UNS S21603 (XM-18) Stainless Steel
S21603 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. XM-18 is the ASTM designation for this material. S21603 is the UNS number.
It has a moderately high tensile strength among the wrought austenitic stainless steels in the database.
The graph bars on the material properties cards below compare S21603 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
200
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
45 %
Fatigue Strength
360 MPa 52 x 103 psi
Poisson's Ratio
0.28
Reduction in Area
57 %
Rockwell B Hardness
88
Shear Modulus
79 GPa 11 x 106 psi
Shear Strength
490 MPa 70 x 103 psi
Tensile Strength: Ultimate (UTS)
690 MPa 100 x 103 psi
Tensile Strength: Yield (Proof)
390 MPa 57 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
420 °C 790 °F
Maximum Temperature: Mechanical
990 °C 1820 °F
Melting Completion (Liquidus)
1420 °C 2590 °F
Melting Onset (Solidus)
1380 °C 2510 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Expansion
17 µm/m-K
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
50 MJ/kg 21 x 103 BTU/lb
Embodied Water
160 L/kg 20 gal/lb
Common Calculations
PREN (Pitting Resistance)
34
Resilience: Ultimate (Unit Rupture Work)
270 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
25 points
Strength to Weight: Bending
22 points
Thermal Shock Resistance
15 points
Alloy Composition
Among wrought stainless steels, the composition of S21603 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 | 57.6 to 67.8 | |
| Cr | 17.5 to 22 | |
| Mn | 7.5 to 9.0 | |
| Ni | 5.0 to 7.0 | |
| Mo | 2.0 to 3.0 | |
| Si | 0 to 0.75 | |
| N | 0.25 to 0.5 | |
| P | 0 to 0.045 | |
| C | 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 A479: Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels
ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005
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
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010