Gr 8Matching nuts
ASTM A194 Grade 8
Stainless heavy hex nut for B8 studs. Soft, which is why it galls — coat it or use anti-seize, because a seized stainless nut usually has to be cut off.
- Base material
- Austenitic stainless steel, AISI 304
- Heat treatment condition
- Solution treated
- Hardness, max
- 126–300 HBW (B70 HRB minimum)
Service temperature
-254 °C+816 °C−273+900 °C
Use grade 8 with B8, grade 8M with B8M — mixing 304 and 316 across the joint invites galvanic problems in seawater.
Chemical composition
| Element | Min (% by weight) | Max (% by weight) |
|---|---|---|
| C | — | 0.08 |
| Mn | — | 2.00 |
| Si | — | 1.00 |
| P | — | 0.045 |
| S | — | 0.030 |
| Cr | 18.0 | 20.0 |
| Ni | 8.0 | 11.0 |
Mechanical properties
ASTM A194 does not set a separate tensile requirement for nuts. The grade is controlled by hardness and by a proof load test, which is why the strength columns below read as dashes.
| Diameter | Tensile strength, min | Yield strength, min | Elongation, min | Hardness, max |
|---|---|---|---|---|
| Tat ca / All | — | — | — | 126–300 HBW · max 32 HRC |
Recommended coatings
Equivalent grades
- ASME SA194 Gr 8
- AISI 304 nut
- ISO 3506-2 A2
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