Abstract
Friction stir welding (FSW) is an emerging solid-state process and alternative to fusion welding, wherein frictional heat is generated between a nonconsumable rotating steel tool and the work substrate. The present study focuses on the influence of the operating attributes like tool pin contact geometry, welding speed, and tool rotational speed on dissimilar aluminum matrix nanocomposites. AA6061-T6 and AA7075-T651 aluminum alloy plates were joined via double-pass FSW with the inclusion of 5 vol. % of nanoscale h-BN particles. Welding was performed with four rotational speeds (600, 800, 900, and 1000 rpm), three traversing speeds (30, 40, and 60 mm/min), and three distinct tool pin geometry (cylindrical, threaded cylindrical, and square), respectively. Besides, unreinforced and reinforced weldments were analyzed for mechanical properties like tensile strength and microhardness. Microstructural characterization was also carried out using FESEM and XRD techniques. The findings concluded that the reinforced samples welded using a cylindrical tool and double-pass strategy showcased homogenous distribution of nanoparticles with grain refinement, thereby exhibiting improved strength and hardness.
Highlights
Friction stir welding (FSW) is a potentially proven solid-state joining method that can overcome the constraints of fusion welding processes
A weld operated with a high rotational speed of 1000 rpm with 40 mm/min tool feed exhibited a smooth finish on the weld crown. e tool with threaded pin results in a rougher surface, and in the case of the cylindrical tool, visual inspection of the welded joint indicates the relatively smoother; i.e, the better joint formation could be achieved with R4 condition (1000 rpm and 40 mm/min) while the reduced speed of 600 rpm incomplete formation can be seen
Conclusions e FSW emerged as a novel approach for the fabrication of surface composites with the enhancement of the grain structure in the weld zone directing toward microstructural modification
Summary
Friction stir welding (FSW) is a potentially proven solid-state joining method that can overcome the constraints of fusion welding processes. The present study converges with the fabrication of AMNC’s based on combination of such aluminum alloys subjected to friction stir welding with the inclusion of nanoscale nitride particles and assessment of the composites with different tool pin geometries. Spindle speed of 500–1100 rpm, feed of 10–70 mm/min, and cylindrical pin tool were adapted to perform dissimilar welding without reinforcement. 3. Results and Discussion e effects of attributes (tool rotation, 600–1000 rpm, feed rate 30–60 mm/min, tool pin geometries, CYL, THR CYL, SQ, and constant parameters, 5 vol % of reinforcement binder, 10 KN axial load, 0.55 mm plummet depth, and 1 min dwell) on the mechanical and structural characteristics of h-BN reinforced stir composite were investigated to achieve the working window for firm and sound welds. E imperfections in the welded specimens are presented with the help of cross-sectional optical macrocharacterization at 20X magnification. e macrophotographs showed the complete nugget zone, retreating side, and the advancing side of the AA7075 and AA6061
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