| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface coated cutting tool that exhibits excellent wear resistance in cutting a high-hardness steel such as a hardened steel.SOLUTION: In the surface coated cutting tool in which a hard coating layer with an average layer thickness of 2 to 10 μm is deposited to a surface of a tool substrate formed of a WC-based cemented carbide, (a) the hard coating layer includes a compound nitride layer comprising Al, Cr, and B where a content ratio of Cr (by atom) is 0.2 to 0.45 based on the content of Al, Cr, and B and a content ratio of B (by atom) is 0.01 to 0.1, (b) the hard coating layer has a granular crystalline structure in a range to a place 100 μm distant from a tip on a flank of the surface coated cutting tool, an average grain size of a granular crystal grain in a surface of the hard coating layer is 0.1 to 0.4 μm, and an average grain size of a granular crystal grain in a boundary surface between the tool substrate and the hard coating layer is smaller than that of the granular crystal grain in the surface of the hard coating layer by 0.02 to 0.1 μm, furthermore, the diameter-length proportion of crystal grains having a grain size of 0.1 μm or less is no more than 20%. |
