Stainless Steel 409 — UNS S40900 Technical Reference

Stainless Steel 409 (S40900) is included here as a material reference. Magnetic exhaust-grade family; verify the exact stabilised UNS variant.

Scope: Numerical limits below apply only to the named source, product form and condition. They are not measured results, design allowable stresses or guarantees for every product with this UNS. Acceptance follows the purchase order and applicable design/product standards.

1. Selected Chemical Requirements

Basis: Selected alloy-identification data only; confirm the complete table against the exact ordered specification and edition. Values are mass %. This selected-element table does not replace the complete source table and footnotes.

Confirm the exact stabilised 409-family UNS variant and complete chemistry in the ordered specification before using this entry for procurement.

Distinguish historical 409/S40900 from the specific stabilised 409-family UNS variants in the ordered edition. No complete current tubular acceptance table is asserted here.

2. Mechanical Requirements and Delivery Condition

No single tensile/yield/elongation set is asserted as an alloy-wide minimum. Specify product standard, size, manufacturing route, heat treatment/ageing and test direction before selecting acceptance values. “NON-TUBULAR REFERENCE” identifies a reference scope, not a delivery or heat-treatment condition.

3. Designation References

UNS S40900 is the material identifier used here. Cross-system names below are comparison candidates only. EN, JIS and GB/T grades can differ in chemistry, form, condition and testing; substitution requires a technical comparison and project-required approval.

These are recorded designation references, not a certification of equivalence. A dash means no confirmed entry is supplied. A common UNS number or commercial name does not establish branded origin.

4. Fabrication and Service Considerations

Magnetic exhaust-grade family; verify the exact stabilised UNS variant.

Ferritic, martensitic and precipitation-hardening grades have different magnetic, heat-treatment, welding and toughness behaviour from austenitic steels. Do not infer cryogenic toughness or freedom from embrittlement from a generic stainless-steel description. Apply the specified welding and heat-treatment route.

5. Product Standards and Ordering Basis

This entry is primarily a related-material reference. Confirm the actual product form and applicable standard before ordering. Bar, forging and flat-product specifications do not automatically cover seamless pipe/tube.

Selected ferritic grades are covered as tubing by A268/SA-268; confirm the exact UNS and edition. The chemistry reference does not establish acceptance for another product form.

State grade/UNS, form, route, specification/edition, OD/wall/length, condition, examination and documents. ASME SA/SB acceptance and design-code permission require separate checks. EN 10204 type 3.1 is an inspection document, not independent product approval. Chemical and mechanical tests can use different heat/lot sampling bases.

6. Typical Applications

Exhaust and selected heat-resisting parts.

These are examples, not a service-envelope approval. Confirm medium, concentration, temperature, pressure, flow/stagnation, deposits, crevices, stress and fabrication condition.

7. Product Enquiries and Related Pages

Forms, sizes, availability and certification are confirmed in the written quotation. Send an enquiry with the actual specification and service requirements.

Reference review: 30 October 2026. Editions identify the sources used; they do not assert that all named editions remain active or that alternative standards have identical requirements.