I have a home project (making a custom sized link for a dog collar) that requires the use of stainless and figured while I’m buying a sheet of this I might as well buy some that can be welded for use on bike projects or at least practice welding. My local supplier has several grades that say they’re weldable but I can’t see any real benefit/downside other than cost among those grades.
I use 304 tubing and flat bar for racks. It TIG brazes very nicely with silicon bronze (but they probably all do). And although not “high-strength” it’s a bit stronger than mild steel (but less than cromoly). The flat bar does have quite an appetite for drill bits though.
In a frame building book I read the author describing how stainless would wreck drilling bits and cutting tools but using a “grinding tool” made the material more workable? I don’t have personal experience so I don’t know what that means \
In my experience drilling or machining stainless you have to either keep it very cool with flood coolant or commit to the cut and don’t stop till you get through because it hardens as soon as you let up.
I cut nearly everything with a grinding tool anyway (because I’m a bit of a redneck) so that was fine. But had to order a few new drill bits from Ali. Actually the best cutoff wheels for cutting any steel are the ones that say they’re for stainless. Heat-treated tubes like 853 are also a bit harder to drill. But they’re so thin it’s not much of a big deal.
Stick with the regular 304 / 304L which is the classic stainless steel. You don’t need 316 unless you’re doing food or medical equipment. Stay away from the 400 series stuff, which is heat-treatable (IE can become hardened and brittle or change dimension with brazing or welding). Save the 17-4 for when you do a Reynolds 853 build, that’s what their tubes are made out of.
853 is just heat-treated 631, which is CrMnMo. Similar to CrMo and definitely not stainless. 953 was the crazy strong stainless one (now sadly discontinued). And there’s also 921 (which hardly anyone uses either
