数值模拟在金属基复合材料铸造性能研究上的应用

Application of numerical simulation in the casting properties of metal matrix composites

研究了添加增强颗粒对复合材料铸造性能的影响。根据体积分数与各热物性参数之间的函数关系式对ProCAST的数据库进行二次开发,建立了金属基复合材料的物性参数数据库,从而得到增强颗粒的体积分数及合金成分对金属基复合材料的铸造性能的影响关系。以金属型重力铸造摩托车车轮为实际对象,研究了体积分数为5%的Al2O3颗粒增强铝基复合材料Al2O3/A356.2的铸造性能。计算结果表明:加入颗粒后熔体黏度明显增加,导致复合材料流动性降低,轮辐、轮辋薄壁处均出现了收缩缺陷。通过在合金含量允许的范围内提高硅的含量ω(Si)=7.5%可以延长浇注温度到液相线温度的时间,同时降低结晶温度间隔,缩短固液共存时间,提高熔化潜热,从而提高熔体的流动性,增加补缩能力,使轮辐、轮辋薄壁位置的缩松、缩孔明显减少、消失。

The effect of the addition of reinforcing particles on the casting properties of metal matrix composites was studied by numerical simulation. A database of ProCAST was developed based on the function equation between the volume fraction of reinforcing particles and physical property parameters. Gravity die casting of motorcycle wheels was taken as an example to study the casting property of the 5% Al2O3 particle reinforced aluminum matrix composites. The calculated results indicate that the fluidity of the aluminum matrix composites tends to decrease because of the addition of the particles. Melt viscosity of the composite is higher than A356.2. Shrinkage porosity defect appears both in the spoke and rim of the wheel. The mass fraction of silicon is enhanced by 7.5% in the allowed range. The temperature interval from pouring temperature to liquidus temperature can be increased and the crystallization temperature interval can be reduced synchronously. The latent heat of fusion is increased, so as to shorten the solid-liquid coexistence time, enhancing the fluidity of melt and feeding capacity. The shrinkage porosity defect in the spoke and rim of the wheel is decreased and eliminated.