To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carri...To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.展开更多
A two-dimensional computational model coupling an annular electromagnetic stirring（A-EMS） with a macroscopic heat and fluid flow analysis in Al-alloys semisolid slurry preparation was developed.The dynamic evolution...A two-dimensional computational model coupling an annular electromagnetic stirring（A-EMS） with a macroscopic heat and fluid flow analysis in Al-alloys semisolid slurry preparation was developed.The dynamic evolutions of the electromagnetic field,flow field,and temperature field were presented successfully by commercial software ANSYS 10.0 with corresponding experimental verification.A horizontally rotational electromagnetic field and,thereby,a more intensive velocity field were uniformly distributed in the stirred melt even at commercial frequency,and thus,a lower temperature difference in the stirred melt and subsequent uniformly fine microstructures were obtained compared with the normal electromagnetic stirring.The simulation results were in good agreement with experimental ones.展开更多
文摘To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.
基金supported by the Major State Basic Research Development Program of China (No.2006CB605203)the National High-Tech Research and Development Program of China (No.2009AA03Z534)
文摘A two-dimensional computational model coupling an annular electromagnetic stirring（A-EMS） with a macroscopic heat and fluid flow analysis in Al-alloys semisolid slurry preparation was developed.The dynamic evolutions of the electromagnetic field,flow field,and temperature field were presented successfully by commercial software ANSYS 10.0 with corresponding experimental verification.A horizontally rotational electromagnetic field and,thereby,a more intensive velocity field were uniformly distributed in the stirred melt even at commercial frequency,and thus,a lower temperature difference in the stirred melt and subsequent uniformly fine microstructures were obtained compared with the normal electromagnetic stirring.The simulation results were in good agreement with experimental ones.
