Estimation of heat source and thermal efficiency in GTAW process by using inverse techniques

Abstract

This work presents a comparison between two techniques to study thermal phenomenon that occurs in the base metal during welding operations. The techniques combine optimization methods, such as the simulated annealing (SA) and gold section, in two different physical models. The first thermal model considers a quasi-stationary heat conduction in the interior plate, whereas the second one uses the general transient equation of heat diffusion with phase change. In both cases, the heat flux generated by the welding process is estimated, and, from this point, global thermal efficiency and fusion efficiency are also estimated. Moreover, the use of the SA method with the numerical model allows the weld pool geometry identification. In this study, thermocouples are placed on the plate (AISI304) at the opposite side concerning a weld carried out by GTAW (tungsten inert gas). It is concluded that the phase change model demonstrate to be able of identifying the global thermal efficiency and fusion efficiency at each instant of the process.