First class piece of research, Jason. At this moment, I don't fully see the answer, but for sure it points the way to some research and review. I had assumed that the carbon in the case layer was more or less fixed. I guess, in theory, if we allowed it to heat soak long enough we would have a layer of cast iron rather that high carbon steel? Good things to think about!! Many thanks. I'll be back with some more questions. Hope you will continue some research and report.