34CrMo4 steel is a heat treatable steel  which contains at least 0.9%Cr,0.15%Mo as strengthening elements which is similiar like Chinese grade 35CrMo.It has good repeated impact resistance,good fatigue properties in alternating bend stress,but poor in weldability,this steel grade can be welded only with suitable procedure.This material is generally used in the quenched and tempered condition.

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

GradeCSiMnCrMoPS
34CrMo4/1.72200.3-0.37≤ 0.40.6-0.90.9-1.20.15-0.3≤ 0.025≤ 0.035
34CrMoS4/1.72260.3-0.37≤ 0.40.6-0.90.9-1.20.15-0.3≤ 0.0250.02-0.04

3.Relevant Standards

USAUKChinaFrance
4135/4137708A3735CrMo34CD4

4. Mechanical Property

Diameter d mm≤ 1616-4040-100100-160160-250
Thickness t mm< 88-2020-6060-100 100-160
Yield Strength Mpa≥800≥650≥550≥500≥450
Tensile Strength Mpa1000-1200900-1100800-950750-900700-850
Elongation, %≥11≥12≥14≥15≥15
Reduction of area ,%≥45≥50≥55≥55≥60
impact,J≥40≥45≥45≥45
Hardness,HB298-359271-331240-286225-271213-253

5.Forging

34CrMo4 forging temperature:900 – 1100°C

6.Heat Treatment

  • Normalizing:  850 – 880°C,Cooling in air
  • Soft Annealing:650 – 680°C,Cooling in furnace,maximum hardness 223HB
  • Hardening:830 – 890°C,Quenching in oil or water
  • Tempering:540 – 680°C,Cooling in air

7.Application

34CrMo4 heat treatable steel with a typical tensile strength of 800 – 1100N/mm². For automotive and aircraft components with high toughness as crankshafts, axles, axle journals, tyres,gears and any components subject to fatigue stresses.