A356.2 aluminum alloy has the advantages of low density, high specific strength, high specific stiffness, good corrosion resistance and good casting performance. It is widely used in the casting of automobile aluminum alloy wheel hub. Under the casting conditions, the primary α - Al dendrite of the unmodified A356.2 aluminum alloy is coarse, the eutectic silicon is distributed in the form of coarse needle, and the silicon phase is brittle, which makes the alloy matrix crack seriously and reduces the plasticity and strength of the alloy significantly The mechanical properties of A356.2 aluminum alloy are seriously affected. Next, the material characteristics of aluminum alloy wheel hub will be introduced.

　　In the existing technology, rare earth modification has become a hot spot to improve the performance of A356.2. The addition of rare earth can significantly refine the primary α - al phase, play a good modification effect on eutectic silicon, refine the grain size of as cast material, and significantly inhibit the occurrence of recrystallization. It can also improve the strength of aluminum alloy matrix, and significantly improve the tensile strength and elongation of castings.

　　Compared with sodium salt modification and strontium modification, the mechanical properties of al-7si-0.35mg alloy modified by antimony have better mechanical properties. Adding proper amount of antimony modifier into the melt can reduce the aspiration tendency of the melt and improve the impact strength of the alloy. The density and the modification effect of antimony have long-term effects.

　　A method for preparing al-7si-0.35mg-sb aluminum alloy wheel hub is characterized in that: the chemical elements in the Al-Si-Mg alloy system are proportioned, the crucible resistance furnace is heated to 250-500 ℃ for melting and pre curing, the high-purity aluminum block and copper ruthenium alloy are preheated to 100-250 ℃ in the box type resistance furnace, and then gently put into the preheated crucible. The recorder will monitor the aluminum liquid in the crucible furnace in real time After the aluminum block is completely melted, the temperature is stabilized at 730-780 ℃, a certain proportion of silicon is added into the liquid aluminum for 30min, al-10sb master alloy is added, and the temperature is kept at 735 ± 5 ℃ after 10-20min. A certain proportion of pure magnesium is added, fully stirred for more than 15s, kept for 15min, degassed with high-purity nitrogen for 10min, standing for