Elevation of the Fatigue Resistance of Welded Joints by Controlled Synchronization of Electrodynamic Actions

To use contemporary welded transport structures made of alloys based on aluminum, it is necessary to develop new promising methods aimed at extending their service life. As one of these methods, we can mention the procedure of electrodynamic treatment (EDT) aimed at increasing the durability of structures by optimizing the stress-strain state in the zone of expected fatigue fracture. By applying the microprocessor control in the process of two-channel electrodynamic treatment, we can increase the efficiency of treatment due to the controlled synchronization of the components of electrodynamic actions as compared with the efficiency of single-channel treatment. In the course of fatigue testing of the experimental welded samples of AMg6 aluminum alloy for a cyclic amplitude 2σ a = 80–160 MPa, both electrodynamic treatments make their durability N 2.0–2.4 and 2.2–2.7 times higher, respectively, despite the fact that the two-channel treatment is realized with a threefold lower power consumption than the single-channel treatment. Due to the fact that the passage of current pulses through an experimental sample in the course of two-channel electrodynamic treatment becomes impossible, the parameter N becomes 1.5 times lower than in the case of electrodynamic treatment performed with the passage of current; this is connected with the absence of the influence of pulsed electric component, which intensifies the relaxation of residual welding stresses caused by electroplasticity. The two-channel electrodynamic treatment of the weld and the line of fusion doubles the value of N as compared with the corresponding value obtained for EDT solely of the weld. This is explained by the propagation of the zone of compressive stresses to the line of fusion, which results in a smaller range of cyclic stresses than in the case of EDT solely of the weld.