| 摘要 |
The present invention relates to a cutting insert particularly for turning of stainless steel comprising a cemented carbide substrate and a post-treated coating with a substrate of cemented carbide having a composition of 5.0-<8.0 wt% Co, 3.0-8.0 wt% cubic carbides of the metals Ti, Ta and Nb with a Ti/(Ti+Ta+Nb) ratio of 0.05-0.3 and balance tungsten carbide (WC) having a grain size of 1.5-3.5 mu in the as-sintered state. Further, the substrate has a surface zone of 5-30 mu with an enrichment of binder phase and a depletion of cubic carbides, and a coating having a first, innermost layer system of one or several layers of TiC x N y O z with x+y+z<=1 with a total thickness of 0.7-5.5 mu and a second multilayer system consisting of a totally 5-31 alternating layers of Al 2 O 3 and TiC x N y O z (x+y+z<=1), preferably -Al 2 O 3 and TiN, the Al 2 O 3 -layers having an individual layer thickness of <0.5 mu and the TiC x N y O z -layers <0.2 mu with a total thickness of the multilayer of 1.0-5.0 mu. The multilayer is exposed along the edge line and into the rake and flank face. In an alternative embodiment the multilayer is replaced by an Al 2 O 3 -layer. |
