Insight into the pitting corrosion behavior of laser-welded R60702 zirconium alloy in chloride electrolyte

This work aims to analyze the passivation and pitting corrosion behaviors of laser beam welded R60702 zirconium alloy in neutral and acidic chloride-containing electrolytes. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements are carried out to investigate the electrochemical performance of the welding joint. Scanning electron microscope, X-ray diffraction, and three-dimensional profile digital microscope are utilized to reveal the microstructures and corrosion morphologies. The electrochemical results show that the heat-affected zone (HAZ) and weld zone have nearly equal corrosion performance, and both of them are more corrosion-resistant than the base metal. The corrosion morphologies suggest that the HAZ has the lowest sensitivity to pitting corrosion. Moreover, it is unraveled that, in chloride-containing electrolytes, the quantity and distribution of Zr(Fe,Cr)₂ particle phases are the main factors that determine the different corrosion performances of the welding joint.