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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.

Iron (Fe) 37.4 to 48.5
Nickel (Ni) 27.5 to 30.5
Chromium (Cr) 19 to 22
Copper (Cu) 3.0 to 4.0
Molybdenum (Mo) 2.0 to 3.0
Manganese (Mn) 0 to 1.5
Silicon (Si) 0 to 1.5
Carbon (C) 0 to 0.070
Phosphorus (P) 0 to 0.040
Sulfur (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