UNS S21640 Stainless Steel
S21640 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. It has a moderately high ductility and a moderately high tensile strength among wrought austenitic stainless steels.
The graph bars on the material properties cards below compare S21640 stainless steel to: wrought 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
230
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
46 %
Fatigue Strength
320 MPa 47 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
78 GPa 11 x 106 psi
Shear Strength
520 MPa 75 x 103 psi
Tensile Strength: Ultimate (UTS)
740 MPa 110 x 103 psi
Tensile Strength: Yield (Proof)
350 MPa 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
490 °C 920 °F
Maximum Temperature: Mechanical
940 °C 1730 °F
Melting Completion (Liquidus)
1430 °C 2610 °F
Melting Onset (Solidus)
1380 °C 2520 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
15 W/m-K 8.7 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.4 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.8 % IACS
Otherwise Unclassified Properties
Base Metal Price
17 % relative
Density
7.7 g/cm3 480 lb/ft3
Embodied Carbon
3.6 kg CO2/kg material
Embodied Energy
51 MJ/kg 22 x 103 BTU/lb
Embodied Water
150 L/kg 18 gal/lb
Common Calculations
PREN (Pitting Resistance)
26
Resilience: Ultimate (Unit Rupture Work)
280 MJ/m3
Resilience: Unit (Modulus of Resilience)
300 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
27 points
Strength to Weight: Bending
23 points
Thermal Diffusivity
4.0 mm2/s
Thermal Shock Resistance
16 points
Alloy Composition
Among wrought stainless steels, the composition of S21640 stainless steel is notable for containing a comparatively high amount of manganese (Mn) and including niobium (Nb). Manganese is used to improve ductility at elevated temperatures. It also permits a higher nitrogen content than would otherwise be possible. Niobium is primarily used to improve yield strength, particularly at elevated temperatures.
| Fe | 63 to 74.3 | |
| Cr | 17.5 to 19.5 | |
| Ni | 4.0 to 6.5 | |
| Mn | 3.5 to 6.5 | |
| Mo | 0.5 to 2.0 | |
| Nb | 0.1 to 1.0 | |
| Si | 0 to 1.0 | |
| N | 0.080 to 0.3 | |
| C | 0 to 0.080 | |
| P | 0 to 0.060 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
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