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Rheocasting process steps: (a) a solid block of the same alloy, fastened to a stainless-steel rod in advance, (b) dissolved in the melt with synchronous stirring action, and (c) the resulting slurry.
Source publication
With the increasing application of aluminum foundry alloys for automotive and aerospace components, the aluminum industry must pay close attention to component quality and dependability. This article focuses on the interpretation of the relative density and porosity of Al foundry casting and rheocasting alloys AlSi7Mg. The most popular Al-Si alloy...
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... is applied for some time. The semi-solid state interacts with the liquid-solid alloy as the steel rod rotates, and a temperature gradient between the melt and the rod is shown in (Figure 1) [16]. As a result, the melt partially solidifies on the rod's surface [16,17]. ...
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... shape factor of casting and rheocasting application examples is shown in (Figure 10). The shape factor of semi-solid rheocasting area samples is significantly larger than the shape factor of casting. ...
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... shape factor of semi-solid rheocasting area samples is significantly larger than the shape factor of casting. Figure 10. The shape factor of casting and rheocasting application samples. ...
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... practical density data of the casting alloy and rheocasting sample were 2.64 g/cm 3 and 2.69 g/cm 3 ; the results are shown in (Figures 11 and 13). Figure 11. ...
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... practical density data of the casting alloy and rheocasting sample were 2.64 g/cm 3 and 2.69 g/cm 3 ; the results are shown in (Figures 11 and 13). Figure 11. Density values of the cast, the rheocast alloys, and the theoretical density. ...
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... density of the five-area positions of casting and rheocasting application samples is shown in (Figure 12). The shape density in both alloys was increased from the down to top positions. ...
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... shrinkage porosity data of the casting alloy and rheocasting sample were 2.14% and 0.07%. The results are shown in (Figure 13). However, less micro shrinkage porosity occurs when the rheocasting time is extended. ...
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... shrinkage porosity data of the casting alloy and rheocasting sample were 2.14% and 0.07%. The results are shown in (Figure 13). However, less micro shrinkage porosity occurs when the rheocasting time is extended. ...
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... observing the micro-porosity volume of the casting alloy of the five-area sample from near the top casting work, significantly different big and small micro-porosity was found as shown in (Figures 14a and 14b). ...
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... big and small porosity volume of aluminum ALSI7MGalloy was monitored via a scanning electron microscope. The result of (Figure 15) shows the two-area micro porosity volume in the casting alloy sample. (Figure 15 a and b) show two types of micro-porosity volume large and small. ...
Citations
... Due to the interest in this field, several rheocasting process are in the R&D stages, with researchers seeking a less complex formation route for slurries directly from melt with minimal investment in equipment and minimal modifications to the process. The processing energy saving, the reduction in cycle time, the decreased damage to dies, and minimal casting defects, such as porosity and shrinkage, allows for the most cost-effective process [2,10,11]. ...
Nowadays it is common to see the production of complex and critical automotive and aeronautical components reduced in weight for energy efficiency using light alloys with improved microstructural and mechanical properties. The casting processes involved in this trend are strong; in this study, an optimized design of a vertical serpentine channel and a novel design of a horizontal serpentine channel to produce semi-solid slurry (S2S) with thixotropic behavior by self-stirring for rheocasting of A380 and A356 alloys are tested. Simultaneously, chilling during solidification, flow development, and shearing on the alloys to improve the performance of solid fractions and self-stirring at high shear rate are applied. The effects of these conditions on the modification of the morphology transition of the α(Al) phase from dendrite to equiaxed grain are discussed. The results suggest the ability of the mentioned processes to promote the morphological transition of the primary solid due to the produced equiaxed grains of α(Al) phase having sizes between 25–50 µm from A380 alloy processed by vertical self-stirring. On the other hand, the treatment of the A356 alloy using the new horizontal serpentine channel produces equiaxed grains with an average size of 39 µm. Unexpected Si crystals, trapped in the α(Al) phase using both methods with both alloys, are detected. The applied operation parameters were aided by gravity-pouring close to the liquidus temperature, and the obtained microstructural results show the ability for S2S to form alongside thixotropic behavior and non-dendritic solidification by mean of self-stirring in the serpentine channels, suggesting the potential for further experiments under die-casting conditions.
