the only thing i can think of is to clamp the pieces down on all corners and then weld them...keeping them clamped to a solid surface till the pieces cool to room temp....i dont know if its really possible to have no distortion at all on such thin metal

David

Further to Dave's recommendation, with which I agree entirely, Lincoln used to have a booklet called "Guide for the welding shop foreman", in which a lot of methods to prevent, or at least minimize warpage were explained: clamping, as Dave suggests, predeformation of the plates, backstep welding and many others. The booklet was sent free for the asking. Lincoln has a section on this same site, why don't you try it?
Giovanni S. Crisi
Sao Paulo - Brazil

Making your weld without distortion will be almost impossible, but you can limit the distortion by various methods such as:
Install a strongback adjacent to the seam.
Use Heat Sinks adjacent to the seam. (by heat sinks I mean a length of copper or aluminum to attract and absorb distorting heat from the SS)
Utilize sequence welding and backstep. ( Sequencing = Weld a few inches here, and a few inches over there in sequential order to keep the SS from getting too hot , Backstep = Make your welds end at the start of a previous weld.)
You'll figure out what works best in your unique situation.

what i have tried on 16ga.s.s. is set up over a good solid base, cement floor or heavy square tubing. set the sheets tight together at the bottom of the joint & leave a 1/8" gap at the other end. start tack welding the sheets, about an inch apart this will pull the sheets together by the time you get to the gapped end.while tacking, hammer each tack this flattens the sheets back down. if you have to weld both sides ,flip the material over & tack weld in-between each of the previous tacks, hammering them as well, weld the sheets up using some filler wire,when the joint is done hammer it again,then do the other side & hammer it too. by hammering i don't mean use a maul. we also surface our hammer with stainless weld, (some professor mentioned that before) it keeps the steel from your hammer from being imbedded in the stainless, i'm not sure how fancy your job has to be ?(hammer marks!) i couldn't find any literature when i was looking either.

I don't know what kind of application you are using your SS sheet for so I don't know if this will be useful to you or not.
A few years ago, I had a situation where I had to splice 4 sheets of gauge plate together. I think it was 14 ga. but the welds made a long cross so I had distortion in several directions. I had tried strong backs, back step welding, and other strange techniques but not much helped in my case. The longitudinal weld shrinkage was the main problem.
I ended up laying heavy flat bar on the floor under the welded seams and used a large air chisel with a blunt point to "hammer" out the welds. This stretched the metal and relaxed the distortion. The tool marks buffed out fairly well but not completely.
So if your application is not critical you could try that. Or if you have plate rolls wide enough that will "pinch" together, you can leave your weld reinforcement unground and run the plate through the rolls several times. Alternate from one side to the other, using only enough pressure to flatten the welds without significantly rolling the plate. That will stretch the welds without severe marking. Just don't over do it.
If iron contamination / rusting is a concern with your stainless, (of course! why else would you use stainless?) then you won't like these ideas unless you can find a stainless chisel or cladded plate rolls. But maybe you can find another way to stretch the metal.

Hope this helps,
CHGuilford

There is a technique called "Low stress non-distortion (LSND) welding" that allows one to weld thin gauge material without buckling. I have not tried this myself, but have read some articles about it. Some references are:

Q. Guan et al.: Method and apparatus for low stress and non-distortion welding of thin-walled structural elements. Chinese Patent No. 87100959 28 Feb 1987

Q.Guan, R.H.Leggatt, K.W.Brown: Low stress non-distortion (LSND) TIG welding of thin-walled structural elements. The Welding Research Report, 374/1988, Abington, Cambridge, UK.

From the literature, it looks like you need fancy equipment, but if you need repeatable results I believe this is the way to go.

Hope this helps

Niekie

If you can find a shop with a seamer set-up with a TIG or MIG process. A seamer has a brass or copper air cooled bar under the weld and it clamps the edge down until cooled. This is the best that I can think of, you will still have some distoration but nothing compared to manual welding.

hi hiram,,,I recently had a stress relieving company come into our shop to stress relieve a weldment we had fabbed,,and he used a vibration source to bring the piece to its natural frequency and back it off a little ,,and he also showed me pictures of a S.S. weldment that was welded while it was clamped to his equipment and there was no distortion what so ever .And also there was over 25 lbs of mig wire used on this weldment ,,and the distortion was almost not measurable.I cant remember the name of this company at the moment,,,hopr this helps.