Mechanical Behaviour of Gas Metal Arc AA6082-T6 Welments
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The purpose of this work is to determine the mechanical properties of AA6082-T6 plates which have been welded with the Gas Metal Arc technique, which is one of the most common welding technology used in industrial applications. To determine the mechanical properties some tests have been carried out: hardness Vickers test, bend test, tensile test, fatigue test, Charpy V-notch test. In addition, both optical microstructure analysis of the weld and scanning electron microscope examination of selected fracture surfaces have been carried out. The tests have been carried out in both longitudinal and transversal direction with respect to the welding direction. From the tests carried out it is concluded that HAZ softening is the main problem in the GMA weldments. This brings to a reduction in strength equal to 44% with respect to the parent material. The softening can be observed both in the tensile and hardness test. In the tensile test, it has been observed that the yield strength of the welded specimens is much lower compared to the parent material one (both considering the longitudinal and the transverse direction). In the hardness test it has been observed the hardness profile along the plate section. It has been noticed that there is a minimum value of hardness in the heat affected zone, that correspond to the weakest part of the component. This has been proved with the tensile test: all the welded tensile specimens broke in the HAZ approximately at the same distance where the least hard point has been measured in the hardness test. From the Charpy V-notch impact test it has been observed that the specimens tested in the HAZ have the greatest energy absorption capacity. This result gives an indication of the ductility of the material, that has been also observed in the bend test. The bend test results give an indication of the quality of the welding. From this test it is concluded that the quality of the weld is high: no crack was detected during the bend. From the micrography carried out with the confocal microscope it has been measured the porosity ratio of the weld. Pores are present, but with a low density: much lower than the 3% given as an indication of the maximum value for this kind of welding technology.