Plain hot-rolled steel is OK for both. I like to anneal it before
machining if the part needs a good finish, like a bearing

316L stainless isn't too bad either. You can stick weld it (watch out
for the fumes) and then machine even the welded area. I made some
non-rusting roller-bearing wheels for my Wesco lift by welding 316L
pipe to plate, then boring the hub with an HSS boring bar and reaming
with an adjustable reamer, both of which work poorly in difficult
materials.

jw