Corrosion resistance of stainless steel

Corrosion resistance is an important property of stainless steel. Corrosion resistance is determined by chemical composition, Surface states and environmental conditions of stainless steel. Stainless steel in practical applications may corrode and rust due to the erosion of corrosive media, while local corrosion such as intergranular corrosion, pore corrosion, and stress corrosion cracking are more common.

The formation of a uniform and dense passivation film on the surface of stainless steel is an important factor in its corrosion resistance. The local damage of the passivation film is the main cause of local corrosion. Stainless steel is not a non rusting steel, and its good corrosion resistance is only relative and conditional. It is particularly important to keep the surface clean or passivated.

The formation characteristics of passivation film: Under high temperature conditions, the surface of stainless steel will generate oxide skin, with the main component being Cr. The passivation film formed on the surface of stainless steel at room temperature is not a "true" oxide film, and its physical and chemical structure has not yet been fully confirmed. The surface of pure stainless steel will spontaneously form in the atmosphere or other oxygen-containing environments, and this passivation film with self-healing characteristics.