Does quenching a welded work piece in water weaken the weld?

[waxer]

Just as the subject asks, would quenching a work piece thats mild steel in water just after you finished welding on it cause the weld to be any weaker than it would be if cooled naturally?

I noticed a friend doing this yesterday but wasn't sure and I didn't want to talk out of my ***.

Thanks in advance.

[ZACHV]

You will get some good info here on this, but to my limited understanding water quenching a piece will make it more brittle. I don't think it is a big problem if it is not a critical piece, but if it is critical I would definitely not quench it.

[jeffm]

I do believe that hardens the metal. Which sounds cool, but it does become brittle. Not to mention it will be harder to grind, the temp. difference might cause it to warp or crack, etc... just my two cents

So far a friend has told me to try this, and I've seen other weldors do it. How do things like this get started?

[BillC]

Quenching a hot welded part can increase distortion of the part and lock in residual stresses that may cause failure at the weld or in surrounding areas, depending on geometry.

Not recommended unless you have a good reason to do it and have designed the geometry of the part appropriately.

[Roger]

The only time I have seen welds put in water to cool was welding in High School practice welds that were not going to be tested. Probably help produce more practice welds in short class.

My underwater welds were sort of flash cooled as they were welded.