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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.

Iron (Fe) 64.2 to 74
Chromium (Cr) 18 to 21
Nickel (Ni) 8.0 to 11
Silicon (Si) 0 to 2.0
Manganese (Mn) 0 to 1.5
Carbon (C) 0 to 0.2
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

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