ASTM A387 Grade 11 (K11789) 1.25Cr-0.5Mo Steel
ASTM A387 grade 11 steel is an alloy steel formulated for primary forming into wrought products. ASTM A387 Grade 11 is the ASTM designation for this material. K11789 is the UNS number.
It has a fairly high ductility and a moderately low thermal conductivity among wrought alloy steels in the same category.
The properties of ASTM A387 grade 11 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 11 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 27 x 106 psi
Elongation at Break
25 %
Fatigue Strength
200 to 250 MPa 29 to 37 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
320 to 390 MPa 46 to 56 x 103 psi
Tensile Strength: Ultimate (UTS)
500 to 600 MPa 73 to 87 x 103 psi
Tensile Strength: Yield (Proof)
270 to 350 MPa 40 to 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
260 J/g
Maximum Temperature: Mechanical
430 °C 810 °F
Melting Completion (Liquidus)
1460 °C 2660 °F
Melting Onset (Solidus)
1420 °C 2590 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
39 W/m-K 23 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.4 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.5 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.9 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.6 kg CO2/kg material
Embodied Energy
21 MJ/kg 9.1 x 103 BTU/lb
Embodied Water
53 L/kg 6.3 gal/lb
Common Calculations
PREN (Pitting Resistance)
3.1
Resilience: Ultimate (Unit Rupture Work)
100 to 130 MJ/m3
Resilience: Unit (Modulus of Resilience)
200 to 320 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
18 to 21 points
Strength to Weight: Bending
18 to 20 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
15 to 18 points
Alloy Composition
Among alloy steels, the composition of ASTM A387 grade 11 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 | 96.2 to 97.6 | |
| Cr | 1.0 to 1.5 | |
| Si | 0.5 to 0.8 | |
| Mo | 0.45 to 0.65 | |
| Mn | 0.4 to 0.65 | |
| 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