CERMET INSERT AND CUTTING TOOL

摘要

One form of titanium carbonitride based cermet insert having a structure composed of 75 to 90 area% of hard phase and the balance of binding phase wherein the hard phase has a first hard phase composed of a TiCN phase as a core portion and a (Ti, W, Ta/Nb)CN phase as a surrounding portion, a second hard phase consisting of a (Ti, W, Ta/Nb)CN phase and a third phase consisting of a TiCN phase while the binding phase contains 18 to 33% Co, 20 to 35% Ni, 5% or less sum of Ti and Ta and/or Nb and 40 to 60% W. There is provided another form of cermet insert having a structure composed of a hard phase having (Ti, W, Ta/Nb)CN wherein the sum of value of Ti in terms of carbonitride, value of Ta and/or Nb in terms of carbide and value of W in terms of carbide is in the range of 70 to 95 mass%, the value of W in terms of carbide in the range of 20 to 35 mass% and the value of Co and Ni in the range of 5 to 30 mass%, and a binding phase composed mainly of W and Co and/or Ni, 40 to 65 mass% of the constituent W contained in the hard phase. Further, there is provided a cutting tool comprising a holder and, held and fixed thereby, the above-mentioned cermet insert.