Investigation of similar and dissimilar friction stir welded metal matrix composites under variable loading

Recently, increasing requirements to reduce weight in various modern industries have attracted an explicit interest in engineering applications of lightweight structural materials. Accordingly, metal matrix composites (MMCs) have acquired wide popularity due to their remarkable features. Sound joining of these materials has gained importance for applications in engineering structures and components. When compared with conventional joining methods, friction stir welding (FSW) seems to be an outstanding candidate due to its unique properties as a solid-state welding technique. Few researches have been performed on the dissimilar friction stir butt joints of MMC-monolithic aluminum alloy so far and there is little information related to the effects of FSW process on the mechanical properties of both similar and dissimilar MMC welds. The present thesis investigates the weldability of particulate-reinforced MMCs between each other and also with different materials. As a result, similar and dissimilar sound joints without weld defects are achieved. Thereafter, microstructure, mechanical properties and fatigue response of the similar and dissimilar joints are investigated. In general, it has been seen that the mechanical properties of the similar and dissimilar joints are comparable with those of the base materials. It is the first time that the study on the fatigue behavior of MMC-aluminum alloy joint was conducted.