Property Class 12.9 Steel SEMS Screws with Captive Spring Washer combine the dimensional form of DIN 6900-4 with the material properties of grade ISO 898-1 property class 12.9: requires plating or black-oxide protection, magnetic, service range commonly limited to approx. +300 °C; confirm against the coating and the load. This page summarizes the grade data, its corrosion behavior in service, the comparable grades, and the sizes supplied.
Why Choose Property Class 12.9 Steel for SEMS Screws with Captive Spring Washer
The highest common strength class, for high-load machine assembly. For sems screws with captive spring washer, 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 sems screws with captive spring washer 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 SEMS Screws with Captive Spring Washer, 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 SEMS Screws with Captive Spring Washer Available in Property Class 12.9 Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Washer outer diameter (mm) | Cross recess | Common length range (mm) | Reference standard |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.6 | 2.4 | 6.2 | PH1 / PZ1 | 5~30 | DIN 6900-4 |
| M4 | 0.7 | 8.0 | 3.1 | 8.0 | PH2 / PZ2 | 6~40 | DIN 6900-4 |
| M5 | 0.8 | 9.5 | 3.7 | 10.0 | PH2 / PZ2 | 8~50 | DIN 6900-4 |
| M6 | 1.0 | 12.0 | 4.6 | 12.2 | PH3 / PZ3 | 8~60 | DIN 6900-4 |
| M8 | 1.25 | 16.0 | 6.0 | 15.4 | PH4 / PZ4 | 10~60 | DIN 6900-4 |
| M10 | 1.5 | 20.0 | 7.5 | 18.4 | PH4 / PZ4 | 12~60 | DIN 6900-4 |
