Effect of Sulfur Content on the Inclusion and Mechanical Properties in Ce-Mg Treated Resulfurized SCr420H Steel

To clarify the effect of sulfur on inclusions and mechanical properties of Ce-Mg treated resulfurized SCr420H steel. Laboratory experiments were conducted to prepare steels with sulfur contents as 0.01%, 0.06%, and 0.132%. Inclusion evolution in liquid steel, MnS precipitation during solidification, and tensile test results of steel after quenching and tempering were investigated. The results showed that due to the limitation of mass transfer in molten steel, composite inclusion that Ce-O-S wrapped by Ce-Ca-Mg-Al-Si-O, which was named transition state inclusions, can form quickly after adding Ce-Mg lump to the molten steel. As the homogenization of molten steel, the difference of sulfur content in steel can lead to the transition state inclusions transformed into different inclusions. With the increase of sulfur content, the quantity of MnS increased significantly, and the morphology of MnS transformed from “stick” to “dendritic + fishbone”, and then to “fishbone”. Tensile test results and fracture analysis indicate that the decline of inclusion spacing as the increase of sulfur content leads to a shorter physical path of crack propagation in steel. Therefore, the increase of sulfur content can bring about a decrease in the strength and plasticity of the steel. From the perspective of inclusion control, making the MnS inclusion precipitate more dispersive and increasing the distance between inclusions can be considered as a method for preventing the decline of mechanical properties in steel with high sulfur content.

Numerical Investigation of Flow Characteristics of Molten Steel in the Tundish with Channel Induction Heating

In the continuous process, fluid flow is an important physical phenomena in the tundish, as it affects the process of heat transfer, bubble motion and inclusion collision-coalescence and grow up. This paper undertakes a detailed numerical investigation of fluid flow characteristics in the tundish with and without induction heating. The individual unit method and the volume subtraction model are applied to analyze the flow characteristics. A quantitative evaluation method of flow characteristics is proposed to investigate the flow characteristics. In the tundish with and without induction heating, firstly, the main flow behavior of molten steel is mixed flow in the receiving chamber; secondly, the main flow behavior of molten steel is plug flow in the channel; lastly, the main flow pattern is mixed flow, and the minor flow pattern is plug flow in the discharging chamber. The method of the volume subtraction model is an effective way to analyze the flow characteristics in the tundish with channel induction heating.

Generative adversarial network–based real-time temperature prediction model for heating stage of electric arc furnace

For accurately predicting the molten steel temperature of heating stage in electric arc furnace (EAF) in real time, a novel prediction model based on the generative adversarial network (GAN) is proposed in this paper. First, the generator is specially designed based on the simplified energy balance of molten steel combined with long short-term memory (LSTM) network. The sequential smelting variables are used as the input of generator, which is an effective representation of the time-variant EAF operations. Meanwhile, the discriminator is established to indicate the deviation of the changing trend between the generator predicted temperature and the simulated temperature. Here, the simulated temperature is produced according to smelting experience which is a good supplement to the sparse temperature measurements. Subsequently, the loss function of the generator is improved to consider both the accuracy of predicted temperature and the correctness of temperature changing trend. Through alternate training the discriminator and generator, the generator is finally able to predict the temperature of molten steel in real time with a better precision. Experiments with practical data verify the effectiveness of the proposed model.

Physical Experiment and Numerical Simulation on Thermal Effect of Aerogel Material for Steel Ladle Insulation Layer

The selection of lining material for a steel ladle is important to heat preservation of molten steel. Aerogel insulation materials have very low thermal conductivity, however, they are rarely used in steel ladles. In this paper, the application of a new silica aerogel material on the steel ladle insulation layer is tested, and a new calculation method is designed to study its insulation effect. In other words, the ladle wall temperature is obtained by finite element model (FEM) and experiments, then the heat emission from the ladle wall is calculated by the Boltzmann mathematical model according to the ladle wall temperature, and the temperature loss of molten steel is calculated inversely according to the heat emission of ladle wall. Compared with the original steel ladle (comparison ladle), the application effect is analyzed. Due to the stable heat storage of the ladle wall after refining, the validity of the models are verified in ladle furnace (LF) process. The results show that the new calculation method is feasible, and the relevant parameter settings in the FEM and Boltzmann mathematical model are correct. Finally, after using the new aerogel insulation material, the temperature of molten steel is reduced by 16.67 °C, and the production cost is reduced by CNY 5.15/ton of steel.