The Combined Effect of Cooling Slope Plate Casting and Mold Vibration on Microstructure, Hardness and Wear Behavior of Al–Si Alloy (A390)

Abstract

Semisolid casting using the cooling slope plate method (CSP) is known to refine the microstructure of hypereutectic aluminum alloys and enhance their mechanical properties. The current research investigates the combined effect of casting using the CSP and mechanical vibration of the mold on microstructure and wear behavior of A390 alloy. After pouring the alloy on the CSP, the mold (sand/metallic) was vibrated mechanically at 50 Hz during filling and up to solidification. Conventional casting with the same mold vibration conditions was also done for comparison. During CSP casting with mechanical vibration of the mold, the crystal nucleus multiplication inhibits the grain growth, and the dendrite break-up takes place simultaneously, leading to refinement of the microstructure. The double effect of the shear force by melt flow and vibrational turbulence is responsible for fragmentation of the particles. This finding was more pronounced in case of using the sand mold. The quantitative measurements showed that the size of primary Si reduced from ~ 184 μm for the conventional casting in the sand mold without vibration to ~ 70 μm when the mold was vibrated and from ~ 30 μm in case of CSP down to ~ 20 μm when CSP was followed by mechanical vibration of the mold. However, applying the mechanical vibration after CSP in case of the metallic mold increased the size of primary Si from ~ 21 to 36 μm. Accordingly, the improvement in the hardness and wear resistance of the CSP samples due to vibration was more significant in case of using the sand mold.