Experimental Investigation and Parametric Optimization of AA6063/AA6351 Alloys Bimetallic Prepared by Vacuum-Assisted Lost Foam Compound Casting Process

Aluminum alloys, AA6063 and AA6351, were joined together by vacuum-assisted lost foam compound casting process. The process was executed by considering three process parameters: pouring temperature, vacuum pressure and size of sand particles. Experiments were designed by using L-9 orthogonal array. Microstructure and mechanism of joint interface formation were analyzed. Mechanical properties, viz., shear stress, microhardness and impact strength of joint interface, were measured experimentally, and process parameters were optimized by using the Taguchi method. The results indicated that a uniform and defect-free joint interface between AA6063 and AA6351 was achieved. Pouring temperature was the most dominating process parameter that influenced shear stress, microhardness and impact strength. It had the maximum contribution (69.6 to 85.06%) followed by the size of sand particles (9.39 to 21.27%) and vacuum pressure (3.26 to 8.69%). Confirmation experiments indicated that shear stress, microhardness and impact strength lie in the 95% confidence interval of the optimal predicted values obtained by the Taguchi method.