The automotive and agriculture industries are the most typical industries for this stainless steel grade. Bottom line, the smartest thing to do is steer clear of the oxidation to begin with, however , you can chemically correct it. On 3xx stainless I'd personally even suggest sharpening. Something you might want https://www.madanijayateknik.com/service/detail/as-round-bar-plate-sheet-stainless-steel-409-409l-409m-409cb-409ti