In situ observation of deformation and failure behavior in the burn-through instability zone of in-service welding

Based on the in-situ high-temperature SEM and laser scanning confocal microscope (LSCM), the high-temperature plastic deformation and failure behavior of X65 pipeline steel at 1000℃ and 1200℃ were studied in this paper, and the strain evolution behavior in this process was analyzed by DIC technology. In this study, the precipitation and dissolution of carbide at the austenite grain boundary were observed during the in situ heating process. The external load showed a great effect on the growth of the grains, and the grains grew rapidly by swallowing each other. The grain size, material performance, and misorientation played an important role during the deformation and crack evolution. At high temperatures, cracks were mainly initiated and propagated in the position with a large plastic strain. The strain concentration showed a significant effect on crack initiation.