Investigating the effect of process parameters on the temperature field and mechanical properties in pulsed laser welding of Ti6Al4V alloy sheet using response surface methodology

Abstract

Laser welding of Ti6Al4V alloy with 3 mm sheet thickness was studied. The effect of process parameters including laser peak power, pulse duration, and welding speed was systematically investigated on the temperature field of the fusion zone, tensile strength and elongation. The laser welding experiments were performed based on central composite design and response surface method to develop multiple regression models. The accuracy of the regression models was adequate through analysis of variance to make correlations between input parameters and responses. It was found that laser peak power and pulse duration had remarkable effects on weld tensile strength melt pool dimensions and elongation rate. Increasing the laser peak power from 1800 to 2200 W, clearly increased the tensile strength about 300 Mpa. Both the elongation rate and melt pool dimensions significantly increased with augmentation of laser peak power. Increasing welding speed from 3 to 7 mm/s decreased the temperature of the region near the fusion zone from 370 to 130 °C. Increasing welding speed significantly reduced the mechanical strength for 3 mm thickness about 20 percent. On the contrary, this reduction effect is negligible for the elongation rate about 10 percent due to creating high rates of martensitic structure and brittle properties of the weld.