AISI 409 stainless steel is actually a ferritic stainless steel formulated for Principal forming into wrought products. Bottom line, the smartest thing to do is steer clear of the oxidation to begin with, however , you can chemically deal with it. On 3xx stainless I might even propose polishing. You https://www.madanijayateknik.com/service/detail/as-round-bar-plate-sheet-stainless-steel-409-409l-409m-409cb-409ti