In the work, a mathematical description of thermal processes in laser welding with the use of the classical theory of thermal conductivity was performed. The thermal cycle under the action of radiation on the surface was analyzed using the models of overall heat balance, distributed surface, point, circular and linear heat sources. The modeling of welding process consisted in solving the problem of forming thermal fields in viscoelastic polymer materials at a moving inner heat source. It was assumed that the upper part is transparent to laser radiation and the lower one has a set coefficient of light beam absorption, and their thermophysical characteristics depend on temperature. The equations of thermal conductivity and defining equations were formulated, supplemented by the boundary conditions of convective heat transfer and the initial temperature distribution. For the numerical implementation of certain equations the finite element method was used, which is based on an alternative formulation of the problem. The results of mathematical modeling showed the peculiarities of the formation of thermal fields in the transmission laser welding of polymer films at different parameters of welding mode.

Samples of products of domestic nonspherical powders of VT-20 titanium alloy were produced by the method of electron beam 3D fusion. Microstructure of deposited metal is pore-free, finely dispersed and uniform over the entire surface of the section. It is acicular a′-phase of titanium with a small content of b-phase. Sample microhardness is from HV 3960 to HV 4150 MPa. Uniform distribution of alloying elements and decreased content of aluminium due to its volatility in deposition was noted. Presence of insignificant porosity and increased roughness on part edges was detected. The methods of their elimination were obtained. 10 Ref., 1 Table , 11 Figures.

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The process of hybrid laser-microplasma welding of sheet Ti Al titanium alloy of TC grade (up to 3.0 mm) was studied. The recommended technological parameters and conditions of laser-microplasma welding in an argon medium, physical and mechanical properties of welded oints were determined, and the presence of hybrid effect was established. 5 Ref., 3 Tables, 7 Figures.