Experimental and numerical study on fusion zone in the laser welding process of AA6061-T6 overlap joint: using smoothed particle hydrodynamics (SPH)

In this study, a numerical model that employs smoothed particle hydrodynamics (SPH) is presented to simulate the temperature distribution and measure the weld pool surface area of disk laser-welded overlap aluminum sheets. This simulation technique is well suited for performing three-dimensional calculations with high spatial resolution while keeping low computational costs. This simulation models laser welding of AA6061-T6 aluminum sheets, a well-known commercial alloy used in various transportation industries, predicting temperature distribution and the fusion zone surface area. The first approach dictates a comparison of the numerically calculated temperature distribution during laser welding over experimental tests instrumented with thermocouples. The second validation method involves a comparison between numerical simulations of the top surface melt pool area with the experimental measurements extracted from high-speed camera images. The most remarkable results of comparisons between simulated and experimental temperature distributions reveal significant agreement, highlighting the ability of the simulation model to accurately reproduce the thermal phenomena observed in experiments. The effect of laser welding speed and power on the dimensions of the fusion zone was analyzed and highlighted that the higher the welding speed, the narrower the weld pool is. This behavior reflects a reduction in the width and length of the weld pool, resulting in a contraction of its upper surface. The effect of welding parameters on cooling rates and melt zone volume is also discussed. This study will serve as a reference for identifying the main parameters, such as top surface dimensions and melt volume, as well as temperature distribution during laser welding, which could eventually enable a hot cracking criterion to be determined using numerical simulations.