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ACI-ASTM CA15M (J91151) Cast Stainless Steel

ACI-ASTM CA15M steel is a martensitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CA15M is the designation in both the ACI and ASTM systems for this material. J91151 is the UNS number. Additionally, the common industry name is 12 Chromium.

It has a fairly high thermal conductivity among cast martensitic stainless steels. In addition, it has a moderately low base cost and a moderately high electrical conductivity.

The graph bars on the material properties cards below compare ACI-ASTM CA15M 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

210

Elastic (Young's, Tensile) Modulus

200 GPa 28 x 106 psi

Elongation at Break

20 %

Fatigue Strength

330 MPa 48 x 103 psi

Poisson's Ratio

0.28

Reduction in Area

34 %

Shear Modulus

76 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

690 MPa 100 x 103 psi

Tensile Strength: Yield (Proof)

510 MPa 74 x 103 psi

Thermal Properties

Latent Heat of Fusion

270 J/g

Maximum Temperature: Corrosion

390 °C 730 °F

Maximum Temperature: Mechanical

760 °C 1400 °F

Melting Completion (Liquidus)

1450 °C 2640 °F

Melting Onset (Solidus)

1410 °C 2570 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

27 W/m-K 15 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

7.8 g/cm3 490 lb/ft3

Embodied Carbon

2.1 kg CO2/kg material

Embodied Energy

29 MJ/kg 12 x 103 BTU/lb

Embodied Water

100 L/kg 12 gal/lb

Common Calculations

PREN (Pitting Resistance)

15

Resilience: Ultimate (Unit Rupture Work)

130 MJ/m3

Resilience: Unit (Modulus of Resilience)

670 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

25 points

Strength to Weight: Bending

22 points

Thermal Diffusivity

7.2 mm2/s

Thermal Shock Resistance

25 points

Alloy Composition

Among cast stainless steels, the composition of ACI-ASTM CA15M steel is notable for containing comparatively high amounts of chromium (Cr) and molybdenum (Mo). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Molybdenum is used to facilitate tempering. In addition, it offers modest bonuses to a wide range of material properties.

Iron (Fe) 82.1 to 88.4
Chromium (Cr) 11.5 to 14
Molybdenum (Mo) 0.15 to 1.0
Manganese (Mn) 0 to 1.0
Nickel (Ni) 0 to 1.0
Silicon (Si) 0 to 0.65
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 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

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