Met. litʹe Ukr., 2021, Tom 29, №4, P. 36-43
P.B. Kaliuzhnyi, PhD (Engin.), Senior Researcher, e-mail: email@example.com, https://orcid.org/0000-0002-1111-4826
V.S. Doroshenko, Dr. Sci. (Engin.), Senior Research Scientist, Leading Researcher, e-mail: firstname.lastname@example.org, https://orcid.org/0000-0002-0070-5663
Physico-technological Institute of Metals and Alloys of the NAS of Ukraine (Kyiv, Ukraine)
The constant growth of requirements for the quality and properties of cast aluminum alloys contributes to the increasing use in foundry technology of physical methods of external influence on the process of casting formation. Of particular interest is the casting in sand molds, as the most versatile way to obtain shaped castings with complex geometry. In this regard, the article analyzes the modern foundry methods of influencing the structure of castings and crystallization process of aluminum alloys in sand molds. The introduction of additive technologies in foundry production has prompted the study of the influence of the geometry of sand molds made by 3D printing on the process of casting formation. It is determined that the use of skeletal, ribbed shell or multilayer molds allows to control the processes of casting solidification. A fundamentally new foundry method is ablation casting, the essence of which is to erode sand by water jets and rapid cooling of the solidifying casting. The study of this method shows that the rapid cooling of the casting by water jets contributes to the refinement of the microstructure components of aluminum alloys, and, accordingly, the increasing of their mechanical properties. Methods of increasing the properties of aluminum alloys during lost foam casting are becoming widespread. Thus, the application of pressure on the solidifying metal contributes to the refinement of the microstructure of aluminum alloys and increase their strength, ductility and hardness, reducing the porosity of castings. The use of vibration contributes not only to the refinement of microstructural components, but also to changes of their morphology. Mechanical vibration significantly increases the mechanical properties and density of aluminum alloys during lost foam casting. The use of aerodynamic cooling at the stage of casting solidification shows that in the aluminum alloy the size of dendritic cells decreases by 1.5–1.8 times, the size of eutectic silicon decreases by 1.3–1.6 times and the length iron intermetallic needles decreases by 1.4–1.8 times compared to castings obtained by traditional lost foam casting technology. The latter methods are the most promising for controlling the process of metal crystallization during lost foam casting, as the most universal method of manufacturing complex cast parts from aluminum alloys.
Keywords: Aluminum alloy, sand mold, cooling rate, 3D printing, aerodynamic cooling, lost foam casting.
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