ASTM A372 Grade M Class 85 Steel
ASTM A372 grade M class 85 is ASTM A372 grade M steel in the quenched and tempered condition. ASTM A372 Grade M Class 85 is the ASTM designation for this material. Older literature may refer to this material as Type IX Class A, but this is now discouraged.
The graph bars on the material properties cards below compare ASTM A372 grade M class 85 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
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
21 %
Fatigue Strength
450 MPa 66 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
510 MPa 74 x 103 psi
Tensile Strength: Ultimate (UTS)
810 MPa 120 x 103 psi
Tensile Strength: Yield (Proof)
660 MPa 95 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 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
29 points
Strength to Weight: Bending
24 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
24 points
Alloy Composition
| 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
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