CMT welding of zinc coated steels

Završni rad podijeljen je na dva dijela, teorijski i eksperimentalni. U teorijskom dijelu rada opisan je i analiziran CMT - Cold Metal Transfer prijenos metala u električnom luku. Opisan je princip rada CMT postupka, navedene su karakteristike i prednosti CMT postupka, glavna područja primjene postupka, te ograničenja primjene. Navedena je i oprema koja se koristi pri zavarivanju ovim postupkom. Dan je kratki opis svojstava cinka kao tehničkog materijala i nabrojane su prednosti zaštite od korozije pocinčavanjem. Navedeni su najčešći postupci pocinčavanja i ukratko opisani. Ukratko je opisana i procedura pripreme materijala za pocinčavanje. U eksperimentalnom dijelu rada CMT postupkom su zavarena tri para pocinčanih limova, sa različitim debljinama cinkove prevlake. Opisan je sami tijek eksperimenta, navedeni su tehnički i tehnološki podaci o radnim komadima i samom postupku zavarivanja. Nakon zavarivanja, svaki od 3 zavarena uzorka je rezan na pili kako bi dobili makroizbruske, da bismo potom utvrdili koliki je utjecaj na zaštitni sloj cinka uslijed zavarivanja.The thesis consists of two parts, the theoretical and the experimental part. In the theoretical part of the thesis, the CMT – Cold Metal Transfer is described and analyzed. The work principle of the CMT process, the characteristics and advantages of the process are described. Main areas of application and limits of the process are also stated. Furthermore, the welding-system used for the CMT process is described. A brief description of the material zinc and its technical properties is given, with the advantages of using galvanization to protect steel sheets. Most common procedures of galvanization are listed and described, as well as the preparation procedure for the sheets to be galvanized. In the experimental part of the thesis, three pairs of galvanized steel sheets, all with different coating thicknesses, are welded using the CMT process. The course of the experiment is described, technical and technological data about the work piece and the process itself are stated. After the welding process, each of the three welded samples was cut using a saw in order to get macrographs of the welded and etched samples, so we could determine how much of an influence the welding process had on the cink coating