_Aiming at the bright band color difference on the upper surface occurring during the production of wide low-carbon deep-drawing steel for automotive outer panels on the electro-galvanizing line, a systematic study was carried out by means of optical microscopy, SEM, EDS and metallographic analysis. The results showed that the defect was caused by abnormally coarse grains in the surface layer of the cold-rolled substrate, leading to abnormal crystallization during electro-galvanizing. The areas with abnormal electroplating crystallization appeared as small bright spot defects, and a large number of bright spots macroscopically manifested as bright band color difference. Through comprehensive defect inspection and process analysis, it was determined that the high hot rolling coiling temperature and excessive wrapper roll pressure during coiling resulted in coarse grains in the surface layer of the hot-rolled strip, and the heredity of the hot-rolled microstructure led to coarse grains in the surface layer of the cold-rolled substrate. By reducing the coiling temperature from 750 ℃ to 710 ℃ and optimizing the wrapper roll pressure parameters, the defect was successfully eliminated, and the process optimization had no significant effect on the microstructure and properties of the finished product.

To solve the surface sliver defect of threated steel, the macro morphology and micro composition of threated steel were detected by SEM scanning electron microscope and energy spectrum analyzer. The results showed that there were unilateral sliver defects of different sizes at the longitudinal and transverse ribs of the threated steel. The irregular inclusions of Al₂O₃, SiO₂ and Al₂O₃-SiO₂ were detected at the cross section of the sliver defects, with sizes ranging from 40~120 μm. These non-metallic inclusions caused a deterioration in the local plasticity of the threaded steel ingot, leading to the formation of cracks. As the rolling process progressed, these cracks gradually expanded and ultimately resulted in sliver defects. By implementing measures such as reducing the oxygen content at the converter endpoint and enhancing the air-tightness during pouring, the average oxygen content of the molten steel in the tundish was reduced to 25ppm. Consequently, the incidence rate of surface sliver defects in hot - rolled products decreased from 2.7% to 1.5%, effectively preventing the occurrence of sliver defects.

The soft collection chute in the finishing and collection area of the large bar production line at Lingyuan Iron and Steel is a core equipment in the bar packing and collection process. However, the original structure was affected by the frequent impact loads during the bar conveying process, resulting in frequent failures of the chain and the support bearing seats of the rotating sprockets. This not only directly led to production interruptions, but also significantly increased the maintenance difficulty and labor-hour costs due to the limited working space for chain restoration and the cumbersome disassembly and assembly procedures, seriously restricting the maintenance efficiency and the continuous operation ability of the entire production line. To address this production bottleneck, targeted improvement and optimization of the soft collection chute structure were implemented for the soft collection chute, including optimizing the force transmission path, enhancing the structural strength of key components, and conducting adaptive structural design. These measures fundamentally eliminated the problems of chain breakage, bearing seat damage and narrow operation space. After the improvement, the integrated operational stability of the equipment was improved by more than fivefold, while maintenance efficiency was enhanced by 80.0% to 83.3%. This was expected to generate annual direct economic benefits amounting to over 1 million yuan. It not only reduced the consumption of spare parts and maintenance costs, but also decreased the unplanned downtime, achieving a dual improvement in production efficiency and economic benefits.

As the most promising thirdgeneration advanced highstrength automotive steels, medium manganese steel features advantages of low cost and high strengthductility synergy. At present, the addition of Al in Fe-C-Mn-Al medium manganese steel achieves lightweighting, optimizes the microstructure, and improves the strengthductility product. Existing microsegregation models have certain limitations when applied to Fe-C-Mn-Al medium manganese steel. The Lever-rule and Scheil models are both idealized models, whereas the Brody-Flemings, Clyne-Kurz, Ohnaka and Voller-Beckermann models incorporate solidphase backdiffusion and can describe the actual solidification process more accurately, among which the Clyne-Kurz model is the most widely used. However, in conventional microsegregation models, the equilibrium partition coefficient, which is usually treated as a constant, actually varies with temperature (or solid fraction) during real solidification, and the influence of inclusion precipitation should also be considered. By integrating the Clyne-Kurz model, a modified microsegregation model was proposed that considers the temperature dependent equilibrium partition coefficient and the effect of inclusion precipitation on solute concentration. The solute microsegregation and inclusion precipitation behavior in Fe-0.15C-5Mn-(0.018, 0.95, 1.93, 2.97) Al medium manganese steel were systematically revealed. The results show that, taking the M193 steel as an example, the maximum equilibrium partition coefficient of Al is exceeds the minimum value by 7.4% during solidification, while that of N reachesas high as 40.6%. Without considering AlN precipitation, the N concentration increases monotonically with solid fraction during solidification; when AlN precipitation is included, it first rises and then falls. As the Al content increases from 0.95% to 2.97%, the amount of AlN precipitated at the solidification end increase from 0.003 7% to 0.010 0%. The above conclusions are theoretically significant for controlling the solidification microstructure and inclusions of Fe-C-Mn-Al medium manganese steel.

To achieve the green and low-carbon transformation of the ironmaking system, in response to the special thermal behavior issues of Ansteel's self-produced ultra-fine magnetite-hematite mixed concentrate, such as extremely fine particle size, poor pelletizing property, strong oxidation heat release, narrow roasting window, and easy overheating and cracking, a systematic study was carried out on the characterization of raw material physical and chemical properties, optimization of pelletizing parameters and ore blending structure, design of the straight-grate system, and evaluation of metallurgical properties, and a complete set of key technologies for the preparation of fluxed pellets was formed. On this basis, the 4 million t/a fluxed pellet production line with the straight-grate system in Donganshan Sintering Plant of Ansteel Group Mining Co., Ltd. achieved stable operation. The TFe of the fluxed pellets was approximately 64.0%, the SiO₂ was about 3.8%, and the basicity was stable at 1.0. Compressive strength was ≥ 2 800 N per piece, drum strength was >92%, reduction degree was >78%, reduction expansion rate was <12%, low-temperature reduction pulverization rate (RDI_{+3.15 mm}) was > 90%. According to the "Guidelines for Accounting and Reporting of Carbon Emissions in the Iron and Steel Industry (for Trial Implementation) ", after the pelletizing process replaced the original 360 m² sintering machine, the carbon emission intensity of the product decreased from 199.02 kgCO₂/t sintered ore to 40.64 kgCO₂/t pelletized ore, representing a 79.58% emission reduction. This study provides an engineering example for the preparation of fluxed pellets from ultra-fine mixed iron concentrate resources and their low-carbon application.

In recent years, with the intensification of global climate change, a low-carbon economy has become a development trend. As a key area for carbon emissions, the low-carbon transformation of the ironmaking process in the steel industry is of vital importance. Among the contemporary mainstream ironmaking processes, although blast furnace ironmaking dominates, its carbon emissions are high. The direct reduction process has problems such as resource dependence and high energy consumption. The technical economy of the smelt reduction process has not yet been broken through. Meanwhile, hydrogen metallurgy is the core path to achieve "zero-carbon ironmaking", which is theoretically capable of reducing CO₂ emissions by approximately 90%. However, it faces challenges such as high hydrogen production costs, insufficient technological maturity and equipment compatibility. Strategies such as the synergy between the low-carbon upgrading of traditional processes and technological innovation, and the transformation of the energy structure and the collaborative emission reduction of industries are proposed. In the future, traditional blast furnace processes will accelerate their low-carbon transformation, and non-blast furnace ironmaking technologies are expected to achieve large-scale breakthroughs. The maturity of the hydrogen energy industry chain affects the speed of transformation, and multi-party collaboration will help the steel industry achieve the goal of carbon neutrality.

In the long-process steelmaking system, the proportion of carbon emissions is extremely high. Therefore, the development of green and low-carbon technologies in ironmaking is crucial for emission reduction. In allusion to the significant heat loss during the transportation of hot metal ladle without cover insulation, the composition of such heat loss and the corresponding actual carbon emissions were analyzed. A comparative analysis was carried out on the energy-saving and emission-reduction effects of hot metal ladle for heat compensation and ladle covering for heat preservation. The results showed that both methods could increase the molten iron temperature by more than 30 ℃. Empirical applications of these two methods and the achieved carbon emission reduction results indicated that applying cover insulation during hot metal ladle empty period was the most effective measure, which was more conducive to emission reduction. Moreover, it significantly reduced heat loss and carbon emissions with almost no external energy supply. Compensatory heating served as a supplement and auxiliary measure to cover insulation, could realize the self-circulation of blast furnace gas within the traditional blast furnace ironmaking process, which was of great significance for carbon emission reduction.

With the increasing depletion of fossil energy, the energy attributes of hydrogen have drawn significant attention. Hydrogen energy is regarded as the "ultimate energy source of the 21st century". However, such problems as high cost, low volumetric energy density and high tendency for hydrogen embrittlement in hydrogen-exposed materials greatly limit hydrogen energy utilization. Solving three problems mentioned above is the key issuse for the current development of hydrogen energy. Currently mature technological routes for hydrogen production, hydrogen storage, hydrogen transportation and hydrogen utilization, along with their advantages and disadvantages were described. The commonly used hydrogen damage theories and the existing material selection criteria for hydrogen-exposed materials were compared, and future development suggestions such as focusing on the development of high hydrogen-resistant materials, researching hydrogen damage mechanisms, exploring natural hydrogen and increasing the proportion of green hydrogen in hydrogen energy were proposed. It was expected to provide references for expanding the scale of hydrogen energy utilization and expanding its application scenarios.

Four strengthening mechanisms of Cu-rich nanoprecipitate-strengthened steel were summarized, including solid solution strengthening, grain boundary strengthening, dislocation strengthening and precipitation strengthening. The evaluation methods for various strengthening mechanisms were thoroughly elaborated based on the characteristics of both matrix and nanoprecipitates. The results showed that all kinds of strengthening mechanisms were closely related to the interaction with dislocations, and different strengthening mechanisms were coupled with each other in the microstructure. This provided theoretical support for the design of noval Cu-rich nanoprecipitate-strengthened steels.

To improve the prediction accuracy of the primary frequency modulation capability of thermal power units and assist in ensuring grid frequency stability and safe operation of the power system, a primary frequency modulation capability prediction method is proposed that combines the Kepler Optimization Algorithm (KOA) with the Gated Recurrent Unit (GRU) network. Taking the actual operation data of primary frequency modulation of a 350 MW coal-fired thermal power unit as the sample, key characteristic variables were extracted through correlation analysis. The hyperparameters of GRU network model were optimized using KOA to construct a KOA-GRU prediction model, which was further compared with the Long Short-term Memory (LSTM) network model, the Particle Swarm Optimization (PSO) network model, the original GRU network model, and PSO-GRU network model. The results showed that the fitness value of the KOA-GRU network model stabilized at 0.127 after 7 iterations, indicating better convergence performance than the other four models. Meanwhile, the proposed model exhibited superior prediction performance under various evaluation metrics, with the Root Mean Square Error (RMSE) reaching 0.148 MW and the Mean Absolute Error (MAE) dropping to 0.092 MW, which demonstrated high prediction accuracy.