Dan, You didn’t mention what metal or gauge you are working in but
this trick works for a wide range of product. After annealing the
piece simply stretch the length of metal by making L bend on either
end and placing one end in a vise or other stationary clamp and pull
firmly on the other end using pliers until the item has straightened.
With small thin stock two pairs of pliers can be used. Good Luck
J.F.Sholl Fine Jewelry