Residual Stresses Induced in T Butt Welds from Submerged Arc Welding of High Strength Thick Section Steel Members

The overall residual stress profiles of a weld fabricated structures such as a submarine pressure hull fabricated using high strength welds joining quench and tempered steels is complex as they are the net profiles from the build-up or relaxation of the residual stresses induced into the welds and structural members from each step in the fabrication process. The University of Adelaide with its research partners has attempted to increase the knowledge of residual stresses in this type of structure by undertaking a comprehensive residual stress measurement program using test pieces representing each stage of the fabrication of a submarine pressure hull including full scale test pieces. The primary methods of measuring subsurface residual stress profiles was the neutron diffraction method with the Deep Hole Drilling technique (DHD) to validate key results. The X ray diffraction method and Incremental Centre Hole Drilling methods were used for determining surface residual stresses. This paper presents an overview of the results for residual stress profiles resulting from a full penetration double sided T Butt weld joining a T Frame to a thick flat plate by Submerged Arc Welding. The test piece used a specific pass placement strategy that placed the last pass each side on the base plate. The results presented show that the actual profile is considerably different than those for established fracture mechanics residual stress profiles in that these are over conservative. The discussion will include comparison of results to other measurement results undertaken on similar test pieces but undertaken with an alternate pass placement strategy.