Mechanical Properties and Micro-Mechanisms of Chromite Sand Frozen Sand Molds Prepared by Ultrasonic Vibration Assistance

Frozen sand molds are the key material in digital frozen sand mold green casting technology, and their mechanical properties directly affect casting quality. Currently, these molds are primarily prepared by mechanical stirring, mixing, and compaction, which tend to cause imbalanced moisture adsorption and localized wet–dry differences, ultimately impairing the performance and quality of the castings. In this study, an ultrasonic vibration-assisted platform was established to prepare chromite sand frozen sand molds. By introducing ultrasonic vibration into the preparation process, a superior “sand grain–ice crystal” microstructure was constructed, leading to significantly enhanced mechanical properties. The tensile and compressive strengths were increased by approximately 10%, and the optimal process window for achieving the best mechanical performance of chromite sand was obtained.