Numerical investigation of molten pool dimension, temperature field and melting flow during pulsed laser welding of Ti-6Al-4V alloy sheets with different thicknesses

Abstract

In this paper, a transient numerical model of pulsed laser welding is performed to predict the weld depth and width, temperature distribution, and melt flow. The material was made of Ti-6Al-4V with different thicknesses of laser beam energy, and an asymmetric temperature field was obtained. Three different thermal models were used to consider the laser beam energy. The results showed that the combination of Gaussian surface heat flux and heat source provides an accurate prediction of the dimensions and shape of the molten pool. The Marangoni flow due to the surface tension gradient at the surface of the molten pool had the greatest effect on the liquid metal flow. The analysis of the temperature field and dimensions of the weld bead was performed by changing the laser parameters such as welding speed and average power. The results showed that the heat affected zone and molten pool are directed toward the thin sheet. By increasing the movement speed of the laser beam, the molten pool became conical and did not penetrate completely. Also, increasing the average power has the greatest effect on the dimensions of the molten pool, temperature distribution, and liquid metal flow. Increasing the average power from 180 to 240 W increases the maximum temperature in the center of the laser beam by ∼1000 °C.