On the trail of Hydrogen Embrittlement via critical microscale fracture testing
讲座名称：
On the trail of Hydrogen Embrittlement via critical microscale fracture testing
讲座时间：
2019-10-31
讲座人：
邓云
形式：
校区：
兴庆校区
实践学分：
讲座内容：
讲座题目：On the trail of Hydrogen Embrittlement via critical microscale fracture testing
讲座时间：2019年10月31日, 15:00-16:30 PM
讲座地点：强度楼-210
讲座人：邓云
讲座摘要：The hydrogen assisted material degradation of structural materials has received increasing attention during the past decades. Various strong views on mechanisms of hydrogen embrittlement (HE) has been proposed based on a large number of experimental studies, however, none of them is widely agreed so far. The main difficulty lies on the complexity of hydrogen interaction with materials and on the lack of critical experiment approaches to sense the effect.
To this end, we introduce a critical experimental approach of microscale fracture testing together with various in-situ H charging methods (water vapor, H-plasma, electrochemical H-charging) to sense the hydrogen effect from both the aspects of mechanical property and microstructure evolution. The hydrogen assisted cracking phenomenon on the FeAl intermetallic alloy, as a case study, was successfully captured with the proposed approach. The fracture toughness of thenon-ASTM-standard microscale specimen was studiedby a combination of Elastic-Plastic Fracture Mechanics and Finite Element Simulation, and the microstructure of the whole crack area was analysed by Transmission Kikuchi Diffraction (TKD) and Transmission Electron Microscopy (TEM) techniques. We observed an accelerated crack propagation rate in specimens under hydrogen exposure. The hydrogen embrittlement phenomenon was found to occur because of the strong hydrogen-dislocation interactions. The combined effect of hydrogen-enhanced dislocation nucleation and hydrogen-restricted dislocation mobility is responsible for the hydrogen-enhanced cracking behaviour.
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