SURFACE-COVERED CEMENTED CARBIDE MADE CUTTING TOOL HAVING HARD COATING LAYER TO EXHIBIT EXCELLENT CHIPPING RESISTANCE IN HEAVY CUTTING CONDITION

摘要

PROBLEM TO BE SOLVED: To provide a surface-covered cemented carbide made cutting tool having a hard coating layer to exhibit excellent chipping resistance in a heavy cutting condition. SOLUTION: This cutting tool is formed by the physical deposition of the hard coating layer made of complex nitride composed of Al and Nb with an overall average layer thickness of 1-15μm on the surface of a tungsten carbide-based cemented carbide substrate or carbonitride titanium-based cermet substrate. This hard coating layer has a component concentration distribution structure arranged to have an Nb maximum content point and an Nb minimum content point alternately repeatedly in predetermined spaces in the thickness direction and designed to have an Nb content which varies continuously from the Nb maximum content point to the Nb minimum content point and from the Nb minimum content point to the Nb maximum content point. The Nb maximum content point satisfies a composition formula: (Ti1-XNbX)N (wherein X is 0.30-0.50). The Nb minimum content point satisfies a composition formula: (Ti1-YNbY)N (wherein Y is 0.05-0.25 in atomic ratio). The space between the Nb maximum content point and the Nb minimum content point is 0.01-0.1μm. COPYRIGHT: (C)2004,JPO