Parametric optimization of friction stir welding of dissimilar Al 5083 and Al 6061 alloys using taguchi method
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Date
2019-07
Authors
Syazfiqa Farina Binti Muzammil
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Abstract
Friction stir welding is a promising technique for joining the dissimilar metals for applications in aerospace, automobile, defense and shipbuilding. In the present study, friction stir welding (FSW) processing parameter for dissimilar joint Al 5083 alloy and Al 6061 alloy were investigated. The FSW welding parameters investigated are rotational speed (600 rpm, 865 rpm and 1140 rpm), tilt angle (1˚, 2˚ and 3˚) and number of pass (1,2 and 4). Taguchi technique L9 orthogonal array was applied to determine the optimize control factors which will yield better tensile strength of FSW dissimilar joint Al 5083-Al 6061 alloy. The effects of the process parameters on response characteristics (tensile strength and microhardness) were studied. Characterization of macroscopic weld features, microstructure observation, fractography examination, tensile strength and microhardness were examined. There is variation of grain size in different regions (base metal, HAZ, TMAZ and weld nugget) which depends on the process parameters of FSW. The finest grain size is observed in the weld nugget zone compared to other region. Through the Taguchi parametric design approach, the optimum levels of process parameters were determined. Based on S/N response for tensile strength the optimum parameters are 600 rpm rotational speed, 1˚ tilt angle and 2 number of passes, respectively. The different welding parameters influenced the tensile properties and microhardness which largely dependent on the flow of metal in the joint. At 600 rpm rotational speed shows the highest tensile strength 162.37 MPa as compared to 865 rpm and 1140 rpm due to sufficient material flow to promote the joining. While, the tilt angle of 1˚ showed the best strength because it might have optimal contact between the tool pin and specimens. In addition, 2 number of pass have the highest tensile strength because grains underwent plastic deformation and thermal exposure which lead to significant grain refinement. As results, the microstructure consists dynamically recrystallized grains and the grains size is homogeneously is smaller size.