AISI 321 (UNS S32100) Stainless Steel Introduction
AISI 321 stainless steel (UNS S32100) is a titanium stabilized austenitic stainless steel with good general corrosion resistance. It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800–1500 °F (427–816 °C). The alloy resists oxidation to 1500 °F (816 °C) and has higher creep and stress rupture properties than alloys 304 and 304L. It also possesses good low temperature toughness.
Chemical Composition
The following table shows the chemical composition of AISI 321.
Element Content (%) Iron, Fe Balance Chromium, Cr 17.0 - 20.0 Nickel, Ni 9.0 - 12.0 Manganese, Mn 2.00 Silicon, Si 0.75 Carbon, C 0.08 - 0.20 Phosphorus, P 0.045 Sulfur, S 0.030 Titanium, Ti 5 x (C + N) min - 0.70 max
Physical Properties
The following table summarizes the physical properties of AISI 321 stainless steel.
Properties Metric Imperial Density 8.0 g/cm3 0.289 lb/in3 Melting point 1450 °C 2642 °F
Mechanical Properties
The following table shows the mechanical properties of AISI 321 stainless steel.
Properties Metric Imperial Tensile strength 515 MPa 74.9 ksi Yield strength 205 MPa 29.7 ksi Elastic modulus 193-210 GPa 28.0-30.5 ksi Elongation at break (in 50 mm) 50% 50% Hardness, Brinell 217 217
Thermal Properties
The thermal properties of AISI 321 stainless steel are outlined in the following table.
Properties Metric Imperial Thermal expansion co-efficient (@20-100°C/68-212°F) 16.3 µm/m°C 9.03 µin/in°F Thermal conductivity 16.2 W/mK 111.5 BTU in/hr.ft².°F
Applications
AISI 321 stainless steel is mainly used in applications that require resistance to heat and corrosion. It has been used in:
• Automotive exhaust systems
• Expansion joints
• Heat exchangers
• Power generation
• Boilers
• Welded fabrications
• Steel alloy precipitation
• Elevated temperature applications
