Questions about welding 1/4" SS with Mig

admin

I've had a request for stools I make to be built with stainless steel bar instead of cold rolled steel for use outdoors.  I have never welded stainless and have a Millermatic 175. Material will be 1-1/2" x 1/4" stainless bar stock.I know I need to use 308wire and tri-mix gas. The gas is expensive!Any changes I would need to make on my welder settings? Any other tips or suggestions?  I'd like to have the option of welding stainless but I'm not in a position to buy and learn how to TIG at the moment.Last edited by JobeFab; 04-19-2013 at 12:47 PM.Jobe Fabrications
Reply:Spend the money and get the gas and the wire, but try a test piece before you commit to the job. The flat bar will warp a lot, so make sure you can correct it, and give it the right finish first. Also, you may have trouble cuting the SS with the tools you have, so be prepared for some other new equipment. 304 that I buy is enerally pretty tough to work. The 316L I used on a project was a bit easier to work.
Reply:The material will be 304. I have an evolution raptor cold saw, hadn't thought about cutting it. I also have to drill holes with a step bit.  Of course I will do some testing first...thanks for the tips.Jobe Fabrications
Reply:Be sure to use the SS blade on that saw, NOT the mild steel blade.
Reply:Thanks, hadn't thought about that either.Jobe Fabrications
Reply:Keep your stainless stock away from mild steel, grinding dust, anything that will contaminate the surface.  I'd even suggest buying a stainless brush and grinding wheels just for this project.  Cover your workbench with a sheet of aluminum or even plywood, if that's all you've got, to keep the stainless from picking up mild steel that will start rusting.Stainless has half the thermal conductivity of mild steel, so it will hold onto welding heat longer and warp more.  You may need more clamps, fixturing, etc to keep everything true.  Or you may have to come up with a good way to straighten out anything that moves.  depends on where and how you're welding...think about beveling your weld joints so that MIG wire has someplace to go.  1/2" material will give you some room to bevel without worrying about burning through.  Beveling and the right settings will give you welds that need less cleanup.  There's a balance between the right machine settings for half inch material, the size of the bevel, and the amount of distortion you'll get.  might take some experiments to dial it in just right; if it's worth the effort.A coating of clear paint, once your stools are all finished, will go a long way towards keeping the stainless bright and corrosion free.  Remember, stainless is just corrosion resistant, not corrosion proof.  Bird droppings, and other environmental contaminants can still start the corrosion process, even on stainless steel.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks for the info, welding 1/4" and not 1/2".   I'll have to experiment with clamping in my jigs. I already have a bench that is MDF and not steel as I work in mostly bare steel and the steel welding top scratches my work too much.Jobe Fabrications
Reply:One more question about this set up.  Any issues with the welder or gun liner when I switch gases or wire out?  I will mostly be welding mild steel, but swaping out to stainless every once in awhile.Jobe Fabrications
Reply:Gas won't require any changes other than the material selection, but the liner is selected by wire size and may need to be changedLast edited by B_C; 04-23-2013 at 09:43 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock