40C8

40C8 Grade Introduction:

40C8 Carbon steels have carbon as the key alloying element in their composition. They also contain up to 0.4% silicon and 1.2% manganese. In addition, residual elements such as copper, molybdenum, aluminum, chromium, and nickel are present in these steels.

40C8 Grade Application:

  • General Purpose Axles
  • Shafts
  • Gears
  • Bolts and Studs
  • Spindles
  • Automotive and General Engineering Components
  • General Engineering Parts etc

40C8 Equivalent Grades:

Category IS EN DIN AISI/SAE JIS
Medium Carbon Steel 30C8, 35C8, 40C8, 45C8, 50C8, 55C8, CL-III, CL-IV, CL-V EN-8, EN-8D, EN-9 CK-30, CK-35, CK-40, CK-45, CK-50, CK-55, CK-60 1030, 1035, 1040, 1045, 1050, 1055, 1060 –

40C8 Chemical Composition:

Element C Mn Si S P
Content (%) 0.35 – 0.45 0.60 – 0.90 0.10 – 0.35 0.35 Max 0.35 Max

Mechanical Properties:

Property Metric Imperial
Tensile Strength, Ultimate 660 MPa 95700 psi
Tensile Strength, Yield 560 MPa 81200 psi
Bulk Modulus (typical for steels) 140 GPa 20300 ksi
Shear Modulus (typical for steels) 80 GPa 11600 ksi
Elastic Modulus 190 – 210 GPa 19700 – 30458 ksi
Poisson’s Ratio 0.27 – 0.30 0.27 – 0.30

Physical Properties:

Property Metric Imperial
Density 7.85 g/cm³ 0.284 lb/in³

Thermal Properties:

Property Metric Imperial
Thermal Expansion Coefficient 11 µm/m°C 6.11 µin/in°F
Thermal Conductivity 49.8 W/m·K 346 BTU in/hr·ft²·°F

Forging Properties:

Preheat the 40C8 steel carefully, then raise temperature to 1050°C for forging. Do not forge below 850°C. After forging cool 40C8 steel slowly, preferably in a furnace.

Stress Relieving:

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