UNS S21900 (XM-10) Stainless Steel
S21900 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. XM-10 is the ASTM designation for this material. S21900 is the UNS number. Additionally, the common industry name is 21-6-9.
It has a moderately high electrical conductivity among wrought austenitic stainless steels. In addition, it has a fairly high ductility and a moderately high tensile strength.
The graph bars on the material properties cards below compare S21900 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
220
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
50 %
Fatigue Strength
380 MPa 55 x 103 psi
Poisson's Ratio
0.28
Reduction in Area
57 %
Shear Modulus
78 GPa 11 x 106 psi
Shear Strength
510 MPa 73 x 103 psi
Tensile Strength: Ultimate (UTS)
710 MPa 100 x 103 psi
Tensile Strength: Yield (Proof)
390 MPa 56 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
420 °C 800 °F
Maximum Temperature: Mechanical
980 °C 1800 °F
Melting Completion (Liquidus)
1400 °C 2550 °F
Melting Onset (Solidus)
1350 °C 2470 °F
Specific Heat Capacity
480 J/kg-K 0.12 BTU/lb-°F
Thermal Conductivity
14 W/m-K 8.1 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.5 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.9 % IACS
Otherwise Unclassified Properties
Base Metal Price
15 % relative
Density
7.7 g/cm3 480 lb/ft3
Embodied Carbon
3.0 kg CO2/kg material
Embodied Energy
43 MJ/kg 19 x 103 BTU/lb
Embodied Water
160 L/kg 19 gal/lb
Common Calculations
PREN (Pitting Resistance)
25
Resilience: Ultimate (Unit Rupture Work)
300 MJ/m3
Resilience: Unit (Modulus of Resilience)
380 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
26 points
Strength to Weight: Bending
23 points
Thermal Diffusivity
3.8 mm2/s
Thermal Shock Resistance
15 points
Alloy Composition
Among wrought stainless steels, the composition of S21900 stainless steel is notable for containing a comparatively high amount of manganese (Mn). Manganese is used to improve ductility at elevated temperatures. It also permits a higher nitrogen content than would otherwise be possible.
| Fe | 59.4 to 67.4 | |
| Cr | 19 to 21.5 | |
| Mn | 8.0 to 10 | |
| Ni | 5.5 to 7.5 | |
| Si | 0 to 1.0 | |
| N | 0.15 to 0.4 | |
| C | 0 to 0.080 | |
| P | 0 to 0.045 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A473: Standard Specification for Stainless Steel Forgings
Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016
ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels
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