Warpage

[asennad]

How exactly does warpage occur? When the metal gets hot due to the weld it expands then as it cools it contracts - at a different rate?

I am welding square tubing. Would it be safe to have a wet rag standing by to cool the weld off after welding? Would this rapid cooling affect the weld negatively?

 

[Drains]

How exactly does warpage occur? When the metal gets hot due to the weld it expands then as it cools it contracts - at a different rate?

I am welding square tubing. Would it be safe to have a wet rag standing by to cool the weld off after welding? Would this rapid cooling affect the weld negatively?

That'd make it worse! Also, bad for the weld (give you big crystalline formation, so weak)

Distortion... Lay hot weld, let it cool, it shrinks. The parent metal gets hot too, but doesn't get a chance to expand, so as it cools, it shrinks too.

If you lay a run of weld across a piece of square hollow sec'n (tube), the steel will bend in around the weld. So if you want to limit distortion, try to avoid welding across the tube. Fully welding one tube to another may not be desirable... Welding with the length, rather than across, may be better.

The alternatives are restraint (fix the steel in place untill it's cooled post-weld); or pre-heat, so that everything is hot before you start welding. it all cools together with smaller temperature differential; stepped welding, to limit heat input; weld sequencing, to balance heat input and distortion effect.

 

[fluxcored]

Hi asennad

Look at this thread of mine http://www.mig-welding.co.uk/forum/showthread.php?p=89864#post89864

More to do with fixing warpage - maybe you can pick up a few hints there.