Influence of the intermediate annealing temperature on the recrystallization temperature in foil from EN AW 8079 alloy

Večnamenska aluminijasta folija se proizvaja s postopki vročega in hladnega valjanja. Zaradi velikih sil trenja, ki nastopajo med valjanjem, se povzroča plastična deformacija materiala, kar pa vodi do nastanka dodatnih dislokacij, napetosti v materialu, povišanja trdote in trdnosti, posledično pa se zaradi tega manjša raztezek materiala. S pomočjo vmesnega žarjenja se teh napak znebimo, materialu pa povrnemo prožnost. Cilj diplomske naloge je bil ugotoviti vpliv vmesnega žarjenja na temperaturo rekristalizacije za zlitino EN AW 8079. Iz kolobarja pločevine smo odrezali dva vzorca in ju eno uro žarili pri temperaturi 350 °C in 450 °C. S programom Thermo-Calc smo, glede na analizirano kemijsko sestavo, ugotovili katere faze se lahko pojavijo v mikrostrukturi ter predvideli, kako na njihov pojav vpliva temperatura vmesnega žarjenja. Z diferenčno vrstično kalorimetrijo (DSC) smo ugotovili vpliv temperature na taljenje oziroma strjevanje zlitine. Z mikrostrukturno analizo smo analizirali vpliv temperature vmesnega žarjenja na velikost in porazdelitev mikrostrukturnih sestavin ter na velikost kristalnih zrn. Analizirali smo tudi sestavo faz, ki se tvorijo po enournem žarjenju kolobarja na 350 °C in 450 °C. Glede na vse rezultate smo zaključili, da je primernejša temperatura vmesnega žarjenja 450 °C.Multipurpose aluminium foil is made using techniques of hot and cold rolling. During this process, high friction causes plastic deformations of the material, which in turn leads to additional dislocations, tensions in material, higher hardness and toughness. Consequently, tensile strength of the material is lowered. With we can reverse these deformations with intermediate annealing procedure and thereby recover material\u27s flexibility. Goal of diploma thesis was to find out the exact effect of intermediate annealing on temperature of the recrystallization for EN AW 8079 alloy. We have cut two samples from a sheet metal roll and annealed them for an hour at temperature of 350 °C and 450 °C. Afterwards have we, using computer program Thermo-Calc and considering analysed chemical structure, found out which phases can appear in microstructure and predicted, how annealing temperature affects their appearance. We have established, using DSC analysis, effects of temperature on melting and coagulation of alloy. Using microstructure analysis we have analysed effect of intermediate annealing temperature on size and allocation of microstructure components and crystal grain size. We have also analysed composition of phases, which are present after an hour-long annealing of sheet metal roll at 350 °C and 450 °C. Considering all the results we have concluded that temperature of 450 °C is more appropriate for an intermediate annealing of aluminium metal sheet