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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.

Iron (Fe)Fe 57.6 to 67.8
Chromium (Cr)Cr 17.5 to 22
Manganese (Mn)Mn 7.5 to 9.0
Nickel (Ni)Ni 5.0 to 7.0
Molybdenum (Mo)Mo 2.0 to 3.0
Silicon (Si)Si 0 to 0.75
Nitrogen (N)N 0.25 to 0.5
Phosphorus (P)P 0 to 0.045
Carbon (C)C 0 to 0.030
Sulfur (S)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