SURFACE COATED CUTTING TOOL MADE OF CUBIC BORON NITRIDE-BASE ULTRA-HIGH PRESSURE SINTERED MATERIAL HAVING HARD COATED LAYER EXHIBITING CHIPPING RESISTANCE IN HIGH-SPEED HEAVY CUTTING OF HIGH-HARDNESS STEEL

摘要

PROBLEM TO BE SOLVED: To provide a surface coated cutting tool made of cubic boron nitride-base ultra-high pressure sintered material having a hard coated layer exhibiting chipping resistance in high-speed heavy cutting of high-hardness steel. SOLUTION: In this surface coated cutting tool made of cubic boron nitride-base ultra-high pressure sintered material, a hard coated layer is formed by vapor deposition on the surface of an ultra-high pressure sintered material-made insert containing 30 to 95 mass% boron nitride. (a) The hard coated layer includes a lower layer having an average layer thickness ranging from 1.5 to 6μm, and an upper layer having an average layer thickness ranging from 0.3 to 3μm. (b) The lower layer is formed of a deposited composite nitride layer of Cr and Si satisfying the composition formula [Cr1-XSiX]N (wherein X indicates 0.02 to 0.1 by atomic ratio), and (c) the upper layer has an alternately stacking structure of a thin layer A and a thin layer B, both of which have an average layer thickness per layer ranging from 0.01 to 0.3μm. The thin layer A is formed of a composite nitride layer of Cr and Si satisfying [Cr1-XSiX]N (wherein X indicates 0.02 to 0.1 by atomic ratio) and the thin layer B is formed of a chrome nitride (CrN) layer. COPYRIGHT: (C)2007,JPO&INPIT