Many years ago I had ambitions to do some blacksmithing. At that time I bought this book
here . Since than I see the same author has a newer and larger edition, by more than double the pages, with great reviews ........... The Complete-Modern-Blacksmith
here.
Anyway the guy has a great writeup on how to make an anvil out of a piece of railroad rail, including heat treating/hardening the anvil surface. I never got around to it, and probably never will. Hope someone gets something out of one of these books and reports back with the finished anvil.