1. Chemical corrosion: Oil, dust, acid, alkali, salt, etc. that adhere to the surface of the channel steel are converted into corrosive media under certain conditions, causing chemical changes with some components in the channel steel, causing chemical corrosion and rusting; The damage caused by various scratches on the passivation film reduces the safety protection ability of the channel steel, which is very easy to react with organic chemical media, causing chemical corrosion and rusting.
2. Electrochemical corrosion: scratches caused by contact with carbon steel parts and corrosion medium produce Primary battery reaction, resulting in electrochemical corrosion; Electrochemical corrosion is caused by the adhesion of easily rusting chemicals (such as laser cutting slag and splashes) and the generation of rechargeable batteries in the central region of the corrosion medium; The physical defects (undercut, air hole, crack, lack of welding, lack of full welding, etc.) and organic chemical defects (coarse grain, shrinkage porosity, etc.) in the electric welding area react with the corrosion medium to produce Primary battery, thus causing electrochemical corrosion.