I figured this would probably be an issue, and it turn out it is.
I cut some small blanks (~1" x 2" and ~2" X 3") for a project out of 0.018" and 0.024" stainless sheet using the CNC plasma cutter. They’ve dished about 1/8". I need to figure out how to anneal and flatten them, Any suggested references?
In the blacksmithing shop we would heat them to non magnetic temp and then anneal them by putting them in ash and leaving them for 12 hrs to cool very slowly. We could then reheat them and use our flatter too flatten them. There is probably a much easier way however in the sheet metal shop.
You can use vermiculite, too. We also have some ash in the blacksmithing shop trailer (I think). We will have to check.
One problem I need to figure out is temperature. This is 304 stainless, it’s non-magnetic at room temperature.
Turns out the answer was clean the edges up with a file. Once I filed them down to clean metal they had flattened back out. I figured the stresses were less concentrated than that, but it makes sense.