Stainless steel
AISI 321
Manufacturer or standards-body identification; product values do not apply to every form or condition.
Identity / state reference
What distinguishes this material
Titanium stabilization distinguishes 321 from niobium-stabilized 347; neither name alone specifies a service temperature or a welded-component qualification.
- Designation in this reference
- Type 321
- Forms covered by the sources
- Cliffs sheet and strip, 0.010–0.125 in.
- States to distinguish or confirm
- Annealing, stabilization treatment and service exposure are separate facts.
- Temperature and exposure
- No universal service-temperature limit or room-temperature property set is assigned. Use the cited product document and the purchase certificate.
Property evidence for a stated condition
No condition-specific numerical table is reproduced here
The linked sources establish the identity and the stated product/state scope. Obtain the row for your actual form, section, treatment and test conditions before adopting strength, hardness or a thermal limit.
Resolve these conditions next
- What product standard, edition and complete grade are on the material certificate?
- What product form, section size and delivery/heat-treatment condition will be machined?
For machining, take the exact grade, supplied condition and measured hardness where applicable into the tool maker’s application data. A generic material-family speed is not a substitute for an operation and tool-specific recommendation.
Sources and what they establish
Reviewed 23 October 2026. A source’s publication date and the review date are different. The scope below identifies the fields checked.
Cleveland-Cliffs 321 product data
Manufacturer flat-product datasheet; condition and dimensions are product-specific, not all bar, forging or casting supply.
Cleveland-Cliffs 321 product data ↗Source identity, a named product example and a supplied-batch certificate are different evidence. Cross-standard similarity does not approve substitution.
Corrections from the previous article
- Remove automatic cross-grade equivalence and unqualified high-temperature suitability; do not reuse 304 cutting parameters.
- Withdraw the legacy generic hardness (95 HRB) and tensile-strength (620 MPa (90 ksi)) pair: the old page does not establish a matching product, heat treatment, section and test source.
- Remove the unsupported cutting-speed table and machinability percentage; select tooling only after the actual material condition is known.
Other references in Stainless steel
Related references, not equivalent substitutes.