Specifying T-Slot Nuts in Grade 12.9 Steel pairs the dimensional form of T-Slot Nuts (DIN 508) 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 T-Slot Nuts
The highest common strength class, for high-load machine assembly. For t-slot 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 t-slot 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.
Comparable Grades
For T-Slot Nuts, 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 T-Slot Nuts Available in Grade 12.9 Steel
| Thread size | T-slot width (mm) | Nut width b (mm) | Total height h (mm) | Key height h1 (mm) | Hook width e (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M5 | 6 | 8.0 | 8.0 | 4.5 | 6.4 | DIN 508 / GN505 |
| M6 | 8 | 10.0 | 10.0 | 5.5 | 8.4 | DIN 508 / GN505 |
| M8 | 10 | 12.0 | 12.0 | 7.0 | 10.4 | DIN 508 / GN505 |
| M8 | 12 | 14.0 | 12.0 | 7.0 | 12.4 | DIN 508 / GN505 |
| M10 | 12 | 14.0 | 14.0 | 8.0 | 12.4 | DIN 508 / GN505 |
| M10 | 14 | 16.0 | 14.0 | 8.0 | 14.4 | DIN 508 / GN505 |
| M12 | 14 | 16.0 | 17.0 | 10.0 | 14.4 | DIN 508 / GN505 |
| M12 | 18 | 20.0 | 17.0 | 10.0 | 18.4 | DIN 508 / GN505 |
| M16 | 18 | 20.0 | 20.0 | 12.0 | 18.4 | DIN 508 / GN505 |
| M16 | 22 | 25.0 | 20.0 | 12.0 | 22.4 | DIN 508 / GN505 |
| M20 | 22 | 25.0 | 25.0 | 15.0 | 22.4 | DIN 508 / GN505 |
| M20 | 28 | 32.0 | 25.0 | 15.0 | 28.4 | DIN 508 / GN505 |
| M24 | 28 | 32.0 | 30.0 | 18.0 | 28.4 | DIN 508 / GN505 |