Effect of Processing Parameters on Thermo-Mechanically Affected Zone of Friction Stir Processed AZ91 Magnesium Alloy

AZ91 Magnesium alloy was subjected to friction stir processing (FSP). The microstructural analyses of the friction stir processed (FSPed) specimens were carried out and the effects of pass number, rotational speed, and traverse speed upon thermo-mechanically affected zone (TMAZ) were investigated. The TMAZ is consisted of a region with highly elongated grains and a partially recrystalized zone. Decreasing the rotational speed and increasing the traverse speed increased the thickness of recrystallized zone; while, the thickness of the other zone decreased. On the other hand, it lessened the gradient of the grain size from the stir zone (SZ) to the base metal. Applying several FSP passes, lead to more homogeneous TMAZ structure with the finer grain size.