| * Very hard steel (e.g. chisels, quality [[List of blade materials|knife blades]]): HRC 55–66 (Hardened High Speed Carbon and Tool Steels such as M2, W2, O1, CPM-M4, and D2, as well as many of the newer powder metallurgy Stainless Steels such as S30V, CPMS-154, ZDP-189, etc.)<ref>[https://web.archive.org/web/20080531085629/http://www.cutleryscience.com/reviews/blade_materials.html Knife blade materials]</ref> | | * Very hard steel (e.g. chisels, quality [[List of blade materials|knife blades]]): HRC 55–66 (Hardened High Speed Carbon and Tool Steels such as M2, W2, O1, CPM-M4, and D2, as well as many of the newer powder metallurgy Stainless Steels such as S30V, CPMS-154, ZDP-189, etc.)<ref>[https://web.archive.org/web/20080531085629/http://www.cutleryscience.com/reviews/blade_materials.html Knife blade materials]</ref> |