This specification applies to hot-rolled low alloy steels suitable for welded, bolted or riveted construction where enhanced corrosion resistance and savings in weight are required. The steels have improved resistance to atmospheric corrosion when compared with ordinary carbon steel because of additions of alloying elements such as nickel, chromium and copper. Two steel types are provided, according to the carbon and phosphorus contents, with differing levels of yield stress and notch ductility being specified for each type.