焼結硬ぜい材料の加工損傷に関する研究(第1報) : 超硬合金工具材料の破壊挙動

概要

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This investigation examines the fracture initiation from a pre-existing defect and a surface defect by the transverse rupture test for cemented carbides based on fracture mechanics. The stress intensity factor, which was calculated by the pre-existing defect size and the nominal stress acting on the defect, was smaller than the fracture toughness of the materials . Acoustic emission signals were detected before the ultimated fracture of the specimen occurred. The stress intensity factor determined from the stress in AE signal detected and the defect size corresponded to the fracture toughness of grain boundary of carbide particles. Then, it was suggested that a microcrack grew locally near the defect. Taking the microcrack into consideration, it was found that the stress intensity factor coincided with the fracture toughness. For the fracture initiated from the surface defect when the machining damage may be small, the defect size based on fracture mechanics was equal to microcrack length. Therefore this microcrack must be considered in the estimation of machining damage of sintered brittle materials.
公益社団法人精密工学会の論文
1990-03-05