AISI 321 Titanium-Stabilized Stainless Steel for High-Temperature Service
ASTM A240 · Published: 2026-06-03 · Updated: July 2026
AISI 321 is an austenitic stainless steel stabilized with titanium to prevent intergranular corrosion after exposure to temperatures in the 425-850°C range. It is the preferred grade for aircraft exhaust manifolds, expansion joints, and chemical...
AISI 321 is an austenitic stainless steel stabilized with titanium to prevent intergranular corrosion after exposure to temperatures in the 425-850°C range. It is the preferred grade for aircraft exhaust manifolds, expansion joints, and chemical processing equipment operating in the carbide precipitation zone.
Quick Facts
| Category | Stainless Steel |
| Standard | ASTM A240 |
| Density | 8.03 g/cm³ |
| Yield Strength | 205 MPa |
| Tensile Strength | 515 MPa |
Global Equivalents & Cross-Reference
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Frequently Asked Questions
When should I use 321 instead of 304?
Use 321 when the service temperature is between 425-850°C — the range where 304 is susceptible to sensitization (chromium carbide precipitation at grain boundaries). The titanium addition in 321 preferentially forms titanium carbides, preserving chromium for corrosion resistance.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu