Sulfuric acids are commonly used in acidic cleaning processes of steel surfaces. However, steels have low corrosion resistance to hot, acidic environments. The aim of this article is to investigate the effects of boride coating on the corrosion behavior of AISI 8620 steel in a hot H2SO4 acid solution. The boriding process was carried out with Baybora-1, a novel boriding powder. Using the powder pack boriding method at a temperature of 900 degrees C for 2 and 6 h. The thickness of the boride layer formed on the steel surface was measured by scanning electron microscopy (SEM) analysis. The corrosion behavior of the samples in a hot H2SO4 acid solution was determined using the ASTM G31-72 standard. The results showed that pitting-type corrosion occurred when nonborided AISI 8620 steel was exposed to hot sulfuric acid solutions, but the boriding time increased the corrosion resistance of AISI 8620 steel to hot sulfuric acid solutions. It was found that the corrosion resistance of the steel increased 18-fold thanks to the boride coating, which was formed on the surface of AISI 8620 steel by the boriding process. Boriding could be an alternative application to increase the corrosion resistance of steels.
Against the backdrop of the “dual carbon” targets, optimizing blast furnace (BF) ironmaking processes is pivotal for realizing low-carbon smelting. Grounded in fundamental ironmaking principles, this study systematically investigates the 2023 production data of 24 large BFs in China (effective volume > 4000 m 3 ) to uncover the intrinsic relationships between the oxygen consumption and its key influencing factors. Practical methods for reducing oxygen consumption are proposed and demonstrated through a case study of a Chinese large BF, whose fuel consumption has been successfully reduced. Analysis reveals that for large BFs over 4000 m 3 , oxygen consumption reduction of 5 m 3 /t yields corresponding reductions of 4.2 kg/t in fuel ratio and 1.6 kg/t in process energy consumption. Both theoretical analysis and operational verification confirm that reducing oxygen consumption is a crucial pathway toward low-carbon and high-efficiency BF smelting.
Non-metallic inclusions severely impair the quality of ultra-low carbon steel continuous casting slabs, with control efficiency varying across casting stages due to differing molten steel flow, temperature stability and process conditions. Head slabs face inclusion aggregation from unstable initial flow, transition slabs suffer inclusion increases from heat-switching fluctuations, and normal slabs need precise control for consistent cleanliness despite stable conditions. Leveraging the positive charge of inclusions like Al2O3, pulsed electric current (PEC) enables directional migration, aggregation inhibition and efficient removal of inclusions, with proven industrial effects in molten steel purification and SEN anti-clogging. Industrial comparative experiments on a twin-strand caster (comparative/experimental strand without/with PEC) for automotive IF steel were conducted, testing inclusion density and size distribution of the three slab types via ASPEX analyzer. Results show PEC effectively reduces inclusion density (head slab: 0.88 -> 0.84 mm(2), normal slab: 0.69 -> 0.65 mm(2), transition slab: 0.76 -> 0.71 per mm(2)) and optimizes size distribution: fine inclusions (<= 5 mu m) rise significantly, medium/large ones (>5 mu m) drop, and >20 mu m inclusions in normal slabs are eliminated. This study uncovers PEC's regulation mechanism, verifies its universal purification effect, and provides a reliable technical solution for high-quality ultra-low carbon steel production.
The prediction of phosphorus content in molten steel at the end of converter is of great significance to control the quality of steel and reduce the production cost. In order to achieve accurate prediction, aiming at the problem of small sample size and poor stability of single model, this paper proposed a prediction method of terminal phosphorus content combining Dung beetle optimization (DBO) algorithm and ensemble transfer learning strategy(EL-TL). Firstly, the improved Dung Beetle optimization algorithm (IDBO) was improved to optimize the hyperparameters of the Multi-layer Perceptron (MLP). Secondly, the transfer learning strategy was introduced and the multi-kernel maximum mean difference was improved to solve the problem of insufficient prediction accuracy of small samples. Finally, the ensemble learning strategy and adaptive weight improvement were introduced to further solve the problem of insufficient stability and easy overfitting of a single model. The ablation experiment verifies that the proposed method achieves 85% hit rate within the error range of plus or minus 0.002%, which can provide guidance for practical production.
This work is devoted to experimental modeling of metal melt solidification processes under the influence of electromagnetic fields of various topologies. The main objective of the work is to develop a method for improving solidification parameters by changing the topology of the electromagnetic field without changing its amplitude and frequency, and therefore energy consumption. Both classical metallurgical modes of travelling and rotating magnetic fields and more complex combinations of spiral and torsional topologies are considered. Velocity fields of flows arising in the liquid phase under the influence of electromagnetic fields of given topologies are obtained using a low-melting gallium-based alloy and ultrasonic Doppler velocimetry technique. Macroscale solidification characteristics, namely, the velocity of the solidification front and the heterogeneity of its shape, are obtained for all modes. It has been shown that changing the topology of magnetic fields can increase the homogeneity of the solidification front by an order of magnitude. Specifically, the highest ratio of the time-averaged solidification front heterogeneity parameter between the modes reached 11.5 times (29.9 mm for the classical magnetic field distribution and 2.6 mm for the best magnetic field topology option we suggest). The results obtained for the gallium eutectic were confirmed for an aluminum alloy. The use of stirring in the torsional magnetic field mode during the solidification process increased the proportion of the fine-grained solid fraction by 30 percents.
