Stainless steel is known for its resistance to rust and corrosion, thanks to the presence of chromium, which forms a protective layer of chromium oxide on the surface. However, under certain conditions, stainless steel can discolor. Here are some factors that may cause rust and how to prevent it:

Failure of oxide film. The oxide film on the surface of stainless steel plays an anti-corrosion role, but long-term exposure to high temperature, humidity, acid, and alkali environments will destroy the oxide film, causing stainless steel to discolor.

Electrochemical reaction. When stainless steel comes into contact with other metals or electrolytes, it is easily subjected to electrochemical reactions, which result in surface discoloration.

‌Welding heat effect. During the welding process, stainless steel will overheat, causing the oxide film on the surface to fail and cause discoloration. Therefore, engineers usually polish the welding position after welding to restore the original appearance of stainless steel.

‌Improper cleaning. Using unsuitable detergents or cleaning methods may cause the stainless steel surface to discolor. Secondly, if the water stains are not wiped off, the stainless steel surface will turn yellow or rust over time.

‌Excessive temperature. Stainless steel discoloration caused by excessive temperature usually occurs when kitchen utensils are heated long enough. Long-term heating of an empty pot will cause the alloy elements in the stainless steel to oxidize, resulting in discoloration, blackening, and yellowing, among other things.

Grease effects. Certain ingredients and grease may release chemical components at high temperatures, discoloring the surface of the cookware.

‌Gas purity is insufficient. The gas used in the kitchen is not pure enough, and long-term contact with the bottom of the stainless steel will cause yellowing and blackening.