Investigation on mechanical and corrosion characteristics of friction stir welded aluminum alloy aa2014t6 plates

Abstract

Aluminum alloy AA2014 is used in applications where there is greater demand for high strength to weight ratio, like aerospace, naval and automotive applications. AA2014 is a heat treatable alloy and hence possess high strength. Joining of these alloys using conventional welding methods are difficult because of the deterioration of mechanical properties due to high heat input, and due to the defects formed during joining. Friction stir welding (FSW) a solid state welding process, which is widely used in joining of Aluminum alloys, producing sound, defect free joints. This welding technique is employed to join the plates of the alloy AA2014-T6 in this study. In this work the mechanical characteristics and the corrosion behaviour of the friction stir welded AA2014-T6 plates are studied by varying the process parameters, adding reinforcement particles and applying Post weld heat treatment (PWHT). Also a fuzzy logic model is developed to predict the tensile strength and the nugget hardness of the friction stir welded joint of the alloy. Experiments are conducted as per ASTM standards to study the tensile strength, hardness, wear rate and corrosion characteristics of the FSW joints of the alloy AA2014-T6. It is observed that the tensile strength of the joints are highly influenced by the tool rotation speed (TRS) than the weld speed (WS) and the axial force (AF), keeping other tool parameters constant. Corrosion characteristics are studied by conducting polarization tests and Tafel plot using the instrument, electro chemical workstation CH660C. The corrosion media is 3.5% NaCl solution. The welded samples are sliced through the mid plane of the joint to expose the top, bottom and middle layers newline