The Influence of Base Metal Ultrasonic Vibration on the Residual Stress and Joint Strength of AISI 304 SS

To address issues such as high residual stress, coarse weld grain, and poor tensile properties of welded 304 stainless steel using conventional welding methods, ultrasonic transducers were brought into contact with the base metal to apply ultrasonic vibration during welding. Analysis was conducted on the distribution of residual stresses, microstructure, and tensile strength of the welded joints. The results showed that under the action of ultrasonic vibration, the transformation rate from columnar grains to equiaxed grains accelerated, the proportion of equiaxed grains increased, and the grain size became finer. Compared to conventional welding, the microstructure of the welded joints of 304 stainless steel improved with the introduction of ultrasonic vibration, and the residual tensile stress was significantly reduced. The improvement in weld structure enhanced its mechanical properties, and the tensile strength of the welded joints was higher than that of conventional welded joints, with an increase of approximately 3.8% in tensile strength.