A2 Stainless Steel Hex Bolts, Fine Pitch combine the dimensional form of ISO 8765 with the material properties of grade ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70: good general corrosion resistance, largely non-magnetic, service range approx. -200 °C to +400 °C, subject to the property class and the joint. This page summarizes the grade data, its corrosion behavior in service, the comparable grades, and the sizes supplied.
Why Choose A2 Stainless Steel for Hex Bolts, Fine Pitch
The most common stainless group for indoor and general outdoor fasteners. For hex bolts, fine pitch, 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 hex bolts, fine pitch: (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 Hex Bolts, Fine Pitch, 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
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 Bolts, Fine Pitch Available in A2 Stainless Steel
| Size | Fine pitch (mm) | Width across flats s (mm) | Head height k (mm) | Stress area As (mmu00b2) | Common length range (mm) | Property class | Reference standard |
|---|---|---|---|---|---|---|---|
| M8 | 1.0 | 13.0 | 5.3 | 39.2 | 20~80 | 8.8 / 10.9 | ISO 8765 |
| M10 | 1.25 | 16.0 | 6.4 | 61.2 | 25~100 | 8.8 / 10.9 | ISO 8765 |
| M12 | 1.25 | 18.0 | 7.5 | 92.1 | 30~120 | 8.8 / 10.9 | ISO 8765 |
| M14 | 1.5 | 21.0 | 8.8 | 125.0 | 35~140 | 8.8 / 10.9 | ISO 8765 |
| M16 | 1.5 | 24.0 | 10.0 | 167.0 | 40~160 | 8.8 / 10.9 | ISO 8765 |
| M20 | 1.5 | 30.0 | 12.5 | 272.0 | 50~200 | 8.8 / 10.9 | ISO 8765 |
| M24 | 2.0 | 36.0 | 15.0 | 384.0 | 60~240 | 8.8 / 10.9 | ISO 8765 |
