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ASTM A387 Grade 21 Class 2 Steel

ASTM A387 grade 21 class 2 is ASTM A387 grade 21 steel in the normalized and tempered condition. The graph bars on the material properties cards below compare ASTM A387 grade 21 class 2 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

180

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

21 %

Fatigue Strength

250 MPa 36 x 103 psi

Poisson's Ratio

0.29

Reduction in Area

34 %

Shear Modulus

74 GPa 11 x 106 psi

Shear Strength

370 MPa 54 x 103 psi

Tensile Strength: Ultimate (UTS)

590 MPa 86 x 103 psi

Tensile Strength: Yield (Proof)

350 MPa 51 x 103 psi

Thermal Properties

Latent Heat of Fusion

260 J/g

Maximum Temperature: Mechanical

480 °C 890 °F

Melting Completion (Liquidus)

1470 °C 2670 °F

Melting Onset (Solidus)

1430 °C 2600 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

41 W/m-K 24 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.6 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.8 % IACS

Otherwise Unclassified Properties

Base Metal Price

4.1 % relative

Density

7.9 g/cm3 490 lb/ft3

Embodied Carbon

1.8 kg CO2/kg material

Embodied Energy

23 MJ/kg 10 x 103 BTU/lb

Embodied Water

62 L/kg 7.4 gal/lb

Common Calculations

PREN (Pitting Resistance)

6.4

Resilience: Ultimate (Unit Rupture Work)

110 MJ/m3

Resilience: Unit (Modulus of Resilience)

320 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

21 points

Strength to Weight: Bending

20 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

17 points

Alloy Composition

Iron (Fe)Fe 94.4 to 96
Chromium (Cr)Cr 2.8 to 3.3
Molybdenum (Mo)Mo 0.9 to 1.1
Manganese (Mn)Mn 0.3 to 0.6
Silicon (Si)Si 0 to 0.5
Carbon (C)C 0.050 to 0.15
Phosphorus (P)P 0 to 0.025
Sulfur (S)S 0 to 0.025

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Further Reading

ASTM A387: Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum

ASTM A182: Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service

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

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