| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface-coated sintered alloy-made cutting tool displaying excellent defect resistance in interrupted double cutting. SOLUTION: In this surface-coated sintered alloy-made cutting tool, formed by chemical evaporation and/or physical evaporation of a hard coating layer constituted by a Ti compound layer consisting of single layer of one kind or double layer of two or more kinds of TiC layer, TiN layer, TiCN layer, TiCO layer, TiNO layer, and TiCNO layer or the Ti compound layer and an Al2O3 layer by a mean layer thickness of 4 to 15μm on a surface of a carbide tungsten group carbide alloy base substance having a composition consisting of a connection phase containing 85 to 95 wt.% crystal growth of isotropic WC phase to be mainly composed of Co of the rest and inevitable impurities, a surface part of the base substance is formed with a surface toughness layer of WC-provided hexagonal crystal structure by observing a base substance surface by an optical microscope with non-isotropic WC phase of flatted shape by preferential growth of [001] surface existing by 20 to 60 area % in ratio occupied in the WC phase and the rest indicating a composition consisting of the isotropic WC phase further with the isotropic WC phase existing over a depth of 50 to 500μm from the surface.
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