A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. When thin hex castle nut are specified in this grade, the dimensions remain per GB/T 6181 / ISO 4035; the material determines corrosion behavior (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.
Why Choose A2 Stainless Steel for Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053)
The most common stainless group for indoor and general outdoor fasteners. For thin hex castle nut — gb/t 6181 / iso 4035 (series 053), 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 |
Galvanic & Galling Considerations
Two important notes for stainless thin hex castle nut — gb/t 6181 / iso 4035 (series 053): (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 Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053), the alternative stainless grade is A4 (316). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.
Sizes of Thin Hex Castle Nut — GB/T 6181 / ISO 4035 (Series 053) Available in A2 Stainless Steel
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Total height m (mm) | Slot width (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 4.0 | 1.2 | ISO 7036 / GB/T 6180 |
| M4 | 0.7 | 7.0 | 7.66 | 5.0 | 1.5 | ISO 7036 / GB/T 6180 |
| M5 | 0.8 | 8.0 | 8.79 | 6.7 | 1.8 | ISO 7036 / GB/T 6180 |
| M6 | 1.0 | 10.0 | 11.05 | 7.7 | 2.0 | ISO 7036 / GB/T 6180 |
| M8 | 1.25 | 13.0 | 14.38 | 9.8 | 2.5 | ISO 7036 / GB/T 6180 |
| M10 | 1.5 | 16.0 | 17.77 | 12.4 | 2.8 | ISO 7036 / GB/T 6180 |
| M12 | 1.75 | 18.0 | 20.03 | 15.8 | 3.5 | ISO 7036 / GB/T 6180 |
| M14 | 2.0 | 21.0 | 23.36 | 17.8 | 4.0 | ISO 7036 / GB/T 6180 |
| M16 | 2.0 | 24.0 | 26.75 | 20.8 | 4.5 | ISO 7036 / GB/T 6180 |
| M18 | 2.5 | 27.0 | 30.14 | 22.5 | 4.5 | ISO 7036 / GB/T 6180 |
| M20 | 2.5 | 30.0 | 33.53 | 24.0 | 5.5 | ISO 7036 / GB/T 6180 |
| M24 | 3.0 | 36.0 | 39.98 | 29.5 | 6.0 | ISO 7036 / GB/T 6180 |
| M30 | 3.5 | 46.0 | 50.85 | 36.0 | 7.0 | ISO 7036 / GB/T 6180 |
| M36 | 4.0 | 55.0 | 60.79 | 43.0 | 8.0 | ISO 7036 / GB/T 6180 |
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, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
