Distinguishing Welding Defects from the Stress Concentration Zone Using Metal Magnetic Memory Field Parameters

Abstract

In this study, we propose a technique for differentiating MMMT signals from the welding defects and stress concentration zones by evaluating changes in the intensity of the magnetic memory signal and gradient of its change. The results demonstrate that the average and maximum values of the magnetic field intensity gradient vary relative to the presence of a welding defect zone; this gradient can be seen as the area under the magnetic field intensity curves. These parameters can be considered as a basis for distinguishing welding defects from the stress concentration zone. Finally, we present diagnosis and damage determinations of various welding defects and stress concentrations and propose a connection to magnetic and non-magnetic defects. The technique presented here can be potentially used to enhance the MMMT application for better diagnosis and understanding of welded joints and failure mechanisms.