Fatigue Life Improvement of Welded Joins with Accumulated Fatigue Damage by Surface Plastic Deformation

The fatigue life of butt and T-joint welds made of 09G2S steel, subjected to high-frequency mechanical impact (HFMI) treatment, has been investigated for both as-welded joints and those with accumulated fatigue damage. The fatigue tests have determined that the residual fatigue life of the welded joints treated with HFMI after accumulating fatigue damage is influenced by both the level of accumulated damage and the maximum cyclic stress applied before and after the treatment. The efficiency of HFMI treatment in terms of extending the residual fatigue life of welded joints with accumulated fatigue damage has been quantitatively evaluated.