The effect of process parameters on the friction stir processed AS7U3G aluminium alloy

Friction stir processing (FSP) is a solid-state process leading to very significant microstructural modifications. Despite the large number of studies, most of the work that has been done in the FSP field focuses on microstructural evolution, tensile properties, hardness, fatigue strength, corrosion resistance etc. However there is not much information available on correlation of FSP parameters with evolution of defect free processed zone. In order to produce a defect free processed zone, selecting the best processing parameters is very important. In this investigation, the effect of two main FSP parameters (such as tool rotational speed which was kept constant and tool transverse speed which was varied) on the formation/ evolution of defect free processed zone was studied. It is found that at a tool rotational speed 600 rpm and a traverse speed of 12 mm/min the processed zone is defect free. Numerous investigations have been conducted to understand material flow behavior during FSW/FSP. However, the flow process of material during FSW/FSP is still not well-understood, and different explanations have been proposed. In this investigation an attempt has been made to understand the flow of material during FSP and it is reported.