A2 Tool Steel - DIN 1.2363 - X100CrMoV5 - JIS ~SKD 12

What is A2 steel used for?

Properties like wear resistance and chipping resistance make A2 a good fit for applications requiring extreme accuracy of size, as well as for very large parts like large blanking dies, trimming dies, coining dies, wear inserts and precision tools.

Is A2 steel corrosion resistant?

The AISI A2 has some corrosion resistance though not as much as a stainless steel can offer. The typical stainless steel has a minimum mass fraction of 10.5% chromium, A2 has a mass fraction of 4.8 - 5.5% of chromium. If corrosion resistance is a high priority a stainless steel should be considered.

Is A2 steel magnetizable?

A2 like other steels contains iron, is ferromagnetic and can be magnetizable.

A2 Steel heat treatment

Precaution needs to be taken while heat treating A2 to prevent decarburization.

Annealing A2 steel

A2 should be protected and be heated uniformly to a temperature of 1560°F (850°C). Cool the furnace at 20°F (10°C) per hour to a temperature of 1200°F (650°C) and then cool further in air. 

Stress relieving A2 steel

To relieve stress after rough machining, heat the work piece to a temperature of 1200°F (650°C) and hold it for 2 hours. Cool in the furnace to a temperature of 930°F (500°C) and then can be cooled down further in air.

How to harden A2 steel tool steel

A2 tool steel is heat treated by preheating the work piece to a temperature of 1200-1300°F (650-750°C), then rapidly heat to 1690-1780°F (925-970°C) and hold for 30 minutes until the part is uniformly heated through. Then cool to room temperature in dry mild air. To prevent decarburization and oxidation, parts should be protected during the A2 tool steel heat treatment.

Quenching A2 steel

Quenching should be done as quickly as possible. To avoid excessive distortion and/or quench cracking, cooling should be uniformly and a sufficient cooling rate should be considered.

• Oil for small and simple parts
• Vacuum furnace with overpressure of gas at cooling
• Circulating air or atmosphere
• Martempering bath or fluidized bed at 360-430°F (180-220°C) or 840-1020°F (450-550°C) followed by cooling in air.

Tempering A2 steel

As soon as the parts have reached a temperature of about 150°F (66°C) after quenching, they should be tempered immediately. The normal tempering temperature for A2 is a range from 300-500°F (149-260°C). 

For tools subjected to shock for example, a double temper is recommended at a temperature of 900-1000°F (482-538°C), holding the temperature for 1 hour at least for small parts and 1 hour per inch (25.4 mm) of thickness for larger pieces.

For more information please have a look at the A2 steel tempering chart below:

A2 Steel dimensional changes

A2 like other tool steels will hold its size best when quenched from the accurate hardening temperature. A2 will shrink after tempering if it is overheated and should not be hardened from a temperature above 1175°F (968°C) and expands when tempered below 600°F (316°C)

A2 Steel sub-zero treatment and aging

For maximum dimensional stability, parts should be treated at sub-zero and/or artificially aged.

A2 Steel sub-zero treatment

Immediately after quenching, the work piece should be sub-zero treated to between -40 to -110°F (-40 to -80°C), soaking them for 2-3 hours following tempering or aging. Sub-zero treatment will increase the hardness of 154-160 BHN (1-3 HRC). Due to cracking, it is not advised to use this treatment for intricate shapes.

A2 Steel aging 

For aging, tempering after quenching is replaced by aging at 230-285°F (110-140°C), holding time 25-100 hours.

A2 Steel Electrical Discharge Machining (EDM)

Performing EDM in the hardened and tempered condition, remove the recast layer completely by stoning and polishing. Then give the tool another temper at approx. 50°F (25°C) below the prior tempering temperature and soak at this temperature for 2 hours.

A2 Steel surface treatment

To reduce friction and increase wear and corrosion resistance some cold work tool steels are surface treated, using nitriding, titanium nitriding or hard chrome plating.

Nitriding A2 steel

Nitriding gives the surface of the material a hard layer with an excellent resistance to wear and galling. To suit the application, the thickness of the layer should be considered well.

A2 Steel machinability

Forging A2 steel

Heat the parts uniformly to a temperature range of 1950-2050°F (1066-1121°C), forging should be avoided below the temperature of 1700°F (927°C). Reheat the material as often as necessary. To cool larger parts, heat the furnace to about 1550°F (843°C), place the part in the furnace and soak at this temperature until the parts are uniformly heated throughout, then turn off the furnace and let the work pieces cool slowly in the furnace. Note that this is not an annealing, the parts should be annealed as described here in the section “Annealing A2 steel” after the parts have cooled down from forging.

Welding A2 steel

Good results can be achieved when welding tool steel, if the proper precautions are taken during welding (increased working temperature, joint preparation, choice of filler metals and the welding procedure). In the event that the parts are to be polished or photo-etched, it is necessary to work with a suitable electrode type of matching composition.

A2 Steel wear resistance

The wear resistance for the A2 is 4 on a scale where 1 is low and 6 is high.

A2 Steel tensile strength

The A2 has a tensile strength of approx. 118.2 KSI on delivery (0.145 KSI = 1MPa). In order to reach this value, a tensile test is performed to show how much force is needed to stretch or elongate a sample before it breaks.

A2 Tool steel yield strength

The A2 steel yield strength is at approx. 184 - 319 KSI (1269 - 2200MPa). The yield strength value shows how much force is needed to elongate a sample of steel before it breaks. The yield strength is impacted by the carbon content and heat treatment of the various steel grades.

A2 Steel working hardness

The working hardness for the A2 tool steel is in a range of 601 - 658 BHN (58 - 62 HRC).

A2 Steel specific heat capacity

The specific heat capacity of A2 steel is at 0.460J/g-°C (0.110BTU/lb-°F). This value shows how much heat is needed  to heat 1lb of material by 1 Fahrenheit.

A2 Steel continuous TTT-diagram

The following diagram shows the micro changes over time at different temperatures which are important during heat treatment. They show the optimum conditions for the processes such as hardening, annealing and normalizing.

A2 Steel isothermal TTT-diagram

The following diagram shows the structural changes at micro levels over time at a constant temperature. It shows at what temperatures the different phases, e.g., perlite, martensite and bainite start to form.

A2 Steel Properties

A2 Steel cold work

The A2 is an air hardening steel which can be cold worked, care should be taken when cold working it and stress relieving should be applied. Internal stresses may lead to cracking or distortion. Cold working might influence the ductility when cold working as the material gets brittle and might crack.

Cold working the A2, which has good toughness and wear resistance, has the advantage of providing better dimensional tolerances than hot working.

A2 Steel Density

The typical density of the A2 is 0.284 lb/in3 (7.86g/cm3) at room temperature.

A2 Steel thermal conductivity

The heat conductivity for A2 is at 15.8 W/(m*K) (110 BTU/(h-ft*°F)) at room temperature.

A2 Steel thermal expansion coefficient

This diagram shows how much A2 might expand or contract when the temperatures change which can be very important when working with high temperatures or strong temperature changes.

A2 Steel modulus of elasticity (Young’s Modulus)

The stress and strain modulus or modulus of elasticity (Young’s modulus) for the A2  is at 29400 KSI (203 GPa).

Is A2 a knife steel?

Though A2 can be used as a knife or blade steel with a combination of wear resistance, toughness, edge retention and can be easily sharpened. It is only used for tactical knives or hunting knives.

While it has some corrosion resistance, A2 is not a stainless steel and knives made of this steel grade should be maintained on a regular basis and kept out of damp environments to prevent corrosion.

A2 Steel conclusion

The A2 is a reliable choice as it has a good balance of wear resistance and toughness. As it has a good dimensional stability when heat treating, this material is often used for tooling applications. Care should be taken during heat treatment to guarantee the best performance and prevent warping. When maintained properly this material grade can have a long service life.

A2 Steel datasheet

As a steel supplier we provide you with the datasheet for A2 steel in PDF format.

A2 Steel equivalent or alternatives

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