Alexandru-Vladut Oprea*, Ion Mihai Vasile, Ionelia Voiculescu and Robert Catalin Ciocoiu
June 29, 2023
DOI : 10.56831/PSEN-03-061
Projection welding is a joining process based on the electrical resistance of metal components that have small protrusions on the areas where assembly is desired. In this case, the welding electrodes that ensure the transfer of the electric current have a flat geometry, which allows uniform pressing of the areas with protrusions, which have the role of ensuring the concentration of the current lines for the formation of welding points. Excessive deformation can cause the protrusions to collapse rapidly, causing greater dispersion of the current and limiting the effect of localized heating and melting, and welding no longer occurs. The process is widely used in the electrical, electronic, automotive, food and construction industries, etc. The paper analyzes the effect of regime parameter values during the resistance welding process on the joints made between 2 steel components with surfaces protected by aluminization. The surface of one of the components was imprinted with 5 equidistant protrusions created by plastic deformation to concentrate the electric current lines and achieve melting points with a limited surface area. The thin layer of aluminum deposited on the surfaces of the parts has the role of protection against corrosion, but it produces hard compounds located on the welding interface. The chemical micro-composition analyzes performed with the EDAX method highlighted the diffusion effects of chemical elements in the welding area and the formation of hard compounds Al-rich loccated on the fusion line of the welded points. The microstructure of the welded areas was analyzed and the fracture strength tests of some welded samples were performed to establish the most suitable values of the welding process for this application.
Keywords: projection welding; current; microstructure; tensile test; microhardness