Abstract: Studies show that considering the mechanism of improving the fatigue performance, ultrasonic peening and TIG dressing are complementary. A new compound treating method of improving fatigue performance of high-strength welded joint is that firstly treated the welded toe by TIG-dressing and then performed ultrasonic peening. Test results indicated that：(1) In the given range of stress level, contrasted with the specimens in as welded condition the fatigue strength of the specimens treated by ultrasonic peening is increased by about 95% and the fatigue life is prolonged by 3.6～62 times. The fatigue strength of the specimens treated by TIG-dressing is increased by about 34% and the fatigue life is prolonged by 0.4～1.3 times. And while the fatigue strength of the speci-mens treated by compound treating by TIG-dressing adding ultrasonic peening is increased by about 120% and the fatigue life is prolonged by 28～125 times. (2) The fatigue strength can be even improved by compound treating ultrasonic peen-ing adding TIG dressing on the basis of ultrasonic peening or TIG dressing. In the range of high stress, contrasted with simple ultrasonic peening treating TIG dressing adding ultra-sonic peening compound treating has definitive predominance because compound treating overcome the decreasing of fa-tigue performance improvement of welded joint treated by simple ultrasonic peening.

Key words: adding TIG dressing, Compound treating by ultrasonic peening, Fatigue performance, TIG dressing, Ultrasonic peening