Effect of Process Parameters on Angular Distortion of Gas Tungsten Arc Welded SS 302 and MS Plate

Tungsten Inert Gas (TIG) welding is a widely applied manufacturing process. Angular distortion is a major problem and most pronounced among different types of distortion in the butt welded plates. This angular distortion is mainly due to nonuniform transverse shrinkage along the depth of the plates welded. Restriction of this distortion by restraint may lead to higher residual stresses. However, these can be reduced by providing initial angular distortion in the negative direction if the magnitude of angular distortion is predictable. It is difficult to obtain a complete analytical solution to predict angular distortion that may be reliable over a wide range of processes, materials, and process control parameters. ANOVA is applied for the optimization of weld parameters control. In this study the transverse distortion of TIG, welding process was evaluated using weld current, filler rod diameter, length of plate and time gap between passes as the main parameters. A L9 orthogonal array was selected for the design of experiments towards the distortion optimization caused by butt welding. A mathematical model was developed correlating the process parameters with angular distortion. A source code was developed in MATLAB 16 to do the optimization. Direct and interaction effects of the process parameters were analyzed and presented in the graphical form. Further, these mathematical models help to optimize the GTAW process and to make it a cost-effective one by eliminating the weld defects due to angular distortion.