Abstract
The influence of welding residual stress on fatigue crack propagation behavior of welded joints has been investigated for decades whereas a common consensus has not yet been achieved. This paper has presented our attempt in quantifying welding residual stress redistribution and its contribution to fatigue crack propagation behavior. A well-characterized welding residual stress distribution in a bead-on-plate high strength steel welded joint attained in previous work has been used to study its effect on fatigue crack propagation behavior. Middle tension specimens with identical longitudinal bead-on-plate weld beams have been employed for welding residual stress redistribution measurement and fatigue crack propagation testing. Novel concept of “Elastic redistribution” and “Plastic redistribution” of welding residual stress under cyclic loading has been proposed and their quantified contribution on fatigue crack propagation has been clarified separately by a newly defined effective driving force parameter. Meanwhile, effect of welding residual stress on plasticity induced crack closure has also been investigated by FEM via node release scheme with the help of previously measured crack closure data, and has been subsequently incorporated into the proposed effective driving force parameter. It turned out that the correlation of the fatigue crack propagation rate data under several applied stress ratios was more reasonable for the investigated high strength steel welded joint employing the proposed effective driving force parameter compared with the existing assessment procedure to consider welding residual stress.
