Grade 8.8 Steel Hex Bolts, Grade C pairs the standard ISO 4016 with a Grade 8.8 Steel base material. The sections below cover why engineers select this grade for hex bolts, grade c, its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 8.8 Steel for Hex Bolts, Grade C
The workhorse medium-carbon alloy grade for structural joints. For hex bolts, 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 |
Corrosion Behavior in Service
Carbon and alloy steel hex bolts, grade c require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Galvanic & Galling Considerations
For hex bolts, 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.
Sizes of Hex Bolts, Grade C Available in Grade 8.8 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Head height k (mm) | Product grade | Reference standard |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 8.0 | 8.63 | 3.35 | Grade C | ISO 4016 / DIN 601 |
| M6 | 1.0 | 10.0 | 10.89 | 4.15 | Grade C | ISO 4016 / DIN 601 |
| M8 | 1.25 | 13.0 | 14.2 | 5.45 | Grade C | ISO 4016 / DIN 601 |
| M10 | 1.5 | 17.0 | 18.72 | 6.58 | Grade C | ISO 4016 / DIN 601 |
| M12 | 1.75 | 19.0 | 20.88 | 7.68 | Grade C | ISO 4016 / DIN 601 |
| M14 | 2.0 | 22.0 | 24.49 | 9.25 | Grade C | ISO 4016 / DIN 601 |
| M16 | 2.0 | 24.0 | 26.75 | 10.18 | Grade C | ISO 4016 / DIN 601 |
| M18 | 2.5 | 27.0 | 29.56 | 11.72 | Grade C | ISO 4016 / DIN 601 |
| M20 | 2.5 | 30.0 | 33.53 | 12.72 | Grade C | ISO 4016 / DIN 601 |
| M22 | 2.5 | 32.0 | 35.72 | 14.5 | Grade C | ISO 4016 / DIN 601 |
| M24 | 3.0 | 36.0 | 39.55 | 15.35 | Grade C | ISO 4016 / DIN 601 |
| M27 | 3.0 | 41.0 | 45.2 | 17.92 | Grade C | ISO 4016 / DIN 601 |
| M30 | 3.5 | 46.0 | 50.85 | 19.75 | Grade C | ISO 4016 / DIN 601 |
| M36 | 4.0 | 55.0 | 60.79 | 23.35 | Grade C | ISO 4016 / DIN 601 |
| M42 | 4.5 | 65.0 | 71.3 | 27.05 | Grade C | ISO 4016 / DIN 601 |
| M48 | 5.0 | 75.0 | 82.6 | 31.07 | Grade C | ISO 4016 / DIN 601 |