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ASTM A372 Grade M Alloy Steel

ASTM A372 grade M steel is an alloy steel formulated for primary forming into wrought products. It can have a very high tensile strength among wrought alloy steels in the same category. In addition, it has a fairly high base cost and a moderately high electrical conductivity.

The properties of ASTM A372 grade M steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM A372 grade M steel to: wrought alloy steels in the same category (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Brinell Hardness

240 to 280

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

18 to 21 %

Fatigue Strength

450 to 520 MPa 66 to 76 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

510 to 570 MPa 74 to 82 x 103 psi

Tensile Strength: Ultimate (UTS)

810 to 910 MPa 120 to 130 x 103 psi

Tensile Strength: Yield (Proof)

660 to 770 MPa 95 to 110 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

450 °C 850 °F

Melting Completion (Liquidus)

1460 °C 2670 °F

Melting Onset (Solidus)

1420 °C 2590 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

46 W/m-K 27 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

8.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

9.1 % IACS

Otherwise Unclassified Properties

Base Metal Price

5.0 % relative

Density

7.9 g/cm3 490 lb/ft3

Embodied Carbon

2.0 kg CO2/kg material

Embodied Energy

27 MJ/kg 11 x 103 BTU/lb

Embodied Water

61 L/kg 7.2 gal/lb

Common Calculations

PREN (Pitting Resistance)

3.4

Resilience: Ultimate (Unit Rupture Work)

160 MJ/m3

Resilience: Unit (Modulus of Resilience)

1140 to 1580 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

29 to 32 points

Strength to Weight: Bending

24 to 27 points

Thermal Diffusivity

12 mm2/s

Thermal Shock Resistance

24 to 27 points

Alloy Composition

Among alloy steels, the composition of ASTM A372 grade M steel is notable for including vanadium (V) and nickel (Ni). Vanadium has a strong hardening effect, but this effect is particularly sensitive to the type of tempering. Nickel is used to improve mechanical properties, and to make the alloy easier to heat treat.

Iron (Fe) 92.5 to 95.1
Nickel (Ni) 2.8 to 3.9
Chromium (Cr) 1.5 to 2.0
Molybdenum (Mo) 0.4 to 0.6
Manganese (Mn) 0.2 to 0.4
Silicon (Si) 0 to 0.3
Carbon (C) 0 to 0.23
Vanadium (V) 0 to 0.080
Phosphorus (P) 0 to 0.015
Sulfur (S) 0 to 0.010

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM A372: Standard Specification for Carbon and Alloy Steel Forgings for Thin-Walled Pressure Vessels

Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011

Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005

Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015