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ACI-ASTM CH20 (SCS17, J93402) Cast Stainless Steel

ACI-ASTM CH20 steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CH20 is the designation in both the ACI and ASTM systems for this material. J93402 is the UNS number.

It has a fairly high tensile strength and a moderately high ductility among cast austenitic stainless steels.

The graph bars on the material properties cards below compare ACI-ASTM CH20 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

190

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

38 %

Fatigue Strength

290 MPa 42 x 103 psi

Poisson's Ratio

0.27

Shear Modulus

78 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

610 MPa 88 x 103 psi

Tensile Strength: Yield (Proof)

350 MPa 50 x 103 psi

Thermal Properties

Latent Heat of Fusion

310 J/g

Maximum Temperature: Corrosion

440 °C 820 °F

Maximum Temperature: Mechanical

1100 °C 2010 °F

Melting Completion (Liquidus)

1410 °C 2570 °F

Melting Onset (Solidus)

1430 °C 2610 °F

Specific Heat Capacity

480 J/kg-K 0.12 BTU/lb-°F

Thermal Conductivity

14 W/m-K 8.1 BTU/h-ft-°F

Thermal Expansion

15 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

7.8 g/cm3 490 lb/ft3

Embodied Carbon

3.7 kg CO2/kg material

Embodied Energy

53 MJ/kg 23 x 103 BTU/lb

Embodied Water

180 L/kg 21 gal/lb

Common Calculations

PREN (Pitting Resistance)

25

Resilience: Ultimate (Unit Rupture Work)

200 MJ/m3

Resilience: Unit (Modulus of Resilience)

300 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

22 points

Strength to Weight: Bending

21 points

Thermal Diffusivity

3.7 mm2/s

Thermal Shock Resistance

15 points

Alloy Composition

Among cast stainless steels, the composition of ACI-ASTM CH20 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)Fe 54.7 to 66
Chromium (Cr)Cr 22 to 26
Nickel (Ni)Ni 12 to 15
Silicon (Si)Si 0 to 2.0
Manganese (Mn)Mn 0 to 1.5
Molybdenum (Mo)Mo 0 to 0.5
Carbon (C)C 0 to 0.2
Phosphorus (P)P 0 to 0.040
Sulfur (S)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

Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016

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