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采用自行研发的自孕育制浆技术制备AM60半固态浆料,利用冷室压铸机对浆料进行流变压铸成形试验,研究压射速度对铸件缺陷形成的影响。结果表明,当压射速度小于0.5m/s时,铸件充型不足;增大至2.0m/s后,铸件充型完整,但充型末端易出现冷隔缺陷;压射速度大于7.0m/s导致铸件出现严重飞边。显微组织分析表明,压射速度增大,铸件内微气孔增多且尺寸增大,铸件边缘液相偏析程度减小,同时内部夹杂增多,夹杂物尺寸较大;当压射速度小于1.0m/s时,初生相形貌发生粗化,液相中二次枝晶增多。因此,高压射速度能在一定程度上提高流变压铸件显微组织的均匀性,但同时使铸件气孔、夹杂缺陷增多,不利于提高半固态压铸件的力学性能。
The semi-solid slurry of AM60 was prepared by self-inoculating pulping technology and the rheological die-casting test of the slurry was carried out by using the cold chamber die-casting machine to study the influence of injection velocity on the formation of casting defects. The results show that when the injection velocity is less than 0.5m / s, the filling of the casting is not enough. When the casting speed increases to 2.0m / s, the casting filling is complete, but the cold- s lead to severe burrs on the castings. Microstructure analysis shows that the injection speed increases, the micro-pores in the casting increases and the size increases, the liquid phase segregation of the edge of the casting decreases, while the internal inclusions increase, inclusions larger; when the injection velocity is less than 1.0m / s, the morphology of the primary phase coarsens and the number of secondary dendrites increases in the liquid phase. Therefore, high injection velocity can improve the microstructure uniformity of rheo-diecasting to some extent, but at the same time, the porosity and inclusions of castings increase, which is not conducive to improve the mechanical properties of semi-solid die-castings.