First of all, you have to establish a correct concept: stainless steel is not "stainless", because the mechanism of stainless steel rust prevention is that alloy elements form a dense oxide film, which isolates oxygen contact and prevents continued oxidation.
Possible causes of stainless steel rusting:
1. Chloride ions exist in the use environment. Chloride ions are widely present, such as salt, sweat, seawater, sea breeze, soil and so on. In the presence of chloride ions, stainless steel corrodes rapidly, even more than ordinary low carbon steel. Therefore, there are requirements for the use environment of stainless steel, and it needs to be wiped frequently to remove dust and keep it clean and dry. (In this way, he can be rated as "improper use".) There is an example in the United States: a company used an oak container to hold a solution containing chloride ions. , Because the oak material is not modern enough, stainless steel is used, and the container leaks due to corrosion 16 days after the replacement.
2. No solution treatment. The alloying elements are not dissolved into the matrix, resulting in a low alloy content in the matrix structure and poor corrosion resistance.
3. This titanium- and niobium-free material has an inherent tendency to intergranular corrosion. The addition of titanium and niobium, together with stabilization treatment, can reduce intergranular corrosion. A high-alloy steel that can resist corrosion in the air or in chemically corrosive media. Stainless steel has a beautiful surface and good corrosion resistance. It does not need to undergo surface treatment such as color plating, but instead exerts the inherent surface properties of stainless steel. It is used in many A type of steel, commonly referred to as stainless steel. The representative performance is high alloy steel such as 13 chrome steel and 18-8 chrome nickel steel.