Project Description

31CrMoV9 is a nitriding steel which has at least 2.3%Cr,0.15%Mo,0.1%V as strengthening alloy elements.
Due to its high wear resistance,it is mainly used in the automotive industry and general components mechanical engineering.30CrMoV9 is difficult to weld and therefore should not be used in weld constructions.It can attain surface hardness of 800 HV after nitriding.31CrMov9 is directly involved the nitriding steel 30CrMoV9 (DIN1.7707).31CrMoV9 steel

1.Supply Form & Size & Tolerance

Hot rolled bar:Φ6-Φ130mm,Length:3000-10000mm

Hot Forged round bar:Φ130-Φ1000mm,Length:3000-10000mm

Flat bar/Blcoks:Thickness :120-800mm xWidth:120-1500mm,Length:2000-6000mm

Surface FinishTolerance
Black For Forged condition(0,+5mm)
Black For Rolled condition(0,+1mm)
Rough Turned   (0,+3mm)
GrindingBest h9
PolishedBest h11
PeeledBest H11
Cold DrawnBest H11

2.Chemical Composition

31CrMoV9/1.85190.27-0.340.40-0.70≤ 0.025≤ 0.035≤ 0.40.1-0.22.3-2.70.15-0.25

3.Physical Property

Density ,g/cm3: 7.85

Specific heat capacity, J/(kg.K):460

Thermal conductivity ,W/(m.K):42

Electric resistivity,Ohm.mm2 /m:0.19

Modulus of elasticity ,Gpa: 210

4. Mechanical Property

Diameter d mm16-4040-100100-160160-250
Yield Strength Mpa≥900≥800≥700≥650
Tensile Strength Mpa1100-13001000-1200900-1100850-1050
Elongation, %≥9≥10≥11≥12


Heat the temperature between 1050℃-1150℃,hold suitable time for the steel to be thoroughly heated.Reheat the steel once temperature  below 850°C. Crack is easily occured when improper cooling way after forged,so it  should be cooled as slowly as possible in the furnace or in sand after forged.

6.Heat Treatment

  • Soft Annealing
    Heat to 650-720℃, cool slowly in the furnace. This will produce a maximum Brinell hardness of 248.
  • Hardening
    Harden from a temperature of 870-930℃, followed by oil/polymer or water quenching.
  • Tempering
    Tempering temperature: 580-700℃.
  • Nitriding
    Gas/plasma nitriding temperature (gas, salt bath): 570-580℃
    Gas/plasma nitriding temperature (powder, plasma): 580℃
    Surface hardness after nitriding: 800 HV
Hold time,hHardness,HV

7.Jominy Test -Distance from quenched end mm



31CrMoV9 nitriding steel is used in mechanics automotive and general mechanics, which must be nitrided for very high wear forces, for example, gears, rods or axes.Structural parts of medium and large cross sections and high surface hardness, e.g., valve and gate valves, cylinders for combustion engines, superheated steam valves and fittings.

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