Tool Steel O1 Rectangular Bar 2-1/2" x 1/8" Retail Price

About O1|Oil-hardening tool steel. The simplest and most forgiving tool steel to heat treat. Austenitize at 1450°F, quench in oil, temper. Reaches HRC 57-62. Lower cost than A2 or D2. The tradeoff is more distortion during heat treatment compared to air-hardening grades. Machines well annealed. Used for jigs, fixtures, gauges, blanking dies, and hand tools. Popular with hobbyists and bladesmiths because of the straightforward heat treatment. Compare to A2 (less distortion, more expensive) and W1 (water-hardening, even cheaper but even more distortion).

About Rectangular Bar|Solid rectangular cross-section stock. Functionally similar to flat bar but typically available in thicker, chunkier profiles. The naming varies by supplier — what one calls rectangular bar, another calls flat bar. Used for keys, gibs, wear strips, brackets, and any part where a rectangular starting profile saves setup time versus milling from plate.