ACI-ASTM CG8M (J93000) Cast Stainless Steel
ACI-ASTM CG8M steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CG8M is the designation in both the ACI and ASTM systems for this material. J93000 is the UNS number.
It has a moderately high thermal conductivity among cast austenitic stainless steels. In addition, it has a fairly high ductility and a moderately high tensile strength.
The graph bars on the material properties cards below compare ACI-ASTM CG8M 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
180
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
45 %
Fatigue Strength
280 MPa 40 x 103 psi
Impact Strength: V-Notched Charpy
110 J 81 ft-lb
Poisson's Ratio
0.28
Shear Modulus
79 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
550 MPa 80 x 103 psi
Tensile Strength: Yield (Proof)
300 MPa 44 x 103 psi
Thermal Properties
Latent Heat of Fusion
300 J/g
Maximum Temperature: Corrosion
420 °C 790 °F
Maximum Temperature: Mechanical
1020 °C 1860 °F
Melting Completion (Liquidus)
1450 °C 2640 °F
Melting Onset (Solidus)
1400 °C 2550 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
16 W/m-K 9.3 BTU/h-ft-°F
Thermal Expansion
16 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
20 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
4.1 kg CO2/kg material
Embodied Energy
56 MJ/kg 24 x 103 BTU/lb
Embodied Water
160 L/kg 19 gal/lb
Common Calculations
PREN (Pitting Resistance)
31
Resilience: Ultimate (Unit Rupture Work)
210 MJ/m3
Resilience: Unit (Modulus of Resilience)
220 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
4.3 mm2/s
Thermal Shock Resistance
12 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CG8M steel is notable for containing a comparatively high amount of molybdenum (Mo). Molybdenum is used to facilitate tempering. In addition, it offers modest bonuses to a wide range of material properties.
| Fe | 58.8 to 70 | |
| Cr | 18 to 21 | |
| Ni | 9.0 to 13 | |
| Mo | 3.0 to 4.0 | |
| Mn | 0 to 1.5 | |
| Si | 0 to 1.5 | |
| C | 0 to 0.080 | |
| 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
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
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015