This paper investigated the effects of MnS inclusions on inducing pitting in steel. Three different cooling methods were used to control the morphology, size, and distribution of MnS inclusions. AC (alternating current) impedance spectroscopy experiments and potentiodynamic polarization experiments were carried out for different sizes of MnS inclusions. The corrosion immersion experiment was conducted to study the pitting corrosion process in different morphologies of MnS inclusions. The experiment results showed that pitting corrosion occurred around MnS inclusions and pitting was induced along the junction of MnS inclusions and their surrounding steel matrix. Also, the sensitivity of inducing-pitting of MnS inclusions was changed with the change of the average size of MnS in steel and it had a critical size of MnS. The deeper the MnS inclusions were buried in steel matrix, the more difficult it was for it to dissolve and fall off. Herein, it would cause greater damage.

To study the effect of Al₂O₃ inclusions on pitting corrosion in steel, our researchers utilized industrial pure iron as the raw material with the addition of a proper amount of pure aluminum powder to form Al₂O₃ inclusions. Corrosion experiments were performed by exposing the samples to a 6% FeCl₃ solution at room temperature (25 °C) for different lengths of time. Microscopic corrosion morphology was observed by scanning electron microscope (SEM), and the size change of the inclusions was quantitatively analyzed with Image Pro Plus. The experimental results showed that pitting corrosion arose preferentially around the Al₂O₃ inclusions, and that pitting corrosion initiated at the junction of the Al₂O₃ inclusions. The steel matrix dissolved and micro-cracks occurred as the Al₂O₃ inclusions that were buried shallowly below the surface of the steel matrix promoted corrosion of the steel matrix. As corrosion progressed, the shallowly buried Al₂O₃ inclusions began to appear on the surface, and the small, shallow inclusions fell off and formed micro pits. Furthermore, the clustered distribution of alumina inclusions had a greater effect on pitting initiation than the alumina inclusions distributed alone.

Steel products have experienced long-standing problems such as unstable product quality and low product homogeneity. In the continuous casting process, realizing constant-temperature pouring is an effective way to improve product homogeneity. Plasma heating can compensate for the temperature drop during casting with a tundish and maintain a stable degree of superheating of the molten steel in the tundish. Plasma heating has a certain impact on the cleanliness of the molten steel and on the tundish covering flux in the tundish while compensating for the temperature drop. This paper uses SEM-EDS, XRD and FactSage to analyze the cleanliness of molten steel and the characteristics of the tundish covering flux before and after plasma heating. The results show that the number density of inclusions in the tundish is significantly lower after heating, improving the floating removal of small-sized inclusions; after heating, the surface morphology of the tundish covering flux sample appears transparent and glassy, with uniform morphology. XRD results show that the tundish covering flux after plasma heating exhibits no crystal precipitation and is amorphous and that there is a certain regularity before and after heating; there are no obvious changes in the composition of the tundish covering flux in the liquid phase area.

Steel products have experienced long-standing problems such as unstable product quality and low product homogeneity. In the continuous casting process, realizing constant temperature pouring is an effective way to improve product homogeneity. Plasma heating can compensate for the temperature drop during casting with a tundish and maintain a stable degree of superheating of the molten steel in the tundish. Plasma heating has a certain impact on the cleanliness of the molten steel and on the tundish covering flux in the tundish while compensating for the temperature drop. This paper uses SEM-EDS, XRD and FactSage to analyze the cleanliness of the molten steel and the characteristics of the tundish covering flux before and after heating. The results show that the number density of inclusions in the tundish is significantly lower after heating, improving the floating removal rate of small-sized inclusions; after heating, the surface morphology of the tundish covering flux sample appears transparent and glassy, with uniform morphology; XRD results show that the tundish covering flux after plasma heating exhibits no crystal precipitation and is amorphous and that there is a certain regularity before and after heating; there are no obvious changes in the composition of the tundish covering flux in the liquid phase area.

In the continuous casting process, the flow velocity of molten steel at the surface of the mold directly influences the melting of the flux, slag entrainment behavior, and the uniformity of heat transfer. Fast and accurate prediction of the magnitude and distribution of surface-flow velocity is crucial for defect suppression and ensuring continuous casting quality. In this study, a three-dimensional electromagnetic–fluid dynamic coupled model was established and validated to simulate the molten steel flow behavior under various casting speeds, Electromagnetic Stirring (EMS) currents, EMS frequencies, and Submerged Entry Nozzle (SEN) immersion depth. Subsequently, the maximum surface velocity in the mold was fitted to derive a predictive formula under different conditions; the median range and width of the surface high-velocity range were predicted in a similar way. As a result, a regression model derived from Computational Fluid Dynamics (CFD) was built to predict the maximum mold surface velocity and the high-velocity range within milliseconds. The reliability of the regression model was verified by newly generated simulation results, with the relative error between the predicted and simulated maximum surface velocities kept within 2%. It was shown that the maximum surface velocity increases with casting speed and EMS current but decreases with EMS frequency. The median range of the high-velocity range decreases with increasing casting speed and current. The immersion depth of SEN had a minimal impact on the maximum surface velocity in the mold and the high-velocity range. This regression model is beneficial for rapid mold design and for predicting potential slag entrainment, breakout risks, and billet defects, for the purpose of intelligent continuous casting.