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 6 μm, and an upper layer having an average layer thickness ranging from 0.3 to 3 μm. (b) The lower layer is formed of a deposited composite nitride layer of Cr and Si satisfying the composition formula [Cr_1-XSi_X]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 0.3 μm. The thin layer A is formed of a composite nitride layer of Cr and Si satisfying [Cr_1-XSi_X]N (wherein X indicates 0.02 to 0.1 by atomic ratio) and the thin layer B is formed of a titanium nitride (TiN) layer.;COPYRIGHT: (C)2007,JPO&INPIT