Effect of Welding Conditions on TIG Welded AISI 304 Stainless Steels Using FEM and Experimental Methods

Classical approaches to the modeling of welding, whilst accurate, are not readily usable in the industry. The time and cost associated with running such models appear to be the main reasons contributing to the situation. The use of computer simulative techniques has the potential to significantly reduce the cost of welded fabrications by allowing for predictions to be made long before a single weld bead is put down on the workshop floor. In this paper, a computational procedure is presented to analyze temperature fields during TIG welding process using a non linear transient thermal analysis in ANSYS [1]. Various phenomena associated with welding like temperature dependent material properties, effects of latent heat of fusion are accounted for in the model. The heat loss through radiation and effect of shielding gas are neglected here. This work has considered only a 2D analysis considering axis symmetric model. The analysis was done on AISI 304 stainless steels. The effect of welding conditions on the weld microstructure is studied over a range of heat input values and welding speed and the columnar to equiaxed transition (CET) is investigated. The influence of the welding conditions is related to changes in temperature gradient G, and local solidification velocity R, at the solid-liquid interface along the weld pool edge. It was observed that increase in the welding speed increases the equiaxed fraction. The effect of alloy composition on CET was neglected during this study. The results of finite element analysis were compared with experimental results and were found in good agreement. Based on these studies, a simplified modelling procedure of reasonable accuracy was proposed.