Self-Drilling Screws manufactured in A2 Stainless Steel (A2-70 (304)) are dimensioned to DIN 7504. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A2 Stainless Steel for Self-Drilling Screws
The most common stainless grade for indoor and general outdoor fasteners. For self-drilling 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-Drilling Screws in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Comparable Grades
For Self-Drilling Screws, the alternative stainless grade is A4 (316). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Sizes of Self-Drilling Screws Available in A2 Stainless Steel
| Size | Nominal diameter (mm) | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Drill point capacity (mm) | Common length range (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|---|
| ST3.5 | 3.5 | 1.27 | 6.9 | 2.1 | 0.7~2.0 | 13~25 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |
| ST3.9 | 3.9 | 1.29 | 7.5 | 2.3 | 0.7~2.5 | 13~32 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |
| ST4.2 | 4.2 | 1.41 | 8.2 | 2.5 | 0.7~3.0 | 13~38 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |
| ST4.8 | 4.8 | 1.59 | 9.5 | 2.9 | 0.7~4.0 | 16~50 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |
| ST5.5 | 5.5 | 1.81 | 10.9 | 3.3 | 1.0~5.0 | 19~60 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |
| ST6.3 | 6.3 | 1.81 | 12.5 | 3.8 | 1.0~6.0 | 19~80 | DIN 7504 K/N | Tek self-drilling screw, drill flute point |