Stress-Strain State of Welded Joints of AMg6 Alloy after Electrodynamic Treatment During Welding

According to the results of research, it is established that electrodynamic treatment (EDT) of butt welded joints specimens leads to the transition of residual tensile welding stresses to compression. A mathematical model of the mechanism of impact interaction of the electrode-indenter with the welded plate of AMg6 alloy at EDT at elevated temperatures was developed. The problem was solved in a flat two-dimensional Lagrangian formulation using the ANSYS/LS-DYNA program. The thermal cycle of welding was set by the mechanical characteristics of the AMg6 alloy at temperatures of 150 and 300°C. The results of the calculation of residual stresses under the impact action of the indenter electrode at room and elevated temperatures in prestressed tensile plates of AMg6 alloy with a thickness of 3 mm are presented. The experimental verification of the residual stress-strain state using the method of electron speckle interferometry confirmed the results of mathematical modeling, namely, the reduction of tensile stresses and the increase of compressive stresses in the weld after EDT at a temperature of T = 150°C compared to EDT at T = 20°C. It is shown that the most acceptable (from the investigated temperature values) for EDT of AMg6 alloy is the temperature of 150°C. It is proved that EDT of specimens of butt joints made of AMg6 alloy in the process of TIG welding increases the accuracy of their manufacture, which is characterized by a decrease in the level of their residual longitudinal grooving in comparison with EDT after welding. It has been established that EDT of butt joint specimens made of AMg6 alloy in the process of TIG welding contributes to the optimization of their stress states, which is characterized by an increase in the level of residual welding compressive stresses in the weld compared to EDT after welding.