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Alloy Technical Data Sheet
Type 321 Stainless Steel
Titanium-Stabilized Austenitic Stainless · UNS S32100
Titanium-stabilized austenitic stainless that resists intergranular corrosion after exposure to 800–1500 °F, with higher creep and stress-rupture strength than 304.
General Properties
Type 321 is a stabilized stainless steel with excellent resistance to intergranular corrosion after exposure to the chromium carbide precipitation range of 800–1500 °F (427–816 °C). Titanium additions stabilize it against chromium carbide formation.
Type 321 continues to be used for prolonged service in the 800–1500 °F range, while 304L has replaced it for applications involving only welding or short-time heating. Its higher creep and stress-rupture properties than 304 and 304L allow higher elevated-temperature allowable stresses under the ASME Boiler and Pressure Vessel Code, with a maximum code use temperature of 1500 °F (816 °C) versus 800 °F (426 °C) for 304L.
Chemical Composition
| Element | 321 |
|---|---|
| Carbon | 0.08 |
| Manganese | 2.00 |
| Phosphorus | 0.045 |
| Sulfur | 0.030 |
| Silicon | 0.75 |
| Chromium | 17.00–19.00 |
| Nickel | 9.00–12.00 |
| Titanium | 5 × (C + N) min. to 0.70 max. |
| Nitrogen | 0.10 |
| Iron | Balance |
Mechanical Properties
| Condition | Tensile, ksi (MPa) | 0.2% Yield, ksi (MPa) | Elong. in 2″, % |
|---|---|---|---|
| Annealed | 75 (515) | 30 (205) | 40 |
Maximum hardness Rockwell B95 for strip and sheet.
Physical Properties
| Melting range | 2550–2635 °F (1398–1446 °C) |
|---|---|
| Density | 0.286 lb/in³ (7.92 g/cm³) |
| Specific gravity | 7.92 |
| Modulus of elasticity (tension) | 28 × 10⁶ psi (193 GPa) |
| Specific heat, 32–212 °F | 0.12 Btu/lb·°F (500 J/kg·K) |
Thermal Expansion
| °F | °C | in/in/°F | cm/cm/°C |
|---|---|---|---|
| 68–212 | 20–100 | 9.2 × 10⁻⁶ | 16.6 × 10⁻⁶ |
| 68–1112 | 20–600 | 10.5 × 10⁻⁶ | 18.9 × 10⁻⁶ |
| 68–1832 | 20–1000 | 11.4 × 10⁻⁶ | 20.5 × 10⁻⁶ |
Thermal Conductivity
| °F | °C | Btu/hr·ft·°F | W/m·K |
|---|---|---|---|
| 68–212 | 20–100 | 9.4 | 16.3 |
| 68–932 | 20–500 | 12.3 | 21.4 |
Overall heat transfer depends on more than the conductivity of the metal. Because the austenitic stainless grades keep their surfaces clean, they often transfer heat better in service than metals with higher thermal conductivity.
Electrical Resistivity
| °F | °C | Microhm-in | Microhm-cm |
|---|---|---|---|
| 68 | 20 | 28.3 | 72 |
| 212 | 100 | 30.7 | 78 |
| 392 | 200 | 33.8 | 86 |
| 752 | 400 | 39.4 | 100 |
| 1112 | 600 | 43.7 | 111 |
| 1472 | 800 | 47.6 | 121 |
| 1652 | 900 | 49.6 | 126 |
Magnetic Permeability
Generally non-magnetic in the annealed condition, with magnetic permeability typically less than 1.02 at 200 H.
Corrosion Resistance
General corrosion resistance is similar to unstabilized Type 304. Long heating in the chromium carbide precipitation range may reduce general resistance in severely corrosive media.
Values are typical or specification minimums as noted, provided for information only, and should not be used as design limits or as a guarantee of properties for any particular lot or application. Certified test reports are supplied with each order.Rev. 10/2026