Application of resistance spot welding in automotive industry

Završni rad je podijeljen u dva dijela, teorijski i eksperimentalni dio. U teorijskom dijelu rada klasificirani su i opisani najčešće primjenjivani postupci zavarivanja u autoindustriji s posebnim naglaskom na elektrootporno točkasto zavarivanje. Analizirani su parametri zavarivanja karakteristični za svaki navedeni postupak, te je dan osvrt njihovog utjecaja na geometriju zavara i kvalitetu samog zavarenog spoja. Navedeni su, također, i najčešće korišteni materijali u automobilskoj industriji, sa slikovnim prikazima dijelova konstrukcije, te je obrazložena zavarljivost pojedinih metala koji su implementirani u konstrukciju automobila. U eksperimentalnom dijelu rada provedena je priprema i elektrootporno točkasto zavarivanje ispitnih uzoraka izrađenih od čelika S235. Nerazornim i razornim ispitivanjem ispitan je utjecaj jakosti struje zavarivanja i vremena predgrijavanja kao promjenjivih parametara zavarivanja na kvalitetu i oblik zavarenog spoja, te je ocijenjena adekvatnost odabranih parametaraThe thesis is divided into two parts, a theoretical and experimental part. In the theoretical part of the thesis, the most commonly used welding procedures in the automotive industry are classified and described, with special emphasis on resistance spot welding. The welding parameters characteristic to each of these processes are analyzed, and a review of their influence on the geometry of the welds and the quality of the welded joint is given. The most commonly used materials in the automotive industry are also listed, with pictorial representations of parts of the structure. Weldability of metals that are implemented in the car structure is explained as well. In the experimental part of the thesis, the preparation and resistance spot welding of the specimens made of S235 steel was performed. Non - destructive and destructive testing was conducted in order to examine the influence of welding current value and time of preheating as variable welding parameters on the quality and shape of the welded joint. Adequacy of selected parameters was evaluated as well