Weathering means that due to their chemical composition steels exhibit increased resistance to atmospheric corrosion compared to unalloyed steels. The corrosion retarding effect of the protective layer is produced by the nature of its structure components and the particular distribution and concentration of alloying elements in it.
The anticorrosive properties of weathering steel are based on the protective oxide layer, called patina which forms on the surface of the steel. Under normal weather conditions the patina will form in about 18–36 months, if the surface is alternately wet and dry.
At first, the patina is a reddish brown color, but with time takes on a darker hue. In industrial environments, the patina forms more quickly and is darker in color than in rural areas. In marine environments, the formation of the protective patina may be slower due to chloride exposure.
The anticorrosive properties of weathering steel are better than those of other structural steels in many applications. The steel is self-protecting: the rust layer on the surface becomes a tight oxide layer that slows down the progress of corrosion. The steel is an economical, long-lasting and fully recyclable material.
Weathering means that due to their chemical composition steels exhibit increased resistance to atmospheric corrosion compared to unalloyed steels. The corrosion retarding effect of the protective layer is produced by the nature of its structure components and the particular distribution and concentration of alloying elements in it.
The layer protecting the surface develops and regenerates continuously when subjected to the influence of the weather. The corrosion retarding effect of the protective layer is produced by the nature of its structure components and the particular distribution and concentration of alloying elements in it. The layer protecting the surface develops and regenerates continuously when subjected to the influence of the weather.
Formation, duration of development and protective effect of the covering layer on weathering steels depend largely upon the corrosive character of the atmosphere. Its influence varies and depends mainly upon general weather condition (e.g. continental) macroclimate (e.g. industrial, urban, maritime or countryside climate) and the orientation of the structure components (e.g. exposed to or shaded from the weather, vertical or horizontal position).
