AISI 8642 Alloy Steel (UNS G86420)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


In alloy steels, alloying elements are added in lower quantities to improve its strength and hardenability or in larger quantities to achieve properties like extreme temperature stability and corrosion resistance.

AISI 8642 alloy steel is a nickel-chromium-molybdenum steel. The following section will discuss in detail about AISI 8642 alloy steel.

Chemical Composition

The chemical composition AISI 8642 alloy steels is outlined in the following table.

Element Content (%)
Iron, Fe 96.585 - 97.93
Chromium, Cr 0.75 - 1.2
Manganese, Mn 0.65 - 1.1
Carbon, C 0.37 - 0.44
Molybdenum, Mo 0.15 - 0.3
Silicon, Si 0.15 - 0.3
Sulfur, S ≤0.040
Phosphorous, P ≤0.035

Physical Properties

The following table shows the physical properties of AISI 8642 alloy steels.

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

Mechanical Properties

The mechanical properties of AISI 8642 alloy steels are displayed in the following table.

Properties Metric Imperial
Tensile strength 903 MPa 131000 psi
Yield strength 738 MPa 107000 psi
Modulus of elasticity 205 GPa 29700 ksi
Bulk modulus 140 GPa 20300 ksi
Shear modulus 80 GPa 11600 ksi
Poisson’s ratio 0.29 0.29
Elongation at break 20.40% 20.40%
Hardness, Brinell 269 269
Hardness, Vickers 284 284
Hardness, Knoop 294 294
Hardness, Rockwell C 27 27
Hardness, Rockwell B 99 99
Machinability 65 65

Thermal Properties

The thermal properties of AISI 8642 alloy steels are given in the following table

Properties Metric Imperial
Thermal conductivity 46.6 W/mK 323².°F

Other Designations

Other designations that are equivalent to AISI 8642 alloy steels include the following.

  • ASTM A322
  • ASTM A331
  • ASTM A505
  • ASTM A519
  • SAE J404
  • SAE J412
  • SAE J770

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