Labur T. Technological fundamentals of providing the reliability of welded joints in structures of flying vehicles of plate aluminuim- lithium alloys.

Object of study are welded joints on typical elements of components of high-strength aluminium-lithium alloys 1421 and 1460. The purpose of study is provision of scientific substantiation of the effectiveness of technological methods to guarantee the reliability of welded joints on typical elements of flying vehicle structures of sheet aluminium-lithium alloys. The methods include physico-mechanical testing, numerical methods of fracture mechanics, structural analysis methods such as fractographic, metallographic, X-approximation and optical coherent Fourier analysis, computer technology methods. The result of the study are tecnological recjvvendations on substantiation of rational welding conditions, ensuring a high quality of the welds and 12-20% improvement of the joint reliability parameters. A scientific-practical problem of development of modern and advanced welded structures of flying vehicles with improved tactical-technical characteristics was solved. The novelty consists in that for the firsttime, in keeping wth the concept of reliability of welded joints of flying vechicle structurea, a systemsc integrated investigation has been performed and scientific substantiation has been provided for the influence of the main process factors (heat input, cjvposition of base metal and filler wire, weld shape, individual defects, thermal and thermomechanical treatment) on the structure and properties of joints of aluminium-lithium alloes 1421 and 1460 in arc (consumable and nonconsumable tltctrode) and electron beam welding/ These recommendations were the basis to determine the rational conditions of welding, composition of the base and filler material, sequenceof process operations to form sound welded joints and to provide the required working functions in operation. Applications are in aircraft and rocket construction plants.