DEVELOPMENT OF A COMBINED TECHNOLOGY WITHOUT DEFORMATION WELDING OF ALUMINUM ALLOYS BASED ON THE ACTION OF EXTERNAL ENERGY INFLUENCES

The development of high-tech industries encourages an increase in requirements for metal materials, a complex of their main and special properties, and methods of their one-piece connection

The development of high-tech industries encourages an increase in requirements for metal materials, a complex of their main and special properties, and methods of their one-piece connection.
In recent years, in domestic and international engineering practice, special attention has been paid to the study of the influence of external energy influences on the mechanical characteristics of structural materials. Promising directions for optimizing the performance characteristics of parts and assemblies in various branches of technology are modeling the mechanical properties of structural materials during their processing by the combined action of shock load pulses and electric current (IEC). Electrodynamic processing (EDP) is a new technological process that combines shock and electric pulse processing. EDP is based on the effect of electrodynamic forces on conducting materials during the passage of IEC. By changing the duration and energy of the IEC and the stress waves initiated by them acting on elements of metal structures under EDP, as a result of activation of dislocation and deformation mechanisms, it is possible to adjust the stress state and mechanical characteristics of structural materials [1,2]. The mechanism of action of EDP is based on the formation of plastic tensile deformations, the interaction of which with residual plastic compression deformations in the welded joint helps to reduce residual tensile stresses, improve the accuracy and durability of structures. The use of EDP helps to strengthen and disperse the metal structure due to electroplastic deformation, which increases the mechanical properties of the processed material.
The purpose of the work is to develop scientific bases for regulating stressstrain States and improving the mechanical characteristics of welded joints of light alloys due to the combined use of electrodynamic influence and welding, to develop Currently, Ukraine and the world have not conducted studies of the local thermal effect and the effect of the thermal deformation cycle of welding on the efficiency of regulating the residual stress-strain States of metal materials and welded joints using EDP.
Until now, there was no technology or equipment for the joint combination of EDP with Fusion welding. Taking into account the peculiarities of the process, it is relevant to develop an original electromechanical device for implementing EDP in the conditions of the thermal deformation welding cycle. In order to solve this problem, variants of kinematic schemes have been developed that ensure synchronization of the EDP process with the movement of the welding torch.
The influence of the thermal welding cycle at EDP on the residual shape changes of flat samples made of Amg6 alloy was evaluated. As prototypes, welded plates with dimensions of 400x140x2 mm were used, which were rigidly fixed on the harvesting table. The plates were welded by the Tig method along the central longitudinal axis with the accompanying EDP of the cooling seam metal. After welding, processing and complete cooling of the plates by electronic speckle interferometry, the longitudinal (along the seam line) component of the frequency response of residual welding stresses and residual shape changes of the samples were evaluated.
The study of the stress-strain state of the metal after Edo at different values of the processing temperature (T°EDP) allowed us to choose the optimal distance between the burner and the EDP -L electrode, at which the maximum efficiency of the processing process is achieved under welding conditions ( fig.1). The parameters of the welding mode are crucial for the values T°EDP and L, which affect the processing efficiency. An experimental method was developed and the process of butt argon-arc (TIG) welding of thin-sheet structures with a thickness of 2 mm made of aluminummagnesium alloy, synchronized with simultaneous electrodynamics treatment (EDP) in the area of the thermal welding cycle was tested. The combined effect of the thermal cycle of TIG welding and the effect of pulsed EDP current on the residual welding stresses of butt joints made of aluminum alloy AMg6 is evaluated.
It is shown that the thermal deformation welding cycle has a positive effect on the efficiency of EDP in regulating the residual shape changes f of prototypes. It is noted that EDP in the welding process in comparison with EDP on the finished joint at room temperature provides a decrease in f values by 50 and 20%, respectively.
It is established that the synchronous combination of argon-arc welding with EDP in the framework of a single operation for obtaining a butt joint provides a superposition of local thermal and non-thermal mechanisms of influence, and is more effective in terms of reducing internal stresses, compared to the EDP of the finished weld at normal temperatures.