Corrosion resistance of aluminum alloy AA7022 wire fabricated by friction stir extrusion
(1. Department of Mechanical Engineering, Semnan University, Semnan 3513119111？, Iran;
2. Faculty of Materials & Metallurgical Engineering, Semnan University, Semnan 3513119111？, Iran)
2. Faculty of Materials & Metallurgical Engineering, Semnan University, Semnan 3513119111？, Iran)
Abstract: Friction stir extrusion (FSE) is known as an innovative manufacturing technology that makes it possible to directly produce wire via consolidation and extrusion of metal chips or solid billets. In this study, wire samples were produced using aluminum alloy AA7022 machining chips by the use of the FSE. To this end, the microstructures and mechanical properties of the base material (BM) and the extruded samples were investigated. The corrosion resistance of the given samples was also determined using potentiodynamic polarization technique. The results showed that the samples manufactured at higher rotational speeds possessed good surface quality, the process temperature and the grain size similarly increased following the rise in rotational speed, and the mechanical properties consequently decreased. Using the FSE led to crystallite refinement, increase in volume fraction of grain boundaries, as well as re-distribution of precipitates affecting corrosion resistance. Furthermore, the findings of the corrosion tests revealed that the produced samples by the FSE had adequate corrosion resistance and the growth in die rotation rate augmented current density and subsequently reduced corrosion resistance.
Key words: friction stir extrusion; aluminum alloy wire; grain size; hardness; corrosion resistance