Specifying Nyloc Lock Nuts in Grade 12.9 Steel pairs the dimensional form of Nyloc Lock Nuts (DIN 985 / ISO 7040) with the engineering properties of Grade 12.9 Steel. This page explains when to choose the grade, how it behaves in service, and which grades to compare it against.
Why Choose Grade 12.9 Steel for Nyloc Lock Nuts
The highest common strength class, for high-load machine assembly. For nyloc lock nuts, 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 nyloc lock nuts 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 nyloc lock nuts 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 Nyloc Lock Nuts Available in Grade 12.9 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Total height m (mm) | Metal height (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 4.0 | 2.4 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M4 | 0.7 | 7.0 | 7.66 | 5.0 | 3.2 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M5 | 0.8 | 8.0 | 8.79 | 5.0 | 3.7 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M6 | 1.0 | 10.0 | 11.05 | 6.0 | 4.7 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M8 | 1.25 | 13.0 | 14.38 | 8.0 | 6.14 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M10 | 1.5 | 16.0 | 17.77 | 10.0 | 8.04 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M12 | 1.75 | 18.0 | 20.03 | 12.0 | 9.64 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M14 | 2.0 | 21.0 | 23.36 | 14.0 | 11.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M16 | 2.0 | 24.0 | 26.75 | 16.0 | 13.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M20 | 2.5 | 30.0 | 32.95 | 20.0 | 16.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M24 | 3.0 | 36.0 | 39.55 | 22.0 | 19.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M30 | 3.5 | 46.0 | 50.85 | 25.0 | 24.0 | DIN 985 / ISO 7040 | With nylon insert, single use |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | 29.0 | DIN 985 / ISO 7040 | With nylon insert, single use |