Material specification page for socket head shoulder screw in A4 Stainless Steel. Covers the grade designation (A4-80 (316)), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to GB/T 5281 / ISO 7379.
Why Choose A4 Stainless Steel for Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017)
Specified for marine, coastal and chemical applications. For socket head shoulder screw — gb/t 5281 / iso 7379 (series 017), this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | A4-80 (316) |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C |
| Corrosion characteristic | Superior, including marine and chloride environments |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017), the alternative stainless grade is A2 (304). 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 Socket Head Shoulder Screw — GB/T 5281 / ISO 7379 (Series 017) Available in A4 Stainless Steel
| Shoulder dia (mm) | Thread size | Pitch (mm) | Shoulder length (mm) | Head dia dk (mm) | Head height k (mm) | Reference standard |
|---|---|---|---|---|---|---|
| 5 | M4 | 0.7 | 16 | 9.5 | 5.3 | ISO 7379 / GB/T 5281 |
| 6 | M5 | 0.8 | 20 | 11.0 | 6.5 | ISO 7379 / GB/T 5281 |
| 8 | M6 | 1.0 | 25 | 13.0 | 8.0 | ISO 7379 / GB/T 5281 |
| 10 | M8 | 1.25 | 30 | 16.0 | 10.0 | ISO 7379 / GB/T 5281 |
| 12 | M10 | 1.5 | 40 | 18.0 | 12.0 | ISO 7379 / GB/T 5281 |
| 16 | M12 | 1.75 | 50 | 24.0 | 16.0 | ISO 7379 / GB/T 5281 |
| 20 | M16 | 2.0 | 60 | 30.0 | 20.0 | ISO 7379 / GB/T 5281 |
| 25 | M20 | 2.5 | 80 | 36.0 | 25.0 | ISO 7379 / GB/T 5281 |