| 摘要 |
PROBLEM TO BE SOLVED: To improve heat resisting plastic deformability by limiting the width and cobalt content ratios of an internal composition, a soft surface band and a hard intermediate band of a cemented carbide base body, and the average layer thickness of a hard coating layer. SOLUTION: A mixed composition consisting of Co at 5-12 wt.% as a bound phase forming component, (Ta, Zr, W) C and/or CN at 5-30 wt.% as a first dispersed phase, and WC for the rest as a second dispersed phase is prepared. This mixed powder is dried and molded, and then sintered under a control condition to obtain a cemented carbide base body. This base body has a soft surface band with the maximum Co content ratio to the interior being 1.1-1.5 and the minimum Co content ratio to the first dispersed phase being 0.1-0.8, in a range of 10-50μm from the surface, and a hard intermediate band with the minimum Co content ratio to the interior being 0.5-1.0 and with the minimum Co content ratio of the first dispersed phase to the internal first dispersed phase being 1.3-3.0 is formed in a range of 10-20μm adjacently to the soft surface band. A Ti group hard coat with an average film thickness of 5-30μm, is vapor-deposited to the surface of the base body to obtain a cutting tool excellent in heat resisting plastic deformability.
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