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ACI-ASTM CT15C (N08151) Cast Stainless Steel

ACI-ASTM CT15C steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the normalized and tempered condition. CT15C is the designation in both the ACI and ASTM systems for this material. N08151 is the UNS number.

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

The graph bars on the material properties cards below compare ACI-ASTM CT15C 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

140

Elastic (Young's, Tensile) Modulus

200 GPa 28 x 106 psi

Elongation at Break

23 %

Fatigue Strength

130 MPa 19 x 103 psi

Poisson's Ratio

0.28

Shear Modulus

76 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

500 MPa 72 x 103 psi

Tensile Strength: Yield (Proof)

190 MPa 28 x 103 psi

Thermal Properties

Latent Heat of Fusion

310 J/g

Maximum Temperature: Corrosion

560 °C 1040 °F

Maximum Temperature: Mechanical

1080 °C 1970 °F

Melting Completion (Liquidus)

1410 °C 2560 °F

Melting Onset (Solidus)

1360 °C 2480 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

12 W/m-K 6.9 BTU/h-ft-°F

Thermal Expansion

16 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

1.7 % IACS

Electrical Conductivity: Equal Weight (Specific)

1.9 % IACS

Otherwise Unclassified Properties

Base Metal Price

36 % relative

Density

8.0 g/cm3 500 lb/ft3

Embodied Carbon

6.1 kg CO2/kg material

Embodied Energy

88 MJ/kg 38 x 103 BTU/lb

Embodied Water

190 L/kg 23 gal/lb

Common Calculations

PREN (Pitting Resistance)

20

Resilience: Ultimate (Unit Rupture Work)

90 MJ/m3

Resilience: Unit (Modulus of Resilience)

93 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

17 points

Strength to Weight: Bending

17 points

Thermal Diffusivity

3.2 mm2/s

Thermal Shock Resistance

12 points

Alloy Composition

Among cast stainless steels, the composition of ACI-ASTM CT15C steel is notable for containing a comparatively high amount of nickel (Ni) and including niobium (Nb). Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion. Niobium is primarily used to improve yield strength, particularly at elevated temperatures.

Iron (Fe) 40.3 to 49.2
Nickel (Ni) 31 to 34
Chromium (Cr) 19 to 21
Niobium (Nb) 0.5 to 1.5
Manganese (Mn) 0.15 to 1.5
Silicon (Si) 0.15 to 1.5
Carbon (C) 0.050 to 0.15
Phosphorus (P) 0 to 0.030
Sulfur (S) 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM A297: Standard Specification for Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General Application

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

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