Development and characterization of fluxes for submerged arc welding

Abstract

Submerged arc welding (SAW) is characterized by its high reliability, deep penetration, smooth finish and high productivity especially for welding of pipes and boiler joints. A significant percentage of the flux used in submerged arc welding gets converted into very fine particles termed as flux dust due to transportation and handling. If these very fine particles are not removed from the flux before welding, it may results into defect like surface pitting and porosity. At the same time dumping of this flux dust will create pollution. Therefore to reduce the cost of welding and pollution, in the present study, attempts have been made to investigate the feasibility of using developed agglomerated flux by utilizing wasted flux dust in place of parent commercial flux. The chemical composition, tensile strength, toughness, radiographic examination, microstructure and micro hardness of the all weld metal prepared by using the developed flux as well as same parent commercially available flux were compared. These properties for the all weld metal prepared by using the developed flux were found to be in the same range as that being prepared from the parent flux. Mathematical models have been developed for SAW using developed fluxes, prepared from waste flux dust. Response Surface Modelling has been used to predict critical dimensions of the weld bead geometry which affect the load carrying capacity of the weldment. The ANOVA technique has been adopted to check the level and degree of the direct or interactive effect of process variables like welding current, open circuit voltage, welding speed and flux basicity index on the bead width and flux consumption. Main and interaction effects of the process variables on bead geometry are presented in graphical form, using which not only the prediction of important weld bead dimensions but also the controlling of the weld bead quality by selecting appropriate process parameters values is possible. Thus, this work tries to utilize the concept of waste to wealth.