If you were running a scrap yard where you buy and sell scrap metal or dismantle cars etc and buy scrap metal from the public then yes you'd need a salvage dealers license and likely a dismantlers license to deal in scrap metal.
But if you're just picking up scrap metal and then breaking it down and taking it into a scrap yard for some extra income then no you don't need a scrap metal license to sell to another scrap yard.
Many people find and haul scrap metal and sell it to a scrap yard without having a scrap metal dealers license without a problem.