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介绍一种先进的集金属熔化、储存、浆料制备、浆料输送和注射成形于一体的流变注射成形机,并使用该设备生产一批AZ91D镁合金流变注射成形件。研究浇注温度和缸体温度对AZ91D镁合金流变注射成形件组织和力学性能的影响规律。结果表明,流变注射成形工艺可以成功获得初生α-Mg颗粒细小、圆整、均匀分布于基体组织中的AZ91D镁合金成形件。随着浇注温度的下降,初生α-Mg形貌由粗大的蔷薇状逐渐转变为细球状。随着缸体温度的降低,初生α-Mg颗粒的尺寸先下降,之后基本保持不变,其球形度和固相率不断提高。同时,适当地降低浇注温度或缸体温度可以细化α-Mg颗粒和降低孔隙率,这有助于流变注射成形件力学性能的提高。另外,AZ91D镁合金流变注射成形件在力学性能上优于触变注射成形、流变压铸成形和高压铸造。与高压铸造相比,AZ91D镁合金流变注射成形件的抗拉强度、屈服强度和伸长率分别提高了27.8%、15.7%和121%。
An advanced rheological injection molding machine integrating metal melting, storage, slurry preparation, slurry transfer and injection molding is introduced. A batch of AZ91D magnesium alloy rheological injection molded parts are manufactured by using the equipment. The effects of pouring temperature and cylinder temperature on the microstructure and mechanical properties of AZ91D magnesium alloy were investigated. The results show that the AZ91D magnesium alloy forming parts with small, round and uniform distribution of primary α-Mg particles in matrix can be successfully obtained by rheological injection molding. With the pouring temperature decreased, the primary α-Mg morphology gradually changed from coarse rosy to finely spherical. As the cylinder temperature decreases, the size of primary α-Mg particles decreases first, and then remains basically unchanged, and its sphericity and solid fraction increase. At the same time, appropriate reduction of pouring temperature or cylinder temperature can refine α-Mg particles and decrease porosity, which contributes to the improvement of mechanical properties of rheo-injection molded parts. In addition, AZ91D magnesium alloy rheological injection molding is superior to the mechanical properties of thixotropic injection molding, rheological die-casting and high-pressure casting. Compared with high pressure casting, the tensile strength, yield strength and elongation of AZ91D magnesium alloy injection molding increased by 27.8%, 15.7% and 121% respectively.