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.
| Fe | 58 to 66 | |
| Cr | 22 to 24 | |
| Ni | 12 to 15 | |
| Mn | 0 to 2.0 | |
| Si | 0 to 0.75 | |
| C | 0 to 0.2 | |
| P | 0 to 0.045 | |
| 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