The optimum combination of tool rotation rate and traveling speed for obtaining the preferable corrosion behavior and mechanical properties of friction stir welded AA5052 aluminum alloy

This study attempts to find an optimum combination of the welding tool rotation rate (ω) and traveling speed (υ), concerning the corrosion and mechanical properties of Friction Stir Welded (FSWed) AA5052 Aluminum alloy. The effect of the tool speeds on the FSWed AA5052 are investigated via potentiodynamic polarization, open circuit potential (OCP) monitoring, test of the susceptibility to intergranular corrosion, weight loss, tension and micro-hardness tests. Optical microscope and Scanning Electron Microscopy (SEM) were employed for studying the morphology and analyzing the probable intergranular attacks. It was found that by increasing υ up to 200 mm/min at ω = 400 rpm, the microstructural evolution is in a way that the finer grain structure intensifies the anodic reactivity of the Stir Zone (SZ). At faster υ (about 250 mm/min), further grain reinforcement resulted in a predominant effect of passive film formation and thereby an unexpected high corrosion resistant SZ with a proper mechanical characteristics was attained.