HIGH-STRENGTH CEMENTED CARBIDE AND PROCESS FOR PRODUCING THE SAME

摘要

A WC-Co cemented carbide which has high strength and high toughness and is excellent in wearing resistance, toughness, chipping resistance, and heat-crack resistance (the term WC-Co means not only alloys comprising hard particles consisting mainly of WC and particles of one or more iron-group metals including cobalt but also alloys containing hard particles which comprise at least one member selected among carbides other than WC, nitrides, carbonitrides, and borides of the elements in Groups IVa, Va, and VIa of the Periodic Table). A WC-Co powder compact having a surface layer part comprising an M₁₂C- to M₃C-type composite carbide as the main component (M represents a combination of one or more of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W and one or more of Fe, Co, and Ni) is carburized. Thereafter, liquid-phase sintering is conducted to regulate the average particle size of the surface-layer WC using the liquid-phase sintering temperature as an index.