In the 1930’s it was discovered that high vanadium steels could be developed if an increase in carbon was made at the same time. High vanadium steels had very high wear resistance, making them attractive for certain applications. Vanadium carbides are among the hardest carbides which makes it contribute very strongly to wear resistance. This led to high speed steels M4 with 4% vanadium and T15 with 5% vanadium. These steels were developed by James P. Gill of VASCO as described in this article.
With any higher than about 4-5% vanadium, the steels would have very poor toughness; so poor, in fact, that the steel couldn’t be produced because it would crack during forging. Vanadium is a very “strong” carbide former meaning it has a very strong tendency to form carbides. The more vanadium is added the higher the temperature where the carbides form. At sufficiently high temperature the carbides form in the liquid steel where they can grow very rapidly. The large carbides in the final product lead to poor toughness.
I found Knife Steel Nerds not long after they launched. It has been fun to see Larrin end up on all of the various podcasts as the community has learned what incredible work he is doing.
Like his new book, Knife Engineering: Steel, Heat Treating, and Geometry , I am going to order my own copy next time I sit down to do some online shopping.View Linked Article