ASTM A387 Grade 12 (K11757) 1Cr-0.5Mo Steel
ASTM A387 grade 12 steel is an alloy steel formulated for primary forming into wrought products. ASTM A387 Grade 12 is the ASTM designation for this material. K11757 is the UNS number.
It has a moderately low electrical conductivity among wrought alloy steels in the same category. In addition, it can have a moderately low tensile strength and has a fairly high ductility.
The properties of ASTM A387 grade 12 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 12 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
140 to 160
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
25 %
Fatigue Strength
190 to 230 MPa 28 to 33 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
300 to 330 MPa 43 to 48 x 103 psi
Tensile Strength: Ultimate (UTS)
470 to 520 MPa 67 to 75 x 103 psi
Tensile Strength: Yield (Proof)
260 to 310 MPa 38 to 45 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
430 °C 800 °F
Melting Completion (Liquidus)
1470 °C 2670 °F
Melting Onset (Solidus)
1420 °C 2600 °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
7.2 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.8 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.6 kg CO2/kg material
Embodied Energy
21 MJ/kg 8.9 x 103 BTU/lb
Embodied Water
51 L/kg 6.1 gal/lb
Common Calculations
PREN (Pitting Resistance)
2.7
Resilience: Ultimate (Unit Rupture Work)
98 to 110 MJ/m3
Resilience: Unit (Modulus of Resilience)
180 to 250 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
16 to 18 points
Strength to Weight: Bending
17 to 18 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
14 to 15 points
Alloy Composition
Among alloy steels, the composition of ASTM A387 grade 12 steel is notable for containing comparatively high amounts of chromium (Cr) and manganese (Mn). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however.
| Fe | 97 to 98.2 | |
| Cr | 0.8 to 1.2 | |
| Mn | 0.4 to 0.65 | |
| Mo | 0.45 to 0.6 | |
| Si | 0.15 to 0.4 | |
| C | 0.050 to 0.17 | |
| 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
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