Why does stainless steel rust ?

Most people think that the "magic" of stainless steel is that it will never rust , however,it is a misunderstanding about it . Stainless steel is just more resistant to corrosion than other ordinary carbon or alloy steels.   If you find your stainless steel products get rust ,there  could be three reasons:

1 . It could be the chemical composition or structure of the material or the processing couldn't reach the standards of stainless steel ,in other words,"fake" stainless steel.

2. It could be the stainless steel products are used in very corrosive environment , such as it being used by the sea or in factory area.The chlorine(Cl) in the air and pollutants are corrosive to stainess steel .

3.Improper or lack of regular  maintenance could also lead to rust of stainless steel,especially when the surface is scratched or there is corrosive deposits on the surface, or wrong cleaners are adoped.