ACI-ASTM CA6NM (J91540) Cast Stainless Steel
ACI-ASTM CA6NM steel is a martensitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CA6NM is the designation in both the ACI and ASTM systems for this material. J91540 is the UNS number.
The graph bars on the material properties cards below compare ACI-ASTM CA6NM steel to: cast martensitic stainless steels (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
250
Elastic (Young's, Tensile) Modulus
200 GPa 28 x 106 psi
Elongation at Break
17 %
Fatigue Strength
380 MPa 55 x 103 psi
Poisson's Ratio
0.28
Reduction in Area
40 %
Shear Modulus
76 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
850 MPa 120 x 103 psi
Tensile Strength: Yield (Proof)
620 MPa 90 x 103 psi
Thermal Properties
Latent Heat of Fusion
280 J/g
Maximum Temperature: Corrosion
390 °C 740 °F
Maximum Temperature: Mechanical
770 °C 1420 °F
Melting Completion (Liquidus)
1450 °C 2630 °F
Melting Onset (Solidus)
1400 °C 2560 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
25 W/m-K 14 BTU/h-ft-°F
Thermal Expansion
10 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.8 % IACS
Electrical Conductivity: Equal Weight (Specific)
3.2 % IACS
Otherwise Unclassified Properties
Base Metal Price
10 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
2.5 kg CO2/kg material
Embodied Energy
34 MJ/kg 15 x 103 BTU/lb
Embodied Water
110 L/kg 13 gal/lb
Common Calculations
PREN (Pitting Resistance)
15
Resilience: Ultimate (Unit Rupture Work)
130 MJ/m3
Resilience: Unit (Modulus of Resilience)
1000 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
30 points
Strength to Weight: Bending
26 points
Thermal Diffusivity
6.7 mm2/s
Thermal Shock Resistance
31 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CA6NM steel is notable for containing comparatively high amounts of nickel (Ni) and chromium (Cr). Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion. Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance.
| Fe | 78.4 to 84.6 | |
| Cr | 11.5 to 14 | |
| Ni | 3.5 to 4.5 | |
| Mo | 0.4 to 1.0 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| C | 0 to 0.060 | |
| P | 0 to 0.040 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A356: Standard Specification for Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Turbines
ASTM A352: Standard Specification for Steel Castings, Ferritic and Martensitic, for Pressure-Containing Parts, Suitable for Low-Temperature Service
ASTM A743: Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
Corrosion of Stainless Steels, A. John Sedriks, 1996
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010