Fatigue properties of X65 pipie-line steel butt joints

Ultrasonic peening is an efficient method to improve the fatigue strength of welded joints and suchlike structures by bettering the geometry, removing the defects and adjusting residual stress field of the weld toes. The welded joints of X65 steel were peened by the homemade ultrasonic peening device, then we compared the fatigue strength of as welded, peened after welding and base metal. The test results show: the fatigue strength:Δσ(2×10⁶) 219 MPa as welded, Δσ(2×10⁶) 338 MPa as base metal, Δσ(2×10⁶)302 MPa as peened.