Specifying Serrated Lock Washers in Grade 12.9 Steel pairs the dimensional form of Serrated Lock Washers (DIN 6798) 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 Serrated Lock Washers
The highest common strength class, for high-load machine assembly. For serrated 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 serrated 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.
Galvanic & Galling Considerations
For serrated 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.
Sizes of Serrated Lock Washers Available in Grade 12.9 Steel
| For size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness h (mm) | Type | Reference standard |
|---|---|---|---|---|---|
| M3 | 3.2 | 6.0 | 0.5 | Internal-tooth type A | DIN 6798 A/J |
| M4 | 4.3 | 7.6 | 0.5 | Internal-tooth type A | DIN 6798 A/J |
| M5 | 5.3 | 9.2 | 0.6 | Internal-tooth type A | DIN 6798 A/J |
| M6 | 6.4 | 11.0 | 0.7 | Internal-tooth type A | DIN 6798 A/J |
| M8 | 8.4 | 14.8 | 0.8 | Internal-tooth type A | DIN 6798 A/J |
| M10 | 10.5 | 18.0 | 0.9 | Internal-tooth type A | DIN 6798 A/J |
| M12 | 13.0 | 21.5 | 1.0 | Internal-tooth type A | DIN 6798 A/J |
| M16 | 17.0 | 27.0 | 1.2 | Internal-tooth type A | DIN 6798 A/J |
| M20 | 21.0 | 33.0 | 1.5 | Internal-tooth type A | DIN 6798 A/J |
| M3 | 3.2 | 7.0 | 0.5 | External-tooth type J | DIN 6798 A/J |
| M4 | 4.3 | 9.0 | 0.5 | External-tooth type J | DIN 6798 A/J |
| M5 | 5.3 | 10.0 | 0.6 | External-tooth type J | DIN 6798 A/J |
| M6 | 6.4 | 12.0 | 0.7 | External-tooth type J | DIN 6798 A/J |
| M8 | 8.4 | 15.0 | 0.8 | External-tooth type J | DIN 6798 A/J |
| M10 | 10.5 | 19.0 | 0.9 | External-tooth type J | DIN 6798 A/J |
| M12 | 13.0 | 22.0 | 1.0 | External-tooth type J | DIN 6798 A/J |
| M16 | 17.0 | 28.0 | 1.2 | External-tooth type J | DIN 6798 A/J |
| M20 | 21.0 | 34.0 | 1.5 | External-tooth type J | DIN 6798 A/J |