STUDY ON IMPROVEMENT METHOD OF FATIGUE STRENGTH OF WELD JOINTS BY HAMMER PEENING ON BASE METAL

Abstract

 This paper provides a new hammer peening technology which makes it possible to increase the fatigue strength of welding joints more certainly than before. This hammer peening procedure of applying plastic deformation only to the base material near weld toe enables compressive residual stress to be introduced into the weld toe. In this study, a method which calculate improvement volume of the fatigue strength from required plastic deformation volume after new hammer peening treatment is proposed, based on defining the interrelationships among the compressive residual stress at weld toe, the plastic deformation after peening treatment and the fatigue strength on the fatigue test results of welding joint specimens, and FE-Analysis results. Furthermore, we have performed the bending fatigue test of steel girder with welding joints to verify the validity of the fatigue test results of welding joint specimens.