銅の疲労におけるき裂の発生ならびに伝ぱに関する研究
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概要
- 論文の詳細を見る
Crack nucleation sites, crack propagation paths, and the crack propagation rate were studied on axially loaded specimens of oxygen-free high conductivity copper tested in the high cycle life region. Fatigue tests were conducted under load control without a mean load. The variables of the test conditions were the engineering stress range, the average grain size, and the atmosphere (air and argon gas). Tree crack nucleation sites were observed. They were (1) a grain boundary, especially a triple point, (2) a place where slip lines impinge upon a grain boundary, and (3) a small hole and a crevice along a slip line. The first two of these seemed to be predominant in crack nucleation. The crack propagation paths toward the inside of the material were observed after electropolishing the surface layer of fatigued specimens little by little. It was observed that the crack propagation path within the first 80 percent of the fatigue life was mostly at grain boundaries. The crack propagation rate during the first 80 percent of the life was determined by using an electropolishing technique. The crack propagation rate depended upon the test conditions as well as on the prior stress cycling. The crack propagation was divided into two main stages: the crack nucleation and microcrack development stage, and the crack propagation or macrocrack development stage. Argon gas reduced the macrocrack propagation rate, but did not affect the crack nucleation and microcrack development significantly. Increasing the grain size shortened the crack nucleation stage markedly.
- 社団法人日本材料学会の論文
- 1974-01-15
著者
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中野 善文
Department Of Mechanical Engineering Kyoto University
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SANDOR Bela
Department of Engineering Mechanics, University of Wisconsin
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Sandor Bela
Department Of Engineering Mechanics University Of Wisconsin