Patent ID: 7396371
Filing Date: 2008-07-08
Classification: B22F,C22C,C23C,Y10T

Abstract:
1. A coated cemented carbide cutting tool insert comprising a substrate of cemented carbide having a composition comprising from about 5.0 to less than about 8.0 wt % Co, from about 3.0 to about 8.0 wt % cubic carbides of the metals Ti, Ta and Nb and possibly other carbides of the elements from group IVb, Vb or VIb of the periodic table, the addition of cubic carbide forming elements being such that the Ti/(Ti+Ta+Nb) ratio is from about 0.05 to about 0.3, from about 0.01 to about 0.2 wt % N and balance tungsten carbide (WC) having a grain size of from about 1.5 to about 3.5 μm in the as-sintered state and having a γ-phase depleted and binder phase enriched surface zone which has a depth of from about 5 to about 30 μm, and a coating having a first, innermost layer system of at least two layers of TiC the said coating having a second multilayer system comprising from about 5 to about 31 alternating layers of Al