A4 Stainless Steel (A4-80 (316)) is specified for marine, coastal and chemical applications. When socket head cap screws are specified in this grade, the dimensions remain per ISO 4762 / DIN 912; the material determines corrosion behavior (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C). Both are covered below with the size table.
Why Choose A4 Stainless Steel for Socket Head Cap Screws
Specified for marine, coastal and chemical applications. For socket head cap screws, 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 |
Galvanic & Galling Considerations
Two important notes for stainless socket head cap 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.
Comparable Grades
For Socket Head Cap Screws, 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 Cap Screws Available in A4 Stainless Steel
| Size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Hex key s (mm) | Socket depth t min (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M1 | 0.25 | 1.9 | 1.0 | 0.7 | 0.5 | ISO 4762 / DIN 912 |
| M1.2 | 0.25 | 2.3 | 1.2 | 0.9 | 0.6 | ISO 4762 / DIN 912 |
| M1.4 | 0.3 | 2.6 | 1.4 | 1.0 | 0.7 | ISO 4762 / DIN 912 |
| M1.6 | 0.35 | 3.0 | 1.6 | 1.5 | 0.7 | ISO 4762 / DIN 912 |
| M2 | 0.4 | 3.8 | 2.0 | 1.5 | 1.0 | ISO 4762 / DIN 912 |
| M2.5 | 0.45 | 4.5 | 2.5 | 2.0 | 1.1 | ISO 4762 / DIN 912 |
| M3 | 0.5 | 5.5 | 3.0 | 2.5 | 1.3 | ISO 4762 / DIN 912 |
| M4 | 0.7 | 7.0 | 4.0 | 3.0 | 2.0 | ISO 4762 / DIN 912 |
| M5 | 0.8 | 8.5 | 5.0 | 4.0 | 2.5 | ISO 4762 / DIN 912 |
| M6 | 1.0 | 10.0 | 6.0 | 5.0 | 3.0 | ISO 4762 / DIN 912 |
| M8 | 1.25 | 13.0 | 8.0 | 6.0 | 4.0 | ISO 4762 / DIN 912 |
| M10 | 1.5 | 16.0 | 10.0 | 8.0 | 5.0 | ISO 4762 / DIN 912 |
| M12 | 1.75 | 18.0 | 12.0 | 10.0 | 6.0 | ISO 4762 / DIN 912 |
| M14 | 2.0 | 21.0 | 14.0 | 12.0 | 7.0 | ISO 4762 / DIN 912 |
| M16 | 2.0 | 24.0 | 16.0 | 14.0 | 8.0 | ISO 4762 / DIN 912 |
| M18 | 2.5 | 27.0 | 18.0 | 14.0 | 9.0 | ISO 4762 / DIN 912 |
| M20 | 2.5 | 30.0 | 20.0 | 17.0 | 10.0 | ISO 4762 / DIN 912 |
| M22 | 2.5 | 33.0 | 22.0 | 17.0 | 11.0 | ISO 4762 / DIN 912 |
| M24 | 3.0 | 36.0 | 24.0 | 19.0 | 12.0 | ISO 4762 / DIN 912 |
| M27 | 3.0 | 40.0 | 27.0 | 19.0 | 13.5 | ISO 4762 / DIN 912 |
| M30 | 3.5 | 45.0 | 30.0 | 22.0 | 15.5 | ISO 4762 / DIN 912 |
| M33 | 3.5 | 50.0 | 33.0 | 24.0 | 17.5 | ISO 4762 / DIN 912 |
| M36 | 4.0 | 54.0 | 36.0 | 27.0 | 19.0 | ISO 4762 / DIN 912 |
| M42 | 4.5 | 63.0 | 42.0 | 32.0 | 21.0 | ISO 4762 / DIN 912 |
| M48 | 5.0 | 72.0 | 48.0 | 36.0 | 25.0 | ISO 4762 / DIN 912 |