Preparation Of Composites And Simulation Of Process Design Of AZ80Magnesium Alloy Squeeze Casting

With the rapid development of world industry, the production of magnesium alloy casting is increased rapidly, people put forward the higher request for the quality of magnesium casting pieces, production efficiency and environmental protection. The squeeze casting have been applied broadly in international and received great economy benefits, including magnesium matrix composites; the squeeze casting’s application in domestic now is only in the experiment stage and has a long distance to the developed countries yet. It is significant to study processing and composite of magnesium alloy squeeze casting.Squeeze casting can get high quality parts, which can be applied on manufacturing magnesium alloys parts. Magnesium alloys possess more multipurpose properties than other materials. In order to explore the applicability of the characteristics and laws of magnesium alloy squeeze casting process parameters and prepare high toughness magnesium matrix composites, magnesium alloy squeezing casting process and properties were studied through simulation of squeeze casting mechanical properties, optimization of squeeze casting technological parameters with morphological matrix based on the AZ80magnesium alloy as the research object, and squeezing casting pieces of excellent mechanical properties were prepared using Y+SiC+SC.A theoretical basis and experimental evidence were provided for process optimization and preparation of high toughness magnesium matrix composites of magnesium alloy squeezing casting. The main results can be summarized as follows:(1) Using the software, AZ80was studied to determine the magnesium alloy wheels and sample reasonable squeeze casting process. Squeeze casting of magnesium alloy process features were verified by analyzing the simulation results of the filling and solidifying process of squeeze casting for magnesium alloy wheels and sample, and also predicted the position of defects. As the same time the best combination of parameters was found so as to the processing plan was optimized.(2) A set of optimal process parameters were obtained through analysising the orthogonal test and simulation of AZ80magnesium alloy, which are extrusion pressure of100Mpa, mould preheating temperature of200℃and pouring temperature of700℃. The influences of squeeze casting process parameters on mechanical properties of AZ80magnesium alloy cast extrusion pressure, pouring temperature and holding time in the simulation from strong to weak. It was found the squeeze casting can be achieved very good mechanical properties:σ b=271.4Mpa,δ=7.4%,HRC=98.2in the pouring temperature is700℃, holding time for the15S, the extrusion pressure is100MPa.This is basically consistent with minimum defects of simulation results. Extrusion pressure makes magnesium alloy solidification cooling rate improved and the heat transfer coefficient improved, so an increase of nucleation rate was obtained, which makes grains refined to improve the mechanical properties.(3) Squeeze cast process parameters of AZ80magnesium alloy by morphological matrix were studied. Experiments were conducted by varying squeeze pressure, die pre-heat temperature and pressure duration using L9(33) orthogonal array of Taguchi method. In Taguchi method, a three level orthogonal array has been used to determine the S/N ratio. Analysis of variance is used to determine the most significant process parameters affecting the mechanical properties. The mechanical properties such as ultimate tensile strength, elongation and hardness of the components have been ascertained using multi variable linear regression analysis. Optimal squeeze cast process parameters were obtained. Thus, this method is used to search for optimal squeeze cast process parameters to obtain better mechanical properties of the components.(4) The AZ80squeeze casting magnesium alloy solid/liquid interface front composition undercooling was increased, thus as-cast group was refined, β-Mg17Al12phase network distribution was broken, so as to the mechanical properties of the casting were improved because of the addition of Y; The main reason of AZ80magnesium alloy mechanical properties improvement is that the solid solution strengthening effect of Y and Al-Y phase dispersion strengthening effect, and the combination of Y and Al reduces the formation of the amount of thermal stability lower Mg17Al12phase. Thermal stability of these main diffuse distribution Al2Y particles much higher of Mg17Al12of AZ80alloy on the grain boundary, neighboring grain movement pinning was effectd at high temperatures, the grain boundary and dislocation movement under high temperature were effectively prevented.(5) The internal organization grains of squeeze casting magnesium matrix composites were refined, and a lot of SiC particles were parceled inside alloy grain after squeeze casting, the comprehensive performance of SiCp/AZ80magnesium matrix composite materials were greatly improved. The performance of AZ80magnesium alloy squeeze casting was significantly improved because of addittione of rare earth Y and SiC, organization was more compacted, Al2Y+SiCp mixture were observed in the organizations. This method can be used for the preparation of high-toughness magnesium matrix composites. The best addition amount of rare earth is3%, the best addition amount of SiC is1%, SiC reunion was formed when the more amount of SiC was added, this also like Y, the degree of SiC particle phase dispersion in tissue distribution was reduced, the dispersion strengthening effect at high temperature was weaked, and the uneven of alloy microstructure and composition was caused, easy to stress concentration was caused, high temperature alloy performance degradation was caused.Magnesium alloy squeeze casting process parameters were optimized on the research. The method and train of thought was proposed by using the morphological matrix parameter optimization. Through simulation and experimental verification of magnesium alloy squeeze casting, production costs were saved, efficiency was improved, and AZ80magnesium matrix composites were prepared,so as to the foundation was laided for the magnesium alloy squeeze casting technology further study.