For Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) in Grade 8.8 Steel, the controlling decisions are corrosion, strength and service temperature. This guide summarizes those three for Grade 8.8 Steel Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) and lists every size we supply.
Why Choose Grade 8.8 Steel for Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007)
The workhorse medium-carbon alloy grade for structural joints. For hex head bolt — gb/t 5782 / iso 4014 (series 007), 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 head bolt — gb/t 5782 / iso 4014 (series 007) 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 head bolt — gb/t 5782 / iso 4014 (series 007) 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 Head Bolt — GB/T 5782 / ISO 4014 (Series 007) Available in Grade 8.8 Steel
| Size | Pitch (mm) | Nominal diameter d (mm) | Length L (mm) | Width across flats s (mm) | Width across corners e (mm) | Head height k (mm) |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 3 | 20 | 5.5 | 6.01 | 2.0 |
| M4 | 0.7 | 4 | 25 | 7.0 | 7.66 | 2.8 |
| M5 | 0.8 | 5 | 30 | 8.0 | 8.79 | 3.5 |
| M6 | 1.0 | 6 | 40 | 10.0 | 11.05 | 4.0 |
| M8 | 1.25 | 8 | 50 | 13.0 | 14.38 | 5.3 |
| M10 | 1.5 | 10 | 60 | 16.0 | 17.77 | 6.4 |
| M12 | 1.75 | 12 | 80 | 18.0 | 20.03 | 7.5 |
| M14 | 2.0 | 14 | 80 | 21.0 | 23.36 | 8.8 |
| M16 | 2.0 | 16 | 100 | 24.0 | 26.75 | 10.0 |
| M18 | 2.5 | 18 | 100 | 27.0 | 30.14 | 11.5 |
| M20 | 2.5 | 20 | 120 | 30.0 | 33.53 | 12.5 |
| M24 | 3.0 | 24 | 150 | 36.0 | 39.98 | 15.0 |
| M30 | 3.5 | 30 | 180 | 46.0 | 50.85 | 18.7 |
| M36 | 4.0 | 36 | 200 | 55.0 | 60.79 | 22.5 |