Avoiding hot cracks during laser welding of a workpiece stack-up assembly of aluminum alloy workpieces

[0034]The disclosed method of laser welding a workpiece stack-up assembly that includes two or more overlapping aluminum alloy workpieces can successfully fusion weld the workpieces together while counteracting the susceptibility of the resultant laser weld joint to hot-cracking. The disclosed method, more specifically, seeks to mitigate hot-cracking during the initial and / or final stages of laser beam advancement along a predefined weld path by controlling the power level of the laser beam so as to limit a line energy of the laser beam. By limiting the line energy in this way, excessive fusion of the aluminum alloy workpieces is prevented at the beginning and / or ending portions of the weld path. The line energy of the laser beam can be limited as needed by increasing the power level of the laser beam at a controlled rate during the initial stage of laser beam advancement along the weld path and / or decreasing the power level of the laser beam at a controlled rate during the final st...