Development of a Mathematical Model for Predicting Angular Distortion in Butt Welded Stainless Steel 409M Plates in GMAW Process

Abstract

Angular distortion is almost inevitable in fusion welding processes as it involves localized heating and cooling of materials. Keeping the weld distortion to its minimum is the endeavor of every weld engineer as excessive distortion can not only spoil the physical appearance but also can cause mismatch of joint in fabricated structures. In the present investigative work, an attempt was made to predict the influence of input weld parameters like wire feed rate, voltage, speed of welding and the angle of groove on angular distortion, by developing a mathematical model. This was accomplished by developing a mathematical equation which included the direct, quadratic and interaction effects of input weld parameters and could be used to predict the effects of these parameters on the resulting angular distortion. The experimentation was carried out in a structured manner by using Central Composite Face Centered Design (CCFD) technique. All the selected welding parameters were taken at three levels to accommodate the curvature effect. The final model was developed by using regression analysis and its adequacy was tested by Analysis of variance (ANOVA) approach. Response surface methodology (RSM) was used to graphically plot direct and interaction effects of weld parameters on angular distortion. The validity of the developed model was checked by conducting test runs at different values of input parameters. The comparison of actual and predicted results indicated good conformance.