304 stainless steel is a common stainless steel material with excellent corrosion resistance. However, under certain conditions, rust can still occur. Here's why:
Coating damage: The surface of 304 stainless steel is required to be smooth, if there are defects such as damage, scratches, corrosion and other defects on the surface, it will destroy the continuity of its passivation layer, which will aggravate the impact of air and moisture on its surface material, resulting in rust.
Media erosion: 304 stainless steel usually works in harsh environments such as acids and alkalis, which will erode the passivation layer on the surface and accelerate its rust. Especially under high temperature and high pressure conditions, the passivation layer often fails, further promoting rust.
Grease residues: During the processing or manufacturing process of 304 stainless steel, lubricants such as petroleum, light oil, and butter will be used, and these lubricants residue on the surface may accelerate the rusting of stainless steel. Therefore, the material needs to be cleaned and the lubricant removed thoroughly before processing.
Chemical reaction: When 304 stainless steel is in contact with heavy metals, acids, alkalis and other substances, it will undergo chemical reactions to form compounds, which will make stainless steel lose its basic properties against corrosion, such as rusting in seawater or chlorine-containing media.
Therefore, in the process of using and maintaining 304 stainless steel, it is necessary to pay attention to its use environment and maintenance details, keep the surface smooth, regularly clean and eliminate surface defects, and prevent solid grease or chemical residues, so as to improve the corrosion resistance of 304 stainless steel and prevent rust.