Journal of Welding Science

In the present study, effect of current, welding speed and preheat temperature during FB-TIG welding of AA5083 aluminum alloy was studied. Using the Taguchi method, 9 different tests were designed to investigate the effect of welding parameters on the penetration depth. Consistent with predictions, increasing the current and preheat temperature, and reducing the welding speed led to an increase in penetration depth. The maximum penetration depth of 8.02 mm was achieved at the current of 220 A, welding speed of 120 mm/min, and the preheat temperature of 100 °C. Taguchi analysis showed that increasing the welding current and preheat temperature had a more significant effect than the welding speed. Microstructural analysis indicated that the weld metal is fine-grained, along with coarse-grain in the HAZ of all samples. Many pores were observed in the samples with high welding speed and high welding current in the fusion zone. The sample with the highest heat input had the highest penetration depth. This sample had the highest elongation, equal to 69% of the base metal. Moreover, microhardness test demonstrated that the hardness of this sample dropped sharply from 70 Vickers to 58 Vickers in the HAZ.

5xxx and 6xxx series alloys are among the most widely used aluminum alloys in various industries, including automobile, shipbuilding and aviation industries. In this research, the joint of two alloys AA6061-T6 and AA5052-H12 was investigated at 4 transmission speeds of 60, 90, 120 and 180 mm/min and 3 rotation speeds of 600, 800 and 1000 rpm. These investigations were carried out in the condition that each of the two alloys was placed in two progressive and regressive sides. The results of these studies showed that the highest tensile strength is when the AA5052 sample is placed on the advancing side and the transfer speed is 90 mm/min and the rotation speed is 600 rpm, and in this case, the final tensile strength value is equal to 197 MPa. In addition, the results showed that, generally, the tensile strength decreases with an increase in the transmission speed at a constant rotational speed, and with an increase in the rotational speed at a constant transmission speed, the tensile strength increases. In addition, microscopic and macroscopic examination of the sections of all samples was performed and various areas and defects were examined. According to the investigations carried out on the microstructure, the grain size in the weld nugget compared to the base metal, HAZ and TMAZ decreases. The grain size in HAZ is the largest in all samples, and this causes a decrease in weld strength in this zone.