Welding robot by Joel Sullivan - video

[Frank S]

> perhaps localized induction heating cooled with a spray of liquid nitrogen could do the trick

Wouldn't that cause waves in the sheet? (I ask in ignorance.)

I was referring to the possibility of the need to re surface harden the repairs on a press die
.
I have used heat and cold to flatten thin sheet metal such as hail dents in the roofs of cars.sometimes in reverse by super cooling a very small depression then warming the area around it will do the trick other times vacuum and vibrations in the ultrasonic range will pull a small dent from an auto body other times when ever possible to work from behind the dents can be massaged out.
But as I was saying in the case of a press die a weld repair will leave the area softer than the rest of the die that was why my suggestion of heat and rapid cooling.