Process modeling for laser beam welding of Ti-6Al-4V

The focused laser beam alongside the electron beam, is one of the highest power density sources available to industry today. Laser welding of titanium alloys has been of interest especially in the aerospace industries, where quality of it,; products is very important. The application of the laser beam, however, causes a thermal-mechanical response in the workpiece and thus a complicated pattern of residual stresses is set up. It is of interest to characterize and analyze the development of residual stresses, which has a profound effect in component strength and fatigue life. In this paper, a process model suitable for the prediction of residual stresses induced during the. laser welding of Ti-6Al-4V is described. For the purpose of model validation, processing trials have been carried out. The heat transfer during welding has been characterized and the fusion zone has been,observed, which have enabled a suitable thermal model to be developed. The residual stresses have been measured using the synchrotron x-ray diffraction technique, and it is shown that the predictions are in, reasonable agreement with the observations. The modeling is then used to rationalize the state of residual stresses induced.