Material specification page for serrated flange lock nuts in Property Class 12.9 Steel. Covers the grade designation (ISO 898-1 property class 12.9), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to DIN 6923.
Why Choose Property Class 12.9 Steel for Serrated Flange Lock Nuts
The highest common strength class, for high-load machine assembly. For serrated flange lock 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 |
Corrosion Behavior in Service
Carbon and alloy steel serrated flange lock 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 Serrated Flange Lock 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 Serrated Flange Lock Nuts Available in Property Class 12.9 Steel
| Thread size | Pitch (mm) | Across flats s (mm) | Flange diameter dc (mm) | Total height m (mm) | Flange thickness c (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M4 | 0.7 | 7 | 9.0 | 5.0 | 1.0 | DIN 6923 |
| M5 | 0.8 | 8 | 11.8 | 5.0 | 1.0 | DIN 6923 |
| M6 | 1.0 | 10 | 14.2 | 6.0 | 1.1 | DIN 6923 |
| M8 | 1.25 | 13 | 17.9 | 8.0 | 1.2 | DIN 6923 |
| M10 | 1.5 | 15 | 21.8 | 10.0 | 1.5 | DIN 6923 |
| M12 | 1.75 | 18 | 26.0 | 12.0 | 1.8 | DIN 6923 |
| M14 | 2.0 | 21 | 29.9 | 14.0 | 2.1 | DIN 6923 |
| M16 | 2.0 | 24 | 34.5 | 16.0 | 2.4 | DIN 6923 |
| M20 | 2.5 | 30 | 42.8 | 20.0 | 3.0 | DIN 6923 |
