Analysis of residual stresses and variation mechanism in dissimilar girth welded joints between tubular structures and steel castings

The application of cast steel nodes for the welded joints between hollow section structures provides a novel joining method in engineering projects. Its great advantages are the significant improvement of safety and ease of fabrication geometries. The mechanical behavior of welded connection between steel castings and tubular members becomes critical and complicated because of the combined effects of asymmetry of welded detail and mismatch of base material properties. Welding simulation procedure is established in presented paper based on thermal elastic-plastic theory, and verified by corresponding experimental studies. A typical geometry of dissimilar welded joint between steel castings and circular hollow sections is analyzed for the comprehensive understanding of welding residual stress and temperature field in such special dissimilar welded joint. The special distributions and formation laws of residual stresses are revealed considering the combined influence of asymmetrical welded detail and dissimilar base materials. Analysis of different types of welded joints contributes to understanding the impact of welded details on residual stress formation. The results conduct that residual stress profiles and mechanical behavior are out of the expectation based on the knowledge of ordinary girth-welded joint owing to the combined influences of asymmetry geometry of welded joints and dissimilarity of parent materials. Since the dominant effects of asymmetrical geometry of this dissimilar welded joint, residual stress in steel castings is larger than that in hollow section members with higher yield strength. The mechanical behavior of such dissimilar welded joint is essentially different from that of ordinary girth-welded joint.