The rolling process is characterized by strong nonlinearity, multivariable coupling, and variable operating conditions. Traditional mechanism models are difficult to accurately characterize the true state of rolling, while simple data-driven methods lack generalization ability and the decision-making process is difficult to trace. In the background of the technological transition from "smart manufacturing" to "artificial intelligence+" in the manufacturing industry, how to systematically embed industrial mechanisms into AI models has become a core issue that urgently needs to be broken through. This article systematically summarizes three main modes of deep integration between industrial mechanisms and AI from a methodological perspective, namely mechanism and data hybrid modeling, mechanism guided data modeling, and semantic fusion data modeling. On this basis, combined with typical scenarios such as properties prediction, precise control, quality traceability, equipment operation and maintenance, logistics and scheduling, relevant application solutions are presented,which provides a valuable reference for the development of intelligence rolling technology.

To address problems such as that the traditional design of straightening parameters relies on experience and the prediction model suffers from insufficient accuracy, this paper proposes a GA-CNN hybrid model integrating genetic algorithm (GA) and convolutional neural network (CNN). Based on the data from a domestic heavy plate production line, a high-quality dataset is constructed through standardization, five-fold cross-validation for five times and data folding, and a two-stage optimization strategy is innovatively adopted. In the first stage, a CNN model is built to capture plate flatness distortion features; in the second stage, GA is introduced to adaptively optimize network structure and hyperparameters, improving the model prediction accuracy by 26.4%. The results show that the key indicators of the GA-CNN model are significantly better than models such as DNN and random forest, with its mean absolute error of 1.15 and root mean square error of 1.91. In addition, its accuracy on the training set and test set is the highest among other algorithmic models, reaching 94.73% and 93.06% respectively. This paper not only provides theoretical support for intelligent decision-making of straightening process parameters, but also promotes the paradigm transformation of plate and strip manufacturing from experience-driven to data-driven, and provides a reusable technical path for the intelligent manufacturing upgrading of the iron and steel industry.

To address the challenges of insufficient precision in the empirical design of controlled cooling process parameters for steel pipes and the difficulty in balancing high strength and high toughness, this paper proposes an intelligent method integrating machine learning and Bayesian multi-objective optimization. Firstly, Gaussian noise is utilized to augment the collected experimental data of controlled cooling parameters, mitigating the risk of overfitting caused by a limited sample size. Principal component analysis (PCA) is then applied to reduce the dimensionality of linearly redundant features, ensuring a cumulative variance contribution rate of 95%. A mechanical property prediction model for steel pipes is constructed based on the XGBoost algorithm. This model exhibits high-precision predictive capabilities, with a coefficient of determination of 0.96 and a mean absolute percentage error of less than 3% for key mechanical properties. To verify the accuracy of the prediction model, J55 oil casing pipe samples were trial-produced and subjected to tensile testing. The maximum relative error between the experimental mechanical property data and the model's predicted values is 3.14%. Subsequently, multiple sets of high-performance controlled cooling process parameters combinations were successfully identified through the Bayesian multi-objective optimization model. The tensile strength of the optimal solution reaches up to 927 MPa, and the mechanical property indicators of the optimization results all comply with the API SPEC 5CT standard. To examine the practical effectiveness of the Bayesian optimization algorithm, J55 oil casings were manufactured according to the optimized process parameters, and their mechanical properties were tested. The maximum relative error between the experimental results and the model's predicted values is 1.84%. The research results indicate that the proposed algorithm can achieve accurate prediction of steel pipe performance and efficient process optimization, providing a feasible solution for the intelligent manufacturing of steel pipes.

Skid marks are one of the main factors affecting the thickness quality of hot strip continuous rolling. Accurate tracking and determination of the skid mark position during the rolling process are great significance for strip quality control. Based on rolling theory, this paper proposes a method for position tracking and determination of skid marks in the finishing mill unit during hot strip continuous rolling. First, according to the distribution of skid mark positions on slabs of different lengths during heating in the reheating furnace, the start and end positions of each skid mark on the roughing-rolled transfer bar are calculated, and the positions are further determined using the temperature variation curve at the roughing rolling exit. Second, by matching and calibrating the actual length of the roughing-rolled transfer bar with the finished strip length after finishing rolling, the rolling elongation of each finishing stand is predicted, and the start and end positions of the skid marks on the strip exiting each stand are determined. Finally, based on the rolling characteristics of the strip at the skid mark positions in the finishing mill, the accuracy of the calculated skid mark positions from the second step is verified. Experimental results show that the proposed method validates the accuracy of the rolling length tracking in accordance with the actual rolling characteristic variation, and achieves satisfactory results.

Hydrogen energy, as an important strategic alternative to fossil fuels, utilizes curtailed wind and solar power in western China for water electrolysis to produce hydrogen. This not only significantly enhances energy economics but also strongly drives the transition of China′s energy mix toward renewables, providing crucial support for green and low-carbon development. Pipeline transportation is the optimal solution for large-scale, long-distance hydrogen delivery. This paper systematically reviews the construction progress of major hydrogen pipeline projects both domestically and internationally, summarizes research findings on hydrogen-induced material failure mechanisms and their influencing factors, analyzes pipeline protection optimization strategies, and offers an outlook on the future development trends of hydrogen transportation pipelines. The study indicates that China′s long-distance hydrogen pipelines still lag behind international advanced levels in engineering design experience and large-scale application. The existing theoretical framework for hydrogen embrittlement remains incomplete, and there is an urgent need to develop universal hydrogen damage mechanism models. Current research is hampered by laboratory limitations and data inconsistencies, which constrain engineering practice. At the same time, hydrogen embrittlement prevention and control technologies must overcome challenges in material innovation and compatibility with operating conditions. Studies show that the acicular ferrite microstructure exhibits excellent resistance to hydrogen embrittlement and can serve as a preferred matrix microstructure for pipeline materials. Future efforts should establish multi-factor coupled evaluation systems for operating conditions, verify the engineering reliability of gaseous inhibitors and hydrogen barrier coatings, and further improve the efficiency of long-distance hydrogen transportation. These technological breakthroughs are of great practical significance for enhancing the energy efficiency of hydrogen pipelines and supporting the achievement of the "dual carbon" goals.

Automobile steel not only requires lightweight body, but also requires good formability. Therefore, it is of great engineering significance to develop high strength and high formability automobile steel. Medium manganese steel is a typical representative of this kind of steel. In this paper, the effects of annealing temperature and holding time on the microstructure, mechanical properties and formability of cold rolled medium manganese steel were studied. The results show that under the two-phase zone direct annealing process, the microstructure of the experimental steel is mainly composed of ferrite, austenite and martensite. With the increase of annealing temperature, the yield strength decreases first and then increases, while the tensile strength increases. The elongation, strength-ductility product and residual austenite content increase first and then decrease. The content of favorable texture {111} and {110} increases with the increase of annealing temperature. The comprehensive properties of the experimental steel are the best when annealed at 630 ℃. The tensile strength is 1 144 MPa, the yield strength is 847 MPa, the elongation is 34.4%, the product of strength and elongation is 39.4 GPa·%, and the volume fraction of retained austenite is 23.68%. At the optimal annealing temperature of 630 ℃, with the increase of holding time, the average value of the cupping of the experimental steel increases first and then decreases, and reaches the maximum when the holding time is 15 min. The cold bending experiments with different bending angles and bending radius were carried out on the samples annealed at 630 ℃ for 15 min. The results show that the developed 1 000 MPa grade ultra-high strength automobile steel has no cracks during 0° cold bending and has excellent cold forming performance.

Optimizing the solution treatment process is crucial for enhancing the comprehensive properties of Fe-Mn-Al-C lightweight steels. In this work, the effect of solution treatment temperature on the microstructure and mechanical properties of an Fe-Mn-Al-C steel was systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and tensile testing. The results reveal that the microstructure of the Fe-15Mn-8Al-0.25C lightweight steel consists of a dual-phase austenite-ferrite structure at all solution treatment temperatures. As the solution temperature increases, the grain size first refines and then coarsens, decreasing from 16.1 μm to 13.1 μm and subsequently increasing to 21.3 μm, while the austenite volume fraction and the proportion of high-angle grain boundaries decrease to 31.7% and 34%, respectively. After solution treatment at 1 000 ℃, the experimental steel exhibits excellent mechanical properties with a low yield-to-tensile ratio and a high product of strength and elongation. The fine grain size, appropriate austenite-to-ferrite phase ratio, and moderate proportion of high-angle grain boundaries are the primary reasons for its superior performance. These findings provide a theoretical basis for the chemical composition design and process optimization of dual-phase lightweight steels.

Quenching is a heat treatment process for preparing ultra-high strength steel for construction machinery, but it introduces significant stress during the process, eventually forming residual stress that affects the service performance and lifespan of the material. In this paper, thermal simulation experiments, crack compliance method for residual stress characterization, and an independently developed phase transformation residual stress analysis software package were used to explore the influence of different cooling modes on the rolling direction stress ofplates during quenching. The results show that the phase transformation volume fraction in the first transformation zone is the key factor determining the residual stress level of the material after quenching. When the phase transformation in the second transformation zone begins, the phase transformation volume fration in the first transformation zone increases from 79% to 87%, the extreme difference of the rolling direction residual stress in the thickness direction of the material increases from 538.7 MPa to 669.4 MPa. By intervening in the cooling mode to regulate this parameter, low-stress and high-performance high-strength steel for construction mechinery can be obtained.

In this paper, the effects of the addition of Cu element on the microstructure, mechanical properties and corrosion resistance of a high-Mn cryogenic steel were investigated with the use of metallographic, transmission electron microscope (TEM), tensile, Charpy impact and electrochemical corrosion tests. The purpose of this paper is to systematically explore the effect laws and mechanisms of Cu addition on the microstructure and properties of high-Mn cryogenic steel and to establish a quantitative correlation between composition, microstructure and properties, which can provide theoretical support for the development of a new generation of high-Mn cryogenic steel with high strength, good toughness and excellent corrosion resistance. It is observed that the addition of Cu element leads to a significant increase in the yield strength of the experimental steel and the related strengthening mechanism is solution strengthening. The deformation twinning is found to be suppressed due to the addition of Cu element, which results in the decrease in the total elongation and impact toughness of the experimental steel. A protective oxide film can be formed on the surface of the experimental steel by Cu element, contributing to the improvement in the corrosion resistance of the experimental steel. The high-Mn cryogenic steel with more excellent comprehensive properties can be obtained by the addition of 0.5% mass fraction of Cu element.

In recent years, the demand for high-strength and high-toughness petroleum casing pipes has been growing continuously in the drilling and exploitation of deep and ultra-deep wells. In this study, a high-strength and high-toughness petroleum casing steel was employed as the research material. The influences of soaking temperature and soaking time during heat treatment on the original austenite grain growth behavior were systematically investigated. The effect of original austenite grain size on the strength and toughness of the experimental steel was characterized using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results indicate that within the temperature range of 780-820 ℃, the original austenite grain size increases with the increase of soaking temperature and the prolongation of soaking time. The original austenite grain size has a significant influence on the microstructure after quenching and tempering. A finer original austenite microstructure eventually transforms into finer martensitic laths, accompanied by a higher proportion of high-angle grain boundaries in the microstructure, thereby contributing to better strength and toughness. A kinetic model of austenite grain growth for the experimental steel was obtained through linear regression analysis of the experimental data. The results and conclusions of this study can provide a theoretical foundation for the formulation and parameter optimization of the heat treatment process for high-toughness petroleum casing steel.

In this study, hydrogen microprinting was employed to characterize the distribution of hydrogen in the Q500 experimental steel. Slow strain rate tensile (SSRT) tests were also conducted at various strain rates on the hydrogen-charged steel to examine fracture morphology and crack propagation behavior, aiming to clarify the influence of strain rate on hydrogen-induced crack nucleation and growth. The results show that hydrogen atoms preferentially segregated at M/A islands and their boundaries, at inclusion-matrix interfaces, and at various grain boundaries, including prior austenite grain boundaries, interfaces between granular and lath bainitic ferrite, as well as packet and lath boundaries. After hydrogen charging, with decreasing strain rate, the yield strength, tensile strength, and elongation all decreased, whereas the hydrogen embrittlement index increased correspondingly. The microscopic fracture morphology at the tensile specimen edge gradually transitioned from dimples to river-like patterns. Meanwhile, the number of crack initiation sites increased, and the initiation locations shifted from M/A island boundaries (or M/A island boundaries plus packet boundaries) to M/A island boundaries and lath boundaries. Furthermore, the dominant crack propagation mode gradually changed from intergranular to transgranular fracture.

To address the synergistic control challenge of pickling efficiency and surface quality of hot rolled strip, this study selects three typical steel grades i.e.low carbon aluminum killed steel, carbon manganese steel, and cold rolled high strength steel,and systematically investigates the correlation between the oxide scale structure on the strip surface and its pickling behavior. The results indicate that the oxide scale on low carbon aluminum killed steel is primarily composed of a loose and cracked eutectoid structure (Fe+Fe₃O₄), which can be efficiently removed within 60 s, yielding a bright and defectfree surface. In contrast, the oxide scale on carbon manganese steel mainly consists of dense proeutectoid Fe₃O₄, requiring 180 s for complete pickling, and tends to leave residual scale that causes surface darkening. For cold rolled high strength steel, slow cooling leads to the precipitation of Fe particles and the formation of a 15 μm thickness intergranular oxidation layer, extending the pickling time to 400 s. This is attributed to the Fe particles hindering acid penetration and the intergranular oxidation accelerating grain boundary corrosion, while residual Cl^- may induce surface yellowing. The findings clarify the critical influence of oxide scale structural differences on pickling kinetics, providing a theoretical basis for developing differentiated pickling processes.

Tempering is an important method for controlling residual stress in metallic materials. Previous studies have found that carbide precipitation is the main mechanism of residual stress relaxation during the tempering process. However, quantitative investigations on the effect of carbide precipitation on residual stress relaxation capability are rarely reported. In this study, a combined approach integrating tempering behavior investigation, finite element simulation, and crack compliance residual stress measurement were adopted to reveal the effects of alloy carbide precipitation on stress relaxation and flatness of 700L steel plates, and to predict the evolution of residual stress during the tempering process. The results show that the tempering-induced precipitation of alloy carbides reduces the residual stress on the plate surface from 287 MPa to 95 MPa, and the core residual stress from -189 MPa to -65 MPa (the negative sign indicates compressive stress), with the degree of residual stress relaxation reaching 66.8% and 65.6%, respectively. Simultaneously, the precipitation of alloy carbides significantly contributes to controlling the non-uniform distribution of residual stress:the residual stress difference between the mid-width and edge regions of the plate surface is reduced from 145 MPa to 19 MPa, which lowers the risk of flatness shape defects. Furthermore, following tempering-induced alloy carbide precipitation, the warpage of the 700L plate is reduced from (5±0.7)mm to (2±0.3)mm, demonstrating a marked improvement in flatness.

Multi-pass hot compression tests were conducted on medium carbon steel using a Gleeble-3500 thermal simulation testing machine at a strain rate of 20 s^-1, aiming to simulate its warm rolling process in the warm deformation region of 650-730 ℃. Scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) were employed to systematically investigate the effects of different deformation temperatures, compression amounts, and warm rolling temperatures on the microstructural evolution of ferrite and cementite in the tested steel. The results show that a decrease in warm deformation temperature is conducive to the equiaxed distribution of ferrite grains, while the cementite morphology tends to be spherical and granular. At a warm deformation temperature of 650 ℃, with the increase in compression amount, the spheroidization degree of cementite intensifies, and it aggregates and distributes at the ferrite grain boundaries. Furthermore, as the warm rolling temperature decreases, the cementite morphology transforms from an alternating lamellar and chain-like distribution to a chain-like and discontinuous distribution. Meanwhile, this leads to the average grain size of ferrite reaching the ultrafine-grained ferrite level (0.45 μm), which is mainly related to the high-density dislocations introduced by the decrease in warm rolling temperature.

MnS inclusions significantly affect the microstructure homogeneity and abnormal grain growth behavior during annealing of Mn-Cr high-quality gear steels. This study investigated the effect of manganese-to-sulfur ratio on the number, size, and aspect ratio of MnS inclusions in hot-rolled bars of 20MnCr5 gear steel. Inclusion analysis results showed that increasing the manganese-to-sulfur ratio w(Mn)/w(S) significantly improved the morphology of MnS inclusions, reduced their size and aspect ratio, and increased the number density. In low manganese-to-sulfur ratio steel MS54 (w(Mn)/w(S)=54), the number density of MnS inclusions per unit area was 152.5, accounting for 77.4% of all types of inclusions, among which sub-micron inclusions accounted for 26.7%, and inclusions smaller than 5 μm accounted for 92.1%. In high manganese-to-sulfur ratio steel MS103 (w(Mn)/w(S)=103), the number density of MnS inclusions per unit area increased to 211.3, accounting for 86.4% of all types of inclusions, among which sub-micron inclusions accounted for 32.7%, and inclusions smaller than 5 μm accounted for 96.2%. The particle size distribution was fitted with Gaussian and Boltzmann curves. In MS54 steel, the average and median values of inclusion size were (1.64±0.06) μm and 1.36 μm, respectively, while in MS103 steel, the average and median values of inclusion size were (0.73±0.03) μm and 1.01 μm, respectively. In MS54 steel, 20.6% of inclusions had an aspect ratio of 1-2, and 63.6% of inclusions had an aspect ratio below 5. In MS103 steel, 50.3% of inclusions had an aspect ratio of 1-2, and 76.3% of inclusions had an aspect ratio below 5. The research results provide a scientific basis for elucidating the abnormal grain growth behavior during annealing of Mn-Cr high-quality gear steels.

To explore the heat treatment process of Alloy 28, the effects of different heat treatment temperatures and holding times on its microstructure and tensile properties were studied. The results show that Alloy 28 underwent complete recrystallization after heat treatment, forming equiaxed grains. With the increase in heat treatment temperature, the growth rate of the average grain size exhibited a trend of initially slow and then fast, with the apparent activation energy for grain boundary migration being 248.75 kJ/mol at a holding time of 10 min. As the holding time continued to increase, the average grain size of the alloy gradually increases, following a parabolic growth pattern. Meanwhile, the kinetic time exponent η showed a trend of initially remaining stable, then increasing, and finally stabilizing again with the rise in temperature. The tensile strength of Alloy 28 displayed a trend of initially slow and then rapid decline with increasing temperature, while the reduction in tensile strength with prolonged holding time exhibited a trend of initially fast and then slow. The yield strength of Alloy 28 showed a trend of initially slow and then rapid decline with temperature, and its relationship with the average grain size conformed to the Hall-Petch equation.

The three-roll skew rolling process is an excellent method for fabricating bimetallic composite pipes, offering advantages such as low energy consumption and high interfacial bonding strength after rolling. Prior to rolling, the ends of the pipe billets must be seal-welded to prevent oxidation of the mating metal surfaces and to ensure interfacial bonding performance. Experimental results indicate that the quality of end-sealing welds significantly affects the bonding strength and yield rate of the rolled composite pipes. Based on this observation, this study integrates mechanical performance testing and microstructural characterization to investigate the effects of different welding qualities on deformation compatibility during rolling, interfacial bonding performance after rolling, and the metallurgical bonding length. The results show that pipe billets with high-quality welds can effectively coordinate the deformation of the inner and outer metallic components during the composite rolling process, while also preventing oxidation of the mating metal surfaces. Consequently, a uniformly distributed, high-strength metallurgical bond is formed at the carbon steel/stainless steel interface in the rolled composite pipes. These findings highlight that superior end-sealing weld quality is crucial for the efficient fabrication of bimetallic composite pipes.

Aiming at the problems such as high cost and poor surface quality of traditional hot-rolled dual-phase steel, this article takes a experimental steel with low silicon content composition system as the object, and based on the production line of rlot strip Rolling Mill of Angang Co., Ltd., process characteristics of the ultra-fast cooling system in the continuous rolling production line of Hot Strip Rolling Mill of Angang Co., Ltd., a 600 MPa grade hot-rolled dual phase steel with low cost and high surface quality was developed. Through the matching design of chemical composition and hot rolling process, the developed 600 MPa grade hot-rolled duplex steel has a typical dual-phase microstructure, with a ferrite volume percentage of about 85% and a ferrite grain size of about 6.0 μ m; The yield strength of the strip is 360-390 MPa, the tensile strength reaches 600-630 MPa, the yield strength ratio is 0.57-0.63, and the elongation is greater than 27%. The developed strip have excellent mechanical properties, good surface quality, and low cost, meeting the manufacturing requirements of automotive wheels and other components.

Aiming at the defects such as edge cracking and voids readily occurring during hot rolling of high-carbon martensitic stainless steel 70Cr13Mo, the chemical compositions of molten steel from four batches of 70Cr13Mo and the hot-rolling production process were investigated. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and other testing methods were adopted to analyze the macrostructure of continuous-casting slabs, the microstructure of defect specimens, and carbide distribution. The results show that the aging of water-sealing equipment at the entry and exit of the roughing mill and cooling-water leakage lead to an increased cooling rate and sharp rise in strength at the strip edge. Meanwhile, massive premature precipitation of secondary carbides along grain boundaries significantly reduces the matrix plasticity, which serves as the primary cause for edge cracking of hot-rolled strips. In addition, a large number of (Ti,V)N and its composite inclusions formed in the microstructure tend to act as crack initiation sites, constituting another major factor for defect generation. By adopting rectification measures including strict control over the working condition of roughing-mill water-sealing equipment, optimization of raw-material proportioning, and stringent restriction of titanium-containing scrap steel charged into the furnace for smelting, the occurrence rate of hot-rolling defects has been successfully reduced to zero. This study effectively improves the finished-product yield of 70Cr13Mo steel, and provides theoretical basis and practical guidance for the prevention and control of hot-rolling defects of high-carbon martensitic stainless steel.

In the wet temper rolling process of a double-stand mill, insufficient control of process lubrication may induce strip flatness defects, such as edge waves, center waves, and compound waves. Considering the equipment configuration of the double-stand temper mill and the process characteristics of wet temper rolling, this study established calculation models for entry and exit tensions and analyzed the influence of wet temper lubrication parameters on exit strip flatness. By introducing the heat transfer coefficient during wet temper rolling as an intermediate variable, the relationship between process lubrication parameters and the friction coefficient was established, and influence functions of temper fluid concentration, temperature, and flow rate on strip flatness were developed. In combination with actual production conditions, the investigated ranges of key process lubrication parameters were determined. With the objective of minimizing finished strip flatness fluctuation while ensuring stable mill operation, the concentration, temperature, and flow rate of the temper fluid were comprehensively adjusted, and a process lubrication optimization technology suitable for double-stand wet temper rolling was developed to improve finished strip flatness control. The proposed technology was applied to the actual production of typical steel grades and specifications on a domestic double-stand wet temper mill. The flatness value of the strip at the temper mill exit decreased from 13.2 IU before optimization to 6.5 IU after optimization, demonstrating an effective improvement in the flatness control capability of the double-stand wet temper mill.

In response to the many problems of environmental protection failure, unstable pickling quality, excessive acid consumption and low automation in traditional steel pipe pickling production lines, new dentate disc steel pipe pickling production line with high efficiency, environmental protection and high automation are designed and developed. The production line adopts a modular design concept. By optimizing the pickling process, developing automation equipment, and introducing advanced environmental protection technologies, it can realize the pickling of steel pipes or profiles of different specifications and materials, and realize the automation, efficiency and greening of the pickling process. The production line has little investment, simple operation, low risk, high economic and environmental benefits, and high market promotion value.