Property Class 8.8 Steel (ISO 898-1 property class 8.8) is the workhorse medium-carbon alloy class for structural joints. Specified on self-clinching press-fit nuts 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 Self-Clinching Press-Fit Nuts
The workhorse medium-carbon alloy class for structural joints. For self-clinching press-fit nuts, 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 self-clinching press-fit 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.
Galvanic & Galling Considerations
For self-clinching press-fit 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.
Sizes of Self-Clinching Press-Fit Nuts Available in Property Class 8.8 Steel
| Thread size | Shank diameter (mm) | Length (mm) | Hole in sheet (mm) | Minimum sheet thickness (mm) | Maximum sheet hardness | Material | Installation |
|---|---|---|---|---|---|---|---|
| M3 | 4.20 | 3.30 | 4.22 | 0.8 | HRB 80 | Case-hardened steel | Press, squeeze |
| M4 | 5.40 | 3.80 | 5.42 | 0.8 | HRB 80 | Case-hardened steel | Press, squeeze |
| M5 | 6.35 | 4.20 | 6.38 | 1.0 | HRB 80 | Case-hardened steel | Press, squeeze |
| M6 | 7.95 | 4.80 | 7.98 | 1.0 | HRB 80 | Case-hardened steel | Press, squeeze |
| M8 | 9.55 | 5.70 | 9.58 | 1.5 | HRB 80 | Case-hardened steel | Press, squeeze |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
