Hex Nuts manufactured in A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) are dimensioned to ISO 4032 / ISO 4033. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A4 Stainless Steel for Hex Nuts
Specified for marine, coastal and chemical applications. For hex nuts, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| 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 Nuts in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Hex Nuts, the alternative stainless grade is A2 (304). Choose A2 (304) for general use and A4 (316) wherever chlorides are present; the molybdenum in A4 is the whole difference. Remember that stainless is the corrosion answer, not the strength answer — for load, look at class 8.8 or 10.9 instead.
Using Stainless Fasteners in Aluminum
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Hex Nuts Available in A4 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 | - | Below the ISO 4032 range (M1.6-M64); manufacturer series |
| M1.2 | 0.25 | 3.0 | 3.28 | 1.0 | - | Below the ISO 4032 range (M1.6-M64); manufacturer series |
| M1.4 | 0.3 | 3.0 | 3.28 | 1.2 | - | Below the ISO 4032 range (M1.6-M64); manufacturer series |
| M1.6 | 0.35 | 3.2 | 3.48 | 1.3 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M2 | 0.4 | 4.0 | 4.32 | 1.6 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M2.5 | 0.45 | 5.0 | 5.45 | 2.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M3 | 0.5 | 5.5 | 6.01 | 2.4 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M3.5 | 0.6 | 6.0 | 6.58 | 2.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M4 | 0.7 | 7.0 | 7.66 | 3.2 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M5 | 0.8 | 8.0 | 8.79 | 4.7 | 5.1 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M6 | 1.0 | 10.0 | 11.05 | 5.2 | 5.7 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M8 | 1.25 | 13.0 | 14.38 | 6.8 | 7.5 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M10 | 1.5 | 16.0 | 17.77 | 8.4 | 9.3 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M12 | 1.75 | 18.0 | 20.03 | 10.8 | 12.0 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M14 | 2.0 | 21.0 | 23.36 | 12.8 | 14.1 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M16 | 2.0 | 24.0 | 26.75 | 14.8 | 16.4 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M18 | 2.5 | 27.0 | 29.56 | 15.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M20 | 2.5 | 30.0 | 32.95 | 18.0 | 20.3 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M22 | 2.5 | 34.0 | 37.29 | 19.4 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M24 | 3.0 | 36.0 | 39.55 | 21.5 | 23.9 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M27 | 3.0 | 41.0 | 45.2 | 23.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M30 | 3.5 | 46.0 | 50.85 | 25.6 | 28.6 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M33 | 3.5 | 50.0 | 55.37 | 28.7 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M36 | 4.0 | 55.0 | 60.79 | 31.0 | 34.7 | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M39 | 4.0 | 60.0 | 66.44 | 33.4 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M42 | 4.5 | 65.0 | 71.3 | 34.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M45 | 4.5 | 70.0 | 76.95 | 36.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M48 | 5.0 | 75.0 | 82.6 | 38.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M52 | 5.0 | 80.0 | 88.25 | 42.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
| M56 | 5.5 | 85.0 | 93.56 | 45.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2, M5-M36 preferred sizes) |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Locking method is specifiable independently of the rest: nylon insert, all-metal deformed thread, serrated flange, or none. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
