Why magnets cannot be used on stainless steel?

Magnets typically cannot be used on stainless steel because most stainless steel alloys are non-magnetic due to their austenitic structure. While some types of stainless steel, like ferritic or martensitic grades, can be magnetic, the more common austenitic grades (such as 304 and 316) have a crystal structure that does not respond to magnetic fields. Additionally, the presence of nickel in austenitic stainless steels contributes to their non-magnetic properties.