Ultrasonic peening of girth welds on steel pipe St 590
Design and/or service stresses in welded structures subjected to fatigue loads are limited by the fatigue strength of welded joints. The relative poor fatigue strength of these weld joints can be attributed to the combination of three factors, always present at these locations: a) Local stress concentration due to geometrical discontinuity at the joint b) The presence of sharp crack-like flaws as undercut and slags due to welding itself and c) Large tensile residual stresses at the weld and heat affected zone, HAZ. These three factors are simultaneously modified by one working operation by ultrasonic peening.
