Abstract: A coated turning insert particularly useful for dry and wet machining in low and medium alloyed steels, stainless steels, with or without raw surface zones under severe conditions such as vibrations, long overhang and recutting of chips. The insert is characterized by a WC--Co cemented carbide with a low content of cubic carbides and a rather low W-alloyed binder phase and a coating including an innermost layer of TiC.sub.x N.sub.y O.sub.z with columnar grains and a top layer of TiN and an intermediate layer of .kappa.-Al.sub.2 O.sub.3. The layers are deposited by using CVD-methods.

Abstract: A titanium-based carbonitride cutting tool insert with superior thermal shock resistance is disclosed. This is accomplished by sintering the material under conditions where the melting process is reversed. The melt forms in the center of the material first and the melting front propagates outwards towards the surface. This leads to minimal porosity and a macroscopic cobalt depletion towards the surface. The cobalt depletion, in turn, leads to a favorable compressive residual stress in the surface zone.