Abstract：With the acceleration of global industrialization, the emission of carbon dioxide has been increasing year by year, bringing more and more extreme weather and environmental disasters. CO2 storage technology is currently recognized as a backup technology for achieving carbon neutrality. The development status and future trends of CO2 mineralization technology using steel metallurgical solid waste as feedstock were reviewed. Firstly, the pathways and principles of CO2 mineralization were introduced. The process conditions for direct mineralization are relatively strict, and the solidification of CO2 will consume a large amount of resources. However, the reaction conditions for indirect mineralization are more gentle and the effect is more significant. Then, the most representative and feasible technologies for solid waste mineralization in steel metallurgy were summarized, among which the process route using NH4Cl as a leaching agent exhibits the best industrial potential due to its dual advantages of solvent recycling and mild reaction conditions. In addition, based on the economic analysis of typical pilot experiments, raw material resources and other factors are not the main constraints on the industrialization of CO2 mineralization technology. The key to achieving industrialization is the scaleup test of CO2 mineralization process, the development of recyclable leaching solution, and the establishment of an economic evaluation system.

Abstract： The shock tunnel worked in an ultrahigh pressure hydrogen environment and faced serious risk of hydrogen damage, which put forward strict requirements for hydrogenexposed materials. At present, conventional hydrogenresistant steels might be difficult to meet the equipment requirements. Therefore, in order to ensure the safe operation of equipment in the ultrahigh pressure hydrogen environment, it was of great significance to study the hydrogen damage of steels used in the ultrahigh pressure environment. Based on the research results at home and abroad, the hydrogen damage mechanism and its influencing factors were briefly introduced, then the hydrogen resistance and development status of Cr-Mo steel, singlephase austenitic stainless steel, precipitationstrengthened austenitic alloy and nickelbased alloy was summarized. Finally, the future research focus was prospected.

Abstract： Nitrogenalloyed martensitic stainless steel (NAMSS) was widely used due to its high toughness, hardness, excellent fatigue resistance, good corrosion resistance, and other advantages. The corrosion resistance of NAMSS played a critical role in its service life. The corrosion behavior of NAMSS was of academic and engineering interests. Here, the corrosion behavior of NAMSS was reviewed and analyzed based on domestic and foreign research works. Compared to the conventional martensitic stainless steel, fewer precipitates form in NAMSS, which improves the corrosion resistance of NAMSS. Inclusions retained in NAMSS result in the increase of corrosion nucleation sites, accelerating the corrosion rate. The presence of nitrogen promotes the formation of retained austenite/ reverted austenite in NAMSS, improving the corrosion resistance. However, the excess nitrogen in NAMSS is detrimental to the corrosion resistance. Finally, future research work on the corrosion behavior of NAMSS was suggested.

Abstract： The mechanical properties of high performance bridge steel Q370qE were tested by tensile and impact testing machines. The effects of finishing rolling temperature on mechanical properties, microstructure, grain boundary orientation angle difference, texture, dislocation and precipitate morphology were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that the yield strength, tensile strength and yield strength ratio of the steel increase when the finishing rolling temperature is reduced in the range of 875-803℃. The ductile brittle transition temperature is reduced and the low temperature toughness of the steel is improved. When the final rolling temperature is 803℃, the yield and tensile strength of the steel are 420MPa and 542MPa, respectively. The average Charpy impact energy is 243J at -40℃. Reducing the finishing rolling temperature is beneficial to refine the ferrite grain size and improve the uniformity. The size of pearlite cluster bundle and the number of pearlite structure reduce, some pearlite clusters are degenerated. The pearlite structure changes from dispersed to continuous strip, which increases the banded structure of the steel. The formation of large angle grain boundaries and the reduction of small angle grain boundaries in Q370qE steel, which is conducive to the weakening of grain <001> orientation and the increase of grain <110> orientation. The precipitations of Nb/Ti carbonitride in the grain are refined and spherical. The increase in internal dislocations and a large amount of entanglement in ferrite grains also promote the formation of Nb/Ti carbonitrides on dislocations.

Abstract：Adding titanium containing burden to the blast furnace is one of the measures to protect the furnace hearth. The mechanism of protecting the furnace is not yet clear, and the effectiveness of use varies greatly. Titaniumbearing material use for a long time will also bring some adverse effects on the blast furnace operation. Therefore, the protection mechanism and the failure reason of titaniumbearing material were discussed. The reasonable range of TiO2 content in slag, TiC precipitation temperature in molten iron and the corresponding titanium content were systematically investigated by thermodynamic calculation method so as to guide the production practice and provide a theoretical basis for the operation parameters selection of titaniumbearing material protection for blast furnace operators. The results show that titaniumbearing material protection is mainly achieved by the dual action of reducing the flow rate of molten iron and promoting the formation of composite protective layer of carbon brick. To achieve better protective effect, it is necessary to eliminate the air gap of the hearth sidewall to ensure the integrity of the heat transfer system. Under the current calculation conditions, the TiO2 mass fraction in blast furnace slag, the TiC precipitation temperature in molten iron, and the titanium mass fraction in molten iron are controlled within the range of 1.5%-3.0%, 1300-1400℃, and 0.064%-0.11%, respectively, which can effectively protect the furnace and reduce its adverse effects.

Abstract： Various quality problems often occured on the surface of the billet during continuous casting, which seriously affected the quality of the billet and the smooth flow of production. However, the pattern of the effect of differences in the initial solidification pattern of steel grades on the surface quality defects of cast billets was not clear enough. A series of representative steel grades were selected, and the calculation of thermodynamic equilibrium phase diagram and high temperature mechanical properties were carried out using JmatPro software, combined with the theoretical formulae for the characteristic points of equilibrium Fe-C-X pseudobinary diagram, to comprehensively study the initial solidification modes of different steel grades and their influence laws on the surface quality of casting billets. The results show that for the four different solidification modes of steel grades, the main surface quality defects of casting billets of lowcarbon and hypo-peritectic solidification modes are subcutaneous inclusions and surface longitudinal cracks, which are mainly caused by changes in ultimate yield strength and phase strain due to phase transformation in the high-temperature stage; the surface quality problems of casting billets of hyper-peritectic and high-carbon solidification modes rarely occur. Therefore, the probability of occurrence of defects on the surface of the cast billet is jointly determined by the proportion of the δ phase when the steel undergoes a high-temperature phase transformation (L+δ→γ/δ→γ), the temperature interval and the degree of phase strain in the billet shell. Based on the solidification mode of steel grades and its influence on the surface quality of casting billets, it is important to predict the possible surface quality defects of casting billets and take relevant measures to reduce the incidence of surface defects to improve the quality of continuous casting billets.

Abstract： To address the issue of low detection accuracy of surface defects in hotrolled strip, an improved YOLOv5 algorithm was proposed. Firstly, a multiscale fusion parallel backbone network was designed, in which each feature layer in the auxiliary backbone was connected to each feature layer of the main backbone as input. The expression capacity was improved by utilizing the auxiliary backbone. Secondly, a contentaware reassembly of features (CARAFE) module was introduced into the backbone network and neck to obtain rich semantic information required for detection tasks and mitigate the loss of upsampled semantic information. Finally, a coordinate attention module (CA) was applied to the multiscale fusion parallel backbone to enhance the feature extraction capacity and accurately locate the target position. Experimental results demonstrate that the improved YOLOv5 algorithm achieves a mean average precision (mAP) of 93.1% on the WISCO hotrolled strip surface defect dataset, which is 3.9% higher than the original YOLOv5 algorithm, while maintaining a detection speed of 78.4 frame per second. The above indicators prove the effectiveness and practicability of the proposed algorithm.

Abstract： The effect of rare earth Ce on the CO2 corrosion resistance of 5Cr steel was studied by using high temperature autoclave test to simulate the underground working environment of an oil field. The corrosion rate was calculated by weight loss method, the microstructure was observed by Zeiss metallographic microscope, the morphology and phase of corrosion products were observed and analyzed by field emission scanning electron microscope and X-ray diffractometer, and the types and quantities of inclusions in each test steel were observed and analyzed. The results show that: the metallurgical structure of the test steel is tempered sorbite structure. The addition of rare earth Ce modifies some aluminate inclusions and oxysulfide inclusions into rare earth aluminate and oxysulfide inclusions, thus reducing the local corrosion on the specimen surface and making the corrosion products more continuous and denser. The corrosion rate decreases from 0.2846mm/a to 0.2683mm/a. The corrosion products are mainly Cr2O3.

Abstract： In order to find out the consolidation mechanism of magnesiacontaining iron ore pellet, the phase composition and thermal behavior of magnesium bentonite, preparation process and microstructure of magnesiacontaining iron ore pellet were systematically studied with magnesium bentonite as binder and magnesium source. The results show that the main phases of magnesian bentonite are MgO, quartz and montmorillonite. For the bentonite, the volatilization reaction and combustion reaction of a small amount of combustible organic components occur at low temperature, and the decomposition reaction of MgCO3 occurs at high temperature about 800℃. When the MgO content of pellets is 2.5mass%, under the optimized conditions of 12min of pellet making time, 8.5mass% of pellet moisture, preheating at 1030℃ for 10min, and roasting at 1280℃ for 1min, the drop strength and compressive strength of green pellets are respectively 5.7 times/（0.5m） and 10.21N, and the compressive strength of the preheating pellets and roasting pellets are 525.5N and 2576N, respectively. Magnesium bentonite pellets are mainly composed of Fe2O3 as the main crystalline phase, and there are a small amount of fayalite (CaO·FeO·SiO2, 2FeO·SiO2), magnesium ferrite (MgO·Fe2O3) and glassy phase among Fe2O3 crystal grains. The magnesium bentonite pellets are dominated by Fe2O3 recrystallization consolidation, supplemented by liquid phase bonding of magnesium ferrite. Microstructures of the pellets are homogeneous and dense.

Abstract： With the promotion of the "one package to the end" process in China and the development demand for a large scrap ratio, higher requirements have been put forward for hot metal ladle. In order to prolong the service life of the ladle, the influence of different masonry bottom structures on the stress distribution of the ladle was studied. A multiscale constitutive model of mortarless lining structure was established, and it is verified by comparison with the microscopic and the simplified model. Based on multiscale model, numerical simulations of cross type, parallel type and two radial type mortarless masonry bottom were carried out. The results show that when the joint size is all 0-3 mm, the difference in stress on the heating surface between different masonry methods is not significant, but there is a significant difference in the closure law of the heating surface joint. Compared with the parallel type and the radial type with the short side of the brick parallel to the radial direction, the joint closure of the cross type and the radial type with the long side of the brick parallel to the radial direction is more uniform when heated. The size of the joint can be appropriately increased to optimize the thermal expansion stress of the bottom when the latter two masonry methods are adopted.

Abstract： A mathematical model for dynamically predicting the burden surface was established during the descending process of the coke or ore. The accuracy of the model was verified by a comparison with actual startup experimental results. In addition, a comprehensive analysis of the important parameters affecting the results of the model was undertaken, which is in order to clarify the influence mechanism of different factors on the burden surface. The model also conducts a comprehensive analysis of the six inner and outer repose angle models based on the previous literature. The research results show that models of A and B have a relatively small amount of calculation, which can achieve the function of rapid prediction, and are suitable for the distribution system commonly used in small volume blast furnaces; Model C is not suitable to predict the mode of central coking operation; Models of D, E, and F are more in line with the law of burden surface in the actual charging process, but Models of D and E are suitable for the prediction of the mixed charge structure of sinter and pellets, and Model F is more suitable for the charging system under the high proportion of pellets.

Abstract： The cold rolled coils were manufactured by the same furnace steel with the same process. The annealed coil of phosphoruscontained high strength IF steel was produced by batch annealing and continuous annealing. The effect of two annealing methods on the FeTiP precipitation and secondary working embrittlement of phosphoruscontained high strength IF steel were studied. The embrittlement transition temperature and precipitate characterization of anneal coil produced by two annealing methods were studied by means of low temperature drop hammer impact testing machine, TEM and precipitate extraction quantitative analysis. The results show that the FeTiP precipitates of continuous annealing and batch annealing are mainly concentrated below 100nm. Due to the longer annealing time of batch annealing, the FeTiP precipitates are more than twice that of continuous annealing. According to the amount of containing phosphorus precipitated phase detection results by quantitative analysis method, combined with thermodynamic and kinetic analysis, degree of enrichment in the grain boundary is determined by the maximum deflection coefficient and effective diffusion distance, the segregation of phosphorus at ferrite grain boundary place in batch annealed coil is much more than that of continuous annealed coil. Therefore, compared with batch annealing, continuous annealing can obtain phosphoruscontained high strength IF steel with lower embrittlement transition temperature in its secondary working.

Abstract：The surface defects of strip steel have the problems of noise, uneven illumination, complex texture and weak contrast in local areas. Therefore, a new algorithm of strip surface defect recognition was proposed. Firstly, an improved lower local binary patterns (ILLBP) feature extraction algorithm was proposed, the lowthreshold pattern of local ternary patterns (LTP) was introduced into the local binary patterns (LBP) algorithm to overcome a certain amount of noise and illumination effects. In order to better characterize the complex texture features of strip surface defects, three new texture structures in improved LBP (ILBP) were introduced. At the same time, frequency histograms of LBP local gradient amplitude and local gradient direction were used to replace the frequency histograms of LBP values, which could better characterize the relationship between the contrast of local areas. Finally, in order to further improve the accuracy of strip defect recognition and reduce the influence of redundant features, an improved salps feature selection algorithm (ISSA) was proposed. The simulation results on the NEU dataset show that the proposed algorithm (ILLBP+ISSA) can overcome the effects of uneven illumination, weak local contrast, complex and diverse textures, and has a certain amount of robustness to noise. When the Gaussian noise signal to noise ratio is 50dB, the recognition accuracy of strip surface defects can reach 99.10%, and the accuracy can reach 97.60% at 40dB.

Abstract： As one of the main raw materials for blast furnace ironmaking, the quality of high basicity sinter has an impact on the economic and technical indexes of the ironmaking process. SiO2 has a strong chemical affinity with CaO, so, they are prone to react to form calcium silicate, inhibiting the formation of calcium ferrite as bonding phases. However, the mechanism of SiO2 effect on the mineral composition and microstructure of the Fe2O3-CaO-SiO2 system has been still unclear. The effects of basicity (R) on the formation of calcium ferrite and calcium silicate were investigated by optical microscopy, X-ray diffraction, and SEMEDS methods. The results show that when the molar ratios of Fe2O3 and CaO were 2.0, 2.5 and 3.0, and the basicity range was 1.7≤R<2.8, CaSiO3 and Ca2SiO4 were generated, and CaSiO3 gradually transformed into Ca2SiO4 as the basicity increased. When the basicity was 1.7, it was found that a new phase SFC was generated. When the basicity range was 1.7≤R<2.8, the CaSiO3 phase disappeared and the products phases were Ca2SiO4 and SFC, in which the SFC content increased with the increase of basicity. In addition, the formation process of SFC was found as Fe2O3+CaO→CaFe2O4, CaFe2O4+SiO2→Ca2SiO4, and Ca2SiO4+Fe2O3→SFC. Therefore, the increase of basicity is conducive to increase of Ca2SiO4, affecting the generation of SFC.

Abstract： Synergistic effects of retained austenite, highdensity coherent NiAl and semicoherent (Mo,Cr)2C precipitates were used to design the new cobalt free ultrastrong dual phase steel whose main composition is Fe-Ni-Al-Cr-Mo-Mn-C. The yield strength and tensile strength reach up to 1730MPa and 2105MPa, respectively. The elongation is 12.1% including the uniform elongation of 7.3%, which is in sharp contrast to the traditional maraging steel. Through transmission electron microscopy (TEM), electron backscattering diffraction(EBSD) and other characterization techniques, it was found that the steel contains nearly 12% residual austenite, which is mainly distributed in the prior austenite grain boundary and martensite lath boundary in the form of particles with diameter of 1-2μm. This discontinuous austenite particle greatly improves the strain hardening and uniform elongation without significantly reducing the strength. The brittle cementite was avoided by twophase synergistic precipitation without Co, and then ultrahigh density coherent NiAl and semicoherent M2C precipitates with equivalent radius of about 1.5nm were formed, which significantly improved the strength and plasticity. A new type of lowcost Cobalt free highperformance ultrahigh strength steel was developed by regulating the distribution of soft and hard phases and co-precipitation behavior.

Abstract： After the deoxidation process of spring steel 55SiCr was adjusted from Al-killed to Si-killed in a domestic steel plant, forsterite inclusions became the main type of inclusions in the rotating bending fatigue fracture. By using methods such as Explorer 4 automatic scanning electron microscopy and FactSage, the differences in inclusion control of Si-killed spring steels from different steel mills were investigated, and the precipitation phases of typical inclusion equilibrium solidification processes were calculated. The results show that only a small amount of inclusions crystallize and the crystal size is small in the 9254-M steel made in Kobe Steel, Japan, and the MgO content in the inclusions is controlled very low. The inclusions in the 9254V steel produced by Nippon Steel underwent a glass state crystallization transformation, with a smaller crystal size and an average MgO mass fraction of 14.5 mass% in the inclusions. Only some inclusions crystallize in a 55SiCr steel produced by a domestic steel plant, but larger sized forsterite precipitates, and the MgO content in the inclusions fluctuates widely. As the MgO content in CaO-SiO2-Al2O3MgO system inclusions increases, the inclusions are more likely to crystallize forsterite phase during the solidification and heating process of the casting bloom. The crystallized forsterite and the forsterite formed by erosion and peeling of MgO based refractory materials both become potential sources of forsterite inclusions in rotational bending fatigue fractures.

Abstract： Wear is a common form of mechanical failure, accounting for roughly 80% of mechanical parts failure. Friction and wear not only increase the loss of raw materials and energy, but also jeopardize the safety and reliability of mechanical parts. High entropy alloy, unlike traditional alloy materials, has become a research hotspot in recent years due to its special four effects. The wear rate and amount can be reduced to some extent by adjusting the types and proportions of high entropy alloy elements, as well as selecting appropriate manufacturing methods and heat treatment processes. The categories of wear resistant high entropy alloys were summarized, the effects of different elements and element ratios on the wear properties of high entropy alloys were discussed, and the wear resistance differences of high entropy alloys prepared by different manufacturing methods were summarized. Finally, the future research of high entropy alloys in the field of wearresistant metal materials was anticipated, in conjunction with the current situation and existing problems of high entropy alloys in friction and wear.

Abstract： With the decrease of highquality iron ore in China and the increase in demand for iron ore, lowcost ore blending and sintering had become a new choice. In order to improve the quality of sinter and the efficient utilization of low silicon ore, the hightemperature characteristics of low silicon ore were studied to determine the appropriate low silicon ore blending scheme. So as to further realize the purpose of reducing cost and increasing production of sintering plant, based on the hightemperature basic characteristics of low silicon iron ore powder used in the test, a sintering cup experiment was conducted to study the different ratios of low silicon ore. At the same time, the mineral phase structure of low silicon sintered ore was observed to determine the optimal matching law of low silicon ore. The research shows that when the SiO2 content in the mineral powder is less than 6 mass%, the liquid phase fluidity index increases with the increase of SiO2 mass fraction. As the MgO content increases, and the liquid phase fluidity index shows a downward trend. When the ratio of low silica ore is not more than 36% (mass fraction), increasing the ratio of hematite can increase the production of liquid phase and acicular calcium ferrite. Therefore, optimizing ore blending through liquid phase fluidity can improve the quality of low silicon sintered ore and strengthen the sintering process.

Abstract： With the flue gas waste heat at the outlet of sinter waste heat boiler as the heat source of organic Rankine cycle (ORC), the thermodynamic model and economic model of subcritical ORC system were established, and the effects of flue gas inlet temperature, pinchpoint temperature difference in evaporator and evaporation temperature of working medium on the thermal economic performance were studied under different working mediums. The results show that the higher the flue gas inlet temperature is, the smaller the pinchpoint temperature difference in evaporator is, the greater the system net output power is. The system net output power increases first and then decreases with the increase of evaporation temperature of working medium. The system net output power per unit heat exchange area increases with the increase of pinchpoint temperature difference in evaporator and evaporation temperature of working medium, and increases first and then decreases with the increase of flue gas inlet temperature. When the evaporation temperature of working medium is greater than 95℃, the working medium R600a has the best thermodynamic performance and can obtain the largest net output power, and otherwise, the net output power of working medium R236ea is the largest. When the system thermal cycle parameters are constant, the working medium R601a has the best economic performance and can obtain the largest net output power per unit heat exchange area, but the net output power of which is the smallest.

Abstract： In order to study the effect of blast furnace injection of hydrogenrich gas on the lipflow condition, the energy and mass balance model of blast furnace injection of hydrogenrich gas was established, and the influences of the injection amount of natural gas, coke oven gas and top circulating gas on fuel ratio, direct reduction degree, belly gas amount, hydrogen utilization rate, belly gas amount and CO2 emission were studied. Taking into account factors such as the heat absorption of raw fuel ash, the heat absorption of unburned coal powder, and the heat absorption of methane decomposition, the calculation method for the theoretical combustion temperature of the tuyere has been revised to obtain more accurate results. Hydrogenrich gas injection can reduce the degree of direct reduction, develop indirect reduction and reduce fuel consumption. When the oxygen enrichment rate and coke ratio remain unchanged, natural gas has the greatest influence on the degree of direct reduction, the quality of coke in tuyere and the theoretical combustion temperature, followed by coke oven gas and circulating gas. The direct reduction degree of natural gas, coke oven gas and circulating gas decreases by 0.014, 0.009 and 0.0024, respectively, when the injection volume increases by 10m3， tuyere burning coke volume increased by 3.22, 2.01 and 0.55kg, respectively， theoretical combustion temperature increases by 20℃, 14.33℃ and 10.17℃, respectively. After injecting hydrogen rich gas into the blast furnace, the production and emission of CO2 in the blast furnace decreased. The CO2 emission reduction effect of natural gas injection is the most significant. Compared with the base period, the CO2 emission of 60m3 natural gas injection is reduced by 9.46%.

Abstract： As one of the most commonly used structural material in petroleum mining industrials, austenitic stainless steels exhibit excellent resistance to chloride pitting corrosion and stress corrosion in complex oil and gas combining environments. However, the current research on the environments which Cl--H2S coexists is relatively inadequate. In addition, the effects of Al and Mo alloying elements on the formation of passivation protective film and corrosion resistance mechanism are still unclear. Therefore, in attempt to promote the application of austenitic stainless steels, the corrosion performance of a new designed aluminaforming austenitic stainless steel in Cl- and H2S environments was evaluated by electrochemical tests. Furthermore, the corrosion behavior of the steel was observed by means of XPS, SEM and TEM, and the corrosion resistance mechanism and the interaction regulations in H2S containing environments were revealed. The results show that due to the addition of an appropriate amount of Mo, the pitting corrosion resistance of the aluminaforming austenitic stainless steel without forming of an Alrich passivation film was improved, resulting in good resistance to hydrogen sulfide corrosion.

Abstract： The effect of solution cooling rate on the microstructure and mechanical property of nickelbased superalloy GH4169 was investigated via field emission scanning electron microscopy, high resolution thermal dilatometer and Rockwell hardness test. With the increasing of cooling rate after solid solution heat treatment, the size distribution of γ″ precipitates changes from bimodal mode to unimodal mode, and the average size of γ″ particles decrease gradually. When the cooling rate is faster than 20℃/min, there is no observable γ″ particles in the alloy. Meanwhile, the morphology of δ phase at the grain boundary gradually changes from connected coarse shape to long needle shape, eventually becomes short rod shape. Combined with continuous cooling transformation curve and hardness test results, the cooling rate after solid solution will significantly affect the size, morphology and volume fraction of γ″ phase, resulting in the difference of mechanical properties. With the increase of cooling rate, the results of Rockwell hardness increase monotonically after aging.

Abstract：CFD numerical simulation was adopted to qualitatively and quantitatively analyze the application effects of different structural turbulence inhibitors, diversion wall and their combinations in an asymmetric threeflow tundish. The metallurgical effects of different flow control schemes were discussed for the actual working conditions of ladle incoming flow temperature variation in continuous casting process. The results show that the application of a turbulence inhibitor with eaves can further reduce the turbulence energy and velocity at the free liquid surface, but it doesn′t show obvious advantage in improving the flow characteristics of asymmetric tundish and improving the consistency of each strand. The scheme of turbulence inhibitor T3 combined with No.2 diversion wall can reduce the ratio of dead zone in the tundish by 11.41% and increase the ratio of plug flow region by 15.49% compared to when only the turbulence inhibitor T2 is added, and the consistency of each strand of the tundish is significantly improved. Additionally, when the incoming flow temperature of the tundish increases or decreases by 15K, the scheme of T3+No.2 diversion wall keeps the molten steel flowing towards the surface by the guide hole compared with the turbulence inhibitor T2 only, which is beneficial to the floating up and removal of inclusions, and also can effectively enhance the metallurgical consistency of each strand.

Abstract： The actual hot rolling heating process was simulated by means of thermogravimetric analyzer (TGA), and the oxidation law of 590MPa high strength ship plate steel was studied in a heating furnace atmosphere at 1100-1250℃ for 120min and 1250℃ for 10-120min in the heating furnace atmosphere. By the use of scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), electron probe microanalyzer(EPMA) and Xray diffraction(XRD), the morphology and element distribution on the surface and the crosssections of the oxide layer were investigated, the phase composition of the oxide layer was detected and the oxidation behavior of 590MPa high strength ship plate steel was analyzed. The results show that after holding at different temperatures for 120min, the oxidation weight gain curve conforms to the parabolic law, the oxidation rate gradually increases, and the oxidation rate decreased slightly at 1250℃. After oxidation at 1250℃, the crosssections of the test steel oxide layers are in the following order from outside to inside: outer oxide surface layer, outer oxide inner layer, and transition layer. With the increasing oxidation time, the outer oxide inner layer and the transition layer gradually grow thicker. The outer oxide surface layer consists of the Fe oxides and the composite oxides FeSiO3 and FeCr2O4. The Ni elements are enriched at the interface between the oxide scale and the matrix, preventing the continuing oxidation while the Fe oxides and the Nirich metal particles form the outer oxidized inner layer. A small number of O ions diffuse into the interior of the alloy. The Si and Cr elements undergo selective oxidation and nucleated and grew to form the transition layer. With the prolongation of oxidation time, the outer oxide inner layer and the transition layer gradually thicken.

Abstract： Aiming at the common problems in multistrand continuous casting tundishes for cord steel production, such as the large temperature difference and inconsistent quality of billet among different strands, the flow characteristics of molten steel in a multistrand tundish and the consistency control of the metallurgical effect were studied based on the principle of fluid dynamics. Taking a sevenstrand continuous casting tundish as the investigated object, the flow behavior and temperature distribution characteristics of molten steel in it under different working conditions were analyzed by means of physical simulation and numerical simulation. A new flow control structure with a uniform flow field, temperature field, and small dead zone ratio was obtained through several scheme comparisons. Compared with the prototype structure, the response time of molten steel with the new flow control structure is prolonged by 20 s and the proportion of dead zone is reduced by 4.2%. The maximum temperature difference among seven outlets is only 1℃, which is 4℃ lower than that of the prototype, indicating that the consistency of each strand is significantly improved. In addition, the average removal rate of inclusions with the size of 5-20μm under the new structure is also 6.1% higher than that of the prototype. An overall upgrading effect has been realized for the tundish metallurgical behavior.

Abstract： In order to efficiently and cleanly treat organic solid waste and ironcontaining solid waste, and at the same time give full play to the unique advantages of production equipment in the metallurgical industry, a newly developed iron bath solid waste collaborative treatment technology was introduced. Based on the optimization of the process parameters of the iron bath solid waste cotreatment, the energy and mass balance model of iron bath solid waste treatment furnace was constructed. The material balance and energy balance in the cotreatment of 30% of urban organic solid waste and 70% of steel dust were calculated. The results show that the secondary combustion heat of CO and H2 is the main source of heat during the treatment, and the secondary combustion exothermic heat can reach more than 50% of the total exothermic heat. The main heat loss is the sensible heat taken away when the flue gas is discharged, which can account for 45% of the total heat demand. In actual production, heat can be recovered through the flue gas waste heat recovery system, which is used for the preheating of the incoming gas, effectively reducing the energy consumption of the system. The construction and application of this model provide data support for subsequent industrialization experiments, which is convenient for engineering design and operation optimization.

Abstract：As one of the important indicators for evaluating the quality of sintered ore, the drum index directly affects the stability of blast furnace production. Based on the sintering production data of an iron and steel enterprise, a prediction method of sinter drum index based on feature engineering and image recognition technology was proposed. Firstly, the data preprocessing was completed for the selected 3 categories of 28 important indicators that affect the sinter drum index. Then, the feature parameters that had a greater impact on the target variable were screened out through the SVM-RFE algorithm and the crossvalidation algorithm. Finally, the convolutional neural network was used to train the twodimensional feature image transformed by the data features, and a prediction model of the sinter drum index based on the convolutional neural network was established. The results show that the hit rate of the model is as high as 93.71% with an error margin of ±1%. This method of converting data features into image features effectively improves the prediction ability, and has a good reference for the future development of predictive sintering technology.

Abstract： In recent years, the shortage of resources and the demand for environmental protection have prompted to the emergence of various environmentally friendly processes in the fields of metallurgy, chemical engineering and materials. The melting of solid materials in hightemperature melts is the key reaction of molten reduction, metal element recovery in slag, metallized pellet dissolution and other environmentally friendly production processes, which can improve the heat utilization rate, reduce energy consumption and pollution. However, it is difficult to be directly observed due to the fast reaction speed and high temperature. The research and characterization methods of solid materials melting in hightemperature melt were summarized, which are mainly divided into cylinder rotation method, input method, gas analysis method, etc. By measuring the changes in cylinder diameter (as well as volume and mass), observing the microstructure of reactants, analyzing reaction exhaust gas, and measuring the chemical composition of slag phase, reaction rate, element migration, interface reaction, and reaction degree were characterized. The effects of factors such as molten pool temperature, stirring degree, and pre reduction degree on the reaction behavior during the melting process were explored.

Abstract： Microstructure and creep properties of an experimental 11Cr-6Co-2W-1Mo martensitic creepresistant steel were studied. The results show that the matrix of the steel was the tempered martensite with a small amount of δ-ferrite. The secondary precipitates in the astempered steel were mainly M23C6, MX. Based on the creep rupture data measured over a wide range of stresses and temperatures, the 105h creep rupture strength values at 650℃ as predicted by the LarsonMiller parameter method and the method of combining the new creep model and the MonkmanGrant relationship were 69 and 18MPa, respectively. The much lower prediction by the latter method was due to the fact that the stress exponent as determined on the basis of the new creep model was much lower in the low stress ratio range than in the high stress ratio range. The quantitative analysis of the microstructure and precipitates in the creepruptured specimens showed that, as testing stress decreased, the martensite lath and M23C6 and Laves phase precipitates coarsened much faster in the low stress ratio range than in the high stress ratio range, indicating that the microstructure evolution characteristics during creep was the main cause for the much lower stress exponent in the low stress ratio range than in the high stress ratio range.

Abstract： In order to improve the manganese yield in converter manganese ore direct alloying process, the industrial test of manganese ore direct alloying was carried out in 200t converter. The effects of the addition amount of manganese ore, the addition sequence of manganese ore and slagging material and the end point composition on the manganese yield were investigated. The results show that when the amount of manganese ore added is 6-8kg/t, the manganese yield can be greater than 50%. The best process for directly alloying manganese ore to achieve a higher manganese recovery rate is to add manganese ore in batches every 2min, without adding sintered ore after 6min of blowing. Through the analysis of experimental data, it was found that dephosphorization of molten iron is a prerequisite for improving manganese recovery rate. Only when the carbon mass fraction at the end of the converter is greater than 0.2% and the phosphorus mass fraction is lower than 0.02%, can high manganese recovery rate be achieved. Finally, based on the results of industrial experiments, the optimal blowing process route was determined.

Abstract： In response to the difficulties in controlling strip width, deteriorating strip shape quality, and excessive cutting of strip edges in the next process caused by the spread during the hot rolling process, a brief analysis was first conducted on the spread model, the influencing factors of spread, and the mechanism by which it affects strip shape. It can be known that the setting value of the strip spread and the distribution of the strip spread between the stands and the optimization of the influencing factors of the strip spread are the keys to solve the above problems through the analysis. Therefore, the objective function for calculation the range of strip spread and the objective function for optimizing the distribution of spread and the objective function for optimizing the common influencing factors were established on the basis of the research on the strip spread model and the flatness model. Based on the premise of excellent exit shape, the calculation of the strip spread range and the optimal distribution of the spread range of each stand and the finetuning optimization of the influencing factors were realized. The development of the evaluation technology for the rolling process of the hot strip mill has been completed. After applying it to a domestic hot strip rolling line, the control precision of the width of the strip steel at the exit of the rolling mill and the quality of the shape are improved.

Abstract： The effect of different Al content on the seawater corrosion resistance of grade B steel was comparatively studied by weightloss measurement, scanning electron microscopy (SEM), X-ray diffraction (XRD), polarization curves and impedance curves analysis. The results show that the addition of Al to the B-grade steel helps to improve its seawater corrosion resistance, the corrosion rates of the test steels with 0.5 wt.% Al and 1 wt.% Al additions are 13.8% and 27.6% lower than the comparative steel after corrosion for 720 h. Compared with the comparative steel, the rust layer of Al-containing steel is more closely combined with the matrix after corrosion, and the thickness of the inner rust layer is larger. The addition of Al can reduce the selfcorrosion current density. And FeAl2O4 with cation selectivity is formed in the corrosion product, which inhibits the intrusion of Cl- into the metal matrix and improves the protection of the rust layer, thereby improving the seawater corrosion resistance of steel.

Abstract： By using the orthogonal experimental method, a 1∶4 water model was established to conduct 18 sets of experiments. Range analysis and variance analysis were conducted on the water simulation test results to study the effects of the diameter and position of the retaining wall guide hole, as well as the upward angle of the retaining wall guide hole, on the flow field in the tundish. The optimal flow control device was selected. The mathematical model was established and solved by Ansys Fluent software, which simulated the flow field and temperature field of the tundish before and after optimization, and verify with the water model results. The results show that the elevation angle has the greatest impact on the flow field of the tundish, and the influence of the diameter and position of the lower hole on the flow field of the tundish is greater than that of the upper hole. When the diameter of the lower hole is 100mm, the height of the lower hole is 250mm, and the elevation angle is 20°, the optimization effect on the flow field of the tundish is the best. Compared with the prototype, the average residence time of the optimized tundish is prolonged by 42 seconds, and the dead zone ratio is reduced to 17.9%. The flow uniformity and consistency of each nozzle are good, and the maximum temperature difference is controlled at 2.4K.

Abstract： Salt spray and periodic immersion tests were used to simulate the marine environment to explore the corrosion behavior of Q355B, HSS-3, and S355NL low alloy steels for marine engineering. The corrosion kinetics, rust morphology, composition, and surface corrosion morphology of marine steel were analyzed by weightloss method, scanning electron microscope, and laser confocal microscope. The results show that under the two test conditions, the corrosion rate decreases and tends to be stable with the extension of exposure time; in the salt spray test, the pitting developed horizontally and gradually developed into uniform corrosion. The alternating process of dry and wet in the periodic immersion test accelerated the corrosion of the sample and promoted the longitudinal development of pitting under the rust layer; There is no obvious difference in the composition of corrosion products of the three kinds of offshore steel, which are composed of Fe3O4, α- FeOOH, and γ- FeOOH, S355NL generates more Fe3O4 phase under both test conditions. Because the S355NL rust layer has a higher density, it has the best corrosion resistance in longterm corrosion.

Abstract： During the continuous casting of rare earth steel, the rare earth inclusions with high melting points will float to the slagsteel interface in the mold. If these inclusions cannot be effectively dissolved and absorbed by the mold flux, the physicochemical properties of the slag will be changed and the continuous casting process will be affected consequently. The dissolution mechanism of CeAlO3 in the slag and the effect of w(CaO)/w(Al2O3) (abbreviated as C/A) on the dissolution process was investigated through hightemperature experiments. The experimental results show that a concentration boundary layer of Ce3+ and Ca2+ is formed at the inclusionsslag interface during the dissolution of CeAlO3. The intermediate product CaCeAl3O7 is formed in the mold flux when C/A is 0.8 and as the C/A ratio increases to 1.0, the intermediate product CaCeAl3O7 decreases, but when C/A continues to increase to 1.2, the intermediate product disappears. The dissolution mechanism is that there are more AlO5-4 in low C/A slag, and the Ce3+ formed by the dissolution of CeAlO3 in the concentration boundary layer reacts with Ca2+ and AlO5-4 in the slag to generate the intermediate product CaCeAl3O7. Then the intermediate product dissolves into the slag again. The dissolution method is indirect dissolution. There is less AlO5-4 in high C/A slag, which is not enough to reach the solid phase nucleation concentration and form the intermediate product, and CeAlO3 is dissolved in the slag by ionic diffusion. Therefore, when the C/A is lower than or equal to 1, the dissolution method of CeAlO3 in the slag is indirect dissolution. The dissolution method of CeAlO3 in the slag changes to direct dissolution when the C/A is more than 1.

Abstract： Serious refractory materials damage at slag line in LF furnace could be observed after long term service, the degree of damage determines whether the ladle needs to be maintained or not. In order to figure out the ladle maintenance period and decrease the production cost, the damage degree of refractory materials at slag line would be judged by smelters. Direct measurement and numerical simulation are the two common methods used nowadays. However, the direct measurement requires specific equipment arrangement and adjustment to ensure accuracy, while the numerical simulation has great demand on the computational resources and time. In order to provide accurate ladle offline maintenance time, based on LF refining record data and supporting ladle offline maintenance data of a certain steel plant, training data was generated by screening and preprocessing the original data according to LF refining principles and refractory materials erosion mechanism. The update principle of the neural network parameters based on error back propagation algorithm was also modified according to the many for one feature of the annual refining and ladle maintenance data. Finally, a prediction model of residual refractory thickness at the slag line with a specific structure has been established via Python and PyTorch. The influences of the neural network type, neural network layer, learning rate and activation function on the performance of the prediction model have been carefully studied. The optimal working parameters could be obtained for the prediction model. Using the selected prediction model to forecast the refractory materials lining thickness after 100 refinement within the test set, 95% prediction errors are less than 10mm.

Abstract： Manganese is a necessary raw material for the development of emerging industries. With the increasing shortage of manganese lump ores, the effective utilization of manganese ore fines and concentrate is of great significance for not only reducing the production cost of ferroalloy but also expanding the source of raw materials. In order to improve the smelting efficiency of electric furnace, it is one of the necessary steps to agglomerate the manganese ore fines and concentrates. Based on the complex composition of natural manganese ore fines with close integration of metal phase and vein minerals, three main agglomeration methods of manganese ore fines and its research progress were reviewed. The requirements of ingredient, technological features, consolidation mechanism and product performance of sintering, pelletizing and briquetting methods were summarized and compared, and it is believed that the smelting efficiency of electric furnaces can be greatly improved by feeding manganese artificial lump ore into electric furnaces. Combined with the background of low carbon emission reduction, the development trend of manganese ore fines agglomeration process in the future is prospected.

Abstract： Hotdip galvanized is an economical and effective surface treatment method for steel materials, and its products play a very important role in corrosion prevention, lifespan extension, and energy conservation of steel. With the development of science and technology and the progress of human society, new alloy coatings and composite Zn coatings with higher corrosion resistance and better economic performance have become the focus of research and development. The corrosion resistance and damage resistance of materials are better after adding the proper amount of Mg and Al to the plating solution so that the hotdip galvanized Zn-Al-Mg alloy layer is widely used. The development of hot-dip galvanized technology was analyzed, and the composition and structure characteristics of Zn-Al-Mg alloy layer in recent years were summarized. The structure evolution and solidification mechanism of the coating during the galvanizing process were described. The wettability between the steel surface and the plating solution, the interface reaction and the diffusion behavior of alloy elements in the interface layer were analyzed. The corrosion resistance of hotdip galvanized Zn-Al-Mg sheet was summarized. Therefore, it was expected to accelerate the development and application of hotdip galvanized Zn-Al-Mg technology in automobiles and other industries.

Abstract：Deformation resistance is an important material and control parameter in the cold rolling process setting; the accuracy of the calculation directly affects the accuracy of the rolling force setting, which in turn affects the control accuracy of the strip flatness and other quality indicators. To deal with the lowaccuracy set of the deformation resistance mechanism model and inability to consider the genetic influence of the hot rolling process parameters, the whale optimization algorithm (WOA) was used to optimize the BP neural network and establish a prediction model (WOA-BP). The model was trained based on on-site collected historical process parameters of hot and cold rolling. The prediction results of WOA-BP model show that the average absolute value error is 10.42, the average absolute percentage error is 1.22, and the average rootmeansquare deviation is 13.13, which are better than that of the BP neural network model. The WOA-BP model compensates for the shortcomings of BP neural networks in dealing with complex nonlinear problems, such as long training time and low prediction accuracy. Compared with the traditional mechanism model established based on a single cold rolling process, considering the hot rolling process parameters, the prediction error of deformation resistance is reduced from ±15% to ±6%. After being applied to the L2 level system model setting, the average accuracy of rolling force is improved by 209%.

Abstract： As one of the main developed materials in the thirdgeneration advanced high strength steel, medium manganese steel has been widely studied due to its high strength and large elongation. Although a lot of research work has been done, most of them still use the method of repeated experiments based on experience. In order to improve this situation, cementite was added to the model in the work. The dynamic model of austenite growth in the intercritical annealing process of manganese steel in Fe-C-Mn-Al-Si fiveelement system was established by DICTRA software. The three processes of austenite growth and the influence of the distribution of substitution elements were discussed. By field emission scanning electron microscopy (SEM) and X-ray diffraction(XRD) analysis, the microstructure of hot rolled steel after subcritical annealing was observed to be filmlike retained austenite. The results of the combination of experimental data and simulation show that the farend model is more suitable for the study of alloys under actual conditions.