Alloy Steel 4140

Alloy Steel 4140 is a chromium-molybdenum steel with excellent strength, toughness, and fatigue resistance. It is one of the most versatile alloy steels, used extensively for critical machine components that require through-hardening.

Machinability

66/100

Tolerance

±0.01 mm

Category

Carbon & Alloy Steel

Material Properties

PropertyValue
Tensile Strength655 MPa (95 ksi)
Yield Strength415 MPa (60 ksi)
Hardness197 HB
Density7.85 g/cm³
Machinability Rating66/100
Thermal Conductivity42.6 W/m·K
Melting Point1,416–1,460 °C
Tolerance±0.01 mm

Common Grades

4140 Annealed4140 Pre-Hardened4140 Q&T

Advantages

  • Excellent strength and toughness
  • Through-hardenable
  • Good fatigue resistance
  • Versatile

Limitations

  • Poor corrosion resistance
  • Requires coating or plating
  • Higher cost than plain carbon steel

Common Applications

Toolholders

Shafts

Gears

Collets

Sprockets

Couplings

Industries Served

Oil & GasAutomotiveIndustrial MachineryDefense

Available Surface Finishes

Black OxideZinc PlatingHard ChromeNitride

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