Rustbelt

From publisher blurb: Rustbelt "Rusty" (as his friends call him) is the nicest guy with steel skin that you’re likely to meet, like a bulldozer with the heart and manners of a farm-boy. Not only is he as strong and tough as you’d expect from a guy covered in metal plates, but his touch can rapidly rust and corrode. He just has to be careful not to suffer the same fate.