So when you ask about armor plate, are we talking hardened steel or like AR500 targets? Because that changes everything (like what oliviadixon was getting at with setup). A standard 50-amp cutter might struggle, but a big 80-amp industrial one on the right gas mix could maybe do it. I'd be worried about the heat messing with the temper of the steel though. What kind of thickness and material are you picturing?

Hidden problems remind me of a news piece where a shop's paperwork saved them from a lawsuit.