| 摘要 |
PROBLEM TO BE SOLVED: To provide a covered cemented carbide tool having improved characteristics of chipping resistance and abrasion resistance and a prolonged tool life. SOLUTION: WC is used as a matrix, cemented carbide containing a ferrous metal as a binder phase is used as a substrate, and multiple cover layers are provided on the surface of the substrate to form a covered cemented carbide cutting tool. The innermost layer of the cover layers adjacent to the substrate is titanium nitride with the thickness of 0.1-0.3μm, and at least one layer of alumina with the thickness of 0.5-10μm is coated on it. The average crack interval in the cover film of a tip ridge line section is smaller than the average crack interval in the cover film of a flank on the mirror-polished cross sectional structure of the tip ridge line section of the tool. 50% or above of the tips of cracks on the substrate side among the cracks in the cover film of the tip ridge line section exist in the titanium nitride of the innermost layer, in the upper layer than the titanium nitride or on the boundary face of these layer rings. The average length of cracks in the cover film of the tip ridge line section is shorter than the average value of the cover film thickness on the flank, and the alumina layer is polished at least at part of the tip ridge line section.
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