Property Class 8.8 Steel (ISO 898-1 property class 8.8) is the workhorse medium-carbon alloy class for structural joints. Specified on one-way security screws it determines the corrosion behaviour (requires plating (zinc) for corrosion protection) and the service temperature range (commonly limited to approx. +300 °C; confirm against the coating and the load); the dimensions are ours rather than a standard's, and are listed in full below.
Why Choose Property Class 8.8 Steel for One-Way Security Screws
The workhorse medium-carbon alloy class for structural joints. For one-way security screws, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|---|
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
Corrosion Behavior in Service
Carbon and alloy steel one-way security screws 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 one-way security screws 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 One-Way Security Screws Available in Property Class 8.8 Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Head form | Common length range (mm) | Material | Removable |
|---|---|---|---|---|---|---|---|
| M3.5 | 0.6 | 7.0 | 2.4 | Pan | 10~40 | Steel zinc / A2 | No — permanent |
| M4 | 0.7 | 8.0 | 2.8 | Pan | 10~50 | Steel zinc / A2 | No — permanent |
| M5 | 0.8 | 9.5 | 3.2 | Pan | 12~60 | Steel zinc / A2 | No — permanent |
| M6 | 1.0 | 12.0 | 3.8 | Pan | 16~60 | Steel zinc | No — permanent |
| M8 | 1.25 | 16.0 | 4.6 | Pan | 20~60 | Steel zinc | No — permanent |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
