Ultrasonic Treatment of Welded Joint from External, Internal and Two Sides on Reduction of Residual Welding Stresses

The article presents a study on the effects of ultrasonic treatment on residual welding stresses (RWS). Ultrasonic treatment was administered from three orientations: external, internal, and bilateral. Six samples, each with a thickness of 8 mm and composed of steel grade 09G2S, were prepared. The welding of these samples was executed using semi-automatic equipment and adhered to regulatory and technical guidelines. The magneto anisotropic technique, foundational to the operation of the Stress Vision Lab device, was employed to measure residual stresses. Given that this device quantifies residual stress values in arbitrary units, a calibration table was devised to translate these measurements into megapascals (MPA). This calibration was established by correlating values obtained from the ZW-100 testing machine with those measured by the Stress Vision Lab, necessitating the preparation of three additional samples of the same steel grade. Experimental investigations revealed that ultrasonic treatment applied internally to the samples facilitated the most significant reduction in residual (tensile) stresses, with reductions of 37.5% from external application and 27% from internal application. Leveraging the data acquired, a device has been developed to mitigate residual welding stresses within the inner wall of the near-seam zone of pipelines.