A2 Stainless Steel Self-Tapping Screws are stocked to DIN 7976 / ISO 1481. The grade provides good general corrosion resistance and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C. Property data, grade comparison and the full size table follow.
Why Choose A2 Stainless Steel for Self-Tapping Screws
The most common stainless grade for indoor and general outdoor fasteners. For self-tapping screws, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | A2-70 (304) |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C |
| Corrosion characteristic | Good general corrosion resistance |
Corrosion Behavior in Service
A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Self-Tapping Screws in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Galvanic & Galling Considerations
Two important notes for stainless self-tapping screws: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Sizes of Self-Tapping Screws Available in A2 Stainless Steel
| Size | Nominal diameter (mm) | Pilot hole (mm) | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Plate thickness (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|---|
| ST2.2 | 2.2 | 1.7 | 0.71 | 4.2 | 1.4 | 0.5~1.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST2.9 | 2.9 | 2.3 | 0.94 | 5.6 | 1.7 | 0.6~1.6 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST3.5 | 3.5 | 2.8 | 1.27 | 6.9 | 2.1 | 0.8~2.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST3.9 | 3.9 | 3.1 | 1.29 | 7.5 | 2.3 | 0.9~2.5 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST4.2 | 4.2 | 3.4 | 1.41 | 8.2 | 2.5 | 1.0~2.5 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST4.8 | 4.8 | 3.9 | 1.59 | 9.5 | 2.9 | 1.2~3.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST5.5 | 5.5 | 4.5 | 1.81 | 10.9 | 3.3 | 1.5~3.5 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST6.3 | 6.3 | 5.1 | 1.81 | 12.5 | 3.8 | 2.0~4.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST8.0 | 8.0 | 6.7 | 2.12 | 16.0 | 4.8 | 2.5~5.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |
| ST9.5 | 9.5 | 8.0 | 2.12 | 19.0 | 5.7 | 3.0~6.0 | DIN 7976 / ISO 1481 | Cross-recess pan-head self-tapping |