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Friction stir additive manufacturing (FSAM) is a variant of sheet lamination additive manufacturing used to produce large, near-net-shaped 3D parts. Unlike traditional friction stir lap welding, FSAM introduces a new plate to one that is already joined, with the effective area limited to the nugget zone. The present study focuses on exploring the microstructure and microhardness around the nugget zone in a five-plate AA 7075-T651 laminate synthesized at 1000 rpm and 35 mm/min. Microhardness increased vertically in the weldment NZ, reaching 143 HV in the top layer with 2.0 µm fine equiaxed grains. The grains on the advancing and retreating sides were coarser compared to the nugget zone. A W-shaped microhardness profile appeared across layer interfaces. These findings contribute significantly to advancing the FSAM technique, particularly in manufacturing multi-layered, multi-pass laminates. [ABSTRACT FROM AUTHOR]

Laminar composites have widespread applications in the automotive and aircraft industry. This research was aimed to investigate the suitability of fused deposition modeling to produce multi-material laminar composites. Composites comprising of two dissimilar laminates, named as hybrid composites, were printed from acrylonitrile butadiene styrene filament and carbon fiber-reinforced polylactic acid filament (a composite filament) by varying different printing parameters. Tensile tests were conducted to examine the mechanical performance of the produced composite sheet. A detailed analysis of the results revealed that a high ultimate tensile strength is primarily achieved by setting low values of printing speed, layer height, and clad ratio while high elongation is obtained by employing low printing speed, medium layer height, and high clad ratio. The optimum printing conditions were sought out through desirability function with an objective to simultaneously enhance all the considered properties. Further, the composite sheet exhibited a reasonably good combination of tensile properties as compared to its monolithic constituent sheets. Based on the results, it is concluded that the bi-material laminating approach employed herein can produce printed structures with desired properties. [ABSTRACT FROM AUTHOR]