Warpage in plate caused due to welding

[madvarun]

I am welding a square plate onto a pipe. After welding this plate warps or deflects by a certain amount. My question is why does this happen? Is it solely because of the welding heat or expansion in volume of the plate? Or could it be that warpage doesn't take place during heating(caused by the weld) but actually during cooling down since the weld is now filled with internal stresses that may be pulling the plate and thus warping it?

 

[metengr]

Warpage of the plate is caused by residual stresses after welding. Welding involves heating and subsequent cooling along with stresses from solidification of the weld metal. This is a common problem unless accounted for prior to welding. You can perform a search on this site for more information.

 

[unclesyd]

Here is a very reasonable book that has some good information on welding distortion.

https://ssl.lincolnelectric.com/lincoln/apdirect/item.asp?prodnum=DW

 

[chicopee]

I remember back in the 70's when we had welded a plate, it wrapped afterward. The solution to the warpage was to make a hole in the center of the plate.