Abstract:This research aims to investigate the material flow behaviour and microstructure evolution in friction stir welded joints of dissimilar aluminium alloys AA2024/AA5086. AA2024 plate was placed on re- treating side; welded using threaded conical flat shoulder tool rotating at 635 rpm and moving along the joint line with a speed of 75mm/min. Mixing of both the material was clearly visible in stir zone and resulted in features typical to dissimilar friction stir welding and solid state flow patterns beside differe… Show more
“…Similar results were reported by Sharma et al 37 for dissimilar FSW welds of AA2024-AA7039, and Kumar et al 38,39 for AA2014 and AA7075 where weld tensile strength was lower than weak metal and attributed same to more contribution of low strength metal in weld region owing to complex material flow. 40,41 Figure 8. Variation in (a) tensile strength, (b) percentage elongation, and (c) strength efficiency of FSW joints under different in-process cooling conditions.…”
Section: Resultsmentioning
confidence: 99%
“…Similar results were reported by Sharma et al 37 for dissimilar FSW welds of AA2024-AA7039, and Kumar et al 38,39 for AA2014 and AA7075 where weld tensile strength was lower than weak metal and attributed same to more contribution of low strength metal in weld region owing to complex material flow. 40,41 WFC welded joints display higher UTS than FAC and CAC welded joints. Moreover, a marginal increment in UTS has been observed for FAC than CAC welded joints.…”
Heat-carrying capacity of a cooling medium is critical as it governs microstructure evolution and tensile properties during friction stir welding (FSW). In this research, three cooling techniques: conventional air-cooling (CAC), forced air-cooling (FAC), and water flow cooling (WFC), were employed to study the effect on microstructure and mechanical properties in dissimilar FSW of AA2014 and AA7075. In-process cooling significantly influenced weld microstructure, zone size, microhardness, and tensile properties, which varied with the cooling medium. Water flow cooling was the most effective cooling technique due to its higher heat carrying capacity than CAC and FAC. Water flow cooling resulted in a drastically refined grains structure of smaller size in all zones, had higher tensile strength, elongation, and heat-affected (HAZ) hardness than CAC and FAC. Greatly refined grain structure and less dissolution of precipitates in weld nugget zone (WNZ) along with smaller HAZ and thermo-mechanically affected zone (TMAZ) are responsible for improved weld properties of WFC than the FAC and CAC. Forced air-cooling resulted in a higher microhardness value at WNZ, followed by WFC and CAC. Fractured surfaces of the tensile specimen were scrutinized by scanning electron microscope. Cooling did not affect the fracture side and location; however, fracture mode changed with cooling medium viz. ductile for FAC and WFC and mixed-mode for CAC.
“…Similar results were reported by Sharma et al 37 for dissimilar FSW welds of AA2024-AA7039, and Kumar et al 38,39 for AA2014 and AA7075 where weld tensile strength was lower than weak metal and attributed same to more contribution of low strength metal in weld region owing to complex material flow. 40,41 Figure 8. Variation in (a) tensile strength, (b) percentage elongation, and (c) strength efficiency of FSW joints under different in-process cooling conditions.…”
Section: Resultsmentioning
confidence: 99%
“…Similar results were reported by Sharma et al 37 for dissimilar FSW welds of AA2024-AA7039, and Kumar et al 38,39 for AA2014 and AA7075 where weld tensile strength was lower than weak metal and attributed same to more contribution of low strength metal in weld region owing to complex material flow. 40,41 WFC welded joints display higher UTS than FAC and CAC welded joints. Moreover, a marginal increment in UTS has been observed for FAC than CAC welded joints.…”
Heat-carrying capacity of a cooling medium is critical as it governs microstructure evolution and tensile properties during friction stir welding (FSW). In this research, three cooling techniques: conventional air-cooling (CAC), forced air-cooling (FAC), and water flow cooling (WFC), were employed to study the effect on microstructure and mechanical properties in dissimilar FSW of AA2014 and AA7075. In-process cooling significantly influenced weld microstructure, zone size, microhardness, and tensile properties, which varied with the cooling medium. Water flow cooling was the most effective cooling technique due to its higher heat carrying capacity than CAC and FAC. Water flow cooling resulted in a drastically refined grains structure of smaller size in all zones, had higher tensile strength, elongation, and heat-affected (HAZ) hardness than CAC and FAC. Greatly refined grain structure and less dissolution of precipitates in weld nugget zone (WNZ) along with smaller HAZ and thermo-mechanically affected zone (TMAZ) are responsible for improved weld properties of WFC than the FAC and CAC. Forced air-cooling resulted in a higher microhardness value at WNZ, followed by WFC and CAC. Fractured surfaces of the tensile specimen were scrutinized by scanning electron microscope. Cooling did not affect the fracture side and location; however, fracture mode changed with cooling medium viz. ductile for FAC and WFC and mixed-mode for CAC.
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