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Numerical Simulation Of2D Solidification Structure Of AlSi Alloy Based On CA-FD Model

Posted on:2015-08-04Degree:MasterType:Thesis
Country:ChinaCandidate:S T WuFull Text:PDF
GTID:2271330452455203Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Solidification of liquid metal is an important means of materials processing. Themicrostructure after solidification decides the performance of castings directly.Solidification process involves complex physical and chemical change. It is accompaniedby heat transfer, momentum transfer, mass transfer in the macro scale and nucleation,growth kinetics in the micro scale. Experimental research of solidification process is lackof effective and direct method because the process happens at a high temperature and themetal is opaque. With the improvement of computer technology, numerical simulationmethod has been greatly developed. Based on the maturity of macro simulation, more andmore researchers put their emphasis on microstructure simulation.First, the thesis summarizes the recent achievements of previous work and establishesa CA-FD model for dendrite growth by using cellular automaton and explicit finitedifference techniques. On the basis of solute diffusion model, considering the nucleation,dendrite growth kinetics, interfacial energy effects and other factors, the thesis simulated adeveloped dendrites without presupposing the shape of original nuclei successfully. Thenthe CA-FD model was applied to research the effect of melt supercooling on dendriticmorphology, distribution of components. The stabilizing effect of interfacial energy andsolute trapping phenomenon were verified. The Von Neumann and Moore neighborhoodconfiguration were used to simulate dendritic morphology with preferential growthorientation0°and45°respectively. The multi-dendrite morphology was simulated byadding random nucleation into the model.Secondly, a grain structure simulation system was developed by coupling macrotemperature field with micro scale models. The growth behavior of single grain andmultiple grains with different neighborhood configurations were studied. Using thequantitative characterize model presented in this thesis, Characteristic parameters ofdifferent configurations were extracted, which helps the selection of different CA Models.Finally, a visualization program base on OpenCV was developed. The simulationresults can be displayed during the calculation process and can be exported or imported. The statistical analysis of grain structure can be finished in the program, avoiding thedependence on commercial software.
Keywords/Search Tags:Cellular Automaton, Dendritic Growth, Grain Structure, QuantitativeCharacterization Model
PDF Full Text Request
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