SURFACE COATED CUTTING TOOL WITH EXCELLENT CHIP RESISTANCE

摘要

Provided is a surface coated cutting tool in which a hard coating layer exhibits excellent chipping resistance in high-speed intermittent cutting processes. In the surface coated cutting tool having the hard coating layer including a lower layer (Ti compound layer) and an upper layer (Al 2 O 3 layer) formed by vapor-deposition on the surface of the cutting tool body constituted by a WC-based cemented carbide or TiCN-based cermet, the ratio b/a of the number a of crystal grains in the Ti compound layer present in the interface to which the lower layer and the upper layer are adjacent to the number b of crystal grains in the Al 2 O 3 layer is 4 < b/a < 20, and, furthermore, the average grain diameter of crystal grains in the Ti compound layer immediately below the Al 2 O 3 layer is 0.5 µm or less.