The stainless steel used in professional equipment is of high quality, and if properly maintained it can allow long use without incurring in any problem. It would however be wrong to think that stainless steel is indestructible and can resist any kind of damage or corrosion.
Stainless steel (or inoxidizable steel), which is characterized by the presence of chromium within the metal alloy, and possibly other alloying elements (such as molybdenum, nickel, etc.), is so called because of its high resistance to corrosion. This resistance is due to a very thin layer of chromium oxides/hydroxides that forms on the surface of the steel thanks to the oxygen absorbed by exposure to the air of the metal itself. This thin protective layer ensures the metal resistance against corrosion, i.e. it allows it not to rust like normal carbon steel.
However, should this protective layer be damaged by mechanical or chemical action (such as scratches, dents, cuts, use of bleach and corrosive agents, etc.), and if its reformation is prevented by isolating it from the oxygen present in the air, then even the best stainless steel can undergo corrosion phenomena and therefore rust.
