Material specification page for hex slotted castle nut (type 1) in Property Class 12.9 Steel. Covers the grade designation (ISO 898-1 property class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to GB/T 6180 / ISO 7036.
Why Choose Property Class 12.9 Steel for Hex Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049)
The highest common strength class, for high-load machine assembly. For hex slotted castle nut (type 1) — gb/t 6180 / iso 7036 (series 049), this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating or black-oxide protection |
Corrosion Behavior in Service
Carbon and alloy steel hex slotted castle nut (type 1) — gb/t 6180 / iso 7036 (series 049) 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.
Comparable Grades
For Hex Slotted Castle Nut (Type 1) — GB/T 6180 / ISO 7036 (Series 049), class 8.8 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 Property Class 12.9 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 |

