Experimental Investigation And Finite Element Analysis On Centrifugal Casting Of Al-4.5%Cu Alloys

The precision casting fabricated in the centrifugal field have their unique superiority. The investigation of the evolution of defects and microstructures has important theoretical meaningness and practical worthiness to fabrication of high quality castings and shorten the production cycle.In this thesis, aluminum alloy melt feeding and microstructures was deeply analyzed by the combination of experimental research and simulation analsis.In this paper, Centrifugal casting experiment was carried out utilizing the system designed by the laboratory, Al-4.5%Cu alloy obtained in non-vacuum centrifugal casting was tested for the study of the mold-filling and solidification behaviors of aluminum alloy, assistant with casting simulation software ProCAST to compare with the results. The methods against the defects of aluminum alloy in vertical centrifugal field were presented.Specific contents have been accomplished in this thesis as the following. The mold-filling and solidification behaviors of Al-4.5%Cu alloy with different mold rotating rates in the casting process was researched, the casting temperature was measured, and the trend of casting mold and casting temperature change with time was established. The correlations between solidification structural dimensions including grain sizes and dendrite arm spacing and processing parameters such as cooling rate, mold rotating rate and casting modulus were also established. The advanced finite element simulation software and theoretical modeling was utilized to analysis the interfacial heat transfer coefficient between metal and casting mold in centrifugal force field and the gravity field conditions, while the application of advanced ProCAST simulation software was to compare the simulations results between the casting speed and pressure coupling and decoupling during the process of casting. The accuracies and computation times were compared and the correlation was analyzed, which can optimize the process and effectively control the quality of the casting.The results show that: during the casting experiment, the centrifugal mold-filling ability increased significantly compared to gravity casting, but when the rotational rate increased from the 200rpm to 300rpm, its ability to increase the filling is limited. Secondary dendrite arm spacing during Gravity and centrifugal casting experiment increased with the modulus. In the Gravity experiments, the average grain size increases with the increase of modulus, while in the centrifugal force field, the average grain size decreases with the increase of modulus. For the simulation of gravitational casting process, the simulation results of the coupled and uncoupled velocity and pressure are similar in the mold-filling and solidification behaviors, and the CPU-times used and the calculation precisions are approaximately same. For the centrifugal casting simulations, the coupled algorithm is much more accurate than that with non-coupled algorithm.