| 摘要 |
PROBLEM TO BE SOLVED: To improve chipping resistance of a throw-away tip for a small diametrical drill. SOLUTION: This throw-away tip is constituted of cemented carbide including at least one kind of cobalt tungsten carbide respectively containing tungsten carbide as a hard phase component and cobalt as a binding phase component and selected from Co3 W3 C, Co6 W6 C, Co2 W4 C and Co3 W9 C4 and a peak strength ratio of 0.03-0.15 expressed with I1 /I2 at the time when strength of the maximum peak out of a composite peak of (333) and (511) of Co3 W3 C of the cobalt tungsten carbide, a composite peak of (333) and (511) of Co6 W6 C, a composite peak of (333) and (511) of Co2 W4 C and a peak of (301) of Co3 W9 C4 is specified as I1 and peak strength of (001) of WC is specified das I2 .
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