Effect of high energy density welding processes on inclusion and microstructure formation in steel welds

Inclusion formation and microstructure development in autogenous laser and electron beam welds made on a submerged arc weld deposit were investigated. Oxygen loss from the submerged arc wield metal deposit to the atmosphere occurred during electron and laser beam welding owing to the low pressure and helium shielding, respectively. Rapid weld cooling rates and changes in oxygen concentration resulted in different inclusion characteristics in these welds. The measured inclusion characteristics were compared with calculations obtained using an inclusion model. Acicular ferrite and bainitic microstructures were observed in electron beam welds, and predominantly martensitic microstructures were observed in laser welds.