A4 Stainless Steel (A4-80 (316)) is specified for marine, coastal and chemical applications. When square nuts are specified in this grade, the dimensions remain per DIN 557; 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 Square Nuts
Specified for marine, coastal and chemical applications. For square nuts, 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 square nuts: (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 Square Nuts, 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 Square Nuts Available in A4 Stainless Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 8.0 | 11.1 | 4.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M6 | 1.0 | 10.0 | 13.9 | 5.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M8 | 1.25 | 13.0 | 18.0 | 6.5 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M10 | 1.5 | 17.0 | 23.6 | 8.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M12 | 1.75 | 19.0 | 26.5 | 10.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M16 | 2.0 | 24.0 | 33.5 | 13.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
| M20 | 2.5 | 30.0 | 42.0 | 16.0 | DIN 557 / DIN 562 | Square nut, general / channel use |