Effect of Compositional Variation in TiO₂-Based Flux-Cored Arc Welding Fluxes on the Thermo-physical Properties and Mechanical Behavior of a Weld Zone

The effect of compositional variation in TiO₂-based flux-cored arc welding fluxes on viscosity, wettability, and electronegativity was studied. The thermo-physical properties of the retrieved fluxes and their relationship with the mechanical properties of the weld zone, including tensile strength and micro-Vickers hardness, after welding were identified. Microstructural observation under similar welding conditions revealed significant grain coarsening at a corrected optical basicity (Λ^corr) of 0.62, resulting in reduced strength and hardness due to greater heat transfer. Welding fluxes containing TiO₂-based simple structural units should result in greater heat transfer due to the deficiency in complex [AlO₄]⁵⁻- and [SiO₄]⁴⁻-based structural units, as identified through spectroscopic analyses using fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electronegativity of the retrieved fluxes was also evaluated since higher electronegativity results in greater absorption of electrons in the arc, resulting in arc condensation towards the center direction. Consequently, deeper penetration could be obtained, where the highest electronegativity was identified to be approximately 0.62 of the corrected optical basicity. Thus, both the thermal conductivity and electronegativity of the welding fluxes were identified to determine the heat transfer phenomenon during flux-cored arc welding.