Multicomponent enabled MWCNTs-TiO2 nano-activating flux for controlling the geometrical behavior of modified TIG welding joint process

A comprehensive geometrical behavior against the multicomponent nano-activating flux, multi-walled carbon nanotubes-titanium oxide (MWCNTs-TiO2), was configured in this study. The specimens were investigated for macro-morphologies of the weld seams, distortions, weld depths, and depth to thickness (D/T) ratios. The scrutinized behavior of distortions has reported a decremented effect for every step addition of flux. The traveling trends of vertical distortions individually started from 5.334, 6.146, and 6.455 mm for without flux and eventually ended to 3.896, 4.112, and 4.713 mm respectively up to 2 wt% of MWCNTs-TiO2. A similar beneficial effect on weld depths of flux addition observed from optical micrographs, which revealed the radiating radii of semi-circular profiles with increasing penetration. The centripetal Marangoni convection (change in surface tension) and constriction of tungsten inert gas (TIG) welding arc column found responsible mechanisms for significant uplifting of geometrical behavior. However, the extended drive phenomenon due to the presence of TiO2 created electrical resistance effect, which provokes constricted droplet melting mode of filler. The use of MWCNTs provided heterogeneous nucleation that freezes the weld penetration along with limiting the distortion, attributed to the enormous mismatch of coefficient of thermal expansion (CTE) with AA6061. The experimental results also revealed the better performance of flux at higher welding current (200A), which triggered D/T >1 (at 1.5 wt% and 2 wt% MWCNTs-TiO2) in contrast to 160A and 180A.