Cao Hanxue, Zhang Qiang, Zhu Weikai, Cui Sheng, Yang Qin, Wang Zhibai, Jiang Bin
College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China.
National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China.
Materials (Basel). 2024 Oct 12;17(20):4990. doi: 10.3390/ma17204990.
Aluminum alloy die casting has achieved rapid development in recent years and has been widely used in all walks of life. However, due to its high pressure and high-speed technological characteristics, avoiding hole defects has become a problem of great significance in aluminum alloy die casting production. In this paper, the filling visualization dynamic characterization experiment was innovatively developed, which can directly study and analyze the influence of different injection rates on the formation and evolution of alloy flow patterns and gas-induced defects. As the injection speed increased from 1.0 m/s to 1.5 m/s, the average porosity increased from 7.49% to 9.57%, marking an increase in the number and size of the pores. According to the comparison with Anycasting, simulation results show that a liquid metal injection speed of 1.5 m/s when filling the flow front vs. the previous injection rate of 1.0 m/s caused fractures when filling at the same filling distance. Therefore, the degree of the broken splash at the flow front is more serious. Combined with the analysis of transport mechanics, the fracturing is due to the wall-attached jet effect of the liquid metal in the filling process. It is difficult for the liquid metal to adhere to the type wall in order to fuse with subsequent liquid metal to form cavity defects. With an increase in injection velocity, the microgroup volume formed via liquid breakage decreases; thus the volume of air entrapment increases, finally leading to an increase in cavity defects.
近年来，铝合金压铸技术取得了快速发展，并已广泛应用于各行各业。然而，由于其高压、高速的工艺特点，避免孔洞缺陷已成为铝合金压铸生产中一个具有重要意义的问题。本文创新性地开展了充型可视化动态表征实验，该实验能够直接研究和分析不同注射速率对合金流动模式形成与演变以及气体诱发缺陷的影响。随着注射速度从1.0米/秒增加到1.5米/秒，平均孔隙率从7.49%增加到9.57%，这标志着孔隙数量和尺寸的增加。与Anycasting软件的模拟结果对比显示，当填充距离相同时，充型过程中液态金属注射速度为1.5米/秒时的流动前沿与先前1.0米/秒的注射速率相比，前者在充型时会导致断裂。因此，流动前沿处破碎飞溅的程度更为严重。结合传输力学分析，这种断裂是由于液态金属在充型过程中的壁面附着射流效应。液态金属难以附着在型壁上以便与后续液态金属融合，从而形成型腔缺陷。随着注射速度的增加，因液体破碎形成的微团体积减小；因此，卷入的空气体积增加，最终导致型腔缺陷增加。
