ACI-ASTM CN7MS (J94650) Cast Stainless Steel
ACI-ASTM CN7MS steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CN7MS is the designation in both the ACI and ASTM systems for this material. J94650 is the UNS number.
It has a moderately low thermal conductivity and a moderately high ductility among cast austenitic stainless steels.
The graph bars on the material properties cards below compare ACI-ASTM CN7MS 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
160
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
39 %
Fatigue Strength
200 MPa 29 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
540 MPa 79 x 103 psi
Tensile Strength: Yield (Proof)
230 MPa 34 x 103 psi
Thermal Properties
Latent Heat of Fusion
340 J/g
Maximum Temperature: Corrosion
420 °C 790 °F
Maximum Temperature: Mechanical
1040 °C 1910 °F
Melting Completion (Liquidus)
1400 °C 2540 °F
Melting Onset (Solidus)
1350 °C 2460 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
12 W/m-K 7.0 BTU/h-ft-°F
Thermal Expansion
16 µm/m-K
Otherwise Unclassified Properties
Base Metal Price
28 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
5.1 kg CO2/kg material
Embodied Energy
71 MJ/kg 31 x 103 BTU/lb
Embodied Water
180 L/kg 22 gal/lb
Common Calculations
PREN (Pitting Resistance)
28
Resilience: Ultimate (Unit Rupture Work)
170 MJ/m3
Resilience: Unit (Modulus of Resilience)
140 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
19 points
Strength to Weight: Bending
19 points
Thermal Diffusivity
3.2 mm2/s
Thermal Shock Resistance
13 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CN7MS steel is notable for containing comparatively high amounts of silicon (Si) and nickel (Ni). Silicon content is typically governed by metallurgical processing concerns, but it can also be added for the purpose of improving oxidation resistance. Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion.
| Fe | 45.4 to 53.5 | |
| Ni | 22 to 25 | |
| Cr | 18 to 20 | |
| Si | 2.5 to 3.5 | |
| Mo | 2.5 to 3.0 | |
| Cu | 1.5 to 2.0 | |
| Mn | 0 to 1.0 | |
| C | 0 to 0.070 | |
| 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 A743: Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005
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
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010