Under the mounting pressure of global climate change, deep decarbonization of the energy-intensive steel and chemical industries is imperative for achieving carbon neutrality goals. However, existing literature has predominantly focused on biomass applications within single industrial sectors, overlooking the significant potential of cross-sectoral synergy. Addressing this gap, an innovative integrated “biomass-steel-chemical” collaborative framework is proposed. This framework utilizes biomass as the central nexus to bridge the two major industries through comprehensive energy coupling, material recycling and value chain extension. Specifically, the system valorizes high-grade waste heat (sensible heat from molten slag and flue gas) and solid by-products (steel slag) generated during steel manufacturing to drive the efficient thermochemical conversion of biomass into key platform intermediates, such as biochar and synthesis gas. In downstream applications, these green products are strategically allocated: biochar serves as a renewable fuel or reducing agent in metallurgical processes, while synthesis gas functions as a high-quality feedstock for chemical synthesis. By constructing a synergistic ecosystem characterized by material closed-loop circulation and hierarchical energy utilization, this model transcends traditional linear production structures. Analysis indicates that this integrated approach achieves emission reduction benefits where “system effects outweigh individual factor effects”, offering a novel pathway for the green, circular and high-efficiency development of the steel and chemical sectors.

To clarify the regulatory mechanism of limestone calcination process on the properties of active lime, a flux limestone from Jiangxi province was selected as the research object. The synergistic effects of raw material particle size, calcination temperature and holding time on the activity and microstructure of lime were systematically investigated by controlling the above parameters. The results show that the lime prepared under the conditions of raw material particle size of 10-20mm, calcination temperature of 1000℃ and holding time of 60min exhibits the optimal comprehensive performance, with an activity of 385mL and a CaO mass fraction of 93.03%. All the indicators are significantly superior to the technical requirements for first-grade products specified in the industry standard Metallurgical Lime (YB/T 042-2014). Combined with the characterization analysis by X-ray diffraction and scanning electron microscopy, it is found that the raw materials with excessively fine particle size (5-10mm) will induce agglomeration due to the reduced thermal resistance of particles, thereby deteriorating the lime activity. Excessively high calcination temperature (>1000℃) will accelerate the thermal motion rate of Ca²⁺ and O^2-, leading to the rapid formation of CaO crystal nuclei, excessive grain refinement and decreased crystallinity, which ultimately impairs the lime activity. Overlong holding time (>60min) will promote the coarsening of CaO grains and induce sintering fusion between particles, resulting in the collapse of internal pores of lime, dense structure formation and thus a significant reduction in activity. The optimized calcination process for high-performance active lime is clarified, which provides key technical support for the green and low-carbon production of metallurgical fluxes.

The top-bottom combined blown converter represents the mainstream steelmaking process at present, and optimization of its bottom blowing system is crucial for improving smelting efficiency. However, research on the optimization of bottom blowing arrangement for large-scale converters with a capacity of over 300t remains relatively scarce. A large-scale top-bottom combined blown converter in a certain steel plant was taken as the research object. The influence laws of the number of bottom blowing elements (8, 12 and 16 nozzles) and arrangement modes (single-ring/double-ring, symmetric/asymmetric) on the bath stirring and mixing effects of large-scale converters were systematically investigated by combining hydraulic physical simulation experiments and numerical simulation methods. The results indicate that, compared with the symmetric arrangement, the double-ring asymmetric distribution mode of bottom blowing elements can significantly improve the dynamic conditions of the converter bath, which is specifically reflected in the increase in average bath velocity, reduction in dead zone ratio and substantial shortening of mixing time. Meanwhile, the number of bottom blowing elements is not positively correlated with the optimization effect, and an obvious synergistic effect exists between their function and the arrangement mode. Through comprehensive comparison, the 12-nozzle double-ring asymmetric distribution (scheme D-3-10) is determined as the optimal scheme. Under this scheme, the average bath velocity reaches 0.286m/s, the dead zone ratio is only 0.55%, the mixing time is shortened to 33s and the bath mixing effect is optimized to the best level.

The development of oxygen-fuel lances with scrap preheating function plays a crucial role in increasing the scrap ratio of converters and reducing carbon emissions in the iron and steel industry. Based on the structure of a six-hole staggered oxygen lance, gas holes were added in the divergent section of its internal Laval nozzle. Moreover, based on numerical simulation of gas jet and combustion processes, the influence laws of the number, angle and opening position of gas holes on coal-oxygen mixing effect, combustion efficiency and NO_x emission were explored in depth. The experimental results show that when the diameter of gas holes is 10mm and the momentum flux ratio is 0.81, the penetration depth of gas into the main oxygen jet is relatively large, and the fuel mixing uniformity index can reach 0.7; when the opening position of gas holes is 0.6L_e (where L_e is the length of the divergent section), the fuel mixing uniformity index also reaches 0.7. Considering various factors such as fuel mixing uniformity, combustion efficiency and NO_x emission level, 60° was determined as the optimal angle for gas injection. This optimized scheme can provide strong technical support for realizing rapid scrap preheating and increasing the scrap ratio of converters.

The high scrap ratio smelting process has significantly reduced the carbon emission intensity in steel production with the increase in scrap usage. However, changes in refining slag composition have altered the corrosion behavior of MgO-C bricks, making the slag corrosion resistance of existing MgO-C bricks inadequate for the requirements of the new process. To address this issue, the corrosion behavior of the CaO-MgO-Al₂O₃-SiO₂-FeO_x (CMASF) slag system on MgO-Cmaterials was investigated, and magnesium aluminate spinel was prepared on the surface of magnesia micropowder via precursor in-situ transformation to explore its mechanism for enhancing corrosion resistance against high-FeO_x molten slag. The results show that the corrosion index of MgO-Cmaterials increases with increasing mass fraction of FeO_x. In an oxidizing atmosphere, the oxidation of carbon materials, pores formed by the consumption of graphite through carbothermal reduction, pore channels left by the dissolution of MgO micropowder, and original cracks on the material surface collectively provide pathways for deep slag penetration. At the experimental temperature, CaO and SiO₂ in the penetrated slag react with MgO in the matrix to form low-melting phases with good fluidity, significantly accelerating the dissolution and corrosion of the modified layer by the molten slag and ultimately leading to structural damage of the material. The corrosion index of MgO-C materials incorporating magnesia micropowder loaded with spinel precursor on the surface is lower than that of MgO-C materials directly prepared using magnesia as raw material. On the one hand, the micro-expansion of in-situ magnesium aluminate spinel uniformly distributed on the micropowder surface increases the matrix density of MgO-C materials, reduces slag penetration channels, and blocks the chain reaction cycle of “oxidative decarburization-slag penetration-dissolution and erosion.” On the other hand, the magnesium aluminate spinel on the micropowder surface effectively absorbs iron from the molten slag and precipitates to form a (Mg,Fe)(Al,Fe)₂O₄ solid solution, increasing slag viscosity, reducing slag penetrationdepth and significantly improving the slag corrosion resistance of the material.

To clarify the formation mechanism of internal crack defects located 10mm below the surface of Q235 steel slabs, samples were taken separately from the cracked areas and normal areas of the slabs, and comparative analyses were carried out. By means of metallographic observation, automatic inclusion scanning and other testing methods, systematic characterizations were performed on the metallographic structures, as well as the quantity, size, positional distribution, types and morphological characteristics of inclusions in the two types of samples. The results show that obvious MnS inclusion aggregation zones exist around the cracks, and the microstructural characteristics near the aggregation zones are significantly different from those of the steel matrix. Widmansttten structures composed of lamellar ferrite and pearlite are prominent around the cracks, while chain-like sulfide inclusions are observed to precipitate in the banded proeutectoid ferrite. Such inclusions damage the continuity of the steel matrix, thereby inducing stress concentration during the continuous casting process, and ultimately act as crack initiation sites to trigger the formation of internal cracks in Q235 steel slabs.

Against the background of continuously increasing global demand for carbon reduction, the application of liquefied natural gas (LNG) as a clean energy source has been continuously expanded, and the research and development of materials for its storage and transportation containers have been made a research hotspot at present. High-manganese steel, with excellent mechanical properties and low-temperature service performance, has been determined as an ideal candidate material for low-temperature equipment such as LNG storage tanks. Thermal simulation tests were carried out to systematically investigate the high-temperature mechanical behavior of high-manganese steel in the temperature range of 800-1200℃. The variation laws of hot ductility and strength, as well as the brittle temperature range, were revealed. Results show that favorable hot ductility is exhibited by high-manganese steel in the range of 800-1000℃, with a reduction of area higher than 40%. In contrast, the hot ductility is significantly degraded in the range of 1050-1200℃, and characteristics of high-temperature brittleness are presented. Fractographic observations indicate that dynamic recrystallization is induced at 1000℃, by which the ductility of the material is improved. At 1100℃, an intergranular fracture morphology resembling rock candy is formed, and typical brittle fracture behavior is demonstrated. Second-phase particles including carbides, nitrides, sulfides and phosphides are precipitated in the fracture region, and the high-temperature mechanical properties of high-manganese steel are significantly affected by these precipitates.

Surface defect detection of continuous casting slabs constitutes a critical component of quality control during steel production. An efficient and accurate online surface defect detection system is the key to realizing intelligent steel manufacturing. Conventional manual detection methods suffer from low efficiency, strong subjectivity and high missed detection rates, which render them unable to meet the requirements of modern production. To address this demand, an online detection method for continuous casting slab surface defects based on improved YOLOv11 is proposed to enhance detection accuracy and efficiency. First, a dataset dedicated to continuous casting slab surface defect detection is constructed, covering various types of common surface defects occurring in the production process, and traditional data augmentation methods are adopted to expand the training samples. Then, in view of the complexity and multi-scale features of continuous casting slab surface defects, an asymptotic feature pyramid network is introduced to strengthen multi-scale feature fusion capability, and an attention mechanism module is integrated to improve the ability of the YOLOv11 model to extract key defect features, thus achieving precise identification and localization of defects. Finally, to realize visualization of detection results and real-time interaction with the production terminal, an online detection system for continuous casting slab surface defects is designed, and the trained improved YOLOv11 model is embedded into the system to achieve engineering application of the model. Experimental results demonstrate that the improved YOLOv11 model achieves indicators exceeding 89% on the self-built dataset, which satisfies the requirements of practical applications and provides a feasible solution for intelligent quality control in steel enterprises.

Weathering steel is widely used in long-term outdoor-exposed structures such as bridges and vehicles due to its excellent resistance to atmospheric corrosion, with alloying serving as a key method to improve its comprehensive properties. Phase transformation instruments, rolling thermal simulation testing machines, universal rolling mills and microstructure characterization equipment were employed to investigate the effects of different Cr contents on the phase transformation behavior, microstructure and mechanical properties of weathering steel. The results indicate that as Cr mass fraction (0.57%, 1.07%, 3.13%) increases, the CCT curves of the experimental steel first shift leftward and then move downward overall relative to those of 05Cr steel. At the same cooling rate, hardness generally follows the order 3Cr > 05Cr > 1Cr. During simulated rolling, as the final rolling temperature increases from 800 to 950℃, grain coarsening leads to a significant overall decrease in hardness for 05Cr, 1Cr and 3Cr steels. Although 3Cr steel exhibits the highest hardness in static CCT and maintains higher or comparable hardness after simulated rolling compared to 05Cr and 1Cr steels, its yield strength after hot rolling is the lowest. In contrast, 1Cr steel shows the lowest hardness values but the highest yield strength after hot rolling, which is closely related to differences in microstructure type, size and dislocation density arising from the sequence of phase transformation and deformation. In summary, Cr not only affects the corrosion resistance of weathering steel but also modifies its phase transformation characteristics, thereby influencing the evolution of both microstructure and mechanical properties.

The influence of different deformation ratios on carbide characteristics and mechanical properties was investigated using Cr14Mo4V steel ingots produced via industrial double-vacuum melting. Through systematic analysis of parameters including carbide size, quantity, area fraction, and angularity index, with particular focus on the size, contour coefficient, circularity of the largest carbide and the quantity of large-sized carbides,it is found that as the deformation ratio increases, the number of large-sized carbides decreases while the number of small-sized carbides increases significantly. Both impact toughness and bending strength improved with increasing deformation ratio. The conventional method for determining the size of the largest carbide failed to establish an effective correlation with mechanical properties. Therefore, multiple morphological characterization parameters for carbides were introduced, revealing to some extent the correlations among carbide evolution, deformation ratio, and mechanical properties. It was found that the circularity of the largest carbide in the annealed state could be used to predict the unnotched impact toughness after tempering, while the quantity of small-sized carbides in the annealed state served as an indicator of bending strength.

Austenitic stainless steel (ASS) shows great application potential in the field of hydrogen storage and transportation, yet it is characterized by low strength and excessive plasticity. Strain strengthening technology can significantly enhance material strength by utilizing partial plasticity, with the strain level being a key factor influencing microstructure and mechanical properties. The effects of different pre-strain levels (0, 5%, 10%, 15%) on the microstructure and mechanical properties of ASS were systematically investigated. The results show that with increasing strain, the yield strength of the tested steel increases significantly, the tensile strength increases slightly, the total elongation decreases, and the yield ratio exhibits an upward trend. At a strain of 10%, the yield strength reaches 535.2MPa, the tensile strength is 697.5MPa, the total elongation is 56.2%, and the yield ratio is 0.77, achieving a reasonable utilization of redundant plasticity. Analysis indicates that the increase in yield strength is mainly attributed to the formation of dislocation bands, dislocation cells and dislocation tangles during the strain strengthening process. After tensile deformation, the proportion of twin boundaries increases slightly, while twin thickness and spacing decrease significantly, which facilitates strain dispersion at the microscale and alleviates stress concentration. Moreover, the large number of parallel and intersecting twins generated during tensile deformation increases the tortuosity of crack propagation paths, thereby enhancing plasticity. Therefore, the primary deformation mechanism of the tested steel is the twinning-induced plasticity effect.

The effect of heating process on austenite grain growth in high-strength microalloyed steel was investigated. Re-solution heat treatment experiments were conducted on Ti-Nb microalloyed steel at different heating temperatures (1050-1250℃) and holding time (1, 5, 10, 20, 30, 60min), and the variation in austenite grain size was analyzed. The results show that heating temperature significantly influences austenite grain size. Austenite grain growth is slow at heating temperatures of1050-1110℃, while coarsening becomes pronounced at 1170-1210℃. When held at 1190℃ for 60min, the average austenite grain size reaches 64.4μm. Holding time also affects austenite grain growth, with a relatively fast growth rate in the first 10min, gradually slowing down from 10 to 20min. The observed austenite growth behavior is mainly attributed to the re-dissolution of Ti-Nb carbonitrides and the coarsening of precipitated particles. Transmission electron microscope (TEM) results indicate that as the heating temperature increases, the number of carbonitride precipitates in the steel gradually decreases, while the size of the residual precipitates increases, leading to a weakened pinning effect on austenite grain boundaries.

To improve the utilization efficiency of low-grade industrial waste heat, a Carnot battery energy storage system combined with a flash evaporation device was proposed, consisting of a two-stage compression heat pump cycle and an organic Rankine cycle (ORC), with low-temperature flue gas emitted from the sintering cooling process in steel enterprises serving as the driving heat source. To investigate the operating characteristics of the system, a steady-state thermodynamic model was established, and the effects of heat pump condensation temperature, flash evaporation temperature, and ORC evaporation temperature on system round-trip efficiency, exergy efficiency, and total exergy loss were analyzed in detail for different ORC working fluids. Exergy losses of the main system components were also examined. The results show that for a given working fluid, reducing the heat pump condensation temperature and increasing the ORC evaporation temperature improve system round-trip efficiency and exergy efficiency while effectively reducing total exergy loss. As the flash evaporation temperature increases, both round-trip efficiency and exergy efficiency exhibit a trend of first increasing and then decreasing. Among the ORC working fluids evaluated, R1233zd(E) demonstrates superior system performance. Under optimal operating conditions, the system round-trip efficiency reaches 63.72%, the exergy efficiency is 34.86%, and the total exergy loss is 1463.9kW. Exergy analysis indicates that the heat pump evaporator contributes the largest exergy loss, with a relative exergy loss rate of approximately 23.71%, followed by the ORC evaporator, while the ORC working fluid pump exhibits the smallest exergy loss at only 0.2%.