Purchase a 2 x 4 45 x 90 mm from your local hardware store and cut to it to fit the diameter of your pan.
Flatten warped sheet metal.
Heat straightening does not symmetrically straighten the metal and is a gradual process.
I don t think the bow is a heat warp i think it s a buckle caused by to much metal at the top caused when the bottom portion of the transom shrunk after the weld cooled.
First anneal the sheet then grip the sheet between two sheets of 1 8 thick flat stock steel sheet gripped tightly using steel g clamps then anneal the steel sheets until they are dull red and let it cool without quenching.
I tried clamping it flat to the welding table while welding but that didn t work.
Another way would be to use a vice to press the strips between two smooth flat blocks.
That is almost too thin to call sheet metal.
You can use either a circular saw or regular handsaw to cut your 2 x 4 to length.
The metal has to do something if there is to much of it.
The simple act of heating metal during the welding process causes stresses within the steel that often lead to distortion or bending.
In order to repair the warping of your pan you are going to need a piece of wood.
Heat straightening involves applying controlled heat to a deformed part of steel in heating and cooling cycles until the metal gradually straightens.
I tried clamping it to the welding table flat then hitting it with a torch hoping that the welding table.
Any ideas on how to make it straight flat again.
Welding this together warped the flat round piece of stainless sheet metal.
A polished flatter and a polished anvil block might do it for you.
It s more like foil.
Still ended up warped.
Fabricators straighten metal using many methods including heat straightening.
Just a very smooth block of half inch stock or even a flat hammer face will do.
A simple small dent on a flat or gently curved panel is the easiest to remove and as long as the backside of the panel can be accessed the dent can be erased using a hammer and dolly hammering.
I ve made this a few times and they always end up warped.