To give one more example before we get to Vanax, I will give a short description of AEB-L using data previously presented in this article about AEB-L. Here is a general equation for Ms with different alloying elements : And Vanax, with its excellent corrosion resistance, has even more chromium. While it decreases Ms by about 12☌ per 1% chromium, stainless steels typically have 10% or more chromium in solution for corrosion resistance. With stainless steels like Vanax, however, chromium can be a significant factor. Martensite start is reduced by about 423☌ per 1% carbon, the next most important is manganese at about 30☌ per 1% Mn.
Carbon is not the only element that reduces the martensite transformation temperature and therefore increases retained austenite, but it is the most significant. You can read about retained austenite and how cryogenic processing helps reduce it in this article.
This amount of retained austenite is typically in the range of 15-20% where peak hardness is achieved: When the transformation is incomplete there is some amount of “retained austenite” which is a much softer phase and therefore when there is a sufficient amount of retained austenite the bulk hardness of the steel is reduced. You can see that the martensite finish temperature can be below room temperature (~20☌) meaning that when the steel is quenched to room temperature the transformation to martensite is incomplete. This also decreases the temperature at which martensite finishes (Mf) its transformation: With increasing carbon, the temperature at which martensite begins to form (Ms) is decreased. Martensite formation is controlled by temperature lower temperature means more martensite until the transformation is complete. The other studies used liquid nitrogen (cryo) after quenching to increase hardness. You can see that for two of the datasheets above, the hardness peaks with a carbon content around 0.9% and then decreases above that carbon content. Carbon is the best element for improving hardness: In its most basic terms, I wrote about the hardness of martensite in this article. And kitchen knife users may appreciate the excellent corrosion resistance of Vanax in the presence of water, salt, and acidic foods.īefore I get into my small heat treatment study, I am going to give some background on what controls peak hardness. The steel may be good for kitchen knives, for example, where very thin edges and high hardness is common. While the datasheet shows it being capable of 59-61 Rc, I was curious about how hard the steel can go. I wrote about Vanax along with other nitrogen-alloyed steels in this article, to describe how the steel is designed. Vanax is an interesting steel because of its good combination of toughness, wear resistance, and corrosion resistance. Thanks to David Suitor, Drakopoulos Stelios, and Maxim Bellehumeur for becoming Knife Steel Nerds Patreon supporters!