Special aspects of recording thermomechanical impact processes during high-voltage capacitor discharge welding

The application of hybrid technologies allows improving welding productivity by reducing welding material consumption, edge preparation time, heat input, and, consequently, the probability of crack formation. Welding of dissimilar metal combinations (copper – aluminum) is best performed using pulsed processes at temperatures below the melting point. A high-voltage capacitor welding process has been developed at Don State Technical University. This process combines several stages: electroerosive cleaning during the burning of an electric arc between the weld surfaces, the convergence of the parts, and the splashing of molten metal from the weld zone followed by plastic deformation of the juvenile surfaces. Thermal force impact on the welded parts is implemented by connecting sequentially the upset mechanism together with the welded parts into the discharge circuit of a pulse current generator, with the total duration not exceeding 200 μs. The discharge circuit parameters (inductive and active resistance, capacitance) were selected to enable welding by means of a damped sinusoidal discharge and to ensure the necessary process energy parameters (capacitor bank capacitance and voltage) and the strength characteristics of the welded joint. A temperature measurement technique based on recording spectral radiation during arcing was developed, which allows evaluating the thermal component of the welding process. Following pressures were calculated: magnetic pressure, pressure generated by the upset mechanism, pressure of molten metal vapor, and impact pressure. Methods for recording the temperature and pressure in the welded parts during impact and plastic deformation were developed. The obtained results allow evaluating the feasibility of joining parts of different thicknesses and heterogeneous combinations of non-ferrous metals during the development of the welding process.