Grade 12.9 Steel Spring Lock Washers pairs the standard ISO 7980 / DIN 127 with a Grade 12.9 Steel base material. The sections below cover why engineers select this grade for spring lock washers, its corrosion and temperature behavior, and the sizes available.
Why Choose Grade 12.9 Steel for Spring Lock Washers
The highest common strength class, for high-load machine assembly. For spring lock washers, 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 |
Galvanic & Galling Considerations
For spring lock washers 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 Spring Lock Washers, 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 Spring Lock Washers Available in Grade 12.9 Steel
| For bolt size | Inner diameter d1 min (mm) | Outer diameter d2 max (mm) | Width b (mm) | Thickness s (mm) | Reference standard |
|---|---|---|---|---|---|
| M2 | 2.1 | 4.4 | 1.6 | 0.5 | ISO 7980 / DIN 127 |
| M2.5 | 2.6 | 5.1 | 2.0 | 0.6 | ISO 7980 / DIN 127 |
| M3 | 3.1 | 6.2 | 2.0 | 0.8 | ISO 7980 / DIN 127 |
| M3.5 | 3.6 | 7.0 | 2.5 | 0.8 | ISO 7980 / DIN 127 |
| M4 | 4.1 | 7.6 | 2.5 | 1.0 | ISO 7980 / DIN 127 |
| M5 | 5.1 | 9.2 | 3.0 | 1.2 | ISO 7980 / DIN 127 |
| M6 | 6.1 | 11.8 | 4.0 | 1.6 | ISO 7980 / DIN 127 |
| M7 | 7.1 | 13.1 | 4.0 | 1.6 | ISO 7980 / DIN 127 |
| M8 | 8.1 | 14.8 | 5.0 | 2.0 | ISO 7980 / DIN 127 |
| M10 | 10.2 | 18.1 | 6.0 | 2.2 | ISO 7980 / DIN 127 |
| M12 | 12.2 | 21.1 | 7.0 | 2.5 | ISO 7980 / DIN 127 |
| M14 | 14.2 | 24.1 | 8.0 | 3.0 | ISO 7980 / DIN 127 |
| M16 | 16.2 | 27.4 | 9.0 | 3.5 | ISO 7980 / DIN 127 |
| M18 | 18.2 | 29.4 | 9.0 | 3.5 | ISO 7980 / DIN 127 |
| M20 | 20.2 | 33.6 | 10.0 | 4.0 | ISO 7980 / DIN 127 |
| M22 | 22.5 | 35.9 | 11.0 | 4.0 | ISO 7980 / DIN 127 |
| M24 | 24.5 | 40.1 | 12.0 | 5.0 | ISO 7980 / DIN 127 |
| M27 | 27.5 | 44.8 | 12.0 | 5.0 | ISO 7980 / DIN 127 |
| M30 | 30.5 | 50.0 | 14.0 | 6.0 | ISO 7980 / DIN 127 |
| M36 | 36.5 | 60.0 | 16.0 | 7.0 | ISO 7980 / DIN 127 |