Die Steel EN31

EN31 is a high carbon Alloy steel which achieves a high degree of hardness with compressive strength and abrasion resistance.

Properties Metric Imperial
Density 7.85 g/cc 0.284 lb/in3

Forge at 1000°/1050°C. Heat slowly, allowing sufficient time at the forging temperature for the steel to be thoroughly soaked through. Re-heat as often as necessary to keep the temperature above 850°C. After forging cool very slowly, preferably in a furnace.


Heat uniformly to 800°C, equalize, then furnace cool. (Hardness about 229 Brinell).

Stress Relieving

If machining operations have been heavy or if the tool has an unbalanced section, remove stresses before hardening by heating up to 700°C, equalize, then cool slowly.


Heat uniformly to 800/820°C until heated through. Allow 30 minutes per inch of ruling section and quench immediately in oil.


Heat uniformly and thoroughly at the selected tempering temperatures and hold for at least one hour per inch of total thickness

Tempering °C 100 150 200 v250 300 350
HRc 64/63 63/62 62/61 60/59 57/56 54/53

Physical Properties

Name of Material Composition in % of Weight Thermal conductivity W/m-k Density Kg/m^3 Melting Point
C Mn Si Cr S P Mg
En-31 IS-103 Crl 1.5 0.52 0.22 1.3 0.05 0.05 - 46.6 7810 1540

Mechanical Properties

Element Objective
Tensile Strength 750 N/mm²
Yield Stress 450 N/mm²
Reduction of Area 45%
Elongation 30%
Modulus of elasticity 215 000 N/mm²
Density 7.8 Kg/m3
Hardness 63 HRC

Heat Treatment

Element Objective
Hardening Temperature 802˚- 860˚ C
Quenching Medium Oil
Tempering Temperature 180˚- 225˚ C
Brinell-Rockwell Hardness 59 - 65