Study on microstructure and impact toughness of laser hybrid welding joints.

In the study, laser-MIG hybrid welding of high-strength shipbuilding steel was conducted. The microstructure and impact toughness were studied. The microstructure of the Filling and capping weld metal (FCWM) is widmanstatten and acicular ferrite. The microstructure of the backing WM (BWM) and the heat-affected zone (HAZ) are bainite. The impact energy of the joints is greater than 110 J at different charpy impact test positions. The reason for the different toughness is related to the proportion and distribution of the microstructure at the V-notch of the impact specimen. Through the observation of the section, it is also found that the section corresponding to the microstructure of the different HAZ will show significant differences in fracture morphology. [ABSTRACT FROM AUTHOR]