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.
| Fe | 40.3 to 49.2 | |
| Ni | 31 to 34 | |
| Cr | 19 to 21 | |
| Nb | 0.5 to 1.5 | |
| Mn | 0.15 to 1.5 | |
| Si | 0.15 to 1.5 | |
| C | 0.050 to 0.15 | |
| P | 0 to 0.030 | |
| 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