303 is the free machining grade of 304 and 416 is the free machining grade of 410. Free machining in these two cases means higher sulphur content. With sulphur incusions [manganese sulphide] you might not get a perfect mirror finish when polishing. Machineability of 410 is better than 304 as 304 is "gummy" as machinists call it. I would guess that most use 416 in the un heat treated form.
|