Stainless Welding


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Old 04-23-06, 09:19 PM
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Stainless Welding

I'm welding a 6" x 4' x 6' box out of 12 gauge 308 stainless steel with a Power Mig using .35 dia wire and a trimix blueshield gas. All welds are on the inside, the outside must be clean. The box os to be filled with paint. I've doing some practice joints and am having problems with weld warp on the outside surface of the metal, even with smaller welds. They can only be so small, as the box will be holding 100's of gallon of paint. any advice on how to minimize / eradicate weld warp with out going at it with the beltsander?
 
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Old 04-24-06, 04:49 PM
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stainless can't get too hot. Use short welds and let it cool between welds. There is also some heat absorbant putty, one brand is pilojig (I did not spell that correct) you can put that on each side of the weld so the heat won't get too far out and warp your metal. The main thing is keep your metal cool.
 
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Old 04-24-06, 08:26 PM
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Thanks Jerome. Would TIG be a better option? More heat control for less warp? i need the strongest, smallest weld possible. I am worried about too many joints between welds, as this thing needs to be water tight.
 
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Old 04-25-06, 09:34 PM
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Originally Posted by rev
Thanks Jerome. Would TIG be a better option? More heat control for less warp? i need the strongest, smallest weld possible. I am worried about too many joints between welds, as this thing needs to be water tight.
Keep your stainless as cool as possible, take your time. With TIG you can see exactly what you are doing. With TIG or MIG I would start a weld an inch and a half from the previous weld and weld back to the last weld. If you see it start to warp start one inch away. If you weld back to your previous weld you will have a better chance of it being watertight. If you use TIG your welds should be a golden brown when you are finished and before you wire brush them. If they are not you are using too much heat.
 
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Old 04-25-06, 09:40 PM
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I forgot something, I did not see that you want to put the welds on the inside. I would make a corner joint and put the welds on the outside, it will look a lot better, and be a lot easier. Good luck
 
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Old 04-26-06, 06:45 PM
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I don't know if it matters but I am better at MIG on inside corners and TIG on outside corners.

You mentioned that the outside corners must be clean. Since you will be welding on the inside will the exposed joint on the outside be a problem? A TIG weld on the outside can be ground smooth and polished so it is not even visible.
 
 

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