The technological regimes of welding that promote uniform distribution of the properties over the length of a welded joint are studied by numerically modeling the formation of a weld seam by a nonmeltin 9 electrode.Introduction. The advent of program-controlled pulsed power sources has recently opened up fundamentally new possibilities in the development of the technologies of welding and welding-assisted deposition on the basis of a dosed energy supplied by an electrical arc according to a given algorithm.It was found empirically [1, 2] that in definite pulse regimes, one can observe some positive phenomena during the formation of a single-piece joint. In particular, metal evaporation from a melt of a welded bath and the zone of thermal effect (ZTE) decreases, the defects in the welded joint become smaller in number, and the internal structure of the weld seam and the ZTE become more uniform. This contributes to the increase in the strength of the single-piece junction. It is assumed that these effects are attributed to the processes of self-arrangement of the substance [3, 4]. Knowledge of the reasons for and the basic features of the self-arrangement of the substance would allow one to design technological processes of welding that ensure the best operational characteristics of the welded joint. It is noteworthy that the pulse-arc technologies of welding are a complex object of the physical and mathematical modeling due to the great variety of the electromagnetic, thermal, chemical, mechanical, and other phenomena pertinent to the technological cycle. In view of this, it is of interest to develop and study some of the basic mathematical models of the pulse-arc welding processes, which most affect the final properties of the welded joint. One of them is the interaction between the electrical arc (as a source of the concentrated thermal energy) and the object to be welded, because the energy supply determines the width and depth of the melted zone, the ZTE dimensions, and the crystallization and the recrystallization in the weld seam and the near-seam zone, which in turn determine the internal micro-and mesostructure.In this work, we numerically solve the spatial dynamic problem of the heat conduction in the pulse heat supply from a moving source of heating (the arc). The effect of the frequency of pulses and the rate of welding on the formation of the thermal pattern in the junction of two steel plates of finite sizes is studied.Formulation of the Problem. Generally, the system of equations which describes the interaction between the electrical arc and the butt-weld plates includes the following equations:9 The spatial heat-conduction equation
