ASTM A193 B8 and B8M identify stainless grades; Class 1 and Class 2 identify different processing and mechanical requirements. Class 1 is carbide solution treated, while Class 2 includes strain hardening, so the grade name without the class is an incomplete critical-bolting specification.
Request a Quote| Ordering detail | Class 1 | Class 2 |
|---|---|---|
| B8 / B8M identity | B8: 304-type; B8M: 316-type | B8: 304-type; B8M: 316-type |
| Processing | Carbide solution treatment | Carbide solution treatment plus strain hardening |
| Mechanical acceptance | Class-specific requirements | Class- and diameter-dependent requirements |
| Marking review | Check applicable standard and certificate | Check class marking convention and certificate |
| Substitution | Not interchangeable by default | Not a blanket upgrade to every Class 1 joint |
A comparison helps frame the enquiry. The responsible engineer approves the material, condition and finished assembly.
Do not confuse alloy identity with strength class. A request for B8M should also identify Class 1 or Class 2, diameter, thread series, finished geometry and companion nuts.
Strain hardening changes mechanical properties without turning B8M into a different stainless chemistry. Requirements vary with size and class; a single generic tensile figure is not a reliable purchasing specification.
If an enquiry or component uses B8MSH shorthand, request the supplier’s explicit grade and class definition. The abbreviation alone does not establish ASTM A193 B8M Class 2 acceptance.
Read the component markings together with the material certificate, manufacturer identity and heat traceability. If a marking or class is unclear, request clarification before releasing the component for assembly.
Send the complete requirement for a defined quotation. EMG confirms the supply and inspection scope against your project documents.
Request a QuoteB8M uses a 316-type stainless grade, but Class 2 adds processing and mechanical requirements. A generic 316 bar certificate does not establish acceptance as a finished B8M Class 2 stud.
Obtain engineering approval. Check the equipment design, mechanical requirements, supplied condition, nuts and any service restrictions rather than assuming higher strength is always acceptable.
Do not rely on shorthand alone. Order the full grade and class, then verify the applicable marking requirements and traceable certificate.
References support material identification, not acceptance of a finished component. Use the applicable standard edition and approved project specification. Alloy trademarks remain the property of their respective owners.
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