Microstructural and Mechanical Behaviors of Friction Stir Welded Dissimilar AA6082‐AA7075 Joints

Abstract

In this research, microstructural events and mechanical behaviors in dissimilar friction stir welding (FSW) of aluminium (Al) alloy AA6082-AA7075 joints have been evaluated to apply aerospace, defense, and military sectors. FSW parametric effects have a more significant impact on the mechanical performances and microstructure of produced joints. FSW tool rotational speed, welding speed, and tool plunge speed were chosen to make the weld joints. The rotational tool speeds of 1600 rpm and 2300 rpm, welding speeds of 40 mm/min and 60 mm/min, and tool plunge speeds of 20 mm/min and 30 mm/min were set as the upper and lower limits. A constant axial force of 5 kN was maintained throughout the joint fabrication process. A taper pin-profiled tool was utilized to produce the butt welded joints. Mechanical properties of microhardness, tensile strength, yield strength, elongation, and bending strength of the joints were analyzed. The response of the stir zone microstructure to processing parameters was evaluated using optical microscopy (OM) and fractographic analysis of a tensile specimen shown by scanning electron microscope (SEM). The weld joints produced at 2300 rpm, tool traveling rate of 40 mm/min, and tool plunge speed of 30 mm/min showed the greatest tensile strength of the 191 MPa hardness of 145 Hv at the weld center and also the maximum bending strength of 114.23 N/mm2 was achieved. The lowest bending strength of 25.38 N/mm2 was obtained at 1600 rpm with 60 mm/min due to inappropriate mixing of the base metals and poor joint quality. Furthermore, this study revealed that a higher tool plunge speed 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.

Microstructural and corrosion behaviours of dissimilar friction stir welded aluminium alloys

“…The welding procedure described in Attah et al [19] was adopted in this work. The frictional heat generated increased at the welding region as a result of the increment in the rotational tool speed [11]. This heat softened the stirred materials without melting them.…”

“…According to their findings, a limited duration of dwell time has the potential to impede the formation of welded joints of superior quality. Sezhian et al [11] and Yoo et al [12] conducted research on the microstructure and mechanical attributes of dissimilar non-ferrous joints, employing rotational and travel speeds as operational factors. The researchers observed that an increase in travel or rotation speed leads to the emergence of irregular border shapes.…”

Investigation on the effect of process parameters on mechanical and microstructural properties of AA8011 similar FSW weld joints

“…A number of small dimples and fractures may be seen on the fracture surface in this tool profile. 29 Size, form, strain hardening in the stir zone and dispersion of precipitates are all critical characteristics for similar welded junctions. The lowest tensile strength of 84.16 MPa was reached in the stir zone using a taper threaded pin profiled tool with a rotating speed of 1300 rpm and a welding speed of 20 mm/min, which was used in conjunction with a taper threaded pin profiled tool.…”

Exit-hole repairing in 7475 aluminium alloy welded joints based on refill friction stir processing

“…It offers numerous advantages over fusion welding, such as the avoidance of defects like hot cracking, porosity, and slag inclusion in welding aluminium alloys. Moreover, FSW produces small weld deformation and exhibits excellent mechanical properties, making it highly promising for applications in the aerospace field [2][3][4][5]. However, the presence of a exit-hole at the end of the FSW welds can significantly reduce the mechanical properties of the joint and render the weld susceptible to corrosion [6].…”