Experimental study and modeling of GTA welding process

It has been well recognized that the geometry of weld pool plays a fundamental role in determining the mechanical properties of weld joints. In this research, a series of experiment has been conducted to investigate the interaction and correlation of welding current, voltage, welding speed, and arc length affecting the formation of weld pool. The effect of arc length on arc efficiency and heat distribution parameter are also examined and addressed in this paper. In addition to the experimental study, a three-dimensional finite element model has been developed to analyze transient heat flow and to predict the formation of the weld pool. The correlation among the parameters including welding current, voltage, welding speed, arc length, open-loop response and the characteristic geometry of weld pool are established. The 3-D FEM can calculate not only the transient thermal histories but also the sizes of weld pool in single-pass arc welding. In order to obtain quality welds, this model will determine the effect of arc length on the formation of weld. Furthermore, the effects of welding parameters on the Gaussian heat source parameters (arc efficiency and heat distribution parameter) are also studied. The experimental calibration and verification are carried out to verify the numerical model. Experimental data are consistent and in quantitative agreement with values from FEM simulations.