A2 Stainless Steel Large-Diameter Lockbolt Assemblies (BS 7805-2) are supplied to BS 7805 Part 2:1997. The grade provides good general corrosion resistance and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A2 Stainless Steel for Large-Diameter Lockbolt Assemblies (BS 7805-2)
The most common stainless group for indoor and general outdoor fasteners. For large-diameter lockbolt assemblies (bs 7805-2), 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 Large-Diameter Lockbolt Assemblies (BS 7805-2) 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
For stainless large-diameter lockbolt assemblies (bs 7805-2) the compatibility question is galvanic rather than galling: joined to aluminum or galvanized steel in wet service, stainless drives corrosion of the less-noble metal. Isolate with a coating, sleeve or non-conductive washer where the joint sees moisture. Note also that stainless is softer than hardened carbon steel, so where the part carries a wear or shear duty, check the load against the grade before substituting.
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 Large-Diameter Lockbolt Assemblies (BS 7805-2) Available in A2 Stainless Steel
| Nominal diameter (mm) | Pin head styles | Collar styles | Strength grade | Assembly | Material options | Reference standard |
|---|---|---|---|---|---|---|
| 12.7 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 15.9 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 19.1 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 22.2 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 25.4 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 28.6 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 31.8 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
| 34.9 | round / truss / countersunk / threaded-head | standard / flanged / low-profile | 8.8 | pin + collar | steel / stainless steel / aluminum alloy | BS 7805 Part 2:1997 |
