At present, A356.2 aluminum alloy is generally selected as the raw material for the production of aluminum alloy automobile hub, mainly because the aluminum alloy of this brand has good casting, cutting and corrosion resistance, and its main chemical composition is shown in Table 1.
It is found from table 1 that the most content of Si and Mg is in addition to the matrix element Al, which shows that the addition of Si and Mg has a great influence on the properties of the alloy. First, Si and Mg will form intermetallic compounds in the casting process, which will change the thermal field environment and atomic diffusion environment in the solidification process of the alloy liquid, and can increase the fluidity of the alloy liquid, The results show that when the mass fraction of Mg is 0.3%, if the mass fraction of Si increases from 6.5% to 7.5%, the fluidity of the alloy will increase by 29.8%; when the mass fraction of Si is 7%, if the mass fraction of Mg increases from 0.2% to 0.4%, the fluidity of the alloy will increase by 14.34%. Secondly, Si can form Mg2Si with Mg in the aging process, and precipitate Si phase at the same time, The strength of the aluminum alloy is greatly improved.
Although A356.2 aluminum alloy has excellent comprehensive properties, researchers still optimize its properties in different ways. Common ones are: adding rare earth elements, adding refiners and optimizing production process. Liu Honglei  showed that adding rare earth elements to A356.2 aluminum alloy can reduce the generation of pinholes during low-pressure casting, In addition, the degassing effect is Y > La > re. ZHY casting can make the tensile strength and elongation of A356.2 aluminum alloy 20% higher than that of ASTM by strictly controlling the temperature of each node and the content of modulation alloy elements, The fatigue strength and impact toughness are increased by 10%.