Research On Rheological Shearing Preparation Technology Of7A09Aluminum Alloy Semi-solid Slurry

7A09aluminum is widely used in aerospace for its excellent strength, corrosionresistance and fatigue resistance. However, coarse grain ring or long strip defects areproduced easily in forging and it doesn’t get a better solution. This problem can besolved by semi-solid processing technology. Slurry preparation has always been animportant research content as the most important step in semi-solid processing. A newdevice of semi-solid slurry preparation is designed and the reform of microstructure andperformance of7A09aluminum alloy is tried in the study.Firstly, the semisolid preparation process is simulated by the software ofPROCAST. The liquid temperature and velocity field variation of aluminum alloy meltare analyzed to help to make the preparation of the experiment next. The microstructureand hardness of the semi-solid billets are analyzed by using optical microscopy andmicro-hardness tester, and the average grain size and average shape factor are analyzed.The semi-solid container is cooled by air, preheat200℃and water. The impact ofcooling methods on semi-solid slurry is researched. Finally, the elements distribution isalso analyzed by backscatter scanning and EDS.The simulation results show that near liquid line casting decreases the liquid flowrate in the inclined tube and increases the flow rate and heat exchange, reduces adhesionphenomena in the vertical tube. The higher inclined angle will not help to get uniformtemperature field and it decreases the export solid fraction for the faster liquid flow rate.Lower inclined angle leads to blockage easily. Rotating speed of the vertical tube haslittle effect on the melt temperature field. The rotating speed impacts the speed field ofupper part greater and the lower part is less affected.The stable, small, nearly spherical grains can be obtained at the liquid linetemperature630℃, inclined tube angle45°and rotating speed70r/min. The averagegrain size reaches52μm, the average shape factor is0.67and the largest hardness valueis152HV. Compare the three cooling methods such as air cooling, preheat200℃andwater cooling, water-cooling method helps to get the best microstructure. The EDSanalysis shows that solid phase region rarely exist segregation and liquid phase regionexist severely segregation.A new rheological preparation process of semi-solid slurry is presented in the study. The metal tube with bend runner could offer more heat transfer and shear factorwhich helps to prepare semi-solid alloy. It provides guiding significance for industrialproduction practices with its simple and efficient features.