Study of addition of nanoparticles on the properties of friction stir welded aluminum alloy

Abstract

iv newlineABSTRACT newlineAluminum due to its high strength to weight ratio and corrosive resistance have wide applications in aerospace, transport, and marine industries. Heat treatable AA6061 is considered the most suitable alloy for marine frames, pipelines, aircraft, etc. However, the joining of aluminum alloys using conventional fusion welding techniques leads to cause barriers like low weldability, solidification cracking, distraction stress, decomposition of ceramic particles, and formation of brittle intermetallic phases. Besides, the weakening of the weld zone for aluminum alloy using the fusion welding process leads to a decrease in weld strength which is due to the non-uniform distribution of ceramic particles and coarsening and dissolution of precipitates. To avoid these limitations, the process that is governed below the melting point of the base material is needed to join aluminum alloys. Friction stir welding (FSW) is more efficient for solving such issues by eliminating the defects that occurred during fusion welding of aluminum alloys. Due to this, the FSW is attained potential attention in automobile, marine, and nuclear power industries to join weld structures on different base matrices, including aluminum, titanium, austenitic steel, and Metal Matrix Composites (MMCs). FSW process also helps to retain the original distribution of ceramic particles in the welded area which leads to enhancement in property gradient. Based on this, the suitability of the FSW process to join AA6061-T6 with and without the addition of Al2O3 and TiO2 nanoparticles in the weld zone is investigated in this thesis work. Also, the effect of FSW parameters on weld quality and evolution of microstructure in the weld region of AA6061-T6 (with/without nanoparticles) was carried out. Experimental analysis was also carried out to evaluate the effect of FSW process parameters, namely tool rotational speed and traverse speed on tensile and wear properties of FSW welds (with/without nanoparticles). The cross weld macrostructural and microstr