Experimental and simulation analysis on the effect of vibratory stress relief on impact toughness of Q345/316 L dissimilar steel welded joints

Abstract

Vibratory stress relief (VSR) is residual stress relieving technology with the characteristics of green, energy-saving, and environmentally friendly. In response to the lack of research on the impact toughness of dissimilar steel welded joints under VSR, In this study, the law of the impact toughness of Q345/316 L dissimilar steel welded joints under VSR treatment is studied. Firstly, a platform-type VSR system is used to perform VSR treatment on the Q345/316 L dissimilar steel welded specimens. Secondly, Charpy impact tests are conducted on the specimens before and after VSR treatment, and the fracture morphology of the Q345/316 L dissimilar steel welded joints is observed based on scanning electron microscopy. Then, a numerical model of Q345/316 L dissimilar steel welding is established using ABAQUS finite element software, and the effect of VSR on the residual stress is analyzed based on the Hole-drilling method. Finally, based on the fracture morphology and residual stress evolution law, the mechanism of improving the impact toughness of Q345/316 L dissimilar steel welded joints under VSR is analyzed. The results show that VSR can effectively improve the impact toughness of dissimilar steel welded joints. The impact toughness of the welded joints after VSR increased by 26.2% compared to the untreated specimens. The residual stress of the specimens generally decreases, and the stress concentration phenomenon is alleviated. The fracture morphology exhibits a significant increase in toughness and an overall reduction in residual stress levels. Based on the comprehensive analysis of fracture morphology and residual stress state, it can be concluded that the reduction and homogenization of residual stress are the main reasons for the improvement of impact toughness.