Effect of Electromagnetic Stirring Conditions on Grain Size Characteristic of Wrought Aluminum for Rheo-forging

This article focuses on the microstructural characteristics of A6061 and A7075 wrought Al alloy slurries fabricated by an electromagnetic stirrer (EMS). Billets fabricated by electromagnetic stirrer under different conditions of stirring current, stirring time, and pouring temperatures were investigated for the microstructure and cooling curves of molten alloy which was directly cooled from liquid state to the mushy state during stirring. From the cooling curves and microstructure examination, it is possible to determine the forming time and stirring time required to obtain an optimum structure. Lower pouring temperatures in the range (650–730 °C) led to finer primary-α Al phase grains in both A7075 and A6061 billets. Higher stirring current led to the finer primary-α Al phase. With respect to the effect of stirring time, the primary-α Al phase still appears in dendritic shape for 20 and 40 s of electromagnetic stirring time. The longer electromagnetic stirring time of 60 s led to a finer primary-α Al phase.