Effect of Tool Rotational Speed on the Microstructure and Mechanical Properties of Bobbin Tool Friction Stir Welded 6082-T6 Aluminum Alloy

Abstract

Samples of 6082-T6 aluminum alloy were welded by bobbin tool friction stir welding at different rotational speeds. The thermal cycles, microstructure, microhardness, and tensile properties of the specimens were investigated. The results show that the maximum temperature at the joint increases first and then decreases with increasing rotational speed, and the maximum temperature is 509 °C at 1000 r/min. The macromorphology of the cross-section of the joint is rectangular, and an ‘’S” line and gray-white texture can be observed. The stirred zone had much smaller equiaxed recrystallized grains. With increasing welding speed, the average grain size in the stirred zone region decreases. The microhardness distribution of the cross-section of all joints is W-shaped. When the rotational speed increases, the hardness of the heat-affected zone decreases gradually, and the hardness of the stirred zone increases. At 600 r/min, the strength is the lowest. The fracture location is between the stirred zone and the thermomechanically affected zone. When the rotational speed is increased, the fracture location is entirely located in the heat affected zone, and the fracture surface is dimple-like; the strength significantly increases and reaches a maximum at 800 r/min.

The influence of welding parameters on macrostructure and mechanical properties of Sc-modified AA2519-T62 FSW joints

“…6b) obtained by twice as high tool rotation speed. Similar observations on the relationship between tool rotation speed and microhardness and grain size in the stir zone have been reported in other investigations [12,24,25].…”

Effect of Corrosion and Surface Finishing on Fatigue Behavior of Friction Stir Welded EN AW-5754 Aluminum Alloy Using Various Tool Configurations

“…As depicted in Figure 8 , measurements were performed three times across the BM, HAZ, TMAZ and NZ on the surface of the welded specimens in the transverse cross-section of the welds. It can be seen that the hardness profiles for all of the tool configurations were similar and shaped like a ‘W’, which is usual for FSW joints of aluminum alloys [ 37 , 38 , 39 , 40 ]. Consequently, for all of the tool configurations the maximum hardness was reached at the NZ.…”

Review on Friction Stir Processed TIG and Friction Stir Welded Dissimilar Alloy Joints

“…A microhardness was reduced to 58 HV0.2 by the dissolution of phase β. In another study, an impact of using a bobbin type tool in friction stir welding of AA6082-T6 plates at different rotational speeds was investigated [26]. This investigation involved the variation of tool rotational speed.…”