The granulation of iron ore is indispensable in sintering process, which ensures the quality of sintering production. Under the background of the iron ore resources gradually depleting and the imported iron ore prices fluctuating, to improve and prefect the granulation process is crucial for enhancing the permeability of the material layer, increasing sintering production efficiency, and reducing energy consumption and production costs. The research progress of sintering granulation strengthening technology and process of iron ore is reviewed, including two aspects: conventional granulation strengthening technology and innovative granulation process. The advantage, disadvantage, and application scope of various technologies and processes are analyzed, aiming to provide reliable theoretical basis and practical guidance for iron and steel enterprises to scientifically select the granulation process according to their own raw material conditions and industrial needs, contributing to improved resource utilization and economic efficiency in sintering production.

Hardenability is a key performance parameter of steel materials, reflecting the ability of steel to achieve uniform hardening during the quenching process, which directly affects the mechanical properties and service life of the steel. Traditional physical models have limited accuracy in predicting hardenability due to their inability to handle complex compositions and process parameters accurately. The application of machine learning models such as Support Vector Machine (SVM), Decision Tree (DT), Neural Network (NN) and deep learning in the prediction of steel hardenability is reviewed, and the prediction accuracy, data requirements and computational efficiency are compared and analyzed. The future research directions are prospected, including key issues such as improving data quality, fusion model and enhancing physical interpretability. With the continued development of machine learning technology, the accuracy and generalizabilityof hardenability prediction are expected to be significantly improved, providing strong scientific support for the intelligent production of steel in the industry.

Spent fuel reprocessing is a key step in the nuclear fuel cycle. Austenitic stainless steel for reprocessing is facing serious nitric acid corrosion problems. In the harsh environment of spent fuel post-processing corrosion,it is difficult for austenitic stainless steel to meet the requirements of equipment. It is of great significance to study the intergranular corrosion of austenitic stainless steel in spent fuel post-processing environment. The research results of the main corrosion mechanisms of austenitic stainless steel anode and cathode in spent fuel reprocessing environment in recent years are summarized. The application of ultra-low carbon austenitic stainless steel, ultra-pure austenitic stainless steel and high silicon austenitic stainless steel in spent fuel reprocessing is introduced. The intergranular corrosion resistance and research status of three austenitic stainless steels are summarized.

Currently, low-silica iron ore resources have become one of the bottlenecks limiting the large-scale production of pellets,and thus the development of medium and high silicon fluxed pellet technology can help promote the development of low-cost pellet production technology.Focusing on high silicon fluxed pellet technology, inorder to investigate the influence of process conditions on the performance and microstructure of fluxed pellets, the influence of thermal regime on the solidification performance of fluxed pellets was investigated, and the composition of the liquid phase and the amount of liquid phase inside the pellets were analyzed by thermodynamic calculation. The results showed that with the increase in the preheating temperature, the strength of preheated pellets gradually increased and the ferrous content gradually decreased. When the preheating temperature reached 900 ℃, the strength of preheated pelletsreached 419.58 N with ferrous content of 0.83%. With the increase in roasting temperature, the strength of roasted pellets firstly increased and then decreased, and when the roasting temperature reached 1 215 ℃, the compressive strength reached 3 188.80 N. The effect of basicity on the mineral phase structure of the roasted pellet was also characterized, and it was concluded that the roasting temperature should not be higher than 1 260 ℃ when producing high silica fluxed pellets.

Blast furnace bag ash is one of the difficult-to-treat iron-containing dusts of Baotou Steel. The content of valuable metals Zn, K, Na and C is high, which cannot be directly recycled inside the steel plant. In order to achieve its high value-added utilization, K and Na elements are extracted by water washing, and then the blast furnace bag ash and EP ash that remove K and Na are synergistically pressed to improve the self-reducing dezincification effect of subsequent iron-containing dust and obtain high-grade iron-containing burden. The water-washed blast furnace bag ash and EP ash were mixed and pressed at a ratio of 7∶3. The influencing factors of the cold compressive strength of the briquette and the optimal briquetting process conditions were explored through orthogonal experiments. It provides a theoretical basis for reducing the pulverization rate of the subsequent carbothermal reduction dezincification process, reducing the furnace adhesion phenomenon, and improving the dezincification efficiency. The results showed that the effects of various factors on the cold strength of the briquette in the order from large to small were sample preparation pressure, drying time, starch addition amount,and bentonite addition amount; under the conditions of the mass fraction of bentonite of 2%, the mass fraction of starchof 0.25%, the mass fraction of CMC of 0.5%, the drying time of 120 min, the pressure of 20 MPa, and the holding time of 60 s, the maximum compressive strength is obtained.

With the development of information technology, fully mining, screening and analyzing the big data of steel production is of great significance for achieving intelligent control, energy conservation and efficiency improvement in steel production. Through in-depth analysis of 425 groups of real-time test data of furnace gas composition of a 200 t converter in a steel plant, based on the carbon integral model, it is transformed into carbon composition and temperature time series data, and the data are normalized and preprocessed.A Long Short-Term Memory (LSTM) network model was developed to predict carbon mass fraction and temperature during the steelmaking process, with feeding and flue gas information serving as input variables. By comparing the measured end-point data from 50 production batches with the model′s predicted values, the results show that the hit rate of the end-point prediction error of the carbon mass fraction within ±0.03% is 96%, and the hit rate of the end-point prediction error of the temperature within ±15 ℃ is 92%. The deviation between actual and predicted values from the LSTM model is minimal, and the end-point hit rate within the specified range surpasses that of ELM and BP models. The LSTM model is beneficial to the dynamic prediction and control of smelting process.

The effect of different aluminum contents on the cleanliness of GCr15SiMn bearing steel was investigated by high temperature reaction experiment and thermodynamic calculation. Results from uncovered Al-O equilibrium experiments reveal that when the Al content exceeds 0.01 wt.%, theTO content in the steel stabilizes at 5×10^-6, with typical inclusions being fine Al₂O₃ particles. This indicates that the oxygen content is completely dominated by the Al deoxidation reaction. Conversely, when the Al content is less than 0.01 wt.%, large-sizedSiO₂-MnO-Al₂O₃ inclusions exceeding 5 μm are observed in the steel. Therefore, it is particularly crucial to ensure that the Al content exceeds 0.01 wt.%. Further results from the slag-steel reaction experiments show that in the experimental group with an initial Al_s content of 0.02 wt.%, the changes in silicon content in the steel and SiO₂ in the slag are minimized when slag-steel equilibrium is achieved. The slag-steel reaction system exhibits greater stability, effectively controlling the oxygen and calcium contents in the steel, with [O] and [Ca] levels measured at8×10^-6 and 2×10^-6, respectively. This conclusion is also supported by the thermodynamic model of slag-steel equilibrium. It has important guiding significance for smelting highly-clean GCr15SiMn bearing steel.

The chromium-containing refractory castables are widely utilized in high-temperature waste incineration gasification furnaces, ultra-high-temperature electric furnaces, and similar applications due to their exceptional performance characteristics. However, during service, these materials may produce toxic, carcinogenic hexavalent chromium (Cr(Ⅵ)), complicating the disposal of spent refractories and posing a serious environmental threat. Thus, the compositional design of these materials must consider both their service performance and the transformation of chromium phases to control Cr(Ⅵ) formation. Given the many deficiencies in the current oxide phase diagrams of chromium-containing castables, a new thermodynamic database was developed for chromium-containing oxides (WustCr). This chromium-specific database was successfully integrated into the thermodynamic calculation software FactSage and effectively utilized for conducting comprehensive phase diagram analyses in chromium-containing oxide systems. Using WustCr database, phase transformations and Cr(Ⅵ) formation in the ternary system Al₂O₃-CaO-Cr₂O₃, quaternary systems Al₂O₃-CaO-Cr₂O₃-Fe₂O₃, Al₂O₃-CaO-Cr₂O₃-MgO and Al₂O₃-CaO-Cr₂O₃-SiO₂, as well as in chromium-containing castables for electric furnace lids were simulated. The calculation results were compared with experimental data, revealing a strong correlation, especially in predicting the evolutions of chromium phases and Cr(Ⅵ) formation. These findings demonstrate that the WustCr thermodynamic database serves as a starting point for thermodynamic modeling of the relevant phase diagrams, providing guidance for designing eco-friendly, high-performance chromium-containing refractory castables.

The precipitation behavior of carbonitrides in microalloyed steels is a key factor in controlling the microstructure and properties of the steel. To elucidate the precipitation mechanism of MX-type (M=Ti/Nb, X=C/N) carbonitrides in Ti/Nb composite microalloyed steels and their influence on phase transformation processes, molecular dynamics (MD) simulation methods were employed to systematically investigate the atomic diffusion behavior, cluster evolution kinetics, and precipitation phase formation patterns in the Ti-Nb-C-N multi-component system. The results indicated that Ti/Nb composite additions significantly enhance interatomic bonding energy, promoting the formation of Ti-Nb-C-N atomic clusters, which preferentially form (Ti,Nb)(C,N) composite carbonitrides in the austenite region. Dispersed MX particles refine grain size through the Zener pinning effect and act as heterogeneous nucleation nuclei during phase transformations, promoting ferrite formation and synergistically achieving simultaneous optimization of strength and toughness. The synergistic mechanism of composite microalloying elements was revealed at the atomic scale, and a relationship between precipitate phase evolution and microstructural evolution was established, providing fundamental theoretical guidance for the development of high-strength, high-toughness microalloyed steels.

The dynamic strain aging behavior of GH4151 alloy at a strain rate of 5×10^-6 s^-1 was studied through high-temperature tensile tests at 650-800 ℃. The evolution characteristics of the alloy’s microstructure were observed and analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that within the temperature range of 650-800 ℃, as the tensile temperature increases, the stress amplitude of GH4151 alloy increases, and the serrated waveform of the stress-strain curve transforms from type A+B to type B+C. When stretched at 650 ℃, the main deformation mechanism of GH4151 alloy is that dislocations shear the secondary γ′ phase to produce stacking faults (SFs). When stretched at 800 ℃, some stacking faults have transformed into microtwins (MTs). The interaction between dislocations of different slip systems and MTs is the main reason for the increase in the serrated amplitude of the stress-strain curve at 800 ℃. The results of atomic-level energy dispersive spectroscopy (EDS) analysis and calculation of the thermal activation energy of serrated flow indicate that the dynamic strain aging of GH4151 alloy is caused by the interaction between dislocations and substitutional atoms (Cr, Co) undergoing pipe diffusion.

The electrochemical behavior of nickel-based superalloy DD6 in 3.5% NaCl solution was investigated. It was found that the alloy could form a stable passivation film in NaCl solution. The potentiodynamic polarization curve and the surface morphology of DD6 alloy after polarization were observed. It was found that the corrosion current density of DD6 alloy in 3.5% NaCl solution was very low, there was no obvious pitting pit on the surface after polarization, and the corrosion resistance was excellent. The wear behavior of DD6 alloy in air and 3.5% NaCl solution was observed respectively. It was found that the friction coefficient in 3.5% NaCl solution was significantly lower than that in air. The wear mechanism of DD6 alloy changed from oxidation wear and abrasive wear(in air) to fatigue wear (in 3.5% NaCl solution) due to the change of medium. The wear scar depth of DD6 alloy in 3.5% NaCl solution is less than that in air, which indicates that DD6 alloy will have slight wear behavior in 3.5% NaCl solution.

Micro-grain casting process can strengthen alloys under medium and room temperature by refining grains. However, the increased transverse grain boundaries may deteriorate the stress rupture and creep proprieties under high temperature creep conditions, leading to premature failure of components. In this work, stress rupture tests under 760 ℃/724 MPa were conducted on K447A alloys produced by conventional, fine-grain and micro-grain casting processes. The original and deformed microstructures were characterized by SEM, EDS and ECCI. The effect of micro-grain casting process on the stress rupture property of K447A alloy was studied and discussed. Results show that the stress rupture life of micro-grain casting K447A alloy is increased to 194 h, which is 134% and 69% higher than that of the conventional and fine-grained ones, respectively. The deformation is dominated by dislocation shearing, and cracks initiate on the sample surface and propagate transgranularly. The refined grains and carbides, the increased γ′ volume fraction and the disappeared dendrite structures induced by micro-grain casting process effectively inhibit crack initiation and propagation, significantly improving the stress rupture life of K447A alloy under this condition. Intergranular oxidation cracks along grain boundaries are observed in micro-grain K447A alloy, while their detrimental effect on mechanical property is much weaker than that of strengthening effect induced by grain refinement, thus significantly improving the stress rupture property of K447A alloy.

The effects of cooling time parameter t_8/5 on the microstructure and ultra-low temperature impact properties of coarse-grained heat-affected zone of high manganese steel for LNG storage tank were investigated by means of thermal simulation. It is found that with the increase of t_8/5 from 10 to 120 s, the impact absorption energy of the coarse-grained heat-affected zone decreases from 175 to 149 J, and the microhardness decreases from 176 to 165HV. At the same time, it is found that the microstructure is single-phase austenite, and the average equivalent austenite grain size increases from 40-50 μm to 88-100 μm. Large-sized austenite grains reduce the threshold stress value generated by deformation twins, which is conducive to the formation of deformation twins, resulting in dynamic Hall-Petch effect, which is the key factor for the coarse-grained heat-affected zone of the test steel to exhibit excellent impact toughness in the ultra-low temperature environment. When t_8/5 increases, the austenite grain size in the coarse-grained heat-affected zone of the test steel also increases. Under the impact load, the ultra-low temperature impact toughness of the coarse-grained heat-affected zone of the test steel gradually decreases with the increase of t_8/5.

The mechanical behavior and fracture failure mode of the dissimilar substrate adhesive spot welded joint of dual phase steel (DP980) and quenched partitioning steel (QP980) with tensile strength not less than 980 MPa under tensile load were studied, and the optimized adhesive spot welding method for prefabricated bumps of substrate was proposed. The results show that before the optimization of the adhesive spot welding process,the solder joints are prone to micro-cracks and micro-hole defects, due to the poor conductivity of the structural adhesive. The failure mode of the joint is the brittle failure mode of the nugget fracture of the solder joint. The peak load is 20 kN and the peak displacement is 1.1 mm. Through the optimized spot welding process of the prefabricated bump, the fracture form is transformed into the ductile fracture of the solder joint button pull-out.The peak load is increased to 24 kN, and the peak displacement is increased to 2.2 mm. The microstructure and hardness distribution of the optimized adhesive spot welded joint are consistent with those of the spot welded joint, which avoids the problem of poor conductivity of the structural adhesive. And its mechanical properties are also better than those of the spot welded joint, which provides a new reliable solution for the adhesive spot welding connection of heterogeneous high-strength steel.