著者

野田 尚昭 赤木 大地 沈 雨濃 高木 怜 池田 朋弘 佐野 義一 高瀬 康

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.851, pp.17-00034-17-00034, 2017 (Released:2017-07-25)

参考文献数

25

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High-speed tensile testing is now being recognized as a standard testing method for evaluating the impact strength of engineering materials. The impact speeds of Izod and Charpy tests cannot be controlled and therefore do not correspond to the real failure of real products. The brittle-ductile transition of structural materials is affected by the temperature and loading speed. In the high-speed tensile test, it is necessary to obtain the strain rate at the notch root accurately to understand the effect of impact load. For smooth specimens, the strain rate can be determined from the tensile speed u/t and specimen length l as εsmooth = u/tl. For notched specimens, however, the strain rate at the notch root εnotch should be analyzed accurately. In this study, therefore, the strain rate concentration factor defined as Ktε = εnotch/εsmooth is studied with varying the notch geometry. To predict the strain rate concentration factor Ktε accurately, the relationship between Ktε and the stress concentration factor Kt* = σmax/σgross is investigated. Here, σgross is the remote tensile stress and P is the tensile load. It is found that the strain concentration factor Ktε can be estimeted from stress concentration factor Kt* when the relative notch depth 2t/D≦0.5 (t : notch depth, D : the specimen diameter).

著者

池田 朋弘 梅谷 拓郎 甲斐 信博 大城 桂作 赤木 大地 野田 尚昭 佐野 義一

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.851, pp.16-00455-16-00455, 2017 (Released:2017-07-25)

参考文献数

26

被引用文献数

2

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In this study, the notch strength σBnotch was investigated for high silicon solid solution strengthened ferritic ductile cast iron in comparison with the tensile strength σBsmooth. High speed tensile tests were conducted on notched and smooth specimens at various strain rate and temperatures. The strain rate-temperature parameter (R parameter) is found to be useful for evaluating the temperature and strain rate upon the notch strength. The required range of R parameter was investigated for welded structural members in several industrial fields. The notch strength σBnotch is always larger than the tensile strength at room temperature σB,smoothRT in the range of R parameter required for the welded structures. Therefore, tensile strength σB,smoothRT is confirmed to be more useful than Charpy absorbed energy for the structural design. It is expected that the high Si ductile cast iron has wide industrial application potentiality.