SURFACE-COAT CUTTING TOOL WITH HARD COATING LAYER EXHIBITING EXCELLENT CHIPPING RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide a surface-coat cutting tool, which exhibits excellent chipping resistance and toughness.SOLUTION: The surface-coated cutting tool has a hard coating layer of a CrNlayer (0.8≤x≤2.0) formed by physical deposition on the surface of a cutting tool body comprising a cemented carbide sintered body. Crystal grains of CrNare made in columnar crystal structure having a height similar to the average layer thickness. For observing crystal grain structure along a horizontal section of the CrNlayer, an area occupied with crystal grains of grain size of 10-100 nm is set to be 90% or more of measured area. In addition, for measuring crystal orientation of crystal grains on the surface by an electron beam back scattering diffraction device, an area occupied with a section of diameter 0.2-4 μm enclosed by crystal interfaces with differential crystal orientation of 15 deg. or more from adjoining measuring points is set to be 20% or more of total area measured. Excellent chipping resistance and toughness are thus provided in discontinuous heavy cutting work.