Vortex formation in the continuous slab casting mould is a troublesome phenomenon that can pull mould powder/slag deep down into the liquid core and potentially damage the product quality. Submerged entry nozzle (SEN) clogging is one of the prime causes of vortex formation. This work is designed to investigate and quantify the inter-related effects of nozzle clogging, casting speed (CS) and SEN submergence depth on vortex frequency and penetration depth through water-model experiments. It is observed that the increase in degree of clogging and CS has an inter-related effect on flow asymmetry and impacted the vortex characteristics. At the combination of highest values of degree of clogging and CS, vortices formed are found to have high values of top-diameter, rotational speed, penetration depth, frequency and life. On the contrary, the SEN submergence depth has showed limited effect on these aspects except the penetration depth. With the increase in SEN submergence depth values, it is found that the number of vortices having depth greater than 80 mm is increased.

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This work investigates the effect of process parameters on joint properties of dissimilar AA6082-T6 and AA7050-T7 friction stir welds and determines the optimal value of process parameters using the grey-based Taguchi technique. At optimum welding parameters, similar friction stir welds of respective parent materials were developed for comparative study. Developed welds were evaluated in terms of macrostructure, microstructure, mechanical properties, and textural behaviour. Two types of plasticized material mixing patterns were observed in the weld nuggets, categorized as intercalated onion ring and interlocking lobes-based flow structures. Through electron backscattered diffraction, the fine nugget grain size was observed in dissimilar weld than weld nugget grain size of similar AA6082-T6 and AA7050-T7 welds. Unlike similar welds, the minimum hardness location lies toward the advancing side for all the dissimilar welds. Dissimilar welds' joint strength and yield strength efficiency were evaluated as 65.65% and 61.25% at optimum welding parameters, respectively. Fracture surface analysis revealed ductile behaviour in all the welded joints.

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