Mat.No. 1.3247, DIN S2-10-1-8, AISI M42

Designation by Standards

Chemical Composition (in weight %)

Description
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.

Applications
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

Soft Annealing
Heat to 820-880^oC, cool slowly in furnace. This will produce a maximum Brinell hardness of 230-300.

Stress Relieving
Stress relieving to remove machining stresses should be carried out by heating to 650^oC, holding for one hour at heat, followed by air cooling. This operation is performed to reduce distortion during heat treatment.

Hardening
Heat up to 450-600^oC, then preheat to 850^oC, and to 1050^oC. Harden from a temperature of 1160-1210^oC followed by oil, air quenching or warm bath 550^oC. Hardness after quenching is 66-68 HRC.

Transformation temperatures: Ac₁=780^oC , Ac₃=855^oC.

Tempering
Tempering temperature: 3 x 1 hour at 520-560^oC.

Tempering Temperature (^oC) vs. Hardness (HRC)

Tempering Diagram

Click the image to enlarge the diagram.

Forging
Hot forming temperature: 1095-982^oC. 

Machinability
Rated at 45% of a 1% carbon steel, the alloy, in its annealed condition, can be turned, drilled, tapped, milled, broached and threaded.

Corrosion Resistance 
Not normally employed in applications requiring corrosion resistance.

Forms manufactured: Please see the Dimensional Sales Program.