Weathering steel refers to the addition of a small number of alloying elements (such as Cu, P, Cr, Ni, Mn, Mo, Al, V, Ti, Re, etc.), so that its atmospheric corrosion resistance to a class of low alloy steel to obtain a significant improvement. Its surface can form a protective rust layer, effectively blocking the penetration and transmission of corrosive media, often the longer the use of time, the more prominent role of its weathering.
Weathering steel has the property of protecting the rust layer against atmospheric corrosion, and can be used to manufacture steel structures such as vehicles, bridges, pylons and containers. Compared with plain carbon steel, weathering steel has better corrosion resistance in the atmosphere; compared with stainless steel, weathering steel has only a trace amount of alloying elements, the total amount of these alloying elements accounted for only a few per cent, unlike stainless steel to reach more than ten per cent, so the price is cheaper.
Weathering steel is usually divided into two categories - welding requirements are not high weathering steel; Cu, P (0.07% to 0.15%) system-based, yield strength is generally below 345MPa, plate thickness is generally no more than 16mm, such as the U.S. ASTMA242 series and Japan's JIS SPA series.
Welded structural weathering steel: Cr-Ni system is the main, containing P amount of 0.04% or less, such as the United States ASTMA588 and A514 series, Japan's JISS MA series.
