| 摘要 |
PROBLEM TO BE SOLVED: To provide a cemented carbide exhibiting excellent performance as a discharge electrode material machinable in a short time with high accuracy in the case of boring a pore with an extremely small diameter of 0.2 mm or less in a structural steel plate by electric discharge machining. SOLUTION: The cemented carbide for a discharge electrode has a composition with 3-7 wt% Co, 0.1-1 wt% of the total amount of one or two kinds of TaC and NbC, and the rest comprising WC and unavoidable impurities. The carbon content of the cemented carbide is in a range from a lower limit value of a two-phase region of WC and Co up to a point of exceeding the upper limit value by 0.05%, and the texture of the cemented carbide has the two-phase region of WC and Co or includes free carbon with a grain diameter or maximum length of 5μm or less (a range surrounded by marks a-c-d-b in the figure). The average grain diameter of WC is 1μm or more, and electrical resistivity is 20μΩcm or less. COPYRIGHT: (C)2006,JPO&NCIPI
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