Abstract
In this paper the effect of arc oscillation and pulsed current of gas tungsten arc welding (GTAW)on the microstructure and mechanical properties of aluminium alloy 2219 was studied. Microstructural characterisation of the weld region was carried out using optical micros copy and Electron probe micro analysis (EPMA). Hardness measurements were carried out using Vickers hardness tester to evaluate the hardness in the base metal and weld zone. The microstructures of Arc oscillation and pulsed current (AOPC) welds and continuous current (CC) welds were compared and their hardness were correlated. It was observed that arc oscillation and pulsed current weld resulted in fine equiaxed grain structure whereas continuous current welds resulted in columnar structure. The significant improvement in mechanical properties of arc oscillation and pulsed current welds may be attributed to the discrete copper segregation. Post weld deformation has improved the mechanical properties of arc oscillation and pulsed current welds significantly. Aging can be carried out at lower temperature with prior deformation to improve the mechanical properties of the weld
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