General-service stainless bar and shape spec, the non-pressure-vessel companion to ASTM A479
ASTM A276 / A276M covers stainless steel bar, billet, and shapes for general fabrication and machining service where the finished part is not the primary pressure boundary in an ASME pressure vessel or B31 piping system. The standard accepts the same UNS S32550 chemistry as ASTM A479 but the testing regime is lighter: A276 does not mandate Charpy V-notch acceptance, intergranular corrosion testing per ASTM A262, or the supplementary requirements common on pressure-vessel bar. For non-pressure components like pump shafts, valve trim sleeves, instrumentation manifold blocks, structural framing, and machining stock for mechanical hardware, A276 is the cost-efficient choice. Where the part will see ASME-rated service (pressure-containing valve body, pump pressure casing, ASME B31 fitting), specify the A479 equivalent.
| Requirement | ASTM A276 | ASTM A479 |
|---|---|---|
| Application scope | General service, non-pressure | Pressure-vessel and ASME B31 piping |
| Per-heat tensile | Required | Required |
| Hardness | Required | Required (≤ 32 HRC for NACE) |
| Charpy V-notch impact | Optional supplementary | Optional but routinely specified for sour service |
| Intergranular corrosion (A262) | Optional | Optional supplementary |
| Microstructure / ferrite content | Required band 35 to 55% | Required band 35 to 55% |
| NACE MR0175 acceptance | Possible if hardness traverse + ferrite-content satisfy | Standard route for sour service |
| NORSOK M-650 acceptance | Restricted to non-pressure parts | Standard route for pressure-vessel parts |
