き裂先端塑性鈍化のフラクトグラフィによる定量的評価

概要

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The effect of notching method on the Charpy impact values of rigid PVC plates was studied and fractographic consideration of the reason why such effect had taken place was given. The results obtained are summarized as follows : (1) Although no geometric difference in the notch shape and the radius of notch root between the test specimens made by a shaper and those by a milling machine was found, the Charpy impact value of the former was about twice of that of the latter. (2) The fracture of the test specimen made by the shaper originated at the inside a little below the notch root as reported previously, while the fracture of the test specimen made by the milling machine originated at the notch root or just inside below the notch root. (3) In the test specimen made by the milling machine, very fine cracks were produced by notching at the deformed layer or at the boundary between the matrix and the deformed layer. It is considered that these very fine cracks act as fracture origins and make the Charpy impact values lower.
1980-06-15