The influence of surface preparation on weld quality in MIG welding of aluminium alloy 6060 T66

V magistrskem delu je predstavljeno varjenje MIG aluminijeve zlitine 6060 T66, ki je imela z različnimi načini odstranjeno oksidno plast, varjenje teh izdelkov pa je trajalo med nič in deset dnevi po odstranitvi plasti. Začetek diplomskega dela obsega teoretične osnove varjenja MIG, s poudarkom na postopku CMT, ki je bil uporabljen pri eksperimentu. Predstavljena je delitev aluminijevih zlitin, njihove lastnosti in uporaba, poudarek pa je na varivosti materialov in vplivu oksidne plasti. Namen eksperimentalnega dela je ugotoviti vpliv načina priprave površine in časa po pripravi površine, ter vpliv varilnih parametrov na trdnost in kakovost izdelanega zvarnega spoja. Površine smo pripravili brez kemičnega čiščenja in s kemičnim čiščenjem. Eden način je bil kemično čiščenje s pasivacijo, drugi kemično čiščenje brez pasivacije, tretji način pa brez čiščenja površine. Nato smo jih varili prvi dan, šesti dan in deseti dan. Preverili smo tudi vpliv mastne oz. neočiščene površine in starega dodajnega materiala. Kakovost zvara smo spremljali z vizualno kontrolo zvara, na mikroobrusih s preverjanjem uvaritve ter z analizo poroznosti zvara. Rezultati, pridobljeni z izvedenimi eksperimenti in na osnovi teoretičnega znanja so pokazali, da so bili vzorci, ki niso imeli očiščene površine v dobrem dobavljenem stanju. Trdnost zvarnega spoja je bila približno enaka pri kemično čiščeni in nečiščeni površini vzorca. Naknadno čiščenje ni spremenilo kakovosti zvarnega spoja.The master’s thesis, the MIG welding of aluminium alloy 6060 T66 is studied. Welding samples were prepared with various methods of surface preparation and welding was done immediately after cleaning, after 6 days and after 10 days. In theoretical part MIG welding and CMT welding is presented. Aluminium Alloys are divided based on the chemical composition. Their properties, use and applications are presented and the influence od oxide layer on weldability is discussed. The aim of the experimental work was to determine the influence of the process of surface preparation and time elapsed after cleaning and before welding on the joint strength and quality of the welded joint. Surfaces were prepared without chemical cleaning and with chemical cleaning. One way was chemical cleaning with passivation, second was chemical cleaning without passivation, and third without cleaning the surface. We welded them on first day, on the sixth day and on tenth day after cleaning the surface. We also checked the influence of greasy uncleaned area and the influence of not properly stored welding consumable. The quality of weld was visualy inspected, on micrographs the with weld depth and depth of fusion was determined and porosity analysed. The results showed, that parts with uncleaned surface were in good condition. Strenght of welded joint was about the same at chemical cleaned and uncleaned surface. Such subsequent cleaning did not change quality of the welded joint