Effect of laser pre-heating on the weld properties of AA6005 by remote laser welding using circular beam wobbling

Abstract The laser pre-heating (LPH) approach is a heating process performed with a laser by applying different amplitude and oscillation patterns without causing any deformation on the surface in order to reach the desired temperature at the joint line of the weld sheet before the joining process. At the beginning of the study, the ideal amplitude-laser power value for full penetration was determined using different circular oscillation path configurations for joining AA6005 sheets. In these processes, called laser beam oscillation welding (LBOW), longitudinal thermal cracks were found to form in the weld line due to high heat input generated by the increased amplitude-laser power. As a result of the analyses of the microstructure and mechanical properties of the LBOW processes, the ideal amplitude-laser power value (3.75 mm-3750 A) with the lowest weld defect was determined as a reference for use in the LPH process. In the other section of the study, using the laser power values calculated by the Rosenthal equation, temperatures of 200 °C, 300 °C and 400 °C were established separately on the sheet surfaces before welding for the LPH process and then the welding process was performed. As a result of the LPH treatment at 300 °C, although the hardness in the FZ region decreased by 20% compared to the reference treatment, the tensile lap strength was 15% higher and the elongation was 1.14% higher. In this context, the LPH process has been found to improve the weld quality in laser welding processes and has improvable properties.