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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

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

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