To provide a surface coated cutting tool in which a hard coating layer exhibits excellent adhesion, lubricity and wear resistance under high-speed heavy cutting conditions of high hardness steel.
The surface coated cutting tool includes, on a surface of a tool base made of a WC-based cemented carbide or a TiCN-based cermet, the hard coating layer comprising a mixed structure of a lower layer comprising an (Al, Cr)N layer or an (Al, Cr, M)N layer and an upper layer comprising NbN of a cubic structure and NbN of a hexagonal structure. In addition, where diffraction peak intensity from a (200) plane of the NbN of the cubic structure is Ic and diffraction peak intensity from a (103) plane and a (110) plane of NbN of the hexagonal structure is Ih when the diffraction peak intensity by X-ray diffraction is inspected for the mixed structure, the surface coated cutting tool has a layer having a diffraction peak intensity ratio satisfying 0.05≤Ic/Ih≤1.0.
Kazuo Tomita
Masayuki Miyake