Specifying Hex Nuts in A2 Stainless Steel pairs the dimensional form of Hex Nuts (ISO 4032 / ISO 4033) with the engineering properties of A2 Stainless Steel. This page explains when to choose the grade, how it behaves in service, and which grades to compare it against.
Why Choose A2 Stainless Steel for Hex Nuts
The most common stainless grade for indoor and general outdoor fasteners. For hex nuts, 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 Hex Nuts in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Galvanic & Galling Considerations
Two important notes for stainless hex 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.
Sizes of Hex Nuts Available in A2 Stainless Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m style 1 (mm) | Nut height m style 2 (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M1 | 0.25 | 2.5 | 2.71 | 0.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.2 | 0.25 | 3.0 | 3.28 | 1.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.4 | 0.3 | 3.0 | 3.28 | 1.2 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.6 | 0.35 | 3.2 | 3.48 | 1.3 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M2 | 0.4 | 4.0 | 4.32 | 1.6 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M2.5 | 0.45 | 5.0 | 5.45 | 2.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M3 | 0.5 | 5.5 | 6.01 | 2.4 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M3.5 | 0.6 | 6.0 | 6.58 | 2.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M4 | 0.7 | 7.0 | 7.66 | 3.2 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M5 | 0.8 | 8.0 | 8.79 | 4.0 | 5.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M6 | 1.0 | 10.0 | 11.05 | 5.0 | 6.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M8 | 1.25 | 13.0 | 14.38 | 6.5 | 8.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M10 | 1.5 | 16.0 | 17.77 | 8.0 | 10.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M12 | 1.75 | 18.0 | 20.03 | 10.0 | 12.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M14 | 2.0 | 21.0 | 23.36 | 11.0 | 14.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M16 | 2.0 | 24.0 | 26.75 | 13.0 | 16.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M18 | 2.5 | 27.0 | 29.56 | 15.0 | 18.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M20 | 2.5 | 30.0 | 32.95 | 16.0 | 20.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M22 | 2.5 | 32.0 | 35.03 | 18.0 | 22.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M24 | 3.0 | 36.0 | 39.55 | 19.0 | 24.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M27 | 3.0 | 41.0 | 45.2 | 22.0 | 27.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M30 | 3.5 | 46.0 | 50.85 | 24.0 | 30.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M33 | 3.5 | 50.0 | 55.37 | 26.0 | 33.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | 36.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M39 | 4.0 | 60.0 | 66.44 | 31.0 | 39.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M42 | 4.5 | 65.0 | 71.3 | 34.0 | 42.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M45 | 4.5 | 70.0 | 76.95 | 36.0 | 45.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M48 | 5.0 | 75.0 | 82.6 | 38.0 | 48.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M52 | 5.0 | 80.0 | 88.25 | 42.0 | 52.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M56 | 5.5 | 85.0 | 93.56 | 45.0 | 56.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |