Patent ID: RE39999

Claim:
A cutting tool insert particularly for turning of steel comprising a cemented carbide body and a coating wherein said cemented carbide body contains WC, 6-15 wt-% Co and 0.2-1.8 wt % cubic carbides of Ti, Ta and/or Nb and a highly W-alloyed binder phase with a CW-ratio of 0.78-0.93 and said coating comprises a first (innermost) layer of TiC x N y O z with a thickness of <1.5 μm, and with equiaxed grains with size <0.5 μm a second layer of TiC x N y O z with a thickness of 2-5 μm with columnar grains with an average diameter of <5 μm and an outer layer of a smooth, fine-grained (0.5-2 μm) κ-Al 2 O 3 with a thickness of 0.5-6 μm.