An insert for a rock bit that includes tungsten carbide particles, and a cobalt binder disposed around the particles, wherein a grain size of the tungsten carbide particles and a content of the cobalt binder are selected to provide a fracture toughness of at least about 18 ksi (in).sup.0.5, a wear number of at least about 2, and a hardness of 85 to 87 Ra is disclosed.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit under 35 U.S.C. .sctn. 120 as a continuation of U.S. patent application Ser. No. 10/396,261, filed Mar. 25, 2003, now U.S. Pat. No. 7,036,614, which is a continuation-in-part of U.S. application Ser. No. 10/017,404, filed Dec. 14, 2001, now U.S. Pat. No. 6,655,478, which are incorporated by reference in their entirety.
Fracture and wear resistant cutting elements are provided. Examples include a cutting element formed of a wear resistant material having a binder composition and a coarse grain size such that the portion of the cutting element formed of the wear resistant material has a fracture toughness of at least about 18 ksi(in).sup.0.5 and a wear number of at least about 1.8. In a particular example, the wear resistant material has a fracture toughness of at least about 20 ksi(in).sup.0.5. A down hole cutting tool incorporating such cutting elements is also provided.
