Gr 7MMatching nuts
ASTM A194 Grade 7M
Grade 7 tempered down to 22 HRC maximum. The only nut to put on an A320 L7M stud when the specification is both cryogenic and sour.
- Base material
- Chromium-molybdenum alloy steel (AISI 4140)
- Heat treatment condition
- Quenched and tempered, hardness-controlled
- Hardness, max
- 159–235 HBW, 22 HRC maximum
Service temperature
-101 °C+427 °C−273+900 °C
Check the certificate: 7 and 7M look identical and are easy to mix up in the store.
Chemical composition
| Element | Min (% by weight) | Max (% by weight) |
|---|---|---|
| C | 0.37 | 0.49 |
| Mn | 0.65 | 1.10 |
| P | — | 0.035 |
| S | — | 0.040 |
| Si | 0.15 | 0.35 |
| Cr | 0.75 | 1.20 |
| Mo | 0.15 | 0.25 |
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 | — | — | — | 159–235 HBW · max 22 HRC |
Recommended coatings
Equivalent grades
- ASME SA194 Gr 7M
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