INVESTIGATION OF THE MICROSTRUCTURES AND MECHANICAL PROPERTIES OF THIN 5083 ALUMINUM ALLOY PLATES WELDED BY DOUBLE PULSE GMAW METHOD

In order to be able to use energy more efficiently, weight reduction solutions in machines, especially used in transportation, are sought by researchers. Aluminum alloys that are one of the light engineering alloys are commonly used in aerospace, automotive and sheet metal industry where the welding of thin plates is very important. Aluminum and its alloys have low weldability due to some characteristic properties such as high thermal conductivity, high electrical conductivity and the insulating oxide layer that has a very high melting temperature compared to aluminum. The weldability of thin aluminum plates is a much bigger problem. Thus, in this study, the thin EN AW-5083 H111 plates were welded by applying low heat input with a double pulse GMAW method. The effects of the used welding parameters on welding quality were investigated. Both macrography and micrography of the cross-sections of welded samples were investigated for metallographical examination by using optical microscopes (stereo and metal microscopes). The mechanical properties of samples were determined by hardness and tensile tests. In order to achieve the hardness distribution in the cross-sections of the welded samples, Vickers microhardness profiles test was carried out. It was observed that the pulse frequency of the current used in the welding process has significant effects on joint strength. HAZ broadened with an increase in pulse frequency. Thus, it has been observed that the joint strength was adversely affected due to the broadening of the inhomogeneous zones in the sample cross-section.