Study on Rheological Squeeze Casting Process of Ultra-high Strength Al-11Zn-1.8Mg-0.9Cu-0.15Zr-0.15Sc Alloy

Abstract

7xxx series Al alloys with excellent mechanical properties are widely applied in aerospace, automotive, and defense industries. However, the casting performance of the alloy is relatively poor, and defects such as shrinkage porosity and thermal cracking are easy to occur during the solidification process. In this study, Al-11Zn-1.8Mg-0.9Cu-0.15Zr-0.15Sc alloy with excellent casting and strength performance developed by our research group, was studied by combining numerical simulation with experimental research. The simulation results show that hot joints appear in the thick wall of the wheel parts as the melt temperature increases. The increase of mold temperature and the decrease of squeeze pressure lead to the increase of the existence time of hot joints, which will aggravate the shrinkage and micro-segregation of castings. The experimental results show that electromagnetic stirring melt treatment can significantly improve melt uniformity, refine grain, and a wheel-shaped part with high performance can be obtained when the melt temperature, the mold temperature, the squeeze pressure are chosen as 660 °C, 200 °C, 50MPa, respectively.