When brown spots appear on the surface of a stainless steel plate, people are surprised to find that the stainless steel introduced by 310S stainless steel plate manufacturers should not rust—they think if it rusts, it is not stainless steel, and the problem may lie in the steel quality. In fact, this is a one-sided misunderstanding resulting from a lack of knowledge about stainless steel. Stainless steel can also rust under certain conditions.

Stainless steel plates have the ability to resist oxidation in the atmosphere, i.e., rust resistance, and also the ability to resist corrosion in media containing acids, alkalis, and salts, i.e., corrosion resistance. However, the level of its corrosion resistance varies depending on the chemical composition of the steel itself, its microstructural state, service conditions, and the type of environmental media. For example, 304 stainless steel has absolutely excellent corrosion resistance in a dry and clean atmosphere, but if it is moved to a coastal area and exposed to sea fog with a high salt content, it will rust quickly, while some other types of stainless steel perform well in such an environment. Therefore, not all types of stainless steel can resist corrosion and avoid rusting under all circumstances.

Manufacturers of 310S stainless steel plates popularize that a stainless steel plate forms a very thin, strong, dense, and stable chromium-rich oxide film (protective film) on its surface. This film prevents oxygen atoms from further penetrating and causing continuous oxidation, thereby resisting corrosion. Once the film is continuously damaged for some reason, oxygen atoms in the air or liquid will continuously penetrate and combine with iron atoms in the steel to form loose iron oxide, and the metal surface will be continuously corroded.