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AISI 312 (S31200) Stainless Steel

AISI 312 stainless steel is a duplex stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 312 is the AISI designation for this material. S31200 is the UNS number.

It has a moderately high thermal conductivity and a moderately low electrical conductivity among wrought duplex stainless steels.

The graph bars on the material properties cards below compare AISI 312 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

250

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

28 %

Fatigue Strength

370 MPa 54 x 103 psi

Poisson's Ratio

0.27

Reduction in Area

56 %

Rockwell C Hardness

27

Shear Modulus

80 GPa 12 x 106 psi

Shear Strength

510 MPa 73 x 103 psi

Tensile Strength: Ultimate (UTS)

780 MPa 110 x 103 psi

Tensile Strength: Yield (Proof)

510 MPa 74 x 103 psi

Thermal Properties

Latent Heat of Fusion

300 J/g

Maximum Temperature: Corrosion

450 °C 840 °F

Maximum Temperature: Mechanical

1100 °C 2010 °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

16 W/m-K 9.2 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.1 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

17 % relative

Density

7.7 g/cm3 480 lb/ft3

Embodied Carbon

3.4 kg CO2/kg material

Embodied Energy

48 MJ/kg 20 x 103 BTU/lb

Embodied Water

170 L/kg 20 gal/lb

Common Calculations

PREN (Pitting Resistance)

33

Resilience: Ultimate (Unit Rupture Work)

190 MJ/m3

Resilience: Unit (Modulus of Resilience)

640 kJ/m3

Stiffness to Weight: Axial

15 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

28 points

Strength to Weight: Bending

24 points

Thermal Diffusivity

4.3 mm2/s

Thermal Shock Resistance

21 points

Alloy Composition

Among wrought stainless steels, the composition of AISI 312 stainless steel is notable for containing a comparatively high amount of chromium (Cr). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance.

Iron (Fe) 62.2 to 69.2
Chromium (Cr) 24 to 26
Nickel (Ni) 5.5 to 6.5
Molybdenum (Mo) 1.2 to 2.0
Manganese (Mn) 0 to 2.0
Silicon (Si) 0 to 1.0
Nitrogen (N) 0.14 to 0.2
Phosphorus (P) 0 to 0.045
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

Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016

ASTM A182: Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service

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

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