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.
| Fe | 92.5 to 95.1 | |
| Ni | 2.8 to 3.9 | |
| Cr | 1.5 to 2.0 | |
| Mo | 0.4 to 0.6 | |
| Mn | 0.2 to 0.4 | |
| Si | 0 to 0.3 | |
| C | 0 to 0.23 | |
| V | 0 to 0.080 | |
| P | 0 to 0.015 | |
| 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