Blue Steel
Blue Steel No.1 (Hitachi Metals Ltd.) is very similar to Blue Steel No.2, but the additional Carbon and Tungsten / Wolfram result in even better edge retention and toughness. The steel is perhaps most commonly seen in high-grade Japanese traditional single-bevel edged knives.
Blue Steel No.2 (Hitachi Metals Ltd.) is made by adding Chromium and Tungsten / Wolfram to White Steel No.2. This results in increased toughness and the production of hard carbide molecules which improve edge retention. Many knife users have noted that while Blue Steel No.2 is very similar to White Steel No.2 in terms of edge sharpness, it has slightly superior edge retention.
