STUDY OF THE PECULIARITIES OF THE LASER WELDING OF ALUMINIUM BASED COMPOSITE MATERIALS

Abstract

The paper considers the problem dealing with the development of the methods of the laser welding of new light composite materials of the increased strength on the base of the aluminum allows, having fiber, dispersive and layered strengthening. Obtaining of their permanent joints requires the application of such innovation solutions, which can be efficiently implemented in industry. One of the solutions may be laser welding process.

The paper studies the characteristic features of the laser welding of the aluminum- based composite materials, necessary experiments for the development of the technological methods for the obtaining qualitative joints were carried out. It is established that among the parameters of the aluminum-based composite materials structure the volume part of the fiber material in the matrix greatly influences the welding process. Analysis of the results of studies shows that when the content of fibers is higher than 30% the welding process becomes more complicated. Main obstacles for the formation of the qualitative joint are high heat input and difference of melting temperatures of the composite materials. As a result of the intensive heating there exists the probability of the fibers destruction and formation of the intermetallidic compounds. The quality of the permanent joints, obtained by fusion welding can be improved by means of strict dosing of the heat input. The studies, carried out allowed to determine the characteristic features of the laser welding of the aluminum-based composite materials, which have matrix filler of different types .It was established that the presence of boron fibers on one hand improves welding properties of the aluminum composite and allows to obtain sound welds but on the other hand-worsens the mechanical properties of the obtained joint. Dispersed alloying of the aluminum composite with the particles of Al₂O₃ leads to the formation of the pores in welded joint, obtained by laser welding. Presence of the steel fibers improves the welding properties but leads to the formation of the intermetallidic compounds. For joining the composites with the binders in the form of the fibers or separate particles it is necessary to use additional technological methods, for instance, welding-soldering. This type of welding is recommended to perform with maximum possible speed (to reduce specific energy intensity). Another special method for welding aluminum composites of all the considered types is the application of the repetitively pulsed radiation with the frequency within the range of 200 – 330 Hz, and relative pulse duration of 1.5 and welding with the aluminum adaptor or welding on the back-up plate with the gap between the ends ~0,6 mm and its filling by means of the filler wire fusion.