Sorry for the late response but I just found this tool I made it to bend 3/8 Stainless. Needed a 180 degree bend with a 1" ID (without cracking). Used a mandrel with a rounded end and bent it probably 5 degrees at a time. It worked well. The tube wasn't collapsed at all.
A designer is an emerging synthesis of artist, inventor, mechanic, objective economist and evolutionary strategist. Buckminster Fuller