Property Class 12.9 Steel (ISO 898-1 property class 12.9) is the highest common strength class, for high-load machine assembly. When hexagon weld nuts are specified in this grade, the dimensions remain per DIN 929; the material determines corrosion behavior (requires plating or black-oxide protection) and the service temperature range (commonly limited to approx. +300 °C; confirm against the coating and the load). Both are covered below with the size table.
Why Choose Property Class 12.9 Steel for Hexagon Weld Nuts
The highest common strength class, for high-load machine assembly. For hexagon weld nuts, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 12.9 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating or black-oxide protection |
Galvanic & Galling Considerations
For hexagon weld 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.
Comparable Grades
For Hexagon Weld 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 Hexagon Weld Nuts Available in Property Class 12.9 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Pilot diameter d2 (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 7.5 | 8.15 | 3 | 4.5 | DIN 929 |
| M4 | 0.7 | 9 | 9.83 | 3.5 | 6 | DIN 929 |
| M5 | 0.8 | 10 | 10.95 | 4 | 7 | DIN 929 |
| M6 | 1.0 | 11 | 12.02 | 5 | 8 | DIN 929 |
| M8 | 1.25 | 14 | 15.38 | 6.5 | 10.5 | DIN 929 |
| M10 | 1.5 | 17 | 18.74 | 8 | 12.5 | DIN 929 |
| M12 | 1.75 | 19 | 20.91 | 10 | 14.8 | DIN 929 |
| M14 | 2.0 | 22 | 24.27 | 11 | 16.8 | DIN 929 |
| M16 | 2.0 | 24 | 26.51 | 13 | 18.8 | DIN 929 |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Height and across-flats are the two most often changed — a thinner nut for clearance, a larger hex for a tool that is already on the line. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
