Grade 8.8 Steel Square Nut, Metric are stocked to GB/T 39 / ISO 4034. The grade provides requires plating (zinc) for corrosion protection and is magnetic; the practical service range is up to approx. +300 °C. Property data, grade comparison and the full size table follow.
Why Choose Grade 8.8 Steel for Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076)
The workhorse medium-carbon alloy grade for structural joints. For square nut, metric — gb/t 39 / iso 4034 (series 076), 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 square nut, metric — gb/t 39 / iso 4034 (series 076) 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 square nut, metric — gb/t 39 / iso 4034 (series 076) 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 Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076) Available in Grade 8.8 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 1.8 | GB/T 39 / DIN 562 |
| M4 | 0.7 | 7.0 | 2.2 | GB/T 39 / DIN 562 |
| M5 | 0.8 | 8.0 | 2.7 | GB/T 39 / DIN 562 |
| M6 | 1.0 | 10.0 | 3.6 | GB/T 39 / DIN 562 |
| M8 | 1.25 | 13.0 | 4.8 | GB/T 39 / DIN 562 |
| M10 | 1.5 | 17.0 | 6.0 | GB/T 39 / DIN 562 |
| M12 | 1.75 | 19.0 | 7.0 | GB/T 39 / DIN 562 |
| M16 | 2.0 | 24.0 | 9.0 | GB/T 39 / DIN 562 |
| M20 | 2.5 | 30.0 | 12.0 | GB/T 39 / DIN 562 |
| M24 | 3.0 | 36.0 | 14.0 | GB/T 39 / DIN 562 |