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ACI-ASTM CA40 (SCS2A, J91153) Cast Stainless Steel

ACI-ASTM CA40 steel is a martensitic stainless steel formulated for casting. It is typically furnished in the heat treated (HT) condition. CA40 is the designation in both the ACI and ASTM systems for this material. J91153 is the UNS number.

It has a fairly low base cost among cast martensitic stainless steels. In addition, it has the lowest ductility and a moderately low embodied energy.

The graph bars on the material properties cards below compare ACI-ASTM CA40 steel to: cast martensitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). The length of each bar shows the given value as a % of the largest value in the relevant set.

Mechanical Properties

Brinell Hardness


Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

10 %

Fatigue Strength

460 MPa 66 x 103 psi

Poisson's Ratio


Shear Modulus

76 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

910 MPa 130 x 103 psi

Tensile Strength: Yield (Proof)

860 MPa 120 x 103 psi

Thermal Properties

Melting Onset (Solidus)

1500 °C 2730 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

25 W/m-K 14 BTU/h-ft-°F

Thermal Expansion

10 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

3.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

3.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

7.4 % relative


7.7 g/cm3 480 lb/ft3

Embodied Carbon

2.0 kg CO2/kg material

Embodied Energy

28 MJ/kg 12 x 103 BTU/lb

Embodied Water

100 L/kg 12 gal/lb

Common Calculations

PREN (Pitting Resistance)


Resilience: Ultimate (Unit Rupture Work)

89 MJ/m3

Resilience: Unit (Modulus of Resilience)

1910 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

33 points

Strength to Weight: Bending

27 points

Thermal Diffusivity

6.7 m2/s

Thermal Shock Resistance

33 points

Alloy Composition

Iron (Fe) 81.5 to 88.3
Chromium (Cr) 11.5 to 14
Silicon (Si) 0 to 1.5
Manganese (Mn) 0 to 1.0
Nickel (Ni) 0 to 1.0
Carbon (C) 0.2 to 0.4
Molybdenum (Mo) 0 to 0.5
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

Advances in Stainless Steels, Raj et al. (editors), 2010

Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005

Corrosion of Stainless Steels, A. John Sedriks, 1996