Property Class 8.8 Steel (ISO 898-1 property class 8.8) is the workhorse medium-carbon alloy class for structural joints. Specified on stainless steel square 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 Stainless Steel Square Nuts
The workhorse medium-carbon alloy class for structural joints. For stainless steel square 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 stainless steel square 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 stainless steel square 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 Stainless Steel Square Nuts Available in Property Class 8.8 Steel
| Thread size | Stainless grade | Weldable | Typical seat | Corrosion duty |
|---|---|---|---|---|
| M5 | A2 (304) | yes | channel groove or frame profile | general indoor and sheltered outdoor |
| M6 | A2 (304) or A4 (316) | yes | channel groove or frame profile | general to marine, by grade |
| M8 | A2 (304) or A4 (316) | yes | channel groove or frame profile | general to marine, by grade |
| M10 | A2 (304) or A4 (316) | yes | channel groove or frame profile | general to marine, by grade |
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, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
