SURFACE-COATED CUTTING TOOL EXERTING EXCELLENT CHIPPING RESISTANCE IN WET TYPE HIGH-SPEED INTERMITTENT CUTTING WORK OF Ti ALLOY

摘要

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool exerting excellent chipping resistance in the wet type high-speed intermittent cutting work of Ti alloy.SOLUTION: There is provided a surface-coated cutting tool in which an α type aluminum oxide layer having at least 0.5-4.0 μm of an average layer thickness is formed by coating on the surface of a tool substrate as a hard coating layer. In the cutting tool, (a) the aluminum oxide layer is configured as the complex composition of crystal grains having plural average grain sizes; (b) the above complex composition is configured from a secondary crystal grain having an average grain size of 0.2-2 μm comprising the aggregate of a primary crystal grain having an average grain size of 10-100 nm; and (c) the lower layer of 0.5-2.0 μm comprising a Ti-Al composite oxynitride is formed on the lower part of the α type aluminum oxide layer. The lower layer of the Ti-Al composite oxynitride is formed by preliminarily firing the thin layer of Ti oxide, and then coating an alumina sol to perform a firing process.SELECTED DRAWING: Figure 1