Study On Subsidiary Stir And Solidification Structure Of Semi-solid Magnesium Alloy Prepared By Solid State Reheated

In order to make semi-solid magnesium alloy microstructure refine and distributing uniformity,a subsidiary stirring device was designed and rebuilt by that the industrialized way of heating as-cast magnesium alloy directly to prepare semi-solid forming slurry.The experiment for improving semi-solid microstructure have been done by this device.Based on the experiment of stirring in the reheating process of semi-solid magnesium alloy and in the isothermal process of as-cast magnesium alloy,the influence of stirring speed,stirring time,isothermal temperature parameter to stirring effect was studied.At last,the characters of semi-solid microstructure of magnesium alloy was analysed in this paper.The main results and conclusions of this paper show:A subsidiary stirring device is self-designed and rebuilt,which holds the characteristics of simple constitution,mechanism stability and reasonable control,by which main factors in the stirring process can be controlled.After stirring the compressed Mg alloy,α phase of semi-solid slurry becomes finer and uniform,and the time of changing from dendries to spheric grain can be shorted. After stirring about uncompressed Mg alloy,the time can be shorted greatly. Those results give some references to industry application of perapering semi-solid slurry by this method.Stiring time,stirring speed and isothermal temperature are the three main factors that influence the stirring result in the process. On this experimental condition,the optimum parameters for preparing semi-solid slurry with SIMA are isothermal temperature(580℃),stiring time (6min～8min),stirring speed (800r/min),and for preparing semi-solid slurry with derictly heat on casting AZ91 are isothermal temperature(570℃),stiring time (8min～10min),stirring speed (800r/min).