RESEARCH ON VARIABILITY OF PHASES IN STRUCTURE OF METAL OF WELDED JOINT

Abstract

The work has developed a new method of assessment of degradation, by determining the degree of heterogeneity of the structure of metal of welded joints, which occurs in the production and prolonged operation of responsible equipment, which is intended for work in difficult conditions of high pressures and temperatures, on the example. The basis of the proposed method is the method of research of metlographic image using optical and mathematical analysis. Given the complex structure of such structures, in the work as a criterion for the evaluation of the formed heterogeneity of the metal of the welded connection, a new parameter is proposed – the variability of phases. To evaluate variability, both in the boundaries of one grain and separate phases, the image of microstructures of different areas of weld metal is investigated: areas of weld, thermal exposure and main metal. The identification of patterns on the degradation of the structure of welded joints was carried out by calculating correlation dependencies, taking into account the values obtained in the construction of histograms of distribution of combinations of conditional colors (phase groups) and their variability. The developed approach to assess the cause and nature of degradation processes of different sections of welded metal connection can be used effectively in the development of new complex production technologies and restoration of thermal power equipment, which will allow to extend its life, to promote economy, reduction of costs for repair and operation.