Ultrasonic Investigation of the Effect of Carbon Content in Carbon Steels on Bulk Residual Stress

Formation of residual stress as a result of welding process is a familiar fact, but its relation with material composition is unknown. This study aims to investigate the effect of carbon content on welding residual stress in carbon steels. For this purpose, samples of ultra-low carbon interstitial free, low carbon and medium carbon steels are selected. Welding is performed as a beam on plate in spite of a joining process. Weld grooves are prepared at center of the rectangular samples. Automated submerged arc technique is preferred for welding process in order to ensure same welding parameters at each sample. Ultrasonic sound waves are used to determine residual stress. This non-destructive technique provides bulk residual stress which is average of shear and normal stresses through thickness of a material. A new approach is practiced to verify experimentally determined bulk residual stress with finite element simulation results. The model geometry of numerical analysis is divided into equivalent parts and average of shear and normal stresses is calculated. Non-destructive ultrasonic technique seems to be in good agreement with finite element analysis.