Iron ore sintering is a high-energy-consuming industry, and its high dependence on fossil fuels and the low concentration of CO in the sintering flue gas conceal the truth of the large total amount of CO emissions, which leads to the continuous emission of CO in the sintering flue gas has been harmful to the atmosphere and human health, and it is facing the great pressure of CO emission reduction. On the basis of commercially applied sintering technologies, the mechanism and characteristics of CO emission from sintering flue gas are discussed, and feasible ways to control CO emission in multiple aspects of source control, process emission reduction and end-of-pipe treatment are summarized. The core of source abatement is to reduce the fuel ratio, process abatement is to improve the combustion conditions of fuels to enhance the conversion rate of CO to CO₂, and end-of-pipe treatment is to separate or oxidize CO to CO₂ by physical or chemical means. hydrogen sintering technology is the future development direction for source abatement, steam blowing sintering technology is introduced for process control, and catalytic oxidation technology has great prospects for removing CO from flue gas in end-of-pipe treatment. CO has great prospects, but efforts are needed to develop highly active catalysts with anti-poisoning and long-standing stability. Finally, feasible technical routes for sintering flue gas CO reduction and their challenges are analyzed, and a coordinated multifaceted control of source-process-end sintering technologies is proposed to achieve the goal of high-efficiency sintering flue gas CO reduction.

This work demonstrated that the silicon carbide addition to pre-alloyed Fe-Mo powder could result either in the formation of steel or iron microstructure depending on the added silicon carbide content. With 1.0 wt. % silicon carbide addition, slowly cooled sintered Fe-Mo-Si-C alloys showed steel microstructures consisting of proeutectoid ferrite and eutectoid transformation product in the form of ferrite + carbide mixture. With 2.0 wt. % silicon carbide addition, slowly cooled sintered Fe-Mo-Si-C alloys with Mo contents of ≥ 0.85 wt.% microstructures comprised ferrite + austenite constituents in the forms of either degenerate upper bainite or ausferrite. With ≥ 3.0 wt. % silicon carbide addition, ductile iron-like microstructures were developed in sintered Fe-Mo-Si-C alloys. The change of microstructures in experimental sintered alloys was attributed to the combined effect of alloying molybdenum, silicon, and carbon elements. Tensile strength and hardness increased with increasing added SiC content while ductility varied with microstructural components.

The copper was the main manufacturing material to produce the coherent lance for enhancing the cooling effect. Due to the low hardness of copper and high-temperature environment, the exit of Laval nozzle would be worn off, resulting in suppressing the impaction ability of supersonic oxygen jet. In order to investigate the effect of wear length on the behavior of coherent jet, both high-temperature experiment and numerical simulation have been carried out, and the axial velocity, total temperature and oxygen fraction were measured in the experimental test to verify the accuracy of simulation model. Based on the result, the overexpand phenomenon was generated due to the Laval nozzle exit wear off, which improved the shock wave intensity at the tip of Laval nozzle, resulting in a lower axial velocity at the velocity potential core. With a longer wear length, the vorticity of the coherent jet periphery is increased, which causes more thermal energy of combustion flame being released prematurely near the coherent lance tip, leading to a shorter velocity potential core.

Ferritic stainless steels are used for automobile exhaust parts because of their high heat and corrosion resistance. Among them, parts located upstream near the engine, so-called hot-end parts, for example, exhaust manifolds, are required to show excellent heat resistance. Since thermal fatigue is induced by repeating heating and cooling with mechanical strain restriction, thermal fatigue resistance is one of the most important properties of upstream exhaust-parts materials.

In this study, the effect of Al addition on thermal fatigue deformation morphology was investigated for high heat-resistant ferritic stainless steel SUS444 which has been used for automobile exhaust parts. In contrast with the steel without Al addition, which fracture morphology in thermal fatigue under the maximum temperature of 1,173 K was necking, cracking was predominant in the steel with Al addition without necking. Al addition has the effect to prevent necking in thermal fatigue under the maximum temperature of 1,173 K due to solid solution strengthening by Al.

In general, the stress-strain relationship of materials obtained by standard uniaxial tensile test, which can identify the hardening behavior only up to necking. Beyond necking, the material behavior is usually estimated by extrapolating or numerical modelling based on hardening behavior prior to the uniform elongation. This study investigated the post-necking hardening behavior of a fully martensitic steel by in-situ synchrotron X-ray diffraction during tensile deformation. From the in-situ results, the dislocation density, lattice strain and phase stress were calculated within the necked region and outside the necked region. A near steady-state flow with some hardening was observed within the necked region of a martensitic steel. However, beyond uniform elongation, outside the necked region the dislocation density and phase stress decreased slightly, suggesting stress relaxation. Steady-state flow and dislocation densities at large strains suggest dynamic recovery occurs in the martensitic steel at room temperature.

Thermal hysteresis in fusion welding causes significant weld deterioration in medium- and high-carbon steels. Therefore, the development of an effective alternative welding process is required. Friction stir welding (FSW) is a solid-state welding process performed in an atmosphere that reduces the risks associated with melting and solidification of metals, making it an effective alternative method. Furthermore, it facilitates a flexible in-process control of heat input, which can be achieved by controlling the welding parameters. Considering these, the authors conducted a series of studies to elucidate the characteristics of FSW for medium- and high-carbon steels, including high-strength tempered steels.

This paper presents the results of applying FSW to 1.4 GPa-grade tempered JIS-S55C steel plates. Five distinct weld types were created by varying the welding parameters, including tool rotation and welding speed. The temperature of the interface between the tool and in-process material was measured using a thermal imaging camera. The microstructure of the welds was evaluated using optical microscopy and field-emission scanning electron microscopy (FE-SEM) with an electron-backscatter diffraction (EBSD) measurement system. The mechanical properties of the welds were evaluated through Vickers hardness and tensile tests. Digital image correlation analysis was employed to analyze the local deformation during the tensile test.

The competition between the ferrite and austenite for nucleation in the melt can result in various solidification sequences in the Fe-based alloy. This study demonstrates that the austenite solidification was initiated by metastable ferrite nucleation followed by ferrite-austenite transformation even in Fe-22mass%Mn-0.7mass%C, where the austenite is the primary phase in equilibrium. Time-resolved X-ray diffraction measurements were performed using a time-resolved X-ray tomography apparatus to identify the metastable ferrite nucleation followed by the austenite solidification. X-ray radiography was performed to observe the microstructure evolution through the metastable ferrite nucleation followed by the austenite solidification. The metastable ferrite nucleation was preferably selected when the completely melted specimen was cooled. During subsequent cooling, the ferrite massively transformed to the austenite in the solid state, and multiple austenite grains were produced in a single ferrite grain through ferrite-austenite transformation. The ferrite-austenite transformation was immediately followed by the coarsening of multiple austenite grains. When the ferrite-austenite transformation occurred in a semisolid state consisting of the ferrite and liquid phase, the liquid phase, which isolated the austenite grains, suppressed the coarsening of austenite grain. The typical austenite grain size ranged from 100 to 500 μm. Thus, the present results suggest that the ferrite-austenite transformation following the metastable ferrite nucleation has the potential to control the austenite grain size in as-cast microstructures.

Fe-9 mass%Ni alloy is widely used as a cryogenic steel owing to its excellent low-temperature strength and toughness. However, Ni is an expensive element, with medium-Mn steel considered an inexpensive alternative. Considering the Fe-10%Mn-0.1%C alloy is brittle at low temperatures, the application of intercritical annealing with two-step hot rolling could lead to toughening. Herein, the effect of intercritical annealing on the toughness of a Fe-10%Mn-0.1%C alloy with elongated prior-austenite grains (PAGs) formed via a two-step hot-rolling process was investigated. Intercritical annealing was performed on the specimens with and without two-step hot rolling. For both specimens, intercritical annealing resulted in softening of α'-martensite and an increase in the amount of retained austenite. In the specimen not subjected to the two-step hot rolling process, the fracture morphology transitioned from ductile to intergranular with a decrease in the temperature. Intercritical annealing improved the toughness when ductile fracture occurred. In the case of intergranular fracture, the effect of intercritical annealing on the toughness was negligible. In the two-step hot-rolled specimen with elongated PAGs, the fracture morphology transitioned from ductile to separation fracture with ductile fracture, and intercritical annealing improved the toughness at all temperature ranges. The improvement in toughness during separation fracture is attributed to the expansion of the plastic zone owing to ductile crack progression and the formation of sub-cracks, which promote the strain-induced transformation of retained austenite and ε-martensite.

The effect of MnS inclusions on the localized corrosion of low-alloy steel in a 0.5 mol/kg (3 %) NaCl solution was investigated to propose countermeasures for inhibiting localized corrosion initiated by MnS inclusions. Low alloy steels without MnS inclusions did not corrode in a 0.5 mol/kg (3 %) NaCl solution, regardless of the addition of Cu. That is, no matrix improvement effect due to solute Cu was confirmed. Slight corrosion occurred in the Cu containing steel with MnS inclusions; however, the MnS inclusions remained. Cu_7.2S₄ precipitated on the MnS in contact with a 0.5 mol/kg (3 %) NaCl solution. Therefore, Cu_7.2S₄ precipitates on the MnS inclusions during immersion, which could suppress the localized corrosion initiated by the MnS inclusions because Cu sulfide is not dissolved based on potential-pH diagram. The addition of Cu in a 0.5 mol/kg (3 %) NaCl solution does not improve the corrosion resistance of the matrix due to solute Cu but does suppress localized corrosion initiating from MnS by precipitating Cu sulfide on MnS.

The effect of MgO/CaO ratio on the viscosity and free running temperature of chromium-containing high-titanium blast furnace slag (CaO-SiO₂-Al₂O₃-MgO-TiO₂-Cr₂O₃) was investigated by a rotating crucible viscometer. When the ternary basicity with a fixed (CaO+MgO)/SiO₂ ratio of 1.41 and the temperature was fixed, the MgO/CaO ratio had an obvious influence on the viscosity of slags. Increasing MgO/CaO ratio from 0.34 to 0.44 caused a slight decrease in the viscosity of the slag, and had an opposite effect when MgO/CaO ratio was more than 0.44. The XRD measurements showed that the technology of ‘‘replacing CaO with MgO'' has an effect on the precipitation temperature of perovskite phase and spinel phase. Accroding to the Raman spectroscopy results, with the increase of MgO/CaO ratio from 0.34 to 0.44, the DOP decreased, and then increased as the MgO/CaO ratio increased from 0.44 to 0.56.

Under certain conditions, the whole roll flatness meter outputs a bimodal waveform signal, which is clearly different from the conventional unimodal waveform signal. Since detection relies on the extraction of crest values and the values of the two waveforms do not have the same linearity, the presence of the two waveforms of different channels will clearly give rise to errors in the calculated flatness distribution. To develop an effective extraction method, it is necessary to accurately analyze the evolution of the waveforms. In this paper, the finite element method is used to calculate the load of the sensor, the stress distribution of each analysis surface and the deformation of the sensor mounting hole during the real-time detection to analyze the mechanism of the waveforms. The results show that unimodal and bimodal waveforms are produced under different strip tension and wrap angle conditions. In addition, the radial stress of the roll surface always presents two stress wave distributions. With increasing strip tension or wrap angle, the phase difference between the two waves increases. The stress distribution will change the deformation trend of the mounting hole and affect the stress distribution state of the sensor. When the phase difference of the stress waves exceeds the covering range of the sensor, the output signal changes from a unimodal waveform to a bimodal waveform. Finally, by setting up an experimental platform with variable tension and wrap angle, the relationship between the output waveforms and the working conditions in the simulation is reproduced.

This study examines the effect of container size on coal briquette's internal structure using the Discrete Element Method. It found that when the frictional resistance between particle and wall was large and the inner diameter small, the difference in particle filling ratio between the upper and lower parts of the briquette was significant. Conversely, with a larger inner diameter, this difference nearly disappeared. The distribution of contact force indicated that the frictional force's inhibiting effect on force transmission lessened with a larger container's inner diameter. The study also revealed that the height of the container affects the briquette's internal structure, and these results can be summarized by the container's height to diameter ratio. Essentially, a larger ratio led to a linear increase in the difference in filling ratio between the upper and lower parts of the briquette.

In the gas wiping process used in hot-dip galvanizing, the coating thickness has two thinning limits. The first is the limit due to splashing of the liquid film of molten zinc, and the second is the thinning limit of the wiping capacity of the equipment.

In this study, we investigated the possibility that wiping efficiency is reduced by the effect of zinc solidification due to gas jet cooling by conducting a gas wiping experiment under various temperature conditions.

A galvanized steel strip with a width of 100 mm was immersed in a molten zinc bath in the air atmosphere. The steel strip was heated by induction heating or a gas burner, and the wiping gas was also heated.

The results clarified the fact that high temperature conditions improved gas wiping efficiency. It is suggested that high wiping efficiency is prevented by an increase in viscosity due to an increasing solid volume fraction in the liquid zinc film surface caused by microscopic solidification. In addition, it was also found that the development of the initial alloy layer reduced the amount of liquid phase, which inhibits wiping.

Air-quenched electric arc furnace slag (AEAFS) is a black sphere or spheroid particle prepared by an air quenching theology using electric arc furnace steelmaking slag as raw materials, possessing the characteristics of small particle size, moderate density and high hardness Combined with the tight supply and demand of the existing abrasive market and the continuous increase in price, AEAFS is tried to be used as a free abrasive for sandblasting processing according to its physical characteristics. In order to make sure that the AEAFS meets the requirement of free abrasive blasting, it is necessary to conduct a comprehensive and in-depth analysis of its physical and chemical properties. The research shows that the AEAFS is a spherical particle with weak magnetism and particle size being mainly 2.8 mm (accounting for more than 90%). Its Vickers hardness is in the range of 600-1000HV; its compressive strength is between 20 and 465N and increases first and then decreases with particle size. The water content is more than 0.019%, except that the particle size is less than 0.5mm. All the others meet the requirements of ISO-11126-6: 2018 standard. The content of f-CaO is between 1.122% and 1.612% increasing with the particle size, AEAFS has good chemical stability and weak acid resistance. In summary, AEAFS meets the performance requirements of the medium used in the sandblasting process and is a potential alternative product for sandblasting abrasives.

Thermal mixing during the gas stirring operation and arc heating in a steel ladle is analyzed through the modern tools of a physical model using PIV (Particle Image Velocimetry) and thermal PLIF (Planar Laser Induced Fluorescence), whose velocity and temperature fields were used to fine-tune and validate a multiphase Eulerian two-phase mathematical model. Agreement on both fluid dynamics and thermal evolution is reasonably good between experiments and the predictions obtained by the mathematical model of the physical model. The analysis coming from the numerical model validated by the physical model measurements included the thermal mixing and energy efficiency of single nozzle injection in centric and eccentric (4/5R) gas injection. It turned out that energy efficiency in the centric gas injection is 20% more efficient than in eccentric injection. Then, under the same heat flux provided, the maximum temperature of the water in the centric gas injection would be higher than the maximum temperature reached in the eccentric mode with the same gas flow rate. Good heat transfer happens when the heat source impinges in a fluid region with high circulation and turbulent dispersion.

Friction stir welding (FSW) is expected to be applied as a welding technique of materials with relatively high melting temperature such as steel materials. Silicon nitride is one of the inexpensive and attractive tool materials for FSW of the thick steel plate. Therefore, in this study, the capability of the silicon nitride tool without groove scroll to weld a low carbon steel plate with a thickness of 15 mm was investigated. The suitability of a tool shape was confirmed by FSW of a thick A5052 plate using a SKD61 tool with same shape as the silicon nitride tool. The defect-free welded specimen of the thick steel plate was obtained using the silicon nitride tool under the optimum welding condition. The silicon nitride tool could be used for FSW of the 15 mm thick steel plate until the welding length of 200 mm without breaking the tool. The groove defect area in the stir zone of the thick steel plate was decreased with decreasing of the tool rotation speed and tool tilt angle. Especially, the tool tilt angle was effective to increase the heat input and the material flow velocity. It is considered that the defect-free weld specimen of the thick steel plate was obtained to sufficient material supply to the RS of the stir zone by decreasing tool tilt angle to 1°.

From the viewpoint of expanding the allowable P limit, the effect of warm tempforming on delayed fracture resistance was evaluated for 0.09% P-doped 0.4%C–1%Cr–0.7%Mn–0.2%Mo steel (mass%). The P-doped steel was warm tempformed at 500 °C with a caliber-rolling reduction of 78% and annealed at 550 °C for 1 h. This thermomechanical treatment created an ultrafine elongated grain structure with a strong <110>// rolling direction fiber texture, in which P definitely cosegregated with Mn and Mo at grain boundaries. The slow-strain-rate-test and immersion test demonstrated that warm tempforming markedly enhanced the delayed fracture resistance of the P-doped steel at a tensile strength of 1100 MPa level, in contrast to conventional quenching and tempering treatment.

Metallurgical industries often discharge slag containing valuable elements that are poorly utilized when producing copper alloys and silicon-manganese alloys. To improve the utilization rate, in this study, a method to mix copper slag with water-quenched silicon-manganese slag and CaO for roasting and modification was proposed. In this work, FactSage 8.0, DSC-TG, and XRD were used to examine the phase change during the modification process and investigate the impacts of the CaO content, roasting temperature, and holding time on the modification effect. The results showed that the addition of water-quenched silicon-manganese slag and CaO could effectively promote the transformation of fayalite to (Mn, Mg, Fe)Fe₂O₄, with the highest conversion rate occurring at a 10% CaO content. An increase in the temperature and prolongation of the time facilitated fayalite transformation, but excessive temperature or time could result in iron loss. The optimal recovery rate and iron grade were achieved with roasting at 1400 °C for 60 min. This method can provide a concentrate suitable for producing copper-containing antibacterial stainless steel and wear-resistant cast iron, and the tailings can be used to produce ceramic materials.

Knowledge of the viscoelastic properties of suspensions is essential for many industrial processes. Although oscillation and creep testing are widely used to measure the viscoelastic properties of complex fluids, few studies on the correlation between the viscoelastic properties measured using these methods have been published. This study aims to provide insights into the differences between these methods and determine which method is better suited for a particular application. The room-temperature viscoelastic properties of a suspension composed of polyethylene beads dispersed in a silicone oil matrix were measured by oscillation and creep testing and compared. The results of oscillation testing indicated that the suspension showed weakly elastic deformation, whereas the results of creep testing revealed that the suspension was relatively elastic, with the liquid phase showing lower viscosity. In addition, the viscosity measured by oscillation testing was lower than that measured by creep testing. When the imposed flow causes microstructural changes, such as when the shear flow and particle‒particle contact induce aggregation, the analyzed flow property considerably differs between testing methods.

Atomic-scale lattice defects beneath various hydrogen embrittlement fracture process regions, i.e., different fracture modes, were compared for martensitic steel. The crack initiation region containing quasi-cleavage (QC) and intergranular (IG) fracture, the crack propagation region mostly consisting of IG fracture, and the final fracture region completely composed of microvoid coalescence (MVC) were extracted from the same fracture surface and analyzed by low-temperature thermal desorption spectroscopy (L-TDS). The relative shapes of the L-TDS curves were different at the sampling positions, demonstrating at the atomic-scale that the types and numbers of lattice defects formed vary depending on the fracture process and fracture mode.

Recently, remarkable advances have been made in statistical analyses based on deep-learning techniques. Applied studies of deep learning have been reported in various industrial fields, including the iron and steel-making industries. The production of iron and steel requires a variety of processes, such as the processing of ingredients, iron-making, casting, and rolling. Consequently, the data acquired from them are diverse, and various tasks exist that can be assisted by deep-learning algorithms. Hence, providing a summary of the application is helpful for researchers specializing in information science to grasp the current trend of applied studies on deep learning techniques and for researchers specializing in each field of the iron and steel-making industry to understand what types of deep learning techniques are being utilized in other specialized fields. Therefore, in this study, we summarize the current studies on the application of deep learning in the iron- and steel-making fields by organizing them into several categories of processes and analytical methodologies. Furthermore, based on the results, we discuss future perspectives on the development of deep-learning techniques in this field.

The microstructure of the B1-type TiC formed during solidification and its mechanical properties were investigated using arc-melted Fe–Ti–C ternary alloys. The TiC formed at relatively high temperatures in the liquid as the primary phase exhibited a dendritic shape. With decreasing temperature and/or decreasing Ti and C content in the liquid, the morphology of the TiC changed to a cubic shape with a {001}_TiC habit plane, a plate shape with a {011}_TiC habit plane, and a needle shape with a preferential growth direction of <001>_TiC. The morphology of the TiC was characterized by the anisotropy of its surface energy and its growth rate. The cubic shape with a {001}_TiC habit plane was formed as a result of the {001}_TiC surface exhibiting the lowest surface energy among the TiC surfaces. However, the plate shape with a {011}_TiC habit plane and the needle shape with a <001>_TiC preferential growth direction likely formed because the slowest and fastest growth rates corresponded to the <011>_TiC and <001>_TiC directions, respectively. At room temperature, the alloy with dendritic TiC was fractured in the elastic deformation region because TiC exhibited no plastic deformation. However, the results obtained at 800°C suggested that the TiC exhibited plastic deformability and that the alloy with the dendritic TiC was also plastically deformed.

A brace-type seismic damper made of an Fe-15Mn-11Cr-7.5Ni-4Si alloy solidified in the ferrite-austenite (FA) mode and SN490B steel, which can be constructed via welding, was proposed. To realize the proposed seismic damper, gas metal arc welding was applied to produce similar FMS/FMS fillet welds and dissimilar FMS/SN490B fillet weld joints. Based on the Schaeffler diagram, similar and dissimilar welding consumables were designed such that the fillet weld metal solidified in the FA mode without solidification cracking. Sound similar fillet welded joints were obtained using two types of welding consumables with different Cr/Ni equivalent ratios although both the similar fillet weld metals had a coarse columnar austenite grain structure. These displayed higher tensile strengths (716–736 MPa) and marginally lower elongations (67–70%) than the FMS alloy. Moreover, a similar fillet weld metal with a chemical composition almost identical to that of the FMS alloy exhibited a remarkable low-cycle fatigue life (5740 cycles). This was shorter than that of the FMS alloy (9351 cycles) owing to the easier formation of α'-martensite. A dissimilar fillet welded joint with a chemical composition within the austenite region was produced without solidification cracking. The dissimilar fillet weld metal showed high tensile strength (867 MPa) and total elongation (61%). These were comparable to those of similar fillet weld metals.

In the continuous casting process, the temperature of liquid steel in tundish determines the casting speed and secondary cooling conditions, and then influences the billet quality. It's very important to measure the temperature of liquid steel in tundish quickly and accurately. However, the initial response lag of blackbody cavity sensor is inevitable since the time is required for the sensor inner wall and the liquid steel reaching thermal equilibrium by heat transfer. In this paper, in order to eliminate the initial response lag of sensor, a heat transfer model of sensor is established. The heat transfer characteristics and cavity integral emissivity of sensor with different depths immersed into liquid steel are analyzed. The analytical solution of sensor temperature is derived by separation of variables method and superposition principle, and is verified by the actual temperature measurement data. Then an innovative method of liquid steel temperature rapid identification is deduced and validated by the actual measurement data. The results show that the initial response lag of sensor is greatly shortened and the temperature measurement efficiency is improved. This study provides a theoretical method for improving the initial response speed of sensor.

The interfacial tension between the liquid steel and molten slag is one of the key properties to control the entrapment of mold flux in molten steel in the continuous casting process. A dynamic change of the interfacial tension is observed when deoxidized iron and silicate slag are in contact, which can be explained by the oxygen absorption and desorption at the iron/slag interface. However, the dynamic change of the interfacial tension is influenced by other surfactant components of the molten iron and slag. Fluoride ions are fundamental component of mold flux, and recognized as the surface active component of molten slag. The effect of fluoride ions in slag on the interfacial tension has not been critically evaluated. Here, the effect of fluoride ions in slag on the interfacial tension between molten iron and molten silicate slag was evaluated at 1823 K, where the fluoride-containing slag compositions were designed to exhibit the same SiO₂ activity and slag viscosity as those of the fluoride-free slag. Compared with the case of molten iron and fluoride-free slag, the interfacial tension between the molten iron and fluoride-containing slag was initially lower. Except the effect of oxygen adsorption, fluoride ion was considered to directly decrease the interfacial tension. However, as the fluoride content in slag was higher, the interfacial tension tended to show the higher value at the final state. This behavior was attributed mainly to fluoride vaporization as SiF₄, which reduce the SiO₂ activity in slag and thus equivalent oxygen content at the iron/slag interface.

Reasonable gas flow distribution plays a decisive role in the smooth operation of blast furnace smelting, but it is difficult to detect the gas flow distribution in blast furnace in real time. An intelligent prediction and identification system of central gas flow distribution based on infrared image of blast furnace and cross-beam temperature measurement is constructed(C-GFD). The system is mainly composed of two models, namely the image model and the prediction and recognition model. In the image model, three kinds of derived parameters, namely, central gas flow area, temperature and offset, are extracted by the image entropy and neighbourhood valley-emphasis (ENVE) Otsu, thermodynamic heat transfer and grey scale centroid algorithms, and then the statistical relationship between the change of image information and the distribution of gas flow is investigated. In the prediction and recognition model is established by the algorithms based on convolutional neural network long and short-term memory (CNN-LSTM) and Euclidean-weighted fuzzy C-mean clustering (E-FCM) to complete the prediction of the three types of derived parameters, and the prediction data is transferred to the recognition model to complete the recognition of the central gas flow distribution pattern. The test results show that the system provides real-time and reliable gas flow reference information for blast furnace operators with 95% accuracy in model prediction and more than 90% accuracy in pattern recognition of various types of central gas flow distribution.

A novel integrated constitutive equation of the flow curve for Ti–6Al–4V alloys is proposed by incorporating the effects of phase fraction in the hot-forging temperature range. The flow curve was obtained using hot-compression tests in the temperature range of 750–1050 °C and strain rate range of 1–25 s^-1. The effects of friction and deformation heat generated during compression were corrected using the inverse analysis method to identify the ideal uniaxial flow curve. The obtained stress parameters were satisfactorily regressed using the rule of mixtures on the α and β phases considering changes in the phase fraction. The integrated flow curve equation incorporating the rule of mixtures of the two phases effectively expressed the flow curve throughout the investigated temperature range. The internal microstructural observation showed that the continuous dynamic recrystallization of the α phase is dominant in the α+β two-phase region, while the deformation of the β phase becomes dominant just below the β transus. The constitutive equation presented here is in good agreement with the temperature dependence of the microstructure.