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ACI-ASTM CA15 (SCS1, J91150) Cast Stainless Steel

ACI-ASTM CA15 steel is a martensitic stainless steel formulated for casting. Cited properties are appropriate for the normalized and tempered condition. CA15 is the designation in both the ACI and ASTM systems for this material. J91150 is the UNS number.

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

The graph bars on the material properties cards below compare ACI-ASTM CA15 steel to: cast martensitic 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

220

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

21 %

Fatigue Strength

370 MPa 54 x 103 psi

Poisson's Ratio

0.28

Reduction in Area

34 %

Shear Modulus

76 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

700 MPa 100 x 103 psi

Tensile Strength: Yield (Proof)

570 MPa 82 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Maximum Temperature: Corrosion

390 °C 730 °F

Maximum Temperature: Mechanical

750 °C 1390 °F

Melting Completion (Liquidus)

1440 °C 2630 °F

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

7.5 % relative

Density

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)

14

Resilience: Ultimate (Unit Rupture Work)

140 MJ/m3

Resilience: Unit (Modulus of Resilience)

820 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

25 points

Strength to Weight: Bending

23 points

Thermal Diffusivity

6.7 mm2/s

Thermal Shock Resistance

26 points

Alloy Composition

Among cast stainless steels, the composition of ACI-ASTM CA15 steel is notable for containing comparatively high amounts of chromium (Cr) and silicon (Si). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Silicon content is typically governed by metallurgical processing concerns, but it can also be added for the purpose of improving oxidation resistance.

Iron (Fe) 81.8 to 88.5
Chromium (Cr) 11.5 to 14
Silicon (Si) 0 to 1.5
Manganese (Mn) 0 to 1.0
Nickel (Ni) 0 to 1.0
Molybdenum (Mo) 0 to 0.5
Carbon (C) 0 to 0.15
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 A217: Standard Specification for Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service

ASTM A743: Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application

Metallic Materials: Physical, Mechanical, and Corrosion Properties, Philip A. Schweitzer, 2003

Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012

Corrosion of Stainless Steels, A. John Sedriks, 1996

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

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