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Results of welding a wide range of light alloys by highly-concentrated heat sources have been analyzed. It is shown that the characteristic defects are hot cracks, internal pores, HAZ softening, weld sagging, undercuts and irregular reinforcement bead formation. It was found that in order to produce sound joints, it is necessary to thoroughly select welding mode parameters, remove the oxide film from billet edges before welding, ensure reliable protection of the weld pool, and in some cases and it is rational to apply preheating or concurrent heating. One of the advanced methods to minimize the susceptibility to formation of the above-mentioned defects is application of hybrid laser-arc and laser-plasma welding processes. The welds produced by electron beam and laser (СО2 - and fiber-optic lasers) welding processes are quite similar visually, by their macrostructure, as well as the main characteristics. The weld strength parameters and heat input required for full penetration of the metal are somewhat different for different welding methods (for fiberoptic laser it is usually 30 % less). 54 Ref., 3 Tabl., 8 Fig. [ABSTRACT FROM AUTHOR]

Light metal alloys (in particular, beryllium and aluminium) are applied in different engineering fields, for instance for fabrication of rocket and aircraft elements. When designing such engineering elements, there is the need to produce welded joints with different types of welds. Laser welding with nonthrough thickness penetration can be used for item sealing, welding-on flanges and welding thin-walled structures of up to 2-3 mm thickness. Toxic fumes form in welding beryllium alloys. Such a peculiarity requires reducing the number of technological experiments, aimed at selection of mode parameters. An up-to-date approach to solving the problem of light alloy welding is performance of preliminary calculated determination of mode parameters with their further experimental verification. Technological verification can be performed on high-strength aluminium alloys close by their physico-mechanical characteristics to beryllium alloys. Therefore, this work is devoted to preliminary determination of mode parameters of laser welding by a sealing weld with nonthrough thickness penetration of thin-walled flanges of cylindrical parts and box-shaped items from light metals and alloys based on Be and Al, taking into account the temperature of heating after welding. A procedure of preliminary calculated determination of mode parameters of laser welding of parts from a berylliumbased alloy is proposed in the work, which is suitable for both through-thickness and nonthrough-thickness penetration. Nonthrough-thickness penetration can be applied for welding-on flanges by a sealing weld. Experimental verification on samples from alloys of Al–Zn–Mg–Cu system and comparison with published data on beryllium alloy welding showed that the error of the proposed procedure is in the range of up to 15 – 20%. [ABSTRACT FROM AUTHOR]