Stainless steels A 1 – A 5 cannot be hardened with heat treatment (the hardness is achieved solely via the mould pressures used in production). The reaction of fasteners made from these materials to being assembled/erected therefore differs from that of fasteners made from tempered steel. Improper assembly can lead to the failure of the properly created joint. In particular when similar matings of materials are screwed together, the danger of cold fretting (“eating away”) exists.
Generally, fasteners made from austenitic steel (A 1 – A 5) are not magnetizable. Since the higher property classes 70 and 80 are reached with the mould pressures during cold forming, however, the material can become slightly magnetic as a result.
Stainless steels are resistant to the cold, which also makes them highly suitable for use at low temperatures: A 2 down to -200°C, A 4 down to -60°C.
The property class 70 generally applies to hexagon head, hexagon socket, six lobe drive, slotted, recessed screws and studs. If no agreement to the contrary is made when the order is placed, screws of this property class will be delivered.