MULTILAYER COATED CEMENTED CARBIDE CUTTING INSERT

摘要

An indexable metalcutting insert is provided having a cobalt cemented tungsten carbide substrate (32) with a multilayer refractory coating (34) thereon. The substrate (32) has a cobalt content of 6.1 to 6.5 weight percent and is characterized by a hardness of 90.8 to 91.6 Rockwell A and a magnetic coercive force of 110 to 180 oerstads. The coating (34) contains at least a plurality of alumina layers (42) which are separated from and bonded to each other by a group IVB metal nitride (44), such as titanium nitride, and which are bonded to the substrate (32) by a backing layer of 5 to 8 mu in thickness, composed of a carbide and/or carbonitride of titanium zirconium and/or hafnium.