切削工具材料の押込み試験における破壊の発生挙動

概要

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The behavior of crack initiation, which result in the brittle failure during the cutting, was simulated experimentally by indentation test techniques for cemented carbide cutting tool materials. In indentation test the cracks were observed at a short distance from indenter-specimen contact zone, and at the center of that contact zone. For the former crack path was grain boundary of carbides and interface of carbide particle and cobalt binder, and the latter propagated in carbide particles mainly. Indenting load at which crack occurred decreased with a increase in the number of indenting cycles, and was affected by tool materials and surface preparations. From the comparison of indentation test with transverse rupture test about fracture source and stress distribution, it was considered that in case of stress concentration such as indentation test fracture originated in carbide grain boundaries and carbide particle-binder interfaces, in the other case such as transverse rupture test fracture initiated from a pore or a coarse grain. The appearance of fracture surface and the stress distribution of the brittle failure of cutting tools is similar to those of indentation test, then it is seemed that the crack, which results in brittle failure, occurs at grain boundaries and interfaces, and grows.
公益社団法人精密工学会の論文
1989-01-05