Rusted tub drain
 

I hired someone to replace tub 5 yrs ago. Never saw a drain rust out so fast. Channellocks can not break it loose. Hoping I can just loosen and replace without having to open wall.

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Looks like really cheap Chinese chrome plating or your using really strong cleaning solvents, (like the acid in liquid drain cleaner!). Opening the wall should not be necessary if the drain shoe is PVC it should unscrew you can add a little heat (propane torch) to soften up any plumber's putty or thread sealant. Good Luck