Grade 8.8 Steel Hex Nuts, Grade C pairs the standard ISO 4034 with a Grade 8.8 Steel base material. The sections below cover why engineers select this grade for hex nuts, grade c, its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 8.8 Steel for Hex Nuts, Grade C
The workhorse medium-carbon alloy grade for structural joints. For hex nuts, grade c, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Galvanic & Galling Considerations
For hex nuts, grade c in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.
Comparable Grades
For Hex Nuts, Grade C, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of Hex Nuts, Grade C Available in Grade 8.8 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Product grade | Reference standard |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 8.0 | 8.63 | 4.7 | Grade C | ISO 4034 / DIN 555 |
| M6 | 1.0 | 10.0 | 10.89 | 5.2 | Grade C | ISO 4034 / DIN 555 |
| M8 | 1.25 | 13.0 | 14.2 | 6.8 | Grade C | ISO 4034 / DIN 555 |
| M10 | 1.5 | 17.0 | 18.72 | 8.4 | Grade C | ISO 4034 / DIN 555 |
| M12 | 1.75 | 19.0 | 20.88 | 10.8 | Grade C | ISO 4034 / DIN 555 |
| M14 | 2.0 | 22.0 | 24.49 | 12.8 | Grade C | ISO 4034 / DIN 555 |
| M16 | 2.0 | 24.0 | 26.75 | 14.8 | Grade C | ISO 4034 / DIN 555 |
| M18 | 2.5 | 27.0 | 29.56 | 15.8 | Grade C | ISO 4034 / DIN 555 |
| M20 | 2.5 | 30.0 | 33.53 | 18.0 | Grade C | ISO 4034 / DIN 555 |
| M22 | 2.5 | 32.0 | 35.72 | 19.4 | Grade C | ISO 4034 / DIN 555 |
| M24 | 3.0 | 36.0 | 39.55 | 21.5 | Grade C | ISO 4034 / DIN 555 |
| M27 | 3.0 | 41.0 | 45.2 | 23.8 | Grade C | ISO 4034 / DIN 555 |
| M30 | 3.5 | 46.0 | 50.85 | 25.6 | Grade C | ISO 4034 / DIN 555 |
| M36 | 4.0 | 55.0 | 60.79 | 31.0 | Grade C | ISO 4034 / DIN 555 |
| M42 | 4.5 | 65.0 | 71.3 | 34.0 | Grade C | ISO 4034 / DIN 555 |
| M48 | 5.0 | 75.0 | 82.6 | 38.0 | Grade C | ISO 4034 / DIN 555 |