ACI-ASTM CN7M (J95150) Cast Stainless Steel
ACI-ASTM CN7M steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CN7M is the designation in both the ACI and ASTM systems for this material. J95150 is the UNS number.
It has the lowest electrical conductivity among cast austenitic stainless steels. In addition, it has the highest thermal conductivity and a fairly low tensile strength.
The graph bars on the material properties cards below compare ACI-ASTM CN7M steel to: cast austenitic 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
140
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
44 %
Fatigue Strength
190 MPa 27 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
480 MPa 70 x 103 psi
Tensile Strength: Yield (Proof)
200 MPa 30 x 103 psi
Thermal Properties
Latent Heat of Fusion
310 J/g
Maximum Temperature: Corrosion
430 °C 800 °F
Maximum Temperature: Mechanical
1100 °C 2010 °F
Melting Completion (Liquidus)
1410 °C 2570 °F
Melting Onset (Solidus)
1450 °C 2640 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
21 W/m-K 12 BTU/h-ft-°F
Thermal Expansion
15 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
1.6 % IACS
Electrical Conductivity: Equal Weight (Specific)
1.8 % IACS
Otherwise Unclassified Properties
Base Metal Price
32 % relative
Density
8.1 g/cm3 500 lb/ft3
Embodied Carbon
5.6 kg CO2/kg material
Embodied Energy
78 MJ/kg 34 x 103 BTU/lb
Embodied Water
210 L/kg 25 gal/lb
Common Calculations
PREN (Pitting Resistance)
29
Resilience: Ultimate (Unit Rupture Work)
170 MJ/m3
Resilience: Unit (Modulus of Resilience)
110 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
17 points
Strength to Weight: Bending
17 points
Thermal Diffusivity
5.6 mm2/s
Thermal Shock Resistance
12 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CN7M steel is notable for containing a comparatively high amount of nickel (Ni) and including copper (Cu). Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion. Copper is primarily used to improve resistance to acids.
| Fe | 37.4 to 48.5 | |
| Ni | 27.5 to 30.5 | |
| Cr | 19 to 22 | |
| Cu | 3.0 to 4.0 | |
| Mo | 2.0 to 3.0 | |
| Mn | 0 to 1.5 | |
| Si | 0 to 1.5 | |
| C | 0 to 0.070 | |
| P | 0 to 0.040 | |
| S | 0 to 0.040 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A743: Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002
Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010