ACI-ASTM CF20 (SCS12, J92602) Cast Stainless Steel
ACI-ASTM CF20 steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CF20 is the designation in both the ACI and ASTM systems for this material. J92602 is the UNS number.
It has a very low embodied energy among cast austenitic stainless steels. In addition, it has a fairly high ductility and a fairly low base cost.
The graph bars on the material properties cards below compare ACI-ASTM CF20 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
50 %
Fatigue Strength
240 MPa 35 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
530 MPa 77 x 103 psi
Tensile Strength: Yield (Proof)
250 MPa 36 x 103 psi
Thermal Properties
Latent Heat of Fusion
300 J/g
Maximum Temperature: Corrosion
420 °C 790 °F
Maximum Temperature: Mechanical
970 °C 1780 °F
Melting Completion (Liquidus)
1420 °C 2580 °F
Melting Onset (Solidus)
1410 °C 2570 °F
Specific Heat Capacity
480 J/kg-K 0.12 BTU/lb-°F
Thermal Conductivity
16 W/m-K 9.3 BTU/h-ft-°F
Thermal Expansion
17 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
16 % relative
Density
7.8 g/cm3 480 lb/ft3
Embodied Carbon
3.1 kg CO2/kg material
Embodied Energy
44 MJ/kg 19 x 103 BTU/lb
Embodied Water
150 L/kg 18 gal/lb
Common Calculations
PREN (Pitting Resistance)
20
Resilience: Ultimate (Unit Rupture Work)
220 MJ/m3
Resilience: Unit (Modulus of Resilience)
160 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
11 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CF20 steel is notable for containing comparatively high amounts of chromium (Cr) and nickel (Ni). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion 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 | 64.2 to 74 | |
| Cr | 18 to 21 | |
| Ni | 8.0 to 11 | |
| Si | 0 to 2.0 | |
| Mn | 0 to 1.5 | |
| C | 0 to 0.2 | |
| 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