Advantages of Casting Partially Crystallized Aluminum Alloys (Reocasting)
Processy litʹâ, 2019, Tom 135, №3, p.33-39
Keywords:
aluminum alloys, rheo-tixocasting, advantages, suspension, thermogram, microstructureAbstract
Receivеd 28.03.2019
UDK 669.715:62-405
At the Physicо-Technological Institute of metals and alloys of National Academy of Sciences of Ukraine a new low-cost combined rheo-tixocasting method has been developed and successfully tested, by creation with rotor multiply crystallization centers in the pre-crystallization temperature range. The rotating vibrating rotor moves the supercooled layers of the melt into its volume and, therefore, due to the vibration and jet flow of the melt, different speeds of movement in the melt nuclei system are created, cleaning the surface of the nuclei of crystals from hydrogen, non-metallic inclusions, which suppresses the preferential growth of crystals in one or another direction and forms globules. A new method of casting is easy to use, guarantees a suspension with a given solids content. The thermograms of the rheo-tixocasting process, the microstructure of the castings, as well as the ingots obtained in the pressing chamber of the LPD machine, are presented. A number of special properties of the metal suspension are given: it has superfluidity due to the liquid phase that envelops the α-solid solution globules; the globules of the solid phase are practically not interconnected and do not form a continuous frame responsible for hot brittleness, which allows to cast high-strength cast and wrought aluminum alloys; due to less shrinkage, the use of a suspension leads to an increased accuracy of castings (due to a decrease in inclines); suspension in the casting process is subjected to compaction due to additionel pressure; the use of a suspension increases the tightness of castings and their plasticity (~ 3 times); by reducing the casting temperature, energy saving is achieved (~ 15–20 %). At the same time increasing the service life of the molds by ~ 15–20 %. Thus, the new combined process of rheo-tixocasting has an undeniable advantage over ordinary LPD.
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Copyright (c) 2019 В. П. Головаченко, Т. Г. Цір, В. М. Дука, А. Г. Вернидуб, Н. П. Ісайчева
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