The effects of welding speed on the microstructure and mechanical properties of marine-grade aluminium (AA5754) alloy welded using MIG welding

Abstract

AA5754 aluminium alloys are commonly used in marine and offshore applications as well as in shipbuilding equipment. It is of great importance to weld this alloy in these industrial areas. This study investigated the penetration, microstructure, and mechanical properties of AA5754 Al alloy sheets that were joined using robotic metal inert gas (MIG) welding at different welding speeds. The joints were welded at three welding speeds by keeping the welding current constant, and then macrostructure and microstructure of the samples taken from these joints were examined. Afterward, their hardness, tensile and bending tests were carried out. It was found that the increase in the welding speed decreased the amount of accumulated metal and the penetration rate. Formation of macro-and micro-porosities was observed in the root sections of the weld seams. It appeared that the welding speed increased, the quantity and size of these defects increased, and the mechanical properties were negatively affected by the increase in the welding speed.