Uticaj parametara zavarivanja trenjem - miješanjem na otpornost prema lomu suočenog spoja legure aluminijuma visoke čvrstoće

Abstract

U disertaciji je predstavljen postupak spajanja topljenjem nezavarljive legure aluminijuma EW AN 7049A u stanju T 652 postupkom zavarivanja trenjem - miješanjem. Korišćenjem pet različitih tipova alata za zavarivanje, varijacijom brzine zavarivanja i broja obrtaja, zavareni spoj dostiže efikasnost od 70% do 80 % zatezne čvrstoće osnovnog materijala. Karakterizacija zavarenog spoja izvedena je standardnim metodama za eksperimentalno određivanje energije udara i udarne žilavosti na Charpy epruvetama, a ispitivanja mehanike loma zavarenih spojeva savijanjem u tri tačke SENB epruveta (ASTM E 1820), poprečno na pravac zavarivanja u zoni najviše pogođenom termomehaničkim uticajem alata. Kriterijumima elasto-plastične mehanike loma ( CTOD-otvaranje vrha prsline i J- integrala) utvrđena je veća otpornost prema širenju prsline u različitim mjestima zavarenog spoja (centru, strani napredovanja i na povratnoj strani metala šava) nego u osnovnom materijalu.

The thesis presents the procedure of joining by melting of unweldable alloy of Al EW AN 7049A of status T 652 by the procedure of friction-stir welding. By using five various types of tools for welding, variation of welding velocity and number of revolutions, the welded joint shall reach the efficiency of 70% -80% of tensile strenght of basic material. Characterization of welded joint was made by standard methods for experimental determination of impact energy and impact toughness on Charpy tubes, and breakage mechanical properties by bending in three points of SENB tubes (ASTM E 1820), transversely to direction of welding in the zone of highly affected thermo mechanical impact of tool. Criteria of elastoplastic mechanics of the fracture (CTOD crack opening displacement and J-integral) determined bigger resistivity to cracking at various locations of welded joint (center, side of advancing and on retreating side of the seam metal) than on the basic material.