AISI 321 (S32100) Stainless Steel
AISI 321 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. 321 is the AISI designation for this material. S32100 is the UNS number. Additionally, the British Standard (BS) designation is 321S12.
The properties of AISI 321 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 321 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
170 to 210
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
34 to 50 %
Fatigue Strength
220 to 270 MPa 32 to 40 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Shear Strength
420 to 460 MPa 61 to 67 x 103 psi
Tensile Strength: Ultimate (UTS)
590 to 690 MPa 85 to 100 x 103 psi
Tensile Strength: Yield (Proof)
220 to 350 MPa 33 to 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
480 °C 890 °F
Maximum Temperature: Mechanical
870 °C 1600 °F
Melting Completion (Liquidus)
1430 °C 2600 °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 9.0 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.4 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
16 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
3.2 kg CO2/kg material
Embodied Energy
45 MJ/kg 20 x 103 BTU/lb
Embodied Water
140 L/kg 17 gal/lb
Common Calculations
PREN (Pitting Resistance)
19
Resilience: Ultimate (Unit Rupture Work)
190 to 230 MJ/m3
Resilience: Unit (Modulus of Resilience)
130 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 22 points
Thermal Diffusivity
4.1 mm2/s
Thermal Shock Resistance
13 to 15 points
Alloy Composition
Among wrought stainless steels, the composition of AISI 321 stainless steel is notable for including titanium (Ti). Titanium is used to broadly improve mechanical properties.
| Fe | 65.3 to 74 | |
| Cr | 17 to 19 | |
| Ni | 9.0 to 12 | |
| Mn | 0 to 2.0 | |
| Si | 0 to 0.75 | |
| Ti | 0 to 0.7 | |
| N | 0 to 0.1 | |
| C | 0 to 0.080 | |
| 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 A182: Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service
ASTM A276: Standard Specification for Stainless Steel Bars and Shapes
Creep-Resistant Steels, Fujio Abe et al. (editors), 2008
Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 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
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