1.Introduction
Stainless steels are engineering materials and it are a complex group of iron based alloys containing at least10.5% chromium and a maximum of 1.2 % carbon. In order to define the stainless steel it can be said that the base alloy for this material is iron which contains a minimum of %11 Chromium (Cr) [1]. The European Standard EN10088 (EN2005) defines stainless steels as iron based alloys containing at least10.5% chromium and a maximum of 1.2% carbon. The main factor for the corrosion resistance of stainless steel is its chromium content. Under the influence of oxygen from air or water, the chromium rapidly forms a very thin, chromium (III) rich oxide film on the surface of the steel.This layer very effectively separates the material from the surroundings.It is adherent, coherent and insoluble under normal conditions. Increasing the chromium content, from the minimum of 10.5% necessary for "stainless steel", to 17 to 20%, greatly increases
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The enhanced corrosion resistance of weathering steel than mild steel or plain carbon steel (CS) is due to the formation in low aggressive atmosphere and well adhering corrosion product layer known as patina.The patina on weathering steel not only offers greater corrosion resistance than on mild steel, but is also responsible for its attractive appearance and self-healing abilities. A new weathering steel compositions have been developed to achieve improved mechanical properties and withstand increasingly aggressive atmospheric conditions from the corrosion point of view, especially in marine environments.The main applications for weathering steel include civil structures such as bridges and other load bearing structures, road installations, electricity posts, utility towers, guide rails, ornamental sculptures, façades, roofing,