Mechanical and Corrosion Behavior of Pure Aluminium Added Friction Stir Weld Joint of Aluminium Alloy

Abstract

Friction stir welding (FSW) of AA2014 aluminium alloy was performed by sandwiching pure aluminium (Al) in the form of strip between the abutting surfaces. Mechanical and corrosion behavior of weld joint with and without pure aluminium addition was compared. Friction stir welding was carried out at rotational speed of 931 rpm and traverse speed of 41 mm/min. Pure aluminium strip of 1 mm thickness was used for incorporating Al in weld nugget zone. Microstructure analysis was carried out using optical microscope and FESEM with energy dispersive spectroscopy (EDS). Microhardness and tensile testing were performed on the weld joints. Corrosion behavior was investigated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (Tafel) test. FESEM analysis was performed before and after corrosion test. Traces of pure aluminium strip were observed in the microstructure. The incorporated strip was found not to be uniformly distributed in the nugget zone. Pure aluminium addition reduced the extent of formation of the second phase particle in the nugget zone as compared to the normal FSW joint i.e. without Al addition. This metallurgical homogeneity resulted in better corrosion resistance of the Al added weld joint than the normal FSW joint.