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UNS S81921 Stainless Steel

S81921 stainless steel is a duplex stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. It has a moderately low tensile strength and a moderately high ductility among wrought duplex stainless steels.

The graph bars on the material properties cards below compare S81921 stainless steel to: wrought duplex 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

260

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

29 %

Fatigue Strength

370 MPa 54 x 103 psi

Poisson's Ratio

0.28

Rockwell C Hardness

27

Shear Modulus

79 GPa 11 x 106 psi

Shear Strength

460 MPa 67 x 103 psi

Tensile Strength: Ultimate (UTS)

710 MPa 100 x 103 psi

Tensile Strength: Yield (Proof)

500 MPa 73 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Maximum Temperature: Corrosion

430 °C 800 °F

Maximum Temperature: Mechanical

990 °C 1810 °F

Melting Completion (Liquidus)

1430 °C 2610 °F

Melting Onset (Solidus)

1390 °C 2530 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

15 W/m-K 8.5 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.2 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

14 % relative

Density

7.7 g/cm3 480 lb/ft3

Embodied Carbon

2.9 kg CO2/kg material

Embodied Energy

41 MJ/kg 18 x 103 BTU/lb

Embodied Water

150 L/kg 18 gal/lb

Common Calculations

PREN (Pitting Resistance)

28

Resilience: Ultimate (Unit Rupture Work)

180 MJ/m3

Resilience: Unit (Modulus of Resilience)

630 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

25 points

Strength to Weight: Bending

23 points

Thermal Diffusivity

4.0 mm2/s

Thermal Shock Resistance

20 points

Alloy Composition

Among wrought stainless steels, the composition of S81921 stainless steel is notable for containing comparatively high amounts of manganese (Mn) and chromium (Cr). Manganese is used to improve ductility at elevated temperatures. It also permits a higher nitrogen content than would otherwise be possible. Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance.

Iron (Fe) 66.7 to 75.9
Chromium (Cr) 19 to 22
Manganese (Mn) 2.0 to 4.0
Nickel (Ni) 2.0 to 4.0
Molybdenum (Mo) 1.0 to 2.0
Silicon (Si) 0 to 1.0
Nitrogen (N) 0.14 to 0.2
Phosphorus (P) 0 to 0.040
Carbon (C) 0 to 0.030
Sulfur (S) 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

Duplex Stainless Steels, Iris Alvarez-Armas and Suzanne Degallaix-Moreuil (editors), 2009

Duplex Stainless Steels: Microstructure, Properties and Applications, Robert N. Gunn (editor), 1997

ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012

Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011

Corrosion of Stainless Steels, A. John Sedriks, 1996

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

Advances in Stainless Steels, Baldev Raj et al. (editors), 2010