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.
| Fe | 95.2 to 96.3 | |
| Ni | 1.7 to 2.0 | |
| Cr | 0.7 to 0.9 | |
| Mn | 0.6 to 0.8 | |
| C | 0.38 to 0.43 | |
| Si | 0.15 to 0.35 | |
| Mo | 0.2 to 0.3 | |
| 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
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