Numerical and experimental studies on the effect of cryogenic treatment on welding residual stress of TIG welded EN8 steel plate

Abstract

Most of the conventional welding process induces Welding Residual Stress (WRS), hydrogen embrittlement and distortions to welded components. The post-weld mechanical behaviour has an impact on both structural integrity and operational effectiveness of the welded component. Traditional Post Weld Heat Treatment (PWHT) is capable of relieving WRS to some extent. Based on recent research, Heat Treatment (HT) cycles are comprised of conventional HT and Cryogenic Treatment (CT) gives better fatigue life to welded components by redistributing the residual stress field. There is a need for further research to explore the impact of different parameters of CT affects the mechanical behaviour of welded specimens. In this study, numerical and experimental investigations are conducted to understand the impact of HT cycles comprised of austenitizing, quenching, CT and tempering process, over the TIG welded EN8 plates. Numerical model is developed for predicting the variation in WRS with each stage of HT cycles and observed a considerable redistribution of WRS after the completion of proposed HT cycle. Using the proposed HT cycle, the influence of different soaking periods of CT over the welded components are studied experimentally and shows that 36 hours soaking period have higher impact on the welded component’s mechanical behaviour.