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Duffman81
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    Tue Jan 18, 2022 8:16 pm

Fuming with myself. I’m pretty new to welding but I get by. I’ve been welding this lid for my copper in my brewery and didn’t realise it was warping. It cooled and now it’s like a fricking half pipe. Maybe not that bad. But a 40mm lift from the centre to the edge. Any ideas how I can get this warp out? It’s just over1500mm in diameter.
I’ve tried heating it and clamping.
I was thinking about “quenching” it. (Not entirely sure that’s a thing with stainless. Either that or I have been watching too much forged in fire.)
Either way. If anyone can help I would be eternally in your debt.
drizzit1aa
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    Tue Oct 05, 2021 8:57 pm

This is one of the times I would do everything no matter how silly it sounds, because it sounds like it's toast unfortunately. You can try quenching but not knowing just where the heat went and how far makes it unlikely it would work ... and be completely flat. Whatever you do try to use this as a learning tool past what you're trying to do, while trying to fix it watch what happens to the plate while and after you do it and file it away for later use.
Next time use chill plates on either side of the joint. Aluminum has worked best for me in sucking up the heat. You'll need to stich weld instead of one long bead and keep an eye on the chill plate temp., the cooler it starts off the more heat it can suck up, too hot and it does nothing for you. I was lucky enough to have some 1" plate drops, I beveled the edge to get my torch in and it has the extra advantage of channeling my argon making the most of it. Make sure you clean your chill plate by sanding it before you use it to make sure you can get as much conductivity to the base metal as you can.
Pretty much if your weld is anything other than silver or lite yellow (straw color) after welding you have put too much heat into it and will get some warpage.
cj737
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    Thu Sep 29, 2016 8:59 am

Hard to discern what you wrote, but if the piece that is warped is stainless, you’re pretty screwed. Stainless warps if you light a cigarette near it, and when welding it, very small stitch welds and skip around A LOT. You must take n extreme amount of care to allow the material to cool before welding more. Otherwise, it’s potato chip time.

Don’t “quench” stainless. Period.

What you can try, is have some rigid straight stock (rectangular tube, T bar, channel, etc) and gently heat the part with propane and clamp it while it hot. Let it cool completely naturally. Release the clamps. If you need to move the material a good distance, you might need to move it in stages (not all at once during one heat cycle). When heated, stainless builds a lot of stress and if it is clamped to “unwarp” it, when you release the clamps it will spring back pretty far.

Everything in welding is about managing heat input. It takes time to learn to be patient and avoiding these costly lessons.
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