Material specification page for spring lock washers in Grade 12.9 Steel. Covers the grade designation (class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to ISO 7980 / DIN 127.
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 |
Corrosion Behavior in Service
Carbon and alloy steel spring lock washers 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 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 |