Gr 8MMatching nuts
ASTM A194 Grade 8M
316 stainless heavy hex nut, the standard mate for B8M studs in chloride and offshore service.
- Base material
- Austenitic stainless steel, AISI 316
- Heat treatment condition
- Solution treated
- Hardness, max
- 126–300 HBW (B70 HRB minimum)
Service temperature
-254 °C+816 °C−273+900 °C
PTFE coating is worth the cost here — it removes the galling risk and adds a consistent friction factor for torque control.
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 | 16.0 | 18.0 |
| Ni | 10.0 | 14.0 |
| Mo | 2.00 | 3.00 |
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 8M
- AISI 316 nut
- ISO 3506-2 A4
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