held for 20 to 45 minutes. Then they are air quenched.

Forging

Forging of D5 steels can be done at 1065°C (1950°F) down to 1750°F. Do not forge below 926°C (1700°F).

Annealing

Annealing of D5 steels should be done at 886°C (1627°F) followed by slow furnace cooling at 4°C (40°F) per hour or less.

Tempering

D5 steels can be tempered at 204°C (400°F) for achieving Rockwell C hardness of 61 and at 537°C (1000°F) for a Rockwell C hardness of 54.

Applications

Applications of D5 steels include thread rolling, blanking or forming dies operating at temperatures below 482°C (900°F).