Assessment of Magnetically Impelled Arc Butt Welded Dissimilar Boiler Graded Steel Tubes: SAE213 T11 and SAE213 T91

Dissimilar SAE 213 T11 and SAE 213 T91 boiler graded steel tubes are welded using magnetically impelled arc butt welding (MIAB) process, a hybrid welding process that combines the advantage of solid state and pressure welding technique. In this research, dissimilar tubes with an outer diameter of 44.5 mm and thickness of 4 mm with a length of 250 mm were joined by using the MIAB welding process. The microstructural behavior and changes of MIAB welded T11 and T91 tubes were analyzed at different zones of the butt-welded tubes using the metallurgical microscope and scanning electron microscope. Micro-Vickers hardness and potentiodynamic polarization test and radiographic testing were conducted. The hardness was taken at different zones along the transverse direction of the join. In the weld interface, the formation of a 2-3 µm martensitic structure leads to the hardness value of 281HV1, and at the base metal of T11 is 217HV1, T91 is 254HV1. The bead width at the welded region is approximately 10-12 µm with the narrow heat-affected zone. The metallurgical bonding between the T11 and T91 dissimilar tubes shows sound joint, which is confirmed with the radiography test.