Low Cap (Acorn) Nuts manufactured in A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) are dimensioned to DIN 917. 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 A2 Stainless Steel for Low Cap (Acorn) Nuts
The most common stainless group for indoor and general outdoor fasteners. For low cap (acorn) nuts, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| 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 Low Cap (Acorn) Nuts in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Comparable Grades
For Low Cap (Acorn) Nuts, the alternative stainless grade is A4 (316). 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 Low Cap (Acorn) Nuts Available in A2 Stainless Steel
| Size | Pitch P (mm) | g2 (mm) | h (mm) | r (mm) | Width across flats s (mm) | t (mm) | w (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 1.05 | 5.5 | 8 | 7 | 4.16 | 1 | DIN 917 |
| M5 | 0.8 | 1.2 | 7 | 10 | 8 | 4.96 | 1 | DIN 917 |
| M6 | 1 | 1.5 | 9 | 12 | 10 | 6.71 | 1.5 | DIN 917 |
| M8 | 1.25 | 1.87 | 12 | 15 | 13 | 9.21 | 2 | DIN 917 |
| M10 | 1.5 | 2.25 | 14 | 20 | 17 | 10.65 | 2 | DIN 917 |
| M12 | 1.75 | 6.4 | 16 | 25 | 19 | 13.15 | 2 | DIN 917 |
| (M14) | 2 | 7.3 | 18 | 28 | 22 | 14.65 | 2 | DIN 917 |
| M16 | 2 | 7.3 | 20 | 30 | 24 | 16.65 | 2 | DIN 917 |
| (M18) | 2.5 | 9.3 | 22 | 32 | 27 | 18.58 | 2 | DIN 917 |
| M20 | 2.5 | 9.3 | 25 | 35 | 30 | 20.58 | 2.5 | DIN 917 |
| (M22) | 2.5 | 9.3 | 28 | 35 | 32 | 21.58 | 3 | DIN 917 |
| M24 | 3 | 10.7 | 30 | 40 | 36 | 23.58 | 3 | DIN 917 |
| M30 | 3.5 | 12.7 | 34 | 60 | 46 | 27.58 | 3 | DIN 917 |
| M36 | 4 | 14 | 44 | 70 | 55 | 35.5 | 4 | DIN 917 |
Dimensions are independent of the material: every size above is available in A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
A2 Stainless Steel is one of the grades the catalog describes. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
