Atmospheric corrosion resistant steel

Atmospheric corrosion resistant steel, also known as weathering steel, is a kind of low alloy steel made by adding a certain amount of alloying elements to ordinary steel, the main alloy composition is Cu, P, Cr, Ni and other elements.

Atmospheric corrosion resistant steel refers to a low alloy steel with good atmospheric corrosion resistance made by adding a certain amount of Cu, P, C or Ni, Mo, Nb, Ti and other alloying elements to the steel. In the industrial and rural atmospheric environment, the weathering steel forms a dense and stable oxide protective film on the surface of its matrix, hindering the entry of corrosive media, and has excellent atmospheric corrosion resistance and other properties, while the rust layer formed by corrosion on the surface of the carbon steel matrix is loose and has micro cracks, which can not really play a protective role on the matrix steel.

Weathering steel has excellent corrosion resistance. It has been widely used in buildings, vehicles, Bridges, towers and other steel structures. There are three main ways to use weathering steel: bare use, coating use and rust layer stabilization treatment.

In many departments such as buildings, Bridges, vehicles, etc., weathering steel and ordinary steel are mostly painted, and the weathering steel after painting shows excellent corrosion resistance compared with ordinary steel. However, due to the increase in the use of coating costs and operating procedures, it is difficult to widely use large components.

The most common use of weathering steel is bare use. Generally, after 3 to 10 years, the rust layer on the surface of weathering steel gradually stabilizes, the corrosion development slows down, and the appearance is a beautiful chocolate color.

Because the process of stabilizing the rust layer of weathering steel is affected by the chemical composition of the steel, the use environment, the water retention and dust accumulation of the structural details and mechanical wear and other conditions, if the improper use destroys the formation conditions of the stable rust layer, weathering steel will also produce serious rust.

In the process of using weathering steel, the initial stage is the same as ordinary steel, corrosion occurs, but then the corrosion rate gradually slows down, after a certain time, the corrosion is almost no longer carried out, so as to achieve the purpose of protecting the matrix, this phenomenon is called the stabilization of the rust layer, and the rust layer in this state is called the stabilization of the rust layer.

From the effect of corrosion products on the corrosion process, the atmospheric corrosion of steel is a process of electrochemical reaction of oxygen in the air through the rust layer in the presence of water film. The rust layer is composed of loose outer rust layer and dense inner rust layer, and the alloying elements in steel are mainly affected by the inner rust layer.