I agree with both of these points. 301 grade spring steel will keep its shape (to an extent), while regular steels will remain deformed if pushed. Keep in mind that your part will have sharp edges, even when deburred and linished, when using sub 2mm sheet metal.
It’s also a very large radius to control with a press break (even using a pipe blade and a huge v block, and would likely need to be rolled instead, before folding the 40mm flanges. This is another issue if you end up using spring steel, as it a can be a challenge to bend in a reliable and controlled manner.