Tool Steel Square Bar D2 Precision Ground is a high-carbon, air-hardening tool steel that provides good resistance to wear. D-2 tool steel provides a good blend of toughness, strength, and affordability. Also, D2 is well suited for cold work tooling applications and provides ease of heat treatment and minimum distortion. The bar is precision ground to a maximum surface finish of 40 Ra with tolerances of +/- 0.001” on the height and width of the bar. Also, the bar is mechanically straightened with a flatness aim of 0.005" per foot.