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ASTM A372 Grade L Alloy Steel

ASTM A372 grade L steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. ASTM A372 Grade L is the ASTM designation for this material. Older literature may refer to this material as Type VII, but this is now discouraged.

It has a very low ductility and a very high tensile strength among wrought alloy steels in the same category.

The graph bars on the material properties cards below compare ASTM A372 grade L 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

350

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

14 %

Fatigue Strength

670 MPa 97 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

700 MPa 100 x 103 psi

Tensile Strength: Ultimate (UTS)

1160 MPa 170 x 103 psi

Tensile Strength: Yield (Proof)

1040 MPa 150 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

430 °C 800 °F

Melting Completion (Liquidus)

1460 °C 2660 °F

Melting Onset (Solidus)

1420 °C 2580 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

44 W/m-K 26 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.5 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.6 % IACS

Otherwise Unclassified Properties

Base Metal Price

3.5 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.7 kg CO2/kg material

Embodied Energy

22 MJ/kg 9.6 x 103 BTU/lb

Embodied Water

54 L/kg 6.4 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

150 MJ/m3

Resilience: Unit (Modulus of Resilience)

2890 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

41 points

Strength to Weight: Bending

31 points

Thermal Diffusivity

12 mm2/s

Thermal Shock Resistance

34 points

Alloy Composition

Among alloy steels, the composition of ASTM A372 grade L steel is notable for including nickel (Ni). Nickel is used to improve mechanical properties, and to make the alloy easier to heat treat.

Iron (Fe)Fe 95.2 to 96.3
Nickel (Ni)Ni 1.7 to 2.0
Chromium (Cr)Cr 0.7 to 0.9
Manganese (Mn)Mn 0.6 to 0.8
Carbon (C)C 0.38 to 0.43
Silicon (Si)Si 0.15 to 0.35
Molybdenum (Mo)Mo 0.2 to 0.3
Phosphorus (P)P 0 to 0.015
Sulfur (S)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

ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015

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