Peculiarities Formation of Welded Joints under the External Electromagnetic Influence

Abstract

Controlling the movement of liquid metal by selecting the parameters of an external electromagnetic effect makes it possible to change the conditions of dynamic equilibrium of the weld pool and, as a result, the formation of a weld. Magnetic process control has advantages over mechanical control methods, since it is carried out without contact with the welding zone. The study of processes leading to a decrease in the concentration of defects in metals, recombination of dislocations, polygonization, recrystallization, defect healing, etc., is an urgent task for technologists. The purpose of the work is to study the laws of formation of phase composition, microhardness, grain, lath, subgrain, dislocation structures of low-alloy steel welds in underwater welding and the relationship of structural parameters with the properties of strength and crack resistance of these joints. Microstructure studies were carried out by light, scanning, and transmission electron microscopy. Mathematical modelling was carried out to optimize the research efficiency. The developed computer application implements the idea of sequential calculation of quantities, where the value of the welding current and the current in the inductor is selected by the researcher. The influence of structural factors at the dislocation level on local internal stresses, which determine the deformation localization zones in the structures of the upper and lower bainites in the deposited metal, is analyzed. The conditions for obtaining high-quality welded joints in the welding of low-alloy steels, which ensure their strength and crack resistance, are established.