321 stainless steel is a titanium-stabilized austenitic stainless steel designed to resist intergranular corrosion that can occur after exposure to temperatures between 427°C and 816°C.
It offers excellent creep resistance, stress rupture strength, and high mechanical properties up to 815°C (1500°F). It exhibits corrosion resistance similar to 304, but is preferred for high-temperature applications such as aircraft engine exhaust systems and industrial heat exchangers.

Reference standards:

• UNS S32100 / S32109
• AMS 5510, AMS 5645
• ASTM A167, A240, A276, A479
• ASME SA167, SA240
• EN 1.4541
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Chemical composition (%)

Element Content (%)
Carbon (C) 0.08 max
Manganese (Mn) 2.00 max
Silicon (Si) 1.00 max
Chromium (Cr) 17.00 – 19.00
Nickel (Ni) 9.00 – 12.00
Phosphorus (P) 0.040 max
Sulfur (S) 0.030 max
Nitrogen (N) 0.10 max
Titanium (Ti) 5x(C+N) – 0.70
Iron (Fe) Balanced
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Mechanical properties (annealed sheet and strip)

Property Value
Tensile strength (UTS) 515 MPa (75,000 psi)
Yield strength 0.2% 205 MPa (30,000 psi)
Elongation in 2″ (50 mm) ≥40%
Maximum hardness 217 HB / 95 RB
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Physical properties

Property Value
Density 7.92 g/cm³
Melting range 1398–1446°C
Modulus of elasticity (tension) 193 GPa
Thermal conductivity 16.3–21.4 W/m·K
Specific heat (20°C) 500 J/kg·K
Electrical resistivity (20°C) 72 µΩ·in
Coefficient of thermal expansion 16.6 ×10⁻⁶ /°C (20-100°C)
Magnetism Non-magnetic in the annealed state
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Corrosion resistance

321 offers resistance similar to 304 to general corrosive agents, but with greater stability against carbide precipitation due to the presence of titanium. It is less suitable for highly oxidizing environments such as concentrated nitric acid.
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Available formats

• Bars: Ø 0.375″ – 9.000″
• Hexagonal bars: Ø 0.250″ – 1.125″
• Coils: thickness 0.010″ – 0.125″
• Sheets: thickness 0.010″ – 0.125″
• Thin strips: thickness 0.0008″ – 0.012″
• Plates: thickness 0.1875″ – 0.250″
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Industrial applications

Thanks to its thermal stability and resistance to intergranular corrosion, 321 is widely used in:
• Aerospace and Defense: Aircraft engine exhausts and manifolds.
• Power Generation: High-temperature heat exchangers.
• Chemical Industry: Equipment for high-temperature chemical processes.
• Motorsport: Exhaust manifolds and fuel systems.
• Petrochemical: Piping systems and tanks.
• Construction: Structures for high-temperature environments.