Investigation and application of the ultrasonic peening equipment used for improving fatigue strength of welded joints

It is a new method to increasing fatigue strength of welded joints and structure by peening welded toes with ultrasonic peening equipment. In this paper we have researched the ultrasonic peening equipment and a new ultrasonic peening prototype model was manufactured. Peening treatment butt and cruciform welded joints of steel 16Mn with ultrasonic equipment. The fatigue experiment of two kinds of joints (butt and cruciform joints) were carried out for both welded state and with peening treatment. The fatigue limits (2 × 106) of butt and cruciform joints of steel 16Mn have been increased by 90% (tension) and 67% (tension), the fatigue life of the peened joints is 30 approx. 100 times as long as the as-welded joints, respectively.