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The possibility of welding in the hard state of tubular connections from titanium and copper with application of electrohydraulic pulse beading and postheating in the narrow temperature-temporal range of the parameters of the process was showed experimentally. The index of the compactness of the obtained joint weld takes on values of 79.3 ± 12.4% here, and the fastness on the cut is at the level of the copper fastness. Formation of metallic connections on the lager part of the contact surface supports the receipt of reliable electric contact on all the surfaces of the joint.

Presented are the results of engineering process of welding of plates from dissimilar metals (steel 20 + copper M1) under conditions of passing of high-density current pulses. Pulse current generator GIT-50, developed in the Institute of Pulse Processes and Technologies of the NAS of Ukraine, was used for welding processes activation. Application of complex investigation method allowed determining that different stages of the process of welded joint formation take place on a contact interaction surface of macroscopic size. It is caused by inhomogeneity of the real surfaces of solid bodies even at high class of their treatment. The results of examination of steel surface fine structure indicate that treatment of the preliminary compressed plates with the high-density pulses results in significant activation of the dislocation transformations, having significant effect on development of the third stage of solid state welding process, i.e. stage of volumetric interaction. 7 Ref., 2 Figures. K e y w o r d s : welded joints, dissimilar materials, high-density current pulses, contact zone, electron microscopy, dislocation structure, activation of contact surfaceBimetallic joints, i.e. joints consisting of dissimilar on their properties metals and alloys [1,2], are widely used in recent time in different products of current engineering. This allows using in full scope the specific properties of each of them as well as reducing the consumption of expansive and scarce metals and obtaining the parts with high service properties. Since the majority of combinations of dissimilar metals and alloys are characterized by different physical-chemical properties, it is clear that such type of differences will result in significant difficulties in receiving their quality welded joints, in particular, under fusion welding conditions. Therefore, different methods of pressure welding are used for performance of such types of dissimilar joints.The necessary condition of welded joint formation for any method of pressure welding is a plastic deformation of the materials being welded [3,4]. However, in some cases the processes of plastic deformation appear to be frozen due to high resistance of corresponding material to deformation. Then the special methods are used intensifying further deformation development. One of the methods, which has found application in industry, is a high-density pulse current (~ 10 9 A/m) impact of the deformed metal [5]. Earlier we have proved an activating effect of current pulses on plastic deformation of the preliminary compressed plates of similar materials (such as steel 20 + steel 20) under effect of high-density current pulses in pressure welding [6].However, now scientific-and-technical literature contains no information on processes, taking place in the near-contact zones of metal of joined plates from dissimilar materials under such effect.An aim of this work is to study an effect of high-density current pulses on the processes promoting activation of the contact surfaces of steel 20 + copper M1 dissi...

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