This is really an interesting and informative thread. For anyone interested in pursuing the science, I recommend "Steel Metallurgy for the Non-metalurgist", by John D. Verhoeven. He is a college prof of metallurgy, and was assisted in writing it by Howard Clark, one of, if not the, best swordmakers this side of Japan. The book is available on line, and there is a free download version that is also available. Happy hunting.