First you aren't *tempering* 6061. Second, it needs to be a lot warmer than boiling water for aging 6xxx series. Third, I doubt tapwater in your area is clean anough to allow you to boil aluminium in it without some unpleasant, structure-weakening corrosion (and no, saucepans are hardly a loaded structure that you'd notice it in, and they *should* be coated anyways).

Frank: There are ways to weld 7075 now, but not in any practical, home engineering way...