effects of friction stir processing on mechanical properties of aa7075 aluminum alloy after joining by gas tungsten arc welding

Friction stir processing (fsp) is a method of changing the properties of a metal through intense, localized plastic deformation. the influence of fsp on the mechanical properties of aa7075-t6 aluminum alloy welded by gas tungsten arc welding (gtaw) was investigated. the original and friction stir-processed welds were assessed, and their microstructure and mechanical properties were compared. fsp was found to produce a great extent of refinement in microstructure accompany with uniformly distributed fine particles. using fsp improved the mechanical properties of the welds, particularly those joined by gtaw, through grain refinement in the fusion zone (fz). the fsp at 1600 rpm and 80 mm/min improved the elongation, tensile strength, and hardness of 7075-t6 aluminum alloy. fsp increased the tensile properties of 7075-t6 gtaw due to grain refinement of the weld zone by 14 percent. elongation increased about 200 percent for the joint fabricated using ws of 80 mm per min and rs of 1600 rpm compared to unprocessed weld. hardness decreased from 120 hv to 60 hv after welding and then increased to 90 hv after fsp. decreasing hardness attributed to welding heat effects, which increase after fsp, is related to grain refinement. this work showed that fsp is an effective method for improving the mechanical properties of fusion welds in 7075 al-zn alloy through microstructural modification.