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AISI 309 (S30900) Stainless Steel

AISI 309 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. 309 is the AISI designation for this material. S30900 is the UNS number.

The properties of AISI 309 stainless steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare AISI 309 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

180 to 210

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

34 to 47 %

Fatigue Strength

250 to 280 MPa 36 to 41 x 103 psi

Poisson's Ratio

0.27

Rockwell B Hardness

84

Shear Modulus

78 GPa 11 x 106 psi

Shear Strength

420 to 470 MPa 61 to 68 x 103 psi

Tensile Strength: Ultimate (UTS)

600 to 710 MPa 87 to 100 x 103 psi

Tensile Strength: Yield (Proof)

260 to 350 MPa 38 to 51 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Maximum Temperature: Corrosion

440 °C 820 °F

Maximum Temperature: Mechanical

980 °C 1800 °F

Melting Completion (Liquidus)

1450 °C 2640 °F

Melting Onset (Solidus)

1400 °C 2550 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

16 W/m-K 9.3 BTU/h-ft-°F

Thermal Expansion

15 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

19 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

3.6 kg CO2/kg material

Embodied Energy

51 MJ/kg 22 x 103 BTU/lb

Embodied Water

170 L/kg 20 gal/lb

Common Calculations

PREN (Pitting Resistance)

23

Resilience: Ultimate (Unit Rupture Work)

200 to 230 MJ/m3

Resilience: Unit (Modulus of Resilience)

170 to 310 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

21 to 25 points

Strength to Weight: Bending

20 to 23 points

Thermal Diffusivity

4.3 mm2/s

Thermal Shock Resistance

14 to 16 points

Alloy Composition

Among wrought stainless steels, the composition of AISI 309 stainless steel is notable for containing comparatively high amounts of chromium (Cr) and nickel (Ni). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion.

Iron (Fe)Fe 58 to 66
Chromium (Cr)Cr 22 to 24
Nickel (Ni)Ni 12 to 15
Manganese (Mn)Mn 0 to 2.0
Silicon (Si)Si 0 to 0.75
Carbon (C)C 0 to 0.2
Phosphorus (P)P 0 to 0.045
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 A167: Standard Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip

EN 10095: Heat resisting steels and nickel alloys

ASTM A276: Standard Specification for Stainless Steel Bars and Shapes

Creep-Resistant Steels, Fujio Abe et al. (editors), 2008

Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005

Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012

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