34HNM, 34CrNiMo6, 1.6582 - Through hardening steel

34CrNiMo6 / 1.6582, 817M40 / EN24, 35NiCrMo6  - through hardening alloy steel acc. to EN 10083-3.

34HNM, 34ChN1M, G35CriMo6-6 – description

Highly hardeanable steel (more than 36HNM) that does not show tempering brittleness, which enables to create very strong and ductile parts thick up to 150mm. Cheaper alloys may be considered for thinner components for best cost/effect ratio.

Steel used for highly stressed, impact-, torsion- and vibration-exposed parts, such as shafts, cranked shafts, press parts, heavily loaded rings, very large screws, such as cylinder cover screws for high-pressure steam turbines, rotors and discs for steam turbines, and all other heavy-duty machine applications requiring large diameter, high strength and significant ductility.

Due to poor weldability, welding should be considered only in exceptional cases. Softening annealing is required before welding. Directly before welding, the product should be heated - up to 300-400°C for parts up to 15mm thick and up to 350-450°C for parts up to 25mm thick. Do not lay welds larger than 25mm. When welding large parts, an intermediate stress relief annealing should be applied. Immidiately after welding the element should be softened or toughtened. If for some reason the part cannot be heat treated immidiately after welding, it must be cooled to ambient temperature very slowly, for example in a furnance, in hot sand or in asbestos mats.

Cutting may be performed with acetylene-oxygen flame or butane-propane-oxygene flame or with plasma stream. The steel must be preheated to 300-450°C before. Cool in calm air afterwards.

Physical and mechanical properties

Physical properties of 34CrNiMo6 steel:

• Density: 7.78 g/cm³
• Specific heat capacity: 0.46 kJ/(kg*K)
• Linear expansion coefficient: 11.7 K^-1
• Thermal conductivity: 0.348 W/(cm*K)
• Electrical resistivity: 0.256 Ω*cm
• Young's modulus: 21.0 kG/mm²

34CrNiMo6 mechanical properties

• Hot-rolled bars:
  • Quenched and tempered (+QT):
    • Diameter D: < 16 mm / Thickness: < 8 mm
      • Re: > 1000 MPa
      • Rm: 1200-1400 MPa
      • A: > 9 %
      • Z: > 40 %
    • Diameter D: 16-40 mm / Thickness: 8-20 mm
      • Re: > 900 MPa
      • Rm: 1100-1300 MPa
      • A: > 10 %
      • KV: > 45 J
      • Z: > 45 %
    • Diameter D: 40-100 mm / Thickness: 20-60 mm
      • Re: > 800 MPa
      • Rm: 1000-1200 MPa
      • A: > 11 %
      • KV: > 45 J
      • Z: > 50 %
    • Diameter D: 100-160 mm / Thickness: 60-100 mm
      • Re: > 700 MPa
      • Rm: 900-1100 MPa
      • A: > 12 %
      • KV: > 45 J
      • Z: > 50 %
    • Diameter D: 160-250 mm / Thickness: 100-160 mm
      • Re: > 600 MPa
      • Rm: 800-950 MPa
      • A: > 13 %
      • KV: > 45 J
      • Z: > 55 %
  • Annealed:
    • Hardness HB: < 248
• Bright and drawn steel bars:
  • Soft annealed and cold drawn (+A +C):
    • Thickness: 16-100 mm - HBW: < 248
  • Soft annealed and peeled (+A +SH):
    • Thickness: 5-10 mm - HBW: < 308
    • Thickness: 10-16 mm - HBW: < 298
    • Thickness: 16-40 mm - HBW: < 293
    • Thickness: 40-100 mm - HBW: < 288
  • Quenched, tempered and peeled or cold drawn, quenched and tempered (+QT+SH / +C+QT):
    • Thickness: 16-40 mm
      • Re: > 900 MPa
      • Rm: 1100-1300 MPa
      • A: > 10 %
      • KV: > 40 J
    • Thickness: 40-100 mm
      • Re: > 800 MPa
      • Rm: 1000-1200 MPa
      • A: > 11 %
      • KV: > 45 J
  • Quenched, tempered and cold drawn (+QT+C):
    • Thickness: 5-10 mm
      • Re: > 770 MPa
      • Rm: 1000-1200 MPa
      • A: > 8 %
    • Thickness: 10-16 mm
      • Re: > 750 MPa
      • Rm: 1000-1200 MPa
      • longation A: > 8 %
    • Thickness: 16-40 mm
      • Re: > 720 MPa
      • Rm: 1000-1200 MPa
      • A: > 9 %
    • Thickness: 40-100 mm
      • Re: > 650 MPa
      • Rm: 1000-1200 MPa
      • A: > 10 %
• Open die forgings, quenched and tempered (+QT):
  • Thickness: < 160 mm
    • Re: > 600 MPa
    • Rm: > 800 MPa
    • A: > 13 %
    • KV: > 45 J
  • Thickness: 160-330 mm
    • Re: > 540 MPa
    • Rm: > 750 MPa
    • A: > 14 %
    • KV: > 45 J
  • Thickness: > 330 mm
    • Re: > 490 MPa
    • Rm: > 700 MPa
    • A: > 15 %
    • KV: > 40 J
• Flat products:
  • Quenched and tempered (+QT):
    • Thickness: < 8 mm
      • Re: > 1000 MPa
      • Rm: 1200-1400 MPa
      • A: > 9 %
      • Z: > 40 %
    • Thickness: 8-20 mm
      • Re: > 900 MPa
      • Rm: 1100-1300 MPa
      • A: > 1000 %
      • KV: > 45 J
      • Z: > 45 %
    • Thickness: 20-60 mm
      • Re: > 800 MPa
      • Rm: 1000-1200 MPa
      • A: > 11 %
      • KV: > 45 J
      • Z: > 50 %
    • Thickness: 60-100 mm
      • Re: > 700 MPa
      • Rm: 900-1000 MPa
      • A: > 12 %
      • KV: > 45 J
      • Z: > 55 %
    • Thickness: > 100 mm
      • Re: > 600 MPa
      • Rm: 800-950 MPa
      • A: > 13 %
      • KV: > 45 J
      • Z: > 55 %
  • Annealed (+A):
    • Hardness HBW: < 248

Heat treatment and working

Recommended working and heat treatment parameters for 34HNM alloy:

• Forging: 1050-850 °C
• Rolling: 1180-850 °C
• Quenching: 830-860 °C
• Tempering: 540-680 °C
• Normalizing annealing: 850-880 °C
• Soft annealing: 680-720 °C

We deliver this steel alloy as:

• Hot-rolled, peeled and drawn bars
• Forged bars