1 0 0 0 OA 銅およびα-黄銅の繰返し変形に伴う加工硬化挙動および疲労強度に対する結晶粒度依存性
- 著者
- 山田 敏郎 幡中 憲治 広瀬 勇次
- 出版者
- 公益社団法人 日本材料学会
- 雑誌
- 材料 (ISSN:05145163)
- 巻号頁・発行日
- vol.22, no.235, pp.335-341, 1973-04-15 (Released:2009-06-03)
- 参考文献数
- 12
- 被引用文献数
- 2 1
Many studies have been carried out in regard to the grain size dependence of fatigue strength of metals. And it has been made clear that fatigue strength of f. c. c. metals greatly depends on the stacking fault energy γ, and the effect of γ on the crack propagation process is different from that on the crack initiation process. In this work, the grain size dependence of the fatigue strength was mainly examined under the rotating bending fatigue test, and the cyclic work hardening behavior under the push-pull fatigue test. Furthermore, the surface structure due to fatigue deformation was observed by means of optical and electron microscopes. From the viewpoints of both microscopic structure and dynamical behavior of the materials, the grain size dependence of fatigue strength was investigated in copper and α-brass.The results obtained are summarized as follows:(1) The grain size dependence in the crack initiation process in α-brass is very remarkable at 200°C as well as at room temperature. This result suggests that the effect of grain size on fatigue strength must be considered from both viewpoints of the configuration of slip line and ageing effect.(2) The grain size dependence in crack propagation process in α-brass is very small at R.T, but it increases at 200°C.(3) The cyclic work hardening in α-brass is larger in fine grains than in coarse grains. On the other hand, in copper almost opposite result was obtained. From these results the difference in grain size dependence under constant stress fatigue test can be explained.
- 著者
- 幡中 憲治 藤満 達朗 安藤 隆之 橘 輝夫 中居 嘉一郎
- 出版者
- 一般社団法人日本機械学会
- 雑誌
- 日本機械学會論文集. A編 (ISSN:03875008)
- 巻号頁・発行日
- vol.55, no.512, pp.773-781, 1989-04-25
- 被引用文献数
- 1
The test system was newly developed for evaluating precisely the strength of ceramics at elevated temperatures, being equipped with the laser beam-type displacement measuring system. Four-point bending tests were performed on the silicon-nitride ceramics at elevated temperatures from 800℃ to 1300℃. The linear relationship held between the load, P and the displacement, 6 at test temperatures below 1200℃. The P vs. δ plot, however, deviated from the linear relationship at temperatures above 1200℃, suggesting the occurrence of plastic deformation. The flexural strength remained unchanged in the test temperature range from room temperature to about 900℃, and then this decreased gradually with further increase in the test temperature. The fracture toughness measured by using the Chevron notch-type specimen was nearly constant in the temperature range from room temperature to about 1100℃. The fracture toughness obtained from the Knoop-indented specimen was discussed in comparison with that from the Chevron notch-type specimen.