Property Class 8.8 Steel Cap (Acorn) Nuts combine the dimensional form of DIN 1587 with the material properties of grade ISO 898-1 property class 8.8: requires plating (zinc) for corrosion 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 8.8 Steel for Cap (Acorn) Nuts
The workhorse medium-carbon alloy class for structural joints. For cap (acorn) 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 |
Galvanic & Galling Considerations
For cap (acorn) 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.
Comparable Grades
For Cap (Acorn) Nuts, class 10.9 or 12.9 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 Cap (Acorn) Nuts Available in Property Class 8.8 Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Total height m (mm) | Dome diameter (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 7.0 | 7.66 | 8.0 | 7.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M5 | 0.8 | 8.0 | 8.79 | 10.0 | 8.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M6 | 1.0 | 10.0 | 11.05 | 12.0 | 10.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M8 | 1.25 | 13.0 | 14.38 | 15.0 | 13.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M10 | 1.5 | 17.0 | 18.90 | 18.0 | 17.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M12 | 1.75 | 19.0 | 21.10 | 22.0 | 19.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M16 | 2.0 | 24.0 | 26.75 | 28.0 | 24.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
| M20 | 2.5 | 30.0 | 33.53 | 34.0 | 30.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
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.
