Abstract
Welding is widely used for construction of many structures. It is well known that residual stress is measured near the bead because base metal is heated near the bead. Tensile residual stress on the surface degrades fatigue strength. Some reduction methods of residual stress are practically used, for example, heat treatment and shot peening. The authors developed a new method for reduction of residual stress using vibration during welding. In this method, single vibration was used. The effectiveness of the method was demonstrated. In this paper, the effect of vibrations with different frequencies on reduction of residual stress is examined. The effect is examined experimentally by butt-welding of thin plates. First, two thin plates are butt-welded using ultrasonic vibrations with different frequencies on each plate. Some plates are welded using single ultrasonic vibration and without ultrasonic vibration for comparison. When thin plates are welded using vibrations with different frequencies, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Second, two thin plates are butt-welded using ultrasonic vibration and vibration with low frequency. Some plates are welded using single vibration and without vibration for comparison. In this case, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Obtained results are examined by analytical method.
