AISI 8720 Alloy Steel (UNS G87200)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Alloy steels comprise a wide variety of steels with compositions that exceed the limitations of Si, Va, Cr, Ni, Mo, Mn, B and C allocated for carbon steels. These steels have elements such as chromium, cobalt, nickel, etc.

In comparison with carbon steels, alloy steels are more responsive to mechanical and heat treatments. Alloy steels can be used in specific melting and deoxidization processes for particular applications.

The following datasheet provides an overview of AISI 8720 alloy steel.

Chemical Composition

The chemical composition of AISI 8720 alloy steel is outlined in the following table.

Element Content (%)
Iron, Fe 96.895-97.97
Manganese, Mn 0.700-0.900
Nickel, Ni 0.400-0.700
Chromium, Cr 0.400-0.600
Molybdenum, Mo 0.200-0.300
Carbon, C 0.180-0.230
Silicon, Si 0.150-0.300
Sulfur, S ≤ 0.0400
Phosphorous, P ≤ 0.0350

Physical Properties

The following table shows the physical properties of AISI 8720 alloy steel.

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

Mechanical Properties

The mechanical properties of AISI 8720 alloy steel are displayed in the following table.

Properties Metric Imperial
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80.0 GPa 11600 ksi
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson's ratio 0.27-0.30 0.27-0.30
Hardness, Brinell (hot rolled and cold drawn) 179-235 179-235
Hardness, Knoop (converted from Brinell hardness) 229 229
Hardness, Rockwell B (converted from Brinell hardness) 93 93
Hardness, Rockwell C (converted from Brinell hardness, value below normal HRC range, for comparison only) 15 15
Hardness, Vickers (converted from Brinell hardness) 217 217
Machinability (hot rolled and cold drawn. Based on 100 machinability for AISI 1212 steel) 65 65

Thermal Properties

The thermal properties of AISI 8720 alloy steel are given in the following table.

Properties Metric Imperial
Thermal conductivity (typical steel) 46.6 W/mK 323 BTU in/hr.ft².°F

Other Designations

Equivalent materials to AISI 8720 alloy steel are:

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

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