O1 Tool Steel Bar Blanks

O1 tool steel bar blanks are the classic oil-hardening tool steel, valued for their predictable heat treatment, excellent dimensional stability during hardening, and fine grain structure that produces keen cutting edges. The nominal composition of 0.90% carbon, 1.0% manganese, 0.50% chromium, and 0.50% tungsten creates a shallow-hardening steel that responds to simple workshop heat treatment while delivering professional-grade tooling performance. Heat treating O1 is straightforward and well-documented. The steel is austenitized at 1,450-1,500°F, soaked for 10-30 minutes depending on cross-section, and quenched in warm oil at 120-150°F. This produces an as-quenched hardness of 63-65 HRC. Tempering at 300-400°F for knife and cutting tool applications yields a working hardness of 59-61 HRC with good toughness. The fine-grained microstructure of O1 is its signature advantage for cutting tools and blades. The tungsten and chromium additions form small, well-distributed carbides that support an extremely fine edge. Knife makers prize O1 for its ability to take and hold a razor edge, and tool and die makers rely on its clean shearing action in blanking dies. The steel also etches beautifully with ferric chloride, producing high-contrast patterns favored by custom knife makers. O1 offers better wear resistance than W1 water-hardening steel and is easier to grind than D2 or A2 in the hardened condition. The trade-off is lower wear resistance compared to those higher-alloy tool steels and essentially no corrosion resistance. Our O1 bar blanks ship in the annealed condition, precision ground to standard flat bar dimensions.