Radiographic Analysis with Parametric Optimization for Minimizing Defects in Metal Inert Gas Welding Using a Substrate

Abstract The present study is an attempt to brief on the reduction of defects using backing material, its thickness and welding parameters namely gas flow rate and current. The evaluation is performed using a radiographic testing method with result analysis of image for studying defects of weld specimen made of SS304L grade stainless steel. The concise overview of lack of weld formed during metal inert gas welding process and its appearance in X-ray film has been analyzed through radiographic images. The type and size of discontinuities in the weld is identified by differences in color density and shape on the radiographic film. From the X-ray image analysis, it is explicit that the reduction in color density and shape is due to the usage of weld backing. Moreover, the dimension of the defect, especially the length is considered for analysis which is obtained using the image processing method. Parametric optimization is done by adopting the Taguchi method and analysis-of-variance technique to identify the influencing parameter considering defect length as the response parameter. The radiographic examination has been carried out to probe the weld joint quality and the image is digitalized to get the defect dimensions, based on which the optimization is worked out. Thus, the result clearly indicates the influence of backing material and its thickness on length of defects.