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Vol.50, No.1, 52 ~ 59, 2012
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| Title |
| Microstructural Effects on Hydrogen Delayed Fracture of 600MPa and 800MPa grade Deposited Weld Metal |
| 강희재 Hee Jae Kang , 이태우 Tae Woo Lee , 윤병현 Byung Hyun Yoon , 박서정 Seo Jeong Park , 장웅성 Woong Seong Chang , 조경목 Kyung Mox Cho , 강남현 Nam Hyun Kang |
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| Abstract |
| Hydrogen-delayed fracture (HDF) was analyzed from the deposited weld metals of 600-MPa and 800-MPa flux-cored arc (FCA) welding wires, and then from the diffusible hydrogen behavior of the weld zone. Two types of deposited weld metal, that is, rutile weld metal and alkali weld metal, were used for each strength level. Constant loading test (CLT) and thermal desorption spectrometry (TDS) analysis were conducted on the hydrogen pre-charged specimens electrochemically for 72 h. The effects of microstructures such as acicular ferrite, grain-boundary ferrite, and low-temperature-transformation phase on the time-tofailure and amount of diffusible hydrogen were analyzed. The fracture time for hydrogen-purged specimens in the constant loading tests decreased as the grain size of acicular ferrite decreased. The major trapping site for diffusible hydrogen was the grain boundary, as determined by calculating the activation energies for hydrogen detrapping. As the strength was increased and alkali weld metal was used, the resistance to HDF decreased. |
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| Key Words |
| ferrous alloys, welding, microstructure, thermal desorption spectrometry, hydrogen delayed fracture |
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