Electrodynamic treatment by electric current pulses as effective method of control of stress-strain states and improvement of life of welded structures

Abstract

The present work was aimed at the development of the new technological process: a postweld electrodynamic treatment of welded joints by pulses of a high-density current. Basing on the numerical solution of Maxwell’s equations for the case of a pulsed electromagnetic field the calculation model of distribution of field components was designed on the basis of integral equations, which allow determining the electromagnetic forces P and current density j in aluminium alloy AMg6 during the process of capacitive energy storage discharge. The calculation data allow accounting for influence of dynamic stresses and electric plasticity effect on change in a stressed state of a metal during the electrodynamic treatment. Comparison of calculated and experimental results showed a good correlation of the obtained data. Using the model, the parameters of the electrodynamic treatment, providing the reduction of residual stresses in welded joints of alloy AMg6, were determined. Generators of the pulse current and electrode devices, realizing the preset parameters of electrodynamic effects at single- and two-channel schemes were designed and manufactured. Results of experimental investigations, carried out on specimens of base metal and welded joints showed that the electrodynamic treatment has a positive effect on structure of the treated metal and allows decreasing greatly the residual stresses in welded joints, increasing their resistance to fatigue and brittle fracture, as well as eliminating the distortion deformations in thin-walled elements of structures. The developed technologies and equipment gave an opportunity to perform the electrodynamic treatment of welded joints of hull structures of ships of aluminium alloy AMg6 and repair welds of an intermediate casing of the aircraft engine of heat-resistant magnesium alloy ML10, thus promoting the increase in their service reliability and life.