CUTTING TOOL MADE OF SURFACE COATED CUBIC BORON NITRIDE SINTERED MATERIAL WITH HARD COATING LAYER EXHIBITING EXCELLENT CHIPPING RESISTANCE AND HEAT-RESISTANT PLASTIC DEFORMABILITY IN HIGH-SPEED INTERMITTENT CUTTING OF HIGH HARDNESS STEEL

摘要

PPROBLEM TO BE SOLVED: To provide a cutting tool made of a surface coated boron nitride sintered material with a hard coating layer exhibiting excellent chipping resistance and heat-resistant plastic deformability. PSOLUTION: The cutting tool comprises the hard coating layer formed on the surface of a tool substrate composed of a cubic boron nitride sintered material. The hard coating layer is composed of (a) a lower layer formed of a compound nitride layer of Ti, Al and Y (yttrium) having the average layer thickness of 0.5-10 μm and satisfying a composition formula: [TiSB1-(X+Z)/SBAlSBX/SBYSBZ/SB]N, wherein X is 0.40-0.60, and Z is 0.005-0.05 at the atomic ratio, and (b) an upper layer formed of a heat-transformed α-type AlSB2/SBOSB3/SBlayer formed by applying heat treatment in a state of forming a titanium oxide layer by vapor deposition in the average thickness of 0.05-1 μm on the surface of an AlSB2/SBOSB3/SBlayer having a κ-type or θ-type crystal structure and the average layer thickness of 0.5-10 μm formed by vapor deposition, to transform the crystal structure of the AlSB2/SBOSB3/SBlayer having the κ-type or θ-type crystal structure, into an α-type crystal structure. PCOPYRIGHT: (C)2006,JPO&NCIPI