Weathering steels: From empirical development to scientific design. A review

The design of the first weathering steels was purely empirical and focused on a small number of conventional alloying elements such as manganese, silicon, chromium, nickel, copper and phosphorus, mainly. The environmental conditions that promote the formation of protective rust layers: existence of wet/dry cycling, absence of very long wetness times, atmospheres without a marine component, etc., were identified by trial and error. This paper makes a bibliographic review of the abundant literature that has been published on the atmospheric corrosion of weathering steels, setting out in chronological order the advances made in the scientific knowledge of important matters such as: atmospheric corrosion mechanisms of weathering steel, formation of protective rust layers, and the role played by alloying elements. The work ends with an overview of the scientific design of new weathering steels, placing special emphasis on the new compositions developed for application in marine atmospheres.