Thermomechanical Analysis of Tungsten Inert Gas Welding Process for Predicting Temperature Distribution and Angular Distortion
Authors: Narang Harendra Kumar , Pandey Chandan , Thakare Jayant Gopal , Saini Nitin , Mahapatra Manas Mohan , Jha Pradeep Kumar 
Published: August 2019

In present research work, discussions have been made to predict the bead geometries and shape profiles of weldments using statistical regression modeling and fuzzy logic techniques. However, the regression and fuzzy logic modeling techniques do not take into account the actual physical properties and phenomena that occur in welding. Moreover, techniques such as regression and fuzzy logic modeling are not suitable for predicting the transient temperature distribution and distortion of arc welded joints. To predict the transient temperature distributions, peak temperature distribution, and residual deformation in welding, deterministic modeling techniques such as thermomechanical analysis are preferred. However, while performing thermomechanical analysis of welded joints, size and reinforcement dimensions of the weld bead need to be incorporated into the model for accurate prediction of transient temperature distributions and distortions. In this work, circularly spread moving heat source has been used for transient thermal modeling of tungsten inert gas (TIG) welding process. In the subsequent sections of this article, the weld thermomechanical analyses for TIG square butt joints are discussed to predict the temperature distributions and angular distortion. The weld dimensions such as weld width, weld depression, and weld bulging have shown great influence on the angular distortion patterns.

1. Introduction
The present work describes the thermomechanical analysis of an open arc process, i.e., tungsten inert gas (TIG) welding of square butt joints by considering the circularly spread moving heat source to predict the angular distortion and thermal profile (Pandey et al. 2016). TIG welding is commonly used for thin sheet joining (Pandey et al. 2018a, 2018b). Generally, for thin sheets, the TIG welding is performed autogenously such that no filler material is required. In some special cases, such as for fillet and groove welding, a filler rod is used in the TIG welding process. The distortion of the TIG weld square butt joints is primarily dependent on the weld width, bead depression, and bulging (Mahapatra et al. 2006). If these factors of weld bead geometries are within tolerable limits, then, the distortion observed in the weld joint is minimum. In TIG weld butt joints, the angular distortion is more prominent because of the presence of upper bead depression and lower bead bulging. Finite element analysis (FEA) simulation of TIG welding is highly effective in predicting the thermomechanical behavior such as temperature distributions and distortions. In this work, numerical and experimental approaches have been applied to predict the thermal profile and angular distortion in a TIG open arc welding process. An Finite element (FE) model has been developed for 3-D analysis of TIG square butt joints for predicting angular distortion based on circularly spread moving heat source and weld geometry.