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Vol.44, No.5, 317 ~ 329, 2006
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| Title |
| Effects of Specimen Thickness and Notch Shape on Drop Weight Tear Test (DWTT) Properties of API X70 and X80 Line-Pipe Steels |
| 신상용 Sang Yong Shin , 황병철 Byoung Chul Hwang , 이성학 Sung Hak Lee , 강기봉 Ki Bong Kang |
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| Abstract |
| In the present study, effects of specimen thickness and notch shape on drop weight tear test (DWTT) properties of API X70 and X80 line-pipe steels fabricated by varying hot-rolling conditions were investigated. The DWTT was conducted on the rolled steels, and the results were discussed in comparison with the Charpy V-notch (CVN) impact test and crack tip opening angle (CTOA) test data. The DWTT results indicated that the steels rolled in the single phase region had the higher upper shelf energy (USE) than the steel rolled in the two phase region because their microstructures were composed of acicular ferrites, which was similar to the CVN test results. The DWTT energy transition temperature (ETT) increased with increasing specimen thickness due to the increase in constraint state, and the ETT of the Chevron notch DWTT was slightly higher than that of pressed notch DWTT. The measured CTOA showed better correlation with the DWTT propagation energy than with the CVN or DWTT total energy as it was related with the crack propagation speed. Since the value of sin(2CTOA) was linearly proportional to the DWTT energy, it could be used as a useful parameter to estimate the CTOA. |
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| Key Words |
| Line-pipe steel, Drop-weight tear test, Charpy V-notch (CVN) impact test, Crack tip opening angle |
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