Laser Beam Welding With Simultaneous Gaussian Laser Preheating

An analytical solution of the dual, laser beam welding process is presented. It is based on a Gaussian distributed leading heat source for preheating, followed by a line source for the actual welding process. The effect of beam distribution parameters as well as interbeam spacing and relative power intensities on the resulting temperature distribution and cooling rate are presented. For a preheating Gaussian source of power 1550 W, the depth of region above 500°C is 2.25 mm, and that above 250°C is 3.5 mm. The cooling rate at the weld centerline without preheating for a temperature of 650° C, input power 1800 W, and welding velocity 20 mm/s is found to be 1004°C/s. Under the same conditions, the cooling rate with a 1550 W preheating Gaussian distributed heat source (beam distribution parameter 1 mm, and interbeam spacing 10 mm) is reduced to 570°C/s.