About W1|Water-hardening tool steel. The simplest and cheapest tool steel. Essentially high-carbon steel (0.70-1.50% C) with the specification controls expected of tool steel. Hardens by water quench to HRC 64-66 on the surface. Only shallow-hardens, so the core stays soft and tough. Maximum distortion during heat treatment among common tool steels. Used for cold heading dies, woodworking tools, hand tools, and springs. Popular with bladesmiths for its fine grain and excellent edge quality. Compare to
O1 (oil-hardening, less distortion, slightly more expensive) and 1095 (similar carbon content, basic carbon steel without tool steel controls).
