AISI 5140 Alloy Steel (UNS G51400)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Alloy steels comprise a wide range of steels whose compositions are more than the limitations of C, Mo, Cr, Va, Mn, Ni, Si, and B which have been fixed for carbon steels. These steels are more responsive to mechanical and heat treatments than carbon steels.

The following datasheet will provide details about AISI 5140 alloy steel.

Chemical Composition

The following table shows the chemical composition of AISI 5140 alloy steel.

Element Content (%)
Iron, Fe 97.395-98.07
Manganese, Mn 0.700-0.900
Chromium, Cr 0.700-0.900
Carbon, C 0.380-0.430
Silicon, Si 0.150-0.300
Sulfur, S ≤ 0.0400
Phosphorous, P ≤ 0.0350

Physical Properties

The physical properties of AISI 5140 alloy steel are outlined in the following table.

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

Mechanical Properties

The mechanical properties of annealed AISI 5140 alloy steel are highlighted in the table below.

Properties Metric Imperial
Tensile strength 570 MPa 82700 psi
Yield strength 295 MPa 42800 psi
Elastic modulus 190-210 GPa 27557-30458 ksi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80 GPa 11600 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Izod Impact 41.0 J 30.2
Hardness, Brinell 167 167
Hardness, Knoop (converted from Brinell hardness) 188 188
Hardness, Rockwell B (converted from Brinell hardness) 85 85
Hardness, Vickers (converted from Brinell hardness) 175 175
Machinability (annealed and cold drawn, based on 100 machinability for AISI 1212 steel) 65 65

Thermal Properties

The thermal properties of AISI 5140 alloy steel are provided in the table below.

Properties Metric Imperial
Thermal conductivity 44.6 W/mK 310 BTU in/hr.ft².°F
Thermal expansion co-efficient (@20-200°C/68-392°F) 12.6 µm/m°C 7 µin/in°F

Other Designations

Equivalent materials to AISI 5140 alloy steel are as follows.

AFNOR 42 C 2 AFNOR 42 C 4 DIN 1.7035 UNI 40 Cr 4 UNI 41 Cr 4 KB JIS SCr 4 H
B.S. 2 S 117 B.S. 530 A 40 B.S. 530 H 40 B.S. 530 M 40 ASTM A322 ASTM A331
ASTM A505 ASTM A519 SAE J404 SAE J412 SAE J770

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