Numerical analysis of arc plasma characteristics in Titanium and calcium type thin diameter self-shielded flux-cored arc welding under different polarity

To explore the influential mechanism of electrode polarity in self-shielded flux-cored arc welding (SS-FCAW) on arc behavior, aiming at the problem that the complex metallurgical reactions make it difficult to construct a numerical model that conforms to the actual situation. Based on the numerical simulation method of computational fluid dynamics (CFD) and the theory of magnetohydrodynamics, a two-dimensional numerical model of arc plasma was constructed. The distribution characteristics of the arc plasma temperature field, current density field, and flow field under different electrode polarities are studied. The results show that the temperature distribution characteristics of the simulated arc are consistent with the experimental spectral analysis results, thereby verifying the effectiveness of the model. Under direct current electrode negative (DCEN), the conductive channels at the bottom of the droplet are radially divergent, resulting in a "gas ball" temperature distribution; under direct current electrode positive (DCEP), the conductive area was relatively small, so the temperature distribution is "long strip". In addition, compared with DCEN, the temperature, current density, and flow velocity of arc under DCEP increase by approximately 26 %, 235 %, and 445 % respectively at 120A; the current increased from 80A to 120A, highest temperatures of arc under DCEN and DCEP increase by approximately 4.5 % and 2.5 % respectively, the current densities increased by 24.8 % and 39.8 %, and the flow velocities increased by 51.7 % and 83.3 %.