Effects of synchronous laser irradiation on anodic dissolution behavior

Laser has been adopted to improve the efficiency and localization of electrochemical machining (ECM), which is referred to as laser and electrochemical machining (LECM). Nevertheless, the electrochemical dissolution behavior under synchronous laser irradiation remains unclear. This study investigated the effects of laser irradiation on the electrochemical dissolution behavior and surface characteristics. The polarization curves and electric current efficiency were measured using synchronous laser irradiation on the electrochemical dissolution area. Furthermore, the evolution of the surface morphology, roughness, chemical content, and residual stress with varying laser power and electric current densities was characterized. Results demonstrated that laser irradiation could remove passivation film, enabling anodic dissolution at a lower potential and enhancing electric current density. Electrochemical impedance spectroscopy (EIS) results revealed that laser irradiation could decrease electrochemical impedance by three orders of magnitude. Moreover, the electric current efficiency could be increased by synchronous laser irradiation with an electric current density of smaller than 3.75 A/cm². XPS results also indicated that laser irradiation favored the anodic reactions. Meanwhile, the surface characteristics relied on the comparison of electric current density and laser power. The enhanced electrochemical dissolution improved the surface finish with an increase in electric current density during LECM. The surface tensile stress increased with increasing laser power, which could accelerate the rate of anodic dissolution. Additionally, laser processing could improve the precision of ECM by locally removing the oxide film. This work contributes to the understanding of the material removal mechanisms of LECM, which would promote the development and utilization of LECM.