Welding and Analysis of Joints between Zinc-Coated Sheet Metal and Aluminum Alloy

Cilj raziskave je bil predstaviti postopek izdelave in analizo zvarnih spojev med aluminijem in pocinkano pločevino. Teoretičen del zajema osnovno predstavitev uporabljenih načinov spajanja, MIG CMT in varjenje z gnetenjem (FSW). Na podlagi pregleda literature, so poleg zapisani tudi ostali uporabljeni postopki za spajanje aluminija s pocinkano pločevino, ki se jih poslužujejo v praksi. Praktični del zajema opise eksperimentov spajanja, ter opise preizkusov in analiz, ki smo jih izvedli za določitev kakovosti spoja. Prekrivni spoj aluminijeve zlitine AA 5086 in pocinkane pločevine s tremi različnimi debelinami cinka smo testirali na natezno trdnost, opravili smo meritev trdote po prerezu po metodi Vickers in izvedli metalorgrafsko analizo. Višjo natezno trdnost so dosegli vzorci varjeni po postopku MIG CMT. Zatem smo izvedli še elektrokemijske preiskave korozije in vzorce izpostavili v slani komori za 480 h. Na podlagi izvedenih preiskav smo ocenili vpliv varilnega postopka, vnosa energije in debeline nanosa cinkove plasti na kakovost izdelanih zvarov. Iz korozijski preiskav smo prikazali korozijsko odpornost spojev in opisali pojav, ter napredovanja korozije v slani komori. Višjo korozijsko odpornost po elektrokemijskih preiskavah so dosegli vzorci, ki so bili varjeni s postopkom MIG.This master\u27s thesis comprises a theoretical and a practical part. The theoretical part contains the basic presentation of the used welding methods, namely metal inert gas (MIG) cold metal transfer (CMT) and friction-stir welding (FSW). Based on the bibliographical sources, the theoretical part also defines other methods of welding aluminum to zinc-coated sheet metal that are used in practice. The practical part of the thesis contains descriptions of the welding experiments, tests, and analyses carried out in order to determine the quality of the joint. We tensile-tested overlap joints between aluminum alloy (AA5086) and zinc-coated metal with coatings of three different thicknesses, measured the hardness on the basis of a selected-sample cross-section, and carried out a metallographic analysis. In continuation, we also conducted an electro-chemical corrosion research, exposing the samples to a salt spray cabinet for 480 hours. On the basis of the research, we were able to estimate the effect of the welding method, energy intake, and the thickness of the zinc-coating layer on the quality of the metal joints. By means of corrosion research, we have demonstrated the durability of the joints and described the process of corrosion in a salt spray cabinet