Grade 8.8 Steel Hex Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049) pairs the standard GB/T 6180 / ISO 7036 with a Grade 8.8 Steel base material. The sections below cover why engineers select this grade for hex slotted castle nut (type 1) — gb/t 6180 / iso 7036 (series 049), its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 8.8 Steel for Hex Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049)
The workhorse medium-carbon alloy grade for structural joints. For hex slotted castle nut (type 1) — gb/t 6180 / iso 7036 (series 049), 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 slotted castle nut (type 1) — gb/t 6180 / iso 7036 (series 049) 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 Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049), 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 Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049) Available in Grade 8.8 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Total height m (mm) | Slot width (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 4.0 | 1.2 | ISO 7036 / GB/T 6180 |
| M4 | 0.7 | 7.0 | 7.66 | 5.0 | 1.5 | ISO 7036 / GB/T 6180 |
| M5 | 0.8 | 8.0 | 8.79 | 6.7 | 1.8 | ISO 7036 / GB/T 6180 |
| M6 | 1.0 | 10.0 | 11.05 | 7.7 | 2.0 | ISO 7036 / GB/T 6180 |
| M8 | 1.25 | 13.0 | 14.38 | 9.8 | 2.5 | ISO 7036 / GB/T 6180 |
| M10 | 1.5 | 16.0 | 17.77 | 12.4 | 2.8 | ISO 7036 / GB/T 6180 |
| M12 | 1.75 | 18.0 | 20.03 | 15.8 | 3.5 | ISO 7036 / GB/T 6180 |
| M14 | 2.0 | 21.0 | 23.36 | 17.8 | 4.0 | ISO 7036 / GB/T 6180 |
| M16 | 2.0 | 24.0 | 26.75 | 20.8 | 4.5 | ISO 7036 / GB/T 6180 |
| M18 | 2.5 | 27.0 | 30.14 | 22.5 | 4.5 | ISO 7036 / GB/T 6180 |
| M20 | 2.5 | 30.0 | 33.53 | 24.0 | 5.5 | ISO 7036 / GB/T 6180 |
| M24 | 3.0 | 36.0 | 39.98 | 29.5 | 6.0 | ISO 7036 / GB/T 6180 |
| M30 | 3.5 | 46.0 | 50.85 | 36.0 | 7.0 | ISO 7036 / GB/T 6180 |
| M36 | 4.0 | 55.0 | 60.79 | 43.0 | 8.0 | ISO 7036 / GB/T 6180 |