Designation by Standards
Chemical Composition (in weight %)
|1.10||max. 0.70||max. 0.40||3.90||9.30||-||1.20||1.50||Co: 8.00|
Capable of very high hardness values, this is a moly type high speed tool steel. The alloy has excellent hot hardness and wear resistance and is commonly employed to machine difficult to machine materials including the superalloys.
Typically employed to machine the superalloys and exotic, M42 is employed in drills, hobs, taps, end mills, milling cutters, form and gear cutters, broaches and chasers.
Physical properties (avarage values) at ambient temperature
Density [g/cm3]: 8.01
Thermal conductivity [W/m.K]: 19.0
Coefficient of Linear Thermal Expansion 10-6 oC-1
Heat to 820-880oC, cool slowly in furnace. This will produce a maximum Brinell hardness of 230-300.
Stress relieving to remove machining stresses should be carried out by heating to 650oC, holding for one hour at heat, followed by air cooling. This operation is performed to reduce distortion during heat treatment.
Heat up to 450-600oC, then preheat to 850oC, and to 1050oC. Harden from a temperature of 1160-1210oC followed by oil, air quenching or warm bath 550oC. Hardness after quenching is 66-68 HRC.
Transformation temperatures: Ac1=780oC , Ac3=855oC.
Tempering temperature: 3 x 1 hour at 520-560oC.
Tempering Temperature (oC) vs. Hardness (HRC)
Hot forming temperature: 1095-982oC.
Rated at 45% of a 1% carbon steel, the alloy, in its annealed condition, can be turned, drilled, tapped, milled, broached and threaded.
Not normally employed in applications requiring corrosion resistance.
All technical information is for reference only.