In aluminum alloy casting, grain refining agents such as titanium, boron, and carbon are widely used to refine and homogenize macrostructures and also improve mechanical properties. However, these grain refining agents may induce serious problems during the recycling stage. In this study, gravity castings with mechanical vibration (0-157 Hz) were conducted and columnar rods (Φ25mm, L210mm) were cast to investigate the effects of mechanical vibration on grain refining, distribution of casting defect, and mechanical properties. Mechanical vibration refined the grains in the middle area of the columnar rods, but the columnar structure remained in their outer region at all vibrational frequencies. The variance of mechanical properties of specimens cast with mechanical vibration became smaller due to the reduction or complete elimination of casting defects in the specimens by mechanical vibration.
