Kuz'menko V. Thermodynamic and structural aspects of selection of structures of fluxes for arc welding (Fundamental theory of fluxes of a neutral type)

The thesis is dedicated to development of fundamental theory of selection of structures of fluxes for electric arc welding. In this paper the causes of impossibility of obtaining high-quality welds using only "acidic" or only of "basic" welding fluxes, conditioned by antagonistic nature of physics-chemical processes in separate zones of a welding bath, are established. Using the results of thermodynamic and X-ray diffraction investigation of slag melts the fundamental theory of selection of neutral flux compositions with optimised technological properties are designed. At the general contents in fluxes of complex oxides SiO2 and Al2O3 equal 40 - 65 % and balanced presence of oxides - stabilizers of structure, such as МnO, TiO2, ZrO2, good technological characteristics of welding process an high mechanical properties of welds are provided. When it is necessary to obtain extra-high mechanical properties of a weld material, including toughness at low temperatures, the contents Al2O3 in such fluxes shouldprevail. The examples of application of such fluxes in an industry are adduced.