ASTM A387 Grade 22 (K21590) 2.25Cr-1Mo Steel
ASTM A387 grade 22 steel is an alloy steel formulated for primary forming into wrought products. ASTM A387 Grade 22 is the ASTM designation for this material. K21590 is the UNS number.
The properties of ASTM A387 grade 22 steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM A387 grade 22 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
150 to 180
Elastic (Young's, Tensile) Modulus
190 GPa 28 x 106 psi
Elongation at Break
21 %
Fatigue Strength
160 to 240 MPa 24 to 35 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
74 GPa 11 x 106 psi
Shear Strength
300 to 380 MPa 44 to 55 x 103 psi
Tensile Strength: Ultimate (UTS)
480 to 600 MPa 70 to 87 x 103 psi
Tensile Strength: Yield (Proof)
230 to 350 MPa 34 to 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
260 J/g
Maximum Temperature: Mechanical
460 °C 860 °F
Melting Completion (Liquidus)
1470 °C 2680 °F
Melting Onset (Solidus)
1430 °C 2600 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
40 W/m-K 23 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
3.8 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
1.7 kg CO2/kg material
Embodied Energy
23 MJ/kg 9.8 x 103 BTU/lb
Embodied Water
58 L/kg 6.9 gal/lb
Common Calculations
PREN (Pitting Resistance)
5.6
Resilience: Ultimate (Unit Rupture Work)
85 to 110 MJ/m3
Resilience: Unit (Modulus of Resilience)
140 to 320 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
17 to 21 points
Strength to Weight: Bending
17 to 20 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
14 to 17 points
Alloy Composition
Among alloy steels, the composition of ASTM A387 grade 22 steel is notable for containing a comparatively high amount of chromium (Cr). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures).
| Fe | 95.1 to 96.8 | |
| Cr | 2.0 to 2.5 | |
| Mo | 0.9 to 1.1 | |
| Mn | 0.3 to 0.6 | |
| Si | 0 to 0.5 | |
| C | 0.050 to 0.15 | |
| P | 0 to 0.025 | |
| S | 0 to 0.025 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
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
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005
Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015