Effect of Friction Stir Processing on Mechanical Properties and Microstructure of the Sand Casting Eutectic Al-12wt%Si Alloy

Friction stir processing (FSP) has the potential for locally enhancing the properties of eutectic Al-12wt %Si alloy. A cylindrical tool with threaded pin was used. The effect of FSP has been examined on sand casting eutectic Al-12wt %Si alloy. The influence of different processing parameters has been investigated at a fundamental level. Effect of (FSP) parameters such as transverse speed (189) mm/min, rotational speed (560, 710, 900) rpm on microstructure and mechanical properties were studied. Different mechanical tests were conducted such as (tensile, micro hardness and impact tests). Image analysis of particle size distributions were used to quantify the level of particle refinement and the homogeneity of the second phase distribution. Hardness and impact measurements were taken across the process zone (PZ), and tensile testing was carried out at room temperatures. After FSP, the microstructure of these alloys was greatly refined. However, differences in microstructure have been observed throughout the process zone (PZ), which tended to be better refined and distributed on the advancing side than the retreating side of the PZ. FSP caused very little changes to the hardness of the material, while tensile and impact properties were greatly improved.