Grade 12.9 Steel Thin Hex Nut — GB/T 901 / DIN 939 (Series 094) pairs the standard GB/T 901 / DIN 939 with a Grade 12.9 Steel base material. The sections below cover why engineers select this grade for thin hex nut — gb/t 901 / din 939 (series 094), its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 12.9 Steel for Thin Hex Nut — GB/T 901 / DIN 939 (Series 094)
The highest common strength class, for high-load machine assembly. For thin hex nut — gb/t 901 / din 939 (series 094), this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | up to approx. +300 °C |
| Corrosion characteristic | Requires plating or black-oxide protection |
Corrosion Behavior in Service
Carbon and alloy steel thin hex nut — gb/t 901 / din 939 (series 094) 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 thin hex nut — gb/t 901 / din 939 (series 094) 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 Thin Hex Nut — GB/T 901 / DIN 939 (Series 094) Available in Grade 12.9 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 1.8 | ISO 4035 / GB/T 6172 |
| M4 | 0.7 | 7.0 | 7.66 | 2.2 | ISO 4035 / GB/T 6172 |
| M5 | 0.8 | 8.0 | 8.79 | 2.7 | ISO 4035 / GB/T 6172 |
| M6 | 1.0 | 10.0 | 11.05 | 3.2 | ISO 4035 / GB/T 6172 |
| M8 | 1.25 | 13.0 | 14.38 | 4.0 | ISO 4035 / GB/T 6172 |
| M10 | 1.5 | 16.0 | 17.77 | 5.0 | ISO 4035 / GB/T 6172 |
| M12 | 1.75 | 18.0 | 20.03 | 6.0 | ISO 4035 / GB/T 6172 |
| M14 | 2.0 | 21.0 | 23.36 | 7.0 | ISO 4035 / GB/T 6172 |
| M16 | 2.0 | 24.0 | 26.75 | 8.0 | ISO 4035 / GB/T 6172 |
| M18 | 2.5 | 27.0 | 30.14 | 9.0 | ISO 4035 / GB/T 6172 |
| M20 | 2.5 | 30.0 | 33.53 | 10.0 | ISO 4035 / GB/T 6172 |
| M24 | 3.0 | 36.0 | 39.98 | 12.0 | ISO 4035 / GB/T 6172 |
| M30 | 3.5 | 46.0 | 50.85 | 15.0 | ISO 4035 / GB/T 6172 |
| M36 | 4.0 | 55.0 | 60.79 | 18.0 | ISO 4035 / GB/T 6172 |