MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF FSW JOINT OF ALUMINIUM ALLOYS

Abstract

is the second most used material for various industrial applications after the steel (Vargel et al., 2004). It is the most plentiful metal in the crust of earth (Handbook Metals, 1990). Duralumin was the first Al-Cu-Mg alloy that was used for aeroplane design. Aluminium gives high strength to weight ratio, high corrosion resistance, good formability which make it attractive for the aerospace, shipping and automotive applications (Minford, 1993). Generally, aluminium alloys are divided in eight different series, according to the composition of the alloy. Mostly, classification of the aluminum alloys is done as heat treatable and non-heat treatable alloys (Mishra and Sidhar, 2016). 2xxx, 6xxx and 7xxx series come under the heat treatable alloys. These alloys are precipitation hardenable and highly sensitive toward the heating. 2xxx and 7xxx series are the high strength aluminium alloys (Threadgill et al., 2009). Alloys of 2xxx series are found to be more corrosion sensitive, so their corrosion resistance is lower than the other aluminium alloys (J R Davis, 1999; Vargel, 2004). Joining is an important step of fabrication and welding is a very common joining technique. Fusion welding has been used for a long time to join the materials. Unfortunately, it is not easy to weld an aluminium alloy using fusion welding (Mathers, 2002). High reactive nature and high thermal conductivity of the aluminium alloys create difficulty during fusion/conventional welding (Maggiolino and Schmid, 2007). Generally, fusion welded aluminium alloys are susceptible to many type of defects. Some of the common problems are porosity, solidification cracking, hot tears, distortion and inclusions of oxide or hydrogen in the weldment (Givi and Asadi, 2014). Melting of the material occurs during the fusion welding and this increases susceptibility of above said defects in the weld joint of aluminium alloys (Padhy et al., 2018). Thus, a process which can join the material without melting is suitable for the aluminium alloys. Friction stir welding is a solid state welding technique which can join the material without melting. It was discovered at ‘The Welding Institute, United Kingdom’ in the year of 1991 (Mishra et al., 2014; Wahid et al., 2018). Shortly, it became popular for the joining of aluminium alloys. Friction stir weld joints were found free from the defects which were common in the fusion weld joints. It was found as very effective joining technique for light weight metallic systems (Donatus, 2017).