SURFACE COATED CEMENTED CARBIDE CUTTING TOOL WITH HARD COATING LAYER DISPLAYING EXCELLENT CHIPPING RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool with a hard coating layer displaying excellent chipping resistance. SOLUTION: In the surface coated cemented carbide cutting tool made by chemically depositing and/or physically depositing the hard coating layer constituted of (a) a Ti compound layer, (b) a TiCN layer and (c) an Al2O3 layer by whole average thickness of 3 to 25μm on the surface of a titanium carbide group cemented carbide substrate, the TiCN layer constituting the hard coating layer and having a longitudinally grown crystal structure is composed of a concentration gradient l-TiCN layer having an upper surface part with a thicknesswise concentration gradient of C and N, which satisfies x: 0.45 to 0.60 and a lower surface part with a thicknesswise concentration gradient of C and N, which satisfies x: 0.05 to 0.40 as an atomic ratio when the upper surface part and the lower surface part are shown by the following composition formula: TiC1-XNX, and the concentration of C and N being stepless or stepwise changed.