Investigation Of Rheocasting-rolling Experimental And Thermal Field Simulation On Semi-solid Magnesium Alloy

Rheocasting-rolling technology of semi-solid magnesium alloy is different from the traditional casting process. It combines the pulping, casting and molding into one, this shortens the technological process and reduces production costs while greatly expands the processing range and improves the quality of the magnesium alloy strips. As the semi-solid magnesium alloy has a unique nature, distribution of cooling temperature field and flow field during pulping, casting and cooling affects the formation of semi-solid structure directly, thereby affecting the quality of the strips obtained, so it is of great significance to study the influence of temperature of pulping, casting and strips cooling during rheocasting-rolling. Numerical simulation has played an important role in the development of manufacturing technology. It is to choose the most suitable processing conditions and reduce production cost by optimizing the rheocasting-rolling process parameters. Treatment of the material parameters and boundary conditions are the foundation of numerical simulation technology, accuracy and reliability of the simulation results are important references for improvement of the manufacturing process.In this paper, based on the self-developed semi-solid rheocasting-rolling equipment, the basic principles of heat transfer and material science were used, simulation and experimental analysis of rheocasting-rolling and strip cooling process were done using software ANSYS, the main work completed are as follows:1) Model of the flow field and temperature field in the casting area were established, analysis of the model was done using software ANSYS/FLOTRAN; numerical simulation of temperature distribution under the parameters such as pouring temperature (632℃,624℃,620℃), rollers'thermal conductivity (10000W·m-2·℃-1,7500W·m-2·℃-1), and casting speed were done, the full solidification time in rheocasting-rolling varies from 0.36S to 0.46S.2) Solidification processes of strips obtained in the experiments were analyzed by comparing the different cooling rates (water and air cooling), it was found that water cooling can increase the hardness of the magnesium alloy strips;3) Effect of aging treatment on the strips were studied, strip hardness after heat treatment under T4 decreased a little, but the apparent hardness of the strips after solution treatment improved, the peak value could reach 80HBW.4) Appropriately reduce the casting temperature can increase the hardness of strip, when the casting temperature decreased from 639℃to 623℃, the hardness rose from the 57HBW to72HBW.