A modified version of friction stir welding process of aluminum alloys: Analyzing the thermal treatment and wear behavior

In this article, the effect of vibration and cooling media on the friction stir welding of 5083Al alloy is investigated. The vibration was introduced by the motor into the fixture inserted under the workpiece while a cooling media (water and lubrication oil) flowed into a canal in the fixture beneath the weld path. A constant rotation speed of 1250 r/min and a traveling speed of 90 mm/min were used for all the welding conditions. The thermal analysis measured by several thermocouples indicated that friction stir vibration welding (FSVW) provided maximum temperature distribution in the workpiece, while friction stir welding with the water cooling exhibited the lowest temperature value. The microstructure observations were conducted by optical microscope, scanning electron microscopy, and transmission electron microscopy. The results indicated substantial grain refinement when vibration and water cooling were simultaneously applied during the friction stir welding process. The hardness values increased from 50 to around 78 (Hv) for friction stir welding and FSVW with water systems, respectively. The joint efficiency (the ratio of the joint strength to the base metal strength) of the joint fabricated by FSVW with water cooling was around 87%, while this quantity was about 66% for the friction stir welding joint. Fracture analysis indicated more ductile behaviors for the samples fabricated by FSVW with the coolant systems. Furthermore, the joint fabricated by FSVW with water cooling exhibited the best wear resistance among all the samples in a pin-on-disk wear test.