Weathering corten steel is not stainless steel, early as ordinary carbon steel will also rust, the latter is different. After corrosion of weathering steel for a period of time, due to the enrichment of trace elements such as Cu and P on the steel surface, a dense amorphous rust layer is formed, and it is firmly combined with the matrix. This layer of stabilized rust layer can resist the invasion of water vapor and harmful ions in the atmosphere to a certain extent, and prevent further corrosion of the matrix metal.