Research Article Microstructural and Mechanical Behaviors of Friction Stir Welded Dissimilar AA6082-AA7075 Joints M. Vetrivel Sezhian, 1 K. Giridharan, 1 D. Peter Pushpanathan, 1 G. Chakravarthi, 1 B. Stalin , 2 Alagar Karthick , 3 P. Manoj Kumar, 4 and Murugesan Bharani 5 1 Department of Mechanical Engineering, Easwari Engineering College, Chennai 600089, Tamilnadu, India 2 Department of Mechanical Engineering, Anna University, Regional Campus Madurai, Madurai 625019, Tamilnadu, India 3 Department of Electrical and Electronics Engineering, KPR Institute of Engineering and Technology, Coimbatore 641407, Tamilnadu, India 4 Department of Mechanical Engineering, KPR Institute of Engineering and Technology, Coimbatore 641407, Tamilnadu, India 5 School of Textile Leather and Fashion Technology, Kombolcha 208, Kombolcha Institute of Technology, Wollo University, South Wollo, Ethiopia Correspondence should be addressed to Murugesan Bharani; bharani.murugesan@kiot.edu.et Received 16 June 2021; Revised 2 August 2021; Accepted 13 September 2021; Published 22 September 2021 Academic Editor: Daniela Pilone Copyright©2021M.VetrivelSezhianetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this research, microstructural events and mechanical behaviors in dissimilar friction stir welding (FSW) of aluminium (Al) alloyAA6082-AA7075jointshavebeenevaluatedtoapplyaerospace,defense,andmilitarysectors.FSWparametriceffectshavea more significant impact on the mechanical performances and microstructure of produced joints. FSW tool rotational speed, weldingspeed,andtoolplungespeedwerechosentomaketheweldjoints.erotationaltoolspeedsof1600rpmand2300rpm, weldingspeedsof40mm/minand60mm/min,andtoolplungespeedsof20mm/minand30mm/minweresetastheupperand lowerlimits.Aconstantaxialforceof5kNwasmaintainedthroughoutthejointfabricationprocess.Ataperpin-profiledtoolwas utilized to produce the butt welded joints. Mechanical properties of microhardness, tensile strength, yield strength, elongation, and bending strength of the joints were analyzed. e response of the stir zone microstructure to processing parameters was evaluatedusingopticalmicroscopy(OM)andfractographicanalysisofatensilespecimenshownbyscanningelectronmicroscope (SEM).eweldjointsproducedat2300rpm,tooltravelingrateof40mm/min,andtoolplungespeedof30mm/minshowedthe greatest tensile strength of the 191MPa hardness of 145Hv at the weld center and also the maximum bending strength of 114.23N/mm 2 was achieved. e lowest bending strength of 25.38N/mm 2 was obtained at 1600rpm with 60mm/min due to inappropriatemixingofthebasemetalsandpoorjointquality.Furthermore,thisstudyrevealedthatahighertoolplungespeed facilitates the formation of equiaxed grains in the thermomechanically affected zone (TMAZ) on the advancing side (AS). Additionally, the increment in tool rotational speed significantly improved the tensile strength, weld joint quality, and joint efficiency. 1. Introduction Aluminum alloys are lightweight and have more applica- tionsintheindustrialsector.Byconventionalfusionwelding techniques,aluminumalloysaretoughtoweld,andthejoint quality is also unsuitable due to welding defects like dis- tortion, cracks, and porosity [1]. FSW has recently been selected as a reliable method for retaining the alloy’s properties when the joining takes place in the solid state. is technique is performed for joining different material combinations, such as aluminum, copper, magnesium, brass, and other material types. FSW tool plays a very im- portant role in the material joining processes [2]. e usage of aluminum alloys is rapidly increasing due to their cast- ability, lightweight structures needing a higher strength ratio, and extraordinary corrosion resistance. e various Hindawi Advances in Materials Science and Engineering Volume 2021, Article ID 4113895, 13 pages https://doi.org/10.1155/2021/4113895