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Vol.42, No.9, 711 ~ 719, 2004
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| Title |
| Analysis of Toughness and Transition Temperature of High-Toughness Pipeline Steels 3. Correlation of Charpy Impact Properties, DWTT, and CTOA |
| 황병철 Byoung Chul Hwang , 신상용 Sang Yong Shin , 이성학 Sung Hak Lee , 김낙준 Nack J. Kim , 강기봉 Ki Bong Kang |
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| Abstract |
| Correlation of Charpy V-notch (CVN) impact properties, drop-weight tear test (DWTT) properties, and crack tip opening angle (CTOA) values of a high-toughness API X70 pipeline steel was investigated in this study. Two-specimen CTOA test (TSCT) was conducted on the rolled steel specimens to measure CTOA, and the test results were related with the CVN and DWTT data to find correlations between them. The CVN total energy density showed almost 1:1 linear correlation with the DWTT initiation energy density. The TSCT test results indicated that the specimens rolled in the single phase region had the larger CTOA as well as the higher CVN and DWTT energies than those rolled in the two phase region because their microstructures were composed of acicular ferrites and fine polygonal ferrites. 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 reliably estimate the CTOA. |
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| Key Words |
| API X70 pipeline steel, Crack-tip opening angle, Drop-weight tear test, Charpy V-notch, CVN, impact test |
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