“…This finding agrees with the works of Paidar et al., 47 Eftekharinia et al., 50 Keneshloo et al., 51 and Moharrami et al. 52 that wear reduction was aided by refinement and even dispersion of reinforced particles. Figure 19.Friction coefficient of (a) TT, (b) TTC, and (c) TC composites.…”
Section: Resultssupporting
confidence: 92%
“…This attribute enhances inter-material flow (around the tip of the pin tool), Mg 2 Si particle distribution, and consequently results in improved wear resistance (reduced friction coefficient) as compared to that of the TC sample. This finding agrees with the works of Paidar et al, 47 Eftekharinia et al, 50 Keneshloo et al, 51 and Moharrami et al 52 that wear reduction was aided by refinement and even dispersion of reinforced particles.…”
This paper investigates the effect of different tool pin morphologies on the inter-mixing capability, microstructure, mechanical properties, corrosion, fracture, and wear behaviors of the dissimilar friction stir welded AA6061-T6 alloy--Al 20wt% Mg2Si composite. Grooved shoulder tools with varying pin profiles such as tapered cylindrical, threaded tapered cylindrical, and triangular tapered pins were used for joining the base materials. The parameter combination of 80 mm/min travel speed and 1000 r/min rotation speed (at which no visible flow-induced defect was obtained) was used for this study. Among the pin profiles, the triangular tapered pin produced significantly improved intermingling/inter-material flow, fragmentation, and dispersion of the primary Mg2Si particles in the AA6061-T6/Al-Mg2Si joint. The triangular tapered tool reduced the average grain sizes of the AA6061 alloy and the Mg2Si particles from 18.4 to 4.6 µm and from 115 to 7.5 µm, respectively. Intermetallic phases of Mg2Si, AlFe, Al3.21Si0.47, and Al0.7Fe3Si0.3 are formed in the weld nugget of all the AA6061/Al-Mg2Si joints. The tensile strengths of the joints fabricated with tapered cylindrical, threaded tapered cylindrical, and triangular tapered tools are 108, 139, and 141 MPa, respectively. Abrasive wear is promoted in the joints fabricated with triangular tapered tool due to the homogeneous dispersion and fragmentation of the inherent hard Mg2Si particles. The corrosion attack is dependent on the fragmentation level of the Mg2Si phase. Triangular tapered pin tool is recommended for dissimilar Al/composite welding due to favorable tool-induced material flow, dispersion, and fragmentation of reinforcement.
“…This finding agrees with the works of Paidar et al., 47 Eftekharinia et al., 50 Keneshloo et al., 51 and Moharrami et al. 52 that wear reduction was aided by refinement and even dispersion of reinforced particles. Figure 19.Friction coefficient of (a) TT, (b) TTC, and (c) TC composites.…”
Section: Resultssupporting
confidence: 92%
“…This attribute enhances inter-material flow (around the tip of the pin tool), Mg 2 Si particle distribution, and consequently results in improved wear resistance (reduced friction coefficient) as compared to that of the TC sample. This finding agrees with the works of Paidar et al, 47 Eftekharinia et al, 50 Keneshloo et al, 51 and Moharrami et al 52 that wear reduction was aided by refinement and even dispersion of reinforced particles.…”
This paper investigates the effect of different tool pin morphologies on the inter-mixing capability, microstructure, mechanical properties, corrosion, fracture, and wear behaviors of the dissimilar friction stir welded AA6061-T6 alloy--Al 20wt% Mg2Si composite. Grooved shoulder tools with varying pin profiles such as tapered cylindrical, threaded tapered cylindrical, and triangular tapered pins were used for joining the base materials. The parameter combination of 80 mm/min travel speed and 1000 r/min rotation speed (at which no visible flow-induced defect was obtained) was used for this study. Among the pin profiles, the triangular tapered pin produced significantly improved intermingling/inter-material flow, fragmentation, and dispersion of the primary Mg2Si particles in the AA6061-T6/Al-Mg2Si joint. The triangular tapered tool reduced the average grain sizes of the AA6061 alloy and the Mg2Si particles from 18.4 to 4.6 µm and from 115 to 7.5 µm, respectively. Intermetallic phases of Mg2Si, AlFe, Al3.21Si0.47, and Al0.7Fe3Si0.3 are formed in the weld nugget of all the AA6061/Al-Mg2Si joints. The tensile strengths of the joints fabricated with tapered cylindrical, threaded tapered cylindrical, and triangular tapered tools are 108, 139, and 141 MPa, respectively. Abrasive wear is promoted in the joints fabricated with triangular tapered tool due to the homogeneous dispersion and fragmentation of the inherent hard Mg2Si particles. The corrosion attack is dependent on the fragmentation level of the Mg2Si phase. Triangular tapered pin tool is recommended for dissimilar Al/composite welding due to favorable tool-induced material flow, dispersion, and fragmentation of reinforcement.
“…2a of dynamic recrystallization. Moharrami et al [30] also showed that multi-pass FSP can significantly refine the as-cast microstructure of Al-25Mg 2 Si composite. Based on their EBSD investigations, a direct relationship was found between FSP passes and the density of grain boundaries.…”
This study was conducted to investigate the capability of multi-pass friction stir processing (FSP) on microstructure modification and mechanical properties improvement of FVS0812 alloy. FSP was performed at different rotation speeds (1250, 1600, 2000, and 2500 rpm) and traverse speeds (8, 12, and 25 mm/min) for one, two, and four passes. According to the results, applying single-pass FSP at optimized conditions (i.e. 1600 rpm and 12 mm/min) enhanced the tensile strength, fracture strain, and microhardness of the alloy by about 1020, 1050, and 60%, respectively. This improvement can be mainly attributed to the intense breakage and uniform distribution of θ-Al 13 Fe 4 and α-Al 12 (Fe,V) 3 Si intermetallics within the matrix, formation of ultrafine recrystallized grains, and elimination of casting defects. Increasing the number of FSP passes up to four slightly decreased the average size of intermetallic particles, but significantly improved their distribution within the matrix which led to 18 and 200% improvement of tensile strength and fracture strain of one-pass FSPed sample, respectively. The fractography results also revealed that multi-pass FSP has changed the fracture mode of Al-8.5Fe-1.3V-1.7Si alloy from low-energy brittle to a more ductile-dimple fracture.
“…They reported that the micron-sized Mg 2 Si particles avoided the excessive mobility of grain boundaries and prevented grain growth through the Zener pinning mechanism. Moharami et al [42] also found that the progressive decrease in the average grain sizes of the material is adjudged to be facilitated by particle-induced pinning as the FSP pass progresses.…”
Section: Microstructural Investigations Of Fsped Az91 Magnesium Alloymentioning
Friction stir processing (FSP) was used to modify the surface layer of the AZ91 magnesium alloy. The treatment was carried out using a jet cooling nozzle, generating a stream of cold air and enabling intensive cooling of the friction stir processed (FSPed) zone. Single-pass FSP was carried out using a tool rotational speed of 500 rpm and travel speed of 30 mm/min. The treatment was conducted using a truncated cone-shaped tool with a threaded side surface. Strong grain refinement and microstructural changes typical for FSP were found in all the samples. Very fine, equiaxed recrystallized grains dominated in the stirring zone. In the samples modified with the jet cooling nozzle, greater grain refinement was obtained than in the case of naturally cooled material. The average grain size in the surface part of the stirring zone was 1.4 μm and 9 μm in the samples with air-cooling and with natural cooling, respectively. Both the naturally cooled specimen and air-cooled specimen were characterized by a distinctly higher hardness than the base material. The average Vickers hardness in the stirring zone was 91 HV0.1 in the FSPed sample with the air-cooling system and 85.5 HV0.1 with natural cooling, respectively. The average Vickers hardness of the as-cast alloy was 64 HV0.1. Slightly higher wear resistance of the FSPed samples using a jet cooling nozzle was found in relation to the naturally cooled sample. Based on the conducted research, high efficiency of the jet cooling nozzle in cooling the modified zone during friction stir processing was found.
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