Ground Oversize Tool Steel Square Bar is ground to a maximum surface finish of 40 Ra with tolerances of + 0.010" to + 0.015" on the height and the width. This material is produced from cross-rolled sheet or plate which produces a finer grain size and enhances the toughness of the material. Lastly, tool steel rectangle bar is 100% free of decarburization is completely spheroidized throughout. Tool Steel Square Bar D2 Oversize 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.