SURFACE-COATED CUTTING TOOL WITH HARD COATED LAYER EXERTING EXCELLENT CHIPPING RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide a coated cutting tool which has a hard coated layer having excellent hardness and ductility, and which therefore exerts favorable chipping resistance and defect resistance in use over a long period.SOLUTION: There is provided the surface-coated cutting tool with a hard coated layer. The hard coated layer includes at least a composite nitride or composite carbonitride layer represented by a compositional formula: (TiAl)(CN). The atomic ratios x and y of included Al and C satisfy 0.60≤x≤0.95 and 0≤y≤0.005. The crystal grain composing the composite nitride or composite carbonitride layer has the cubic and hexagonal structures, and the area ratio of a cubic crystal phase is 30 to 80 area%. The average grain width W of the crystal grain having the cubic structure is 0.05 to 1.0 μm and an average aspect ratio A is 5 or less. The concentration change of Ti and Al at a prescribed cycle exist in the crystal grain having the cubic structure.