Submerged arc welding process: a numerical investigation of temperatures, displacements, and residual stresses in ASTM A516-Gr70 corner joined samples

Abstract

Arc welding processes represent an important category of fusion welding techniques. They are characterised by the use of an electric arc to create heat to melt and join metals. Submerged arc welding belongs to this process category. Its peculiarities are mainly related to the employment of a continuously fed electrode and of a powdered flux to cover the arc providing electrical conduction between electrode and metals to be connected and, at the same time, generating protective gas and slag shields. Current (I), voltage (V), and welding speed (v) are the main process variables, properly set, to guarantee the specific heat (SH) required to achieve sound weld beads. In this research, finite element models were built looking at the macrographs extracted by experimental tests performed in two steps in order to obtain the real area of each pass and setting different welding conditions. Different combinations of I, V, and v were proposed providing, however, a fixed SH to the welding zone according to the required industrial standards. Specifically, tests were executed increasing the ratio V to v (for a constant I) and the ratio I to v (for a constant V) and with a different combination of V and I maintaining constant their product (for a constant v). The influence of the investigated variables’ combination on the weld pool in terms of depth and width was discussed. Finally, the validated numerical models were employed to highlight precisely residual stresses and displacements trend on cross-sectioned weld beads connecting the shown tendencies to the investigated process conditions.