Abstract
This study involves thermal, metallurgical and mechanical analysis during tungsten inert gas welding of Ti-6Al-4V alloy aiming at optimizing the welding current to enhance the mechanical properties. Firstly, a 3D transient FEM simulation of TIG Ti-6Al-4V weld using ABAQUS software, based on a Gaussian distribution of power density in space, has been built to predict the effect of welding current on the heat input, weld bead geometry, temperature and residual stresses distribution across the welding line. Secondly, a validation of FEM with the experimentally measured temperature distribution and welding bead geometries has been presented. Finally, experimental study of the effect of TIG welding current, the suitable range predicted from FEM, on the microstructure, hardness and tensile strength of 12-mm-thick alloy plate is discussed. Using FEM, the suitable range of welding current was predicted to be 130-170 A. There was a close agreement among the experimental results and the FEM simulation data. It has been found that low welding current of 130 A results in high tensile strength and hardness of the welding joint. This is attributed to low heat input, high cooling rate and the formation of a fine grain structure containing martensite-phase with low values of residual stresses.