Property Class 12.9 Steel SEMS Screws with Captive Conical Spring Washers are supplied to DIN 6900-5 Z9 and DIN 6908. The grade provides requires plating or black-oxide protection and is magnetic; the practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load. Property data, grade comparison and the full size table follow.
Why Choose Property Class 12.9 Steel for SEMS Screws with Captive Conical Spring Washers
The highest common strength class, for high-load machine assembly. For sems screws with captive conical spring washers, 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 sems screws with captive conical spring 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 sems screws with captive conical spring 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 SEMS Screws with Captive Conical Spring Washers Available in Property Class 12.9 Steel
| Thread size | Pitch (mm) | Washer inside diameter (mm) | Washer outside diameter (mm) | Washer thickness (mm) | Material options | Reference standard |
|---|---|---|---|---|---|---|
| M2.5 | 0.45 | 2.25~2.35 | 5.7~6.0 | 0.5 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M3 | 0.5 | 2.75~2.85 | 6.64~7.0 | 0.6 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M4 | 0.7 | 3.6~3.72 | 8.64~9.0 | 1.0 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M5 | 0.8 | 4.55~4.67 | 10.57~11.0 | 1.2 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M6 | 1.0 | 5.5~5.62 | 13.57~14.0 | 1.5 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M8 | 1.25 | 7.4~7.55 | 17.57~18.0 | 2.0 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M10 | 1.5 | 9.3~9.45 | 22.48~23.0 | 2.5 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
| M12 | 1.75 | 11.0~11.18 | 28.48~29.0 | 3.0 | steel or A2 stainless | DIN 6900-5 Z9 and DIN 6908 |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Lengths and thread lengths outside the standard table are the commonest request, followed by a drive the standard does not offer and a head marked with your own part number. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
