For hex flange bolts in A4 Stainless Steel, the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for A4 Stainless Steel (A4-80 (316)) is summarized below together with every size supplied.
Why Choose A4 Stainless Steel for Hex Flange Bolts
Specified for marine, coastal and chemical applications. For hex flange bolts, 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 Hex Flange Bolts in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless hex flange bolts: (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 Hex Flange Bolts Available in A4 Stainless Steel
| Size | Pitch (mm) | Flange diameter dc (mm) | Head height k (mm) | Width across flats s (mm) | Reference standard |
|---|---|---|---|---|---|
| M5 | 0.8 | 11.8 | 4.7 | 8.0 | ISO 1665 / DIN 6921 |
| M6 | 1.0 | 14.2 | 5.6 | 10.0 | ISO 1665 / DIN 6921 |
| M8 | 1.25 | 17.9 | 7.2 | 13.0 | ISO 1665 / DIN 6921 |
| M10 | 1.5 | 21.8 | 8.9 | 15.0 | ISO 1665 / DIN 6921 |
| M12 | 1.75 | 26.0 | 10.7 | 18.0 | ISO 1665 / DIN 6921 |
| M14 | 2.0 | 29.9 | 12.3 | 21.0 | ISO 1665 / DIN 6921 |
| M16 | 2.0 | 34.5 | 14.1 | 24.0 | ISO 1665 / DIN 6921 |
| M20 | 2.5 | 42.8 | 17.5 | 30.0 | ISO 1665 / DIN 6921 |
| M24 | 3.0 | 51.1 | 21.0 | 36.0 | ISO 1665 / DIN 6921 |