Fatigue life prediction of 316L stainless steel weld joint including the role of residual stress and its evolution: Experimental and modelling.

• The underlying mechanism of relaxation and redistribution of residual stress under cyclic loading were analyzed. • The correlation between redistributed residual stress and fatigue fracture behavior was discussed. • The role of residual stress on the fatigue performance of weld joints was revealed. • A fatigue life prediction model of weld joints was proposed by considering the residual stress and its redistribution. Weld residual stresses have a great effect on the fatigue strength of welding structures. As an internal stress, the residual stress is unfounded to be treated as the conventional mechanical load during the fatigue safety assessment due to its relaxation and redistribution under cyclic loading. Thus, establishing an accurate model considering the effects of residual stress is critical for fatigue strength design. Therefore, this paper develops a sequential coupling residual stress analysis and a cyclic viscoplastic constitutive model to predict the residual stress evolution and its role on the fatigue life, which has been validated by an experimental measurement of residual stress and a SEM-based observation fatigue fracture morphology. The results show that the role of residual stress on fatigue life is mainly reflected by the increase of mean stress, and its increased magnitudes depends on the stress redistribution. The redistribution of residual stresses is closely correlated to the fatigue fracture behavior of weld joints. And a fatigue life prediction model of weld joints is proposed based on the experimental data of base metal by further considering the residual stress and its redistribution. Finally, the experimental results verify the proposed model on predicting both the fatigue failure location and lives of weld joints, and the predicted lives are within the 1.5 error band. [ABSTRACT FROM AUTHOR]