well we all know if you weld too much too quickly that youll warp the metal but my ? is will cooling it down with water and returning to welding hurt it or should i let it slowly cool down?

You should never cool down a weld with water! At least that I'm aware of... Normally, you try to slow the cooling process with sand or lime, usually done when welding cast.

What are you welding, how thick, length of weld, etc. That info. would help us help you better. If you tack weld in a couple spots it should help.

its question over all, not a specific one. maybe some metal you can cool down with water some you cant???

supposedly it makes the metal and weld more brittle, more likely to crack if you cool it with water

that said, anything i do on my jeep is cooled slowly but on the farm when we're buildin shit like cow pens or feeders or any of that stuff, we spray it with water right after welding it, cause there isn't much if any stress on those pieces