Effect of parallel deposition path and interface material flow on resulting microstructure and tensile behavior of Al-Mg-Si alloy fabricated by additive friction stir deposition
[Display omitted] •AFS-D successfully deposited layers wider than the diameter of the tool offering a new path for large scale AM components.•Aluminum oxide films were dispersed by tool features and provided increased interlayer mixing.•More homogenous grain structures occurring from repeated stirri...
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Veröffentlicht in: | Journal of materials processing technology 2021-09, Vol.295, p.117169, Article 117169 |
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Sprache: | eng |
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•AFS-D successfully deposited layers wider than the diameter of the tool offering a new path for large scale AM components.•Aluminum oxide films were dispersed by tool features and provided increased interlayer mixing.•More homogenous grain structures occurring from repeated stirring in overlapping region.•As-deposited tensile strength was unaffected by the overlapping region compared to similar AFS-D AA6061 single row studies.•Undispersed oxides dominated the fracture surface in place of typical secondary phase continuative particles.
In this paper, the effect of overlapping parallel additive depositions on microstructure and mechanical properties in Additive Friction Stir Deposition (AFS-D) was examined. In particular, the AFS-D process was employed to make parallel depositions of AA6061 with a 6.35 mm overlap to effectively bond the two parallel layers. The AFS-D process draws on similar physics to friction stir welding in that frictional heat and plastic deformation is exploited to deposit metallic materials from the center of a hollow rotating tool as it traverses across the build table to produce consecutive metallurgically bonded layers. In this work, the microstructural aspects of the 6.35 mm overlapping raster interface were characterized using optical and scanning electron microscopy. Aluminum oxide particles were observed at the raster interface, which were located at layer boundaries. Additional grain refinement was also apparent as a direct result of multiple stirring passes within the overlapping deposition region. Mechanical characterization via microindentation and monotonic tensile testing observed a hardness gradient in the overlapping region, but the parallel deposition layers exhibited comparable tensile strength to a single row of deposited AA6061. The influence of existing oxides on the mechanical results was observed to have limited effect on the properties longitudinally across the raster. This study determined that parallel layers of AA6061 can be successfully deposited via the AFS-D technique. The resulting deposit exhibited a strong metallurgical bond across the parallel layers despite the presence of surface oxidation on the unprepared feedstock and substrate. |
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ISSN: | 0924-0136 1873-4774 |
DOI: | 10.1016/j.jmatprotec.2021.117169 |