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To measure textures of hot rolled martensitic and bainitic steels, electron backscatter diffraction (EBSD) is applied to large areas, each covering about a thousand of prior grains. A scanning step is selected to keep reasonable time of the data acquisition still providing in any grain a significant number of analyzed points. Contributions to the transformation texture appearing from deformation and recrystallization components of the parent texture are estimated with the Bain relationship. To assess the parent austenite state, their proportion is then expressed by a scalar parameter. The results are verified by independent metallographic data. Avoiding the reconstruction of prior grains, this statistical approach will facilitate evaluation of complex austenite structures with comparable fractions of dissimilar material states. [ABSTRACT FROM AUTHOR]

In the field of hot rolling big data, the presence of different steel types, specifications, and data heterogeneity poses significant challenges to the accuracy and stability of using single machine learning regression technology for prediction. Therefore, this study proposes a hot‐rolled strip crown prediction method that combines data clustering and fusion modeling. First, this article introduces a relevant mechanism for designing cluster strategies. The optimal clustering strategy is determined through comparative experiments using rolling process parameters, strip size, and main material components as the clustering features. Subsequently, the K‐Means++ algorithm is used to effectively cluster the training and testing datasets based on this strategy, generating multiple clusters for both datasets. Finally, this study establishes seven different training models to match the most suitable regression prediction model for each cluster, and matching between each cluster and the model is determined through rigorous testing. The evaluation of the fusion model shows an R2 value of 0.829 and a root mean square error value of 3.974. The experimental results show that the proposed method outperforms traditional methods in solving the challenges of multiclass classification and data heterogeneity, providing strong data support for the intelligent control of the hot‐rolled strip crown in the future. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to study the formation mechanism of micro-arc oxidation (MAO) coating on AZ31 magnesium alloy and how the annealing process affects its corrosion resistance. Design/methodology/approach: This study involved immersion experiments, electrochemical experiments and slow strain rate tensile experiments, along with scanning electron microscopy, optical microscopy observation and X-ray diffraction analysis. Findings: The findings suggest that annealing treatment can refine the grain size of AZ31 magnesium alloy to an average of 6.9 µm at 300°C. The change in grain size leads to a change in conductivity, which affects the performance of MAO coatings. The MAO coating obtained by annealing the substrate at 300°C has smaller pores and porosity, resulting in better adhesion and wear resistance. Originality/value: The coating acts as a barrier to prevent corrosive substances from entering the substrate. However, the smaller pores and porosity reduce the channels for the corrosive solution to pass through the coating. When the coating cracks or falls off, the corrosive medium and substrate come into direct contact. Smaller and uniform grains have better corrosion resistance. [ABSTRACT FROM AUTHOR]

The objective of the present investigation is to synthesise and characterise the Cu-Al-Ag shape memory alloys with minor Mn addition. Synthesis of Cu-Al-Ag-Mn SMA was done by induction furnace and gravity die casting, with constant Ag/Mn ratio (5% Ag and 2% Mn), the aluminium composition is varied from 8% to 14%. The as-cast sample will be further subjected to thermo-mechanical treatment to produce a sheet which exhibits shape memory effect. This study is to determine the influence of Al content on shape memory characteristics, microstructure, and phase transformation temperatures. The phase fraction of β'1 increased from 56% to 67% along with subsequent reduction of γ1' phase fraction from 23% to 17%, which is essential for improvement of shape memory properties with increase of aluminium constituent. X-ray diffraction revealed that the crystalline size decreased 79 to 32 nm and lattice strains increased from 0.24% to 0.69% with increase of Aluminium. With an increase in aluminium content, the martensite transformation temperature decreased from 386°C to 246°C, and the shape memory effect increased from 81 to 90% strain recovery. The ability to control shape memory characteristics by changing Al composition will improve the scope for this alloy in various shape memory applications. [ABSTRACT FROM AUTHOR]

This paper utilizes the plasma arc as the heat source to successfully fabricate well-formed thin-walled parts using combined cable wire duplex stainless steel 2209. Microstructure of parts exhibited the favorable two-phase ratio and the absence of σ-phase. It was found that appropriate heat input (1.68 kJ/cm) and cooling rate (5 °C/s) can effectively avoid the precipitation of σ-phase. Furthermore, the properties of the as-deposited samples were comparable to those of the samples heat-treated at 1300 °C, proving that no subsequent heat treatment was required for 2209 stainless steel fabricated by plasma arc additive manufacture. The samples showed excellent properties, in which the ultimate tensile strength and yield strength were improved by about 7% and 24% compared with GB/T4237-2015. The impact toughness meets the requirements of EN10028-7-2016, which is about 35% higher than that of the cold metal transfer samples, and the corrosion resistance is comparable to that of hot rolled 2205. [ABSTRACT FROM AUTHOR]

The surface quality of steel strip is a critical indicator of the quality of hot‐rolled strip, so accurate inspection of its surface is essential. However, the complex texture of steel strip surface defects makes the detection challenging. Here, a multi‐scale feature fusion and attention based YOLOv5 (MFFA‐YOLOv5) model is proposed. Specifically, the bottom layer features are up‐sampled and fused not only with the middle layer features, but also with the top layer features, so that the model better captures the surface texture information of the steel strip. Secondly, an improved attention mechanism module is introduced to deal with the global and local information of the steel strip surface by introducing down‐sampling and up‐sampling paths based on Convolutional Block Attention Module (CBAM). Meanwhile, a self‐attention mechanism path is added to improve the capability of feature representation. Experimental results on the NEU‐DET dataset show that the MFFA‐YOLOv5 model significantly outperforms other state‐of‐the‐art methods. [ABSTRACT FROM AUTHOR]

This paper considers the steel reheating process, in which cold slabs are reheated to a temperature suitable for hot rolling operations. Temperature uniformity within the slab is very important during reheating, as non-uniformities often lead to quality concerns in the later stages of the production process. Attaining slab temperature uniformity is quite challenging, therefore, a thorough understanding of the reheating process becomes very important. Due to the extreme conditions inside the furnace, numerical tools like computational fluid dynamics are necessary for such situations. However, when applied to these complex installations, it often leads to very lengthy computational times. This paper develops a computationally efficient transient model to simulate the environment around a slab. This Truncated Transient Slab Model is a coupled model: it uses the temperature and flow profiles from a full-scale steady-state simulation and imposes those on a smaller domain that represents the immediate environment around the slab. The efficiency of the model is compared to the state of the art. With the simulations available in the literature, it was found that the proposed model can simulate a furnace seven times larger (grid size), with much higher grid and time resolutions, using only a third of the computational resources. [ABSTRACT FROM AUTHOR]

Developing low magnetic stainless-steel plates with high yield strength while ensuring good plasticity, corrosion resistance, and paramagnetism is a tough technical challenge, especially under conditions of limited rolling mill capacity and total reduction. In this study, a low magnetic stainless-steel plate with excellent yield strength (620 MPa), ultimate tensile strength (891 MPa), and ductility (42.7%) was prepared by rolling in the non-recrystallization region (below the recrystallization temperature Tnr) and subsequent solution treatment. The effects of different thermomechanical processing techniques on the recrystallization behavior, grain size, dislocation density, grain boundary characteristics, micro-texture, mechanical and magnetic properties of low magnetic stainless steel were studied. Compared with conventional high-temperature hot rolling, rolling in the non-recrystallization region and subsequent solid solution treatment can effectively refine the grain size and form Brass {001} < 211 > texture in the plate, with texture intensity increasing with greater deformation in this region. The main strengthening contribution mechanisms of high yield strength are N-element solid solution strengthening and fine grain strengthening. Due to the high austenite stability and appropriate rolling temperature, the paramagnetism of low magnetic stainless steel was not disrupted after rolling in the non-recrystallization region, and the relative permeability of all samples was less than 1.01. From the perspectives of production efficiency, process difficulty, and economy, the HR3-S process route in this study makes it easier to achieve large-scale industrialization, providing theoretical and process references for developing low magnetic stainless-steel plates toward high yield strength and high paramagnetic stability. [ABSTRACT FROM AUTHOR]

The cooling process of a hot rolled strip on the run-out table (ROT) mainly determines the microstructure and mechanical properties of the final product; therefore, a method of investigation that helps companies follow the optimum cooling scenario is a profound issue. This paper develops a 2D finite element model based on industrial data that predicts the cooling pattern of hot rolled strips, with the potential to be formulated for steel grades dealing with complex boundary conditions, flexible to be applied for any cooling table. Meanwhile, this model investigates the thermal behavior of strips facing different heat transfer mechanisms in the full-scale ROT of Mobarakeh Steel Company (MSC). Moreover, coiling temperature (CT) and cooling pattern are validated through experimental data obtained from the Evraz hot rolling mill. Regarding the simulation of various header configurations, each four-header bottom bank, upper laminar, and water curtain headers deliver 10 ∘ C / s , 10.66 ∘ C / s , and 7.85 ∘ C / s of cooling rate, respectively. The simulations also predict the heat flux in the impingement, parallel, and air-cooling zones to be in the range of 4000–12,000, 500–2500, and 80–400 (w / m 2 K) on the top surface, and 21,000–5400, 700–4200, and 380–170 (w / m 2 K) on the bottom surface, respectively. According to the temperature-dependent attitude of steel properties, the effect of strip's thermo-physical properties on the heat transfer along ROT was examined, illustrating the significant impact of specific heat on cooling, which leads to the endorsement of the functionality of early cooling compared to delayed and distributed strategies for the investigated HSLA (high-strength low-alloy) steel. [ABSTRACT FROM AUTHOR]

To investigate the interconnected effects of manufacturing processes on microstructure evolution during hot-rolling, a through process model is required. A novel numerical implementation of the mean-field approach was introduced to efficiently describe the grain growth of larger systems and extended durations. In this approach, each grain is embedded within an average medium and interacts with the average medium, thus avoiding the complexities of individual grain interactions. The proposed upsampling approach dynamically adjusts the simulation grain ensemble, ensuring efficiency and accuracy regardless of the initial number of grains present. This adaptation prevents undersampling artifacts during grain growth. The accuracy of the model is verified against analytical solutions and experimental data, demonstrating high agreement. Moreover, the effects of different initial conditions are successfully investigated, demonstrating the model's versatility. Due to its simplicity and efficiency, the model can be seamlessly integrated into other microstructure evolution models. [ABSTRACT FROM AUTHOR]

We developed and analyzed a novel non-sparking material based on CuAlBe for applications in potentially explosive environments. Using a master alloy of CuBe, an established material for anti-sparking tools used in oil fields, mines, or areas with potentially explosive gas accumulations, and pure Al, we used an Ar atmosphere induction furnace to obtain an alloy with ~10 wt% Al and ~2 wt% Be percentages and good chemical and structural homogeneity. The new material was tested in an explosive gaseous mixture (10% H2 or 6.5% CH4) under extremely strong wear for 16,000 cycles, and no hot sparks capable of igniting the environment were produced. The material was used in the form of hot-rolled plates obtained from melted ingots. The experimental results reflect the use of a suitable material for non-sparking tools. This material has good deformability during hot rolling, abnormal grain growth during deformation under heat treatment and special thermo-mechanical processing, and no high chemical composition variation. Additionally, there are slightly different corrosion resistance and mechanical properties between the melt and hot-rolled state of CuAlBe material. Through hot rolling, the material's corrosion resistance increased, reducing the chances of generating sparks capable of causing explosions. [ABSTRACT FROM AUTHOR]

Magnesium (Mg)-matrix composites have excellent damping and electromagnetic shielding properties. However, the mismatch between their strength and toughness limits their wide application. The aim of this work is to overcome the strength-toughness mismatch by constructing micro- and nanostructures while maintaining the good functional properties of Mg-matrix composites. Electrophoretic deposition (EPD) was used to spread carbon nanotubes (CNTs) out evenly on a Mg foil matrix. After spark plasma sintering (SPS), the grain organisation was refined, and the interlayer bonding was strengthened by hot rolling deformation. Finally, the microstructure, mechanical properties, damping properties, and electromagnetic shielding properties of the composites were analysed. Compared with the pure Mg laminates, the tensile strength and elongation of the CNT/Mg laminates were increased by 6.4% and 108.4%, respectively, with the significant improvement in toughness resulting from the increase in energy required for crack propagation due to the laminate structure. When the total rolling deflection reaches 80%, the interlayer bond strength of the material is significantly increased, the grain is further refined, and the strength and elongation of the composite material reaches the optimum, with the tensile strength reaching 241.70 MPa and the elongation reaching 6.90%. The interlayer interface and grain refinement also affected the damping Mg and electromagnetic shielding effect of the composites. This work provides an experimental idea for the preparation of high-performance structure-function integrated Mg-based materials. [ABSTRACT FROM AUTHOR]

Structural rolled steels are the primary products of modern ferrous metallurgy. Consequently, enhancing the mechanical properties of rolled steel using energy-saving processing routes without furnace heating for additional heat treatment is advisable. This study compared the effect on the mechanical properties of structural steel for different processing routes, like conventional hot rolling, normalizing rolling, thermo-mechanically controlled processing (TMCP), and TMCP with accelerating cooling (AC) to 550 °C or 460 °C. The material studied was a 20 mm-thick sheet of S355N grade (EN 10025) made of low-carbon (V+Nb+Al)-micro-alloyed steel. The research methodology included standard mechanical testing and microstructure characterization using optical microscopy, scanning and transmission electronic microscopies, energy dispersive X-ray spectrometry, and X-ray diffraction. It was found that using different processing routes could increase the mechanical properties of the steel sheets from S355N to S550QL1 grade without additional heat treatment costs. TMCP followed by AC to 550 °C ensured the best combination of strength and cold-temperature resistance due to formation of a quasi-polygonal/acicular ferrite structure with minor fractions of dispersed pearlite and martensite/austenite islands. The contribution of different structural factors to the yield tensile strength and ductile–brittle transition temperature of steel was analyzed using theoretical calculations. The calculated results complied well with the experimental data. The effectiveness of the cost-saving processing routes which may bring definite economic benefits is concluded. [ABSTRACT FROM AUTHOR]

Herein, the microstructure, low‐temperature toughness, and fracture characteristics of high‐strength low‐alloy (HSLA) steel prepared by various thermomechanical control processes are systematically studied. Three different reheating/rolling temperatures are designed to obtain microstructures with different prior austenite grain sizes: 20.12 μm (S810), 27.58 μm (S910), and 35.19 μm (S1010). After hot rolling, S810 steel with smaller prior austenite grain size can provide high‐density deformed grain boundaries that promote ferrite phase transformation. The S910 and S1010 steels predominantly undergo bainite transformation as the prior austenite grain size and rolling temperature increase. Also, excellent low‐temperature toughness is obtained by reducing the reheating/rolling temperature (i.e., S810 steel), reflecting that Charpy impact energy of the core of the steel plate is 118.53 J at −120 °C. High performances is mainly attributed to the higher ferrite content, grain refinement, lower dislocation density, and higher proportion of high‐angle grain boundaries. Furthermore, fracture morphology analysis demonstrates that the S810 steel exhibits ductile fracture and noticeable plastic deformation at −120 °C, while S910 and S1010 steels exhibit brittle fracture and rapid crack propagation. These findings manifest the applicability of the suggested technique in preparing HSLA steel with excellent low‐temperature toughness. [ABSTRACT FROM AUTHOR]

The hot‐rolled sheets of low‐grade electrical steels undergo complete austenite‐ferrite phase transformation, resulting in fine equiaxed grains in the sheets. These fine initial grains eventually lead to a strong detrimental {111} texture in the final product after cold‐rolling and annealing process. This work, based on the phase transformation delay of columnar grain structure in cast slabs, proposes a novel approach called metastable ferrite hot rolling, namely, a two‐stage heating at 900 °C and then at 1100 °C shortly and hot rolling, to avoid complete transformation and to retain original {100} oriented regions. In addition, low‐temperature annealing is employed to increase grain sizes of hot‐rolled sheets thereby improving the final texture and magnetic properties after cold‐rolling and annealing. The results indicate that metastable ferritic columnar grains can be maintained during the two‐stage heating process at 1100 °C and primarily undergoes subgrain growth. The transformation from ferrite to austenite at 1100 °C is very slow. During the hot rolling with a high 86% reduction by two passes, the notable grain refinement is mainly caused by dynamic recrystallization rather than dynamic phase transformation as evidenced by the observation from the rolling plane. [ABSTRACT FROM AUTHOR]

Low‐carbon martensitic steel is the key material of automobile lightweight. Unfortunately, the strategies for increasing the material strength, such as processing to create line defects (dislocations), tend to decrease the ductility. Herein, a strategy to circumvent this problem in an inexpensive, microalloy low‐carbon (0.32%) martensitic steel by regulating the accelerated cooling stop temperature after hot rolling is developed. Steel with fine austenite grains embedded in a highly dislocated martensite matrix is developed by cold rolling followed by saltwater quenching and low‐temperature tempering. This deformed process produces dislocation hardening, but retains high ductility both through the glide of intensive mobile dislocations. The proposed strategy provides a pathway for the development of high‐strength, high‐ductility materials. [ABSTRACT FROM AUTHOR]

The productivity and capacity release of hot-strip rolling is severely limited by pendular vibration. Previous studies on mill vibration have investigated the influence of rolling parameters on vertical vibration; however, the influence of dynamic stiffness compensation factors on vertical vibration has not yet been considered owing to the limitations of modelling methods. Herein, we develop a simulation model of mill liquid-machine coupling with dynamic stiffness compensation using AMESim software. The established simulation model is used to investigate the effect of this dynamic stiffness compensation on mill vertical vibration under conditions of downfeed thickness difference excitation frequency, thickness difference excitation amplitude, thickness difference excitation phase, and dynamic stiffness compensation signal generation hysteresis. Evidently, the impact of the mill stiffness compensation on the mill vertical vibration differs with the thickness of the excitation frequency, and the impact should be discussed according to the excitation frequency segment. The amplitudes of the roll system vibration and incoming thickness difference excitation are essentially linear, whereas the excitation phase does not affect the frequency or amplitude of the mill vibration. The rolling machine stiffness compensation signal hysteresis also has a significant impact on the mill vibration amplitude. Our findings will improve the mechanism of the hot rolling process and suppress droop vibrations. [ABSTRACT FROM AUTHOR]

Steel slabs are key in-process products in the steel production process. The slab allocation problem is to allocate slabs to suitable orders by considering complicated technical restrictions and multiple management requirements. In practice, thousands of slabs in multiple production lines should be allocated to orders. Due to the complexity and large scale of the problem, it takes planners a long time to make decisions, and the obtained allocation schemes are usually ineffective because of the myopic nature of the rule-based methods. In this article, we present a learning-based solution method for solving a practical slab allocation problem in multiple hot rolling lines. We formulate the problem as an integer programming model, then a data-based method is adopted to evaluate the mismatching cost between slabs and orders. To effectively solve the large-sized problem, a learning-based decomposition strategy is proposed to decompose the original problem into several small-sized subproblems. Then, a branch-and-price algorithm is proposed to optimally solve the subproblems. To further speed up the solution process, a primal heuristics based on column generation is designed to solve the large-sized subproblems. The solution methods have been implemented in a steel company and effectively increased slab utilization and reduced production cost. [ABSTRACT FROM AUTHOR]

At the initial rolling temperature of 400 °C, ZK60 magnesium alloy was hot rolled by three different rolling paths with different roll speed ratios (RSR) of 1:1.15, 1:1.2, and 1:1.5, respectively. The effects of different rolling processes on the microstructure and mechanical properties of the alloy were studied. The microstructure, plasticity, strength, hardness, and texture intensity of rolled samples were analyzed in this work. The results show that the microstructure uniformity of the alloy under multi-path asynchronous rolling (MAR) is significantly improved, which improves the mechanical properties of the material to a certain extent, and effectively weakens the texture intensity of the basal plane and reduces the anisotropy. The amount of randomly oriented grains of ZK60 magnesium alloy rolled by the C-1.5 (path C combined with the RSR of 1:1.5) process are significantly increased, which significantly weakens the basal texture and improves the ductility of the alloy, greatly enhancing the processing and formability of ZK60 magnesium alloy. [ABSTRACT FROM AUTHOR]

Sulfide stress cracking (SSC) failure is a main concern for the pressure vessel steel Q345 used in harsh sour oil and gas environments containing hydrogen sulfide (H2S). Methods used to improve the strength of steel usually decrease their SSC resistance. In this work, a quenching and tempering (Q&T) processing method is proposed to provide higher strength combined with better SSC resistance for hot-rolled Q345 pressure vessel steel. Compared to the initial hot-rolled plates having a yield strength (YS) of ~372 MPa, the Q&T counterparts had a YS of ~463 MPa, achieving a remarkable improvement in the strength level. Meanwhile, there was a resulting SSC failure in the initial hot-rolled plates, which was not present in the Q&T counterparts. The SSC failure was not only determined by the strength. The carbon-rich zone, residual stress, and sensitive hardness in the banded structure largely determined the susceptibility to SSC failure. The mechanism of the property amelioration might be ascribed to microstructural modification by the Q&T processing. This work provides an approach to develop improved strength grades of SSC-resistant pressure vessel steels. [ABSTRACT FROM AUTHOR]

After hot rolling, 304 austenitic stainless steel requires a solution annealing treatment to prevent intergranular corrosion and eliminate work hardening effects. Compared to traditional offline processes, on‐line solution annealing offers advantages in terms of cost and time savings. However, both recrystallization behavior and M23C6 carbide precipitation behavior are significantly influenced by the cooling process after rolling, which poses conflicting requirements. This study investigates the precipitation behavior of M23C6 carbides and the recrystallization softening behavior during the continuous cooling process of hot‐rolled samples. The kinetics equations are derived using the Scheil's additivity rule. The temperature profiles in different regions of the plate are studied using finite element analysis. A practical approach for online solution annealing is proposed and applied in industrial testing. [ABSTRACT FROM AUTHOR]

To avoid cracks during hot rolling, a short process of direct cold rolling following solution treatment of the casting billet for preparing lean duplex stainless steel plates is proposed. The effect of cold rolling reduction on the microstructure, texture, and mechanical properties of UNS S32101 is investigated. The results show that dislocation slip is the main character in ferrite, which leads to dislocation tangles, dislocation cells, high‐density dislocation walls, and deformed microbands. However, twinning and strain‐induced martensite transformation (SIMT) occur in austenite, and the SIMT mechanism of austenite follows the classical model γ → ε → α′ and γ → α′, with the orientation relationship of Kurdjumov–Sachs ({111}γ || {0001}ε || {110}α′$\left(\text{{111}}\right)_{\gamma} \text{ || } \left(\left{\right. 0001 \left.\right}\right)_{\epsilon} \left(\text{ || {110}}\right)_{\text{&amp;amp;amp;amp;amp;amp;amp;alpha;&amp;amp;amp;amp;amp;amp;amp;aposx;}}$ and <101¯>γ || <112¯0>ε || <11¯1>α′$\text{&amp;amp;amp;amp;amp;amp;lt;10} \overset{\cdot}{1} \left(\text{&amp;amp;amp;amp;amp;amp;gt;}\right)_{\gamma} \text{ || &amp;amp;amp;amp;amp;amp;lt;11} \overset{\cdot}{2} \left(\text{0&amp;amp;amp;amp;amp;amp;gt;}\right)_{\epsilon} \text{ || &amp;amp;amp;amp;amp;amp;lt;1} \overset{\cdot}{1} \left(\text{1&amp;amp;amp;amp;amp;amp;gt;}\right)_{\text{&amp;amp;amp;amp;amp;amp;amp;alpha;&amp;amp;amp;amp;amp;amp;amp;aposx;}}$) and Nishyama–Wassermann (N–W) ({111}γ || {110}α′$\left(\text{{111}}\right)_{\gamma} \left(\text{ || {110}}\right)_{\text{&amp;amp;amp;amp;amp;amp;amp;alpha;&amp;amp;amp;amp;amp;amp;amp;aposx;}}$ and <11¯0>γ || <001>α′$\text{&amp;amp;amp;amp;amp;amp;lt;1} \overset{\cdot}{1} \left(\text{0&amp;amp;amp;amp;amp;amp;gt;}\right)_{\gamma} \left(\text{ || &amp;amp;amp;amp;amp;amp;lt;001&amp;amp;amp;amp;amp;amp;gt;}\right)_{\text{&amp;amp;amp;amp;amp;amp;amp;alpha;&amp;amp;amp;amp;amp;amp;amp;aposx;}}$). Meanwhile, at 50%, there is a transition from Cu texture to Brass texture in the austenite phase. At 12.5%, the yield strength is 344 MPa higher than that of the traditional hot rolling process, and the elongation remains about 35%. With the increasing cold rolling reduction, the elongation decreases while the strength rises significantly. Strengthening dislocations, fine‐tuning grains, and SIMT are the primary contributors to the improvement in strength. [ABSTRACT FROM AUTHOR]

To improve the precision of defect categorization and localization in images, this paper proposes an approach for detecting surface defects in hot-rolled steel strips. The approach uses an improved YOLOv5 network model to overcome the issues of inadequate feature extraction capacity and suboptimal feature integration when identifying surface defects on steel strips. The proposed method achieves higher detection accuracy and localization precision, making it more competitive and applicable in real production. Firstly, the multi-scale feature fusion (MSF) strategy is utilized to fuse shallow and deep features effectively and enrich detailed information relevant to target defects. Secondly, the CSPLayer Res2Attention block (CRA block) residual module is introduced to reduce the loss of defect information during hierarchical transmission, thereby enhancing the extraction of fine-grained features and improving the perception of details and global features. Finally, the experimental results indicate that the mAP on the NEU-DET and GC10-DET datasets approaches 78.5% and 67.3%, respectively, which is 4.9% and 2.1% higher than that of the baseline. Meanwhile, it has higher precision and more precise localization capabilities than other methods. Furthermore, it also achieves 59.2% mAP on the APDDD dataset, indicating its potential for growth in further domains. [ABSTRACT FROM AUTHOR]

In this paper, the flow of an incompressible fluid is thermally studied. Investigations into the heat transfer process have been conducted in non-Newtonian fluid flows with chemical reactions and heat sources present. The application of this work is the fluid flow around the stretching sheet; fluid flow on a stretching sheet can be applied to polymer extrusion, drawing or plastic films, hot rolling, casting and other engineering problems. The novelty of this paper is that the governing equations have been solved by a new and efficient semi-analytical approach, the Akbari–Ganji method (AGM). In order to investigate the issue, the finite element method (FEM) has also been applied. Comparing the results of problem-solving with the applied methods with the results of the previous research shows a perfect agreement. The results show that the parameters of Hartmann number and interaction improve the velocity profiles. Additionally, for greater Hartmann number values, raising the parameter of interaction decreases the temperature value, but a smaller value has the reverse effect. As the Hartmann number increases, the fluid velocity decreases and it shows that with the increase of electromagnetic force, the velocity of fluid flow decreases. [ABSTRACT FROM AUTHOR]

During the hot rolling process, the work rolls suffer severe wear, resulting in a relatively short lifespan. Severe roll wear can adversely affect the strip shape while introducing roll wear into the crown calculation model can enhance the model accuracy. Therefore, it is crucial to quantify roll wear during the rolling process. Roll wear is a nonlinear time series and the accuracy of the existing work roll wear mechanistic models is not high. In this paper, a novel prediction model for work roll wear based on TCN-LSTM-Attention is developed. TCN utilizes convolutional structures of local and global information to extract data features, while LSTM focuses on capturing long-term and more complex sequence patterns, effectively handling nonlinear characteristics in data. With the incorporation of attention mechanisms, the model becomes more adept at effectively capturing relationships among different segments within the input sequence, which significantly improves predictive performance and reduces the risk of overfitting. Firstly, outlier cleaning and feature selection are performed using Boruta to construct the data set. Then, the predicted results of the proposed model are compared with the existing time series prediction models. The results indicate that the TCN-LSTM-Attention has the highest prediction accuracy, with an R2 of 0.989 and an RMSE of 0.0082 μm. Finally, the predicted results of work roll wear are combined with the mechanism to correct the strip crown pre-calculation model, which significantly improves the calculation accuracy. [ABSTRACT FROM AUTHOR]

This study focuses on exploring the effects of niobium (Nb)-microalloying on the properties of steel for ultra-high-strength bridge cables during hot-rolling processes. We employed a combination of dual-pass compression tests, stress–strain curve analysis, and Electron Backscatter Diffraction (EBSD) techniques to investigate the influence of Nb-microalloying on the static recrystallization behavior and grain size of the steel. The key findings reveal that Nb-microalloying effectively inhibits static recrystallization, particularly at higher temperatures, significantly reducing the volume fraction of recrystallized grains, resulting in a finer grain size and enhanced deformation resistance. Secondly, at a deformation temperature of 975 °C, Nb-containing steel exhibited finer grain sizes compared to Nb-free steel when held for 10 to 50 s; however, the grain size growth accelerated when the hold time exceeded 50 s, likely linked to the increased deformation resistance induced by Nb. Lastly, this research proposes optimal hot-rolling process parameters for new bridge cable steel, recommending specific finishing rolling temperatures and inter-pass times for both Nb-containing and Nb-free steels during the roughing and finishing stages. This study suggests optimal hot-rolling parameters for both Nb-containing and Nb-free steels, providing essential insights for improving hot-rolling and microalloying processes in high-carbon steels for bridge cables. [ABSTRACT FROM AUTHOR]

The power supply is crucial in the present day due to the negative impacts of poor power quality on the electric grid. In this research, we employed deep learning methods to investigate the power factor, which is a significant indicator of power quality. A multi-step forecast was developed for the power factor in the power supply installation of a hot rolling mill, extending beyond the horizontal line. This was conducted using data obtained from the respective electrical supply system. The forecast was developed via hybrid RNN (recurrent neural networks) incorporating LSTM (long short-term memory) and GRU (gated recurrent unit) layers. This research utilized hybrid recurrent neural network designs with deep learning methods to build several power factor models. These layers have advantages for time series forecasting. After conducting time series forecasting, qualitative indicators of the prediction were identified, including the sMAPE (Symmetric Mean Absolute Percentage Error) and regression coefficient. In this paper, the authors examined the quality of applied models and forecasts utilizing these indicators, both in the short term and long term. [ABSTRACT FROM AUTHOR]

In order to increase a stiffness of cold-formed steel (CFS) elements it is practised to built-up the cross-section. In the analysed case, a main element is strengthened by adding extra chord in contact partially along the column. This additional chord acts as a longitudinal stiffener connected with the main section by series of bolts. Authors check whether rules applied over the years, for hot-rolled elements, can be indiscriminately used in the analysed CFS element. The aim of this study is to experimentally and computationally recognize the normal stress distribution in axially compressed CFS built-up column chords and to evaluate the element load-bearing capacity. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of hot deformation on commercially available Ti-6246 alloy below its β-transus transition temperature at 900 °C, knowing that the α → β transition temperature of Ti-6246 alloy is about 935 °C. The study systematically applies a thermomechanical processing cycle, including hot rolling at 900 °C and solution and ageing treatments at various temperatures, to investigate microstructural and mechanical alterations. The solution treatments are performed at temperatures of 800 °C, 900 °C and 1000 °C, i.e., below and above the β-transus transition temperature, for 9 min, followed by oil quenching. The ageing treatment is performed at 600 °C for 6 h, followed by air quenching. Employing various techniques, such as X-ray diffraction, scanning electron microscopy, optical microscopy, tensile strength and microhardness testing, the research identifies crucial changes in the alloy's constituent phases and morphology during thermomechanical processing. In solution treatment conditions, it was found that at temperatures of 800 °C and 900 °C, the α′-Ti martensite phase was generated in the primary α-Ti phase according to Burger's relation, but the recrystallization process was preferred at a temperature of 900 °C, while at a temperature of 1000 °C, the α″-Ti martensite phase was generated in the primary β-Ti phase according to Burger's relation. The ageing treatment conditions cause the α′-Ti/α″-Ti martensite phases to revert to their α-Ti/β-Ti primary phases. The mechanical properties, in terms of strength and ductility, underwent an important beneficial evolution when applying solution treatment, followed by ageing treatment, which provided an optimal mixture of strength and ductility. This paper provides engineers with the opportunity to understand the mechanical performance of Ti-6246 alloy under applied stresses and to improve its applications by designing highly efficient components, particularly military engine components, ultimately contributing to advances in technology and materials science. [ABSTRACT FROM AUTHOR]

To solve the common issue of transverse thickness variation in finished strip steel during the sevenstand hot continuous rolling process, the deformation of rolls in the rolling process of beam Steel 700L and the genetic characteristics of plate thickness distribution were analysed by finite element simulation. Using actual process parameters from the production of beam Steel 700L, a dynamic rolling finite element model was established. The equivalent stress field between the working rolls and strip steel in each stand and the exit thickness distribution of beam Steel 700L were investigated. Results show that the equivalent stress indicates a gradual increase despite a decreasing reduction rate during rolling. Deviations in thickness between the centre and edges of the strip steel at the exit of each stand become apparent from the second stand onwards, demonstrating a hereditary phenomenon during the rolling process. A comparison of measured and simulated thickness reveals errors within 5 %, validating the accuracy of the simulation. The obtained findings provide a foundational understanding for addressing thickness defects in subsequent beam Steel 700L production. [ABSTRACT FROM AUTHOR]

The concept of production stability in hot strip rolling encapsulates the ability of a production line to consistently maintain its output levels and uphold the quality of its products, thus embodying the steady and uninterrupted nature of the production yield. This scholarly paper focuses on the paramount looper equipment in the finishing rolling area, utilizing it as a case study to investigate approaches for identifying the origins of instabilities, specifically when faced with inadequate looper performance. Initially, the paper establishes the equipment process accuracy evaluation (EPAE) model for the looper, grounded in the precision of the looper's operational process, to accurately depict the looper's functioning state. Subsequently, it delves into the interplay between the EPAE metrics and overall production stability, advocating for the use of EPAE scores as direct indicators of production stability. The study further introduces a novel algorithm designed to trace the root causes of issues, categorizing them into material, equipment, and control factors, thereby facilitating on-site fault rectification. Finally, the practicality and effectiveness of this methodology are substantiated through its application on the 2250 hot rolling equipment production line. This paper provides a new approach for fault tracing in the hot rolling process. [ABSTRACT FROM AUTHOR]

A new functional Fe-30Mn-5Si-xCu (x = 1.5 and 2 wt%) biomaterial was obtained from the levitation induction melting process and evaluated as a biodegradable material. The degradation characteristics were assessed in vitro using immersion tests in simulated body fluid (SBF) at 37 ± 1 °C, evaluating mass loss, pH variation that occurred in the solution, open circuit potential (OCP), linear and cyclic potentiometry (LP and CP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nano-FTIR. To obtain plates as samples, the cast materials were thermo-mechanically processed by hot rolling. Dynamic mechanical analysis (DMA) was employed to evaluate the thermal properties of the smart material. Atomic force microscopy (AFM) was used to show the nanometric and microstructural changes during the hot rolling process and DMA solicitations. The type of corrosion identified was generalized corrosion, and over the first 3–5 days, an increase in mass was observed, caused by the compounds formed at the metal–solution interface. The formed compounds were identified mainly as oxides that passed into the immersion liquid. The degradation rate (DR) was obtained as a function of mass loss, sample surface area and immersion duration. The dynamic mechanical behavior and dimensions of the sample were evaluated after 14 days of immersion. The nanocompounds found on the surface after atmospheric corrosion and immersion in SBF were investigated with the Neaspec system using the nano-FTIR technique. [ABSTRACT FROM AUTHOR]

Strip shape control is a hotspot and challenge in strip rolling, where the development trend of rolling technology is towards high strength, high toughness, and a large width-to-thickness ratio. The influence of material microstructure evolution on strip shape control is being increasingly emphasized. In this paper, a Nb-Ti microalloyed steel is taken as the research object. Thermodynamic and kinetic models focusing on the precipitation of the austenite phase are established to quantify the precipitation process. A coupled model of rolls and strips is built using ABAQUS 2022 software, where the precipitation strengthening model and high-temperature constitutive model are embedded into the finite element model (FEM) through subroutines. A two-dimensional alternating differential model is employed to acquire real-time temperature differences in the width direction of the strip. The effects of precipitation inclusion and exclusion on the strip crown under different operating conditions are compared and analyzed. The results indicate that as the temperature decreases, the strengthening effect increases, reaching around 40 MPa at temperatures above 1000 °C and 96.6 MPa at 800 °C. Furthermore, the inclusion of crown in the precipitation consideration is more sensitive to overall temperature changes, but as the strip width decreases, the sensitivity of crown to temperature decreases. The research findings of this paper provide guidance for improving strip shape control and reducing abnormalities during the rolling process. [ABSTRACT FROM AUTHOR]

An Al-Si matrix foam sandwich (AFS) with 6063 Al alloy cover sheets was fabricated by hot rolling combined with melt foaming. A foamable AlSiMg1/SiCp matrix precursor was prepared by the melting route. Hot rolling at 480 °C was carried out to obtain a mechanical bonding interface between the cover sheet and the foamable precursor. Meanwhile, the pore structure of the AFS was deeply affected by the foaming temperature and foaming time during the foaming process. Different pore growth mechanics of the crack-like pore disappearance mechanism (CDM) and pore active expansion mechanism (AEM) were concluded based on the pressure difference in pores inside and outside. Three bending tests were applied to three types of AFSs with different pore structures to evaluate the relation between pore structures and AFS mechanical properties. The bending property of the AFS with fewer layers of pores is like that of a dense material. The bending property of the AFS with a pore size in the range of 0~1 mm presents a typical sandwich shear failure mode. The AFS with a uniform pore structure, in which the shapes of the pores are predominately polygons and the pore diameter is concentrated in the range of 0.5~3 mm, processes a good energy absorption capacity, and the bending stress–strain curve fluctuates greatly after the first stress drop. [ABSTRACT FROM AUTHOR]

This article addresses the tribological characteristics and the influence of mechanical work on the porosity of spray formed Al–Si–Pb alloys. Al‐alloys are extensively utilized in industry due to their self‐lubricant qualities, particularly in the bearing company. In the case of immiscible alloys, the spray approach is the most convenient way to adopt since it allows for single‐step fabrication. The spray process has a high cooling rate, which affects the microstructure of alloys and results in equiaxed grain morphology. Spray deposition and several factors affecting to it are discussed here. This study examines the effect of secondary processes such as cold rolling, hot rolling, extrusion, and so on on porosity, hardness, tensile strength, and tribological behavior. A comprehensive knowledge of the principles of spray techniques and their respective influence on tribological properties are discussed in this perspective by comparing the available literatures, and a future scope for better development is emphasized. [ABSTRACT FROM AUTHOR]

• The symplectic approach is applied to solve the strip cross section temperature. • The mechanism of residual stress formation in hot strip rolling is studied by fiber rods model. • An analytical model for the coupling of temperature, crown and residual stress is established. • The strip critical exit crown ratio is obtained by using the residual stress analytical model. • Eliminating manifested and latent flatness defects by critical exit crown ratio of strip. Residual stress is introduced during hot-rolled strip production due to various factors, such as temperature distribution, crown change, and metal transverse flow. Excessive residual stress can cause flatness defects in the strip, while insufficient residual stress may result in deformation during subsequent cutting. To explore the mechanism of residual stress formation in hot-rolled strip and how to control it, an analytical model for the coupling of temperature, crown and residual stress is established. Firstly, based on the symplectic space Hamiltonian system, an analytical solution for the strip cross section temperature field in each inter-stand zone is obtained. Then the residual stress analytical model is derived based on the fiber rod model combined with the law of volume invariance, lateral metal flow function and high temperature stress relaxation phenomenon. Meanwhile, to verify the accuracy of the analytical model, a multi field coupled finite element model based on the measured data validation is established. The calculation results of the analytical model are in good agreement with the finite element model. Furthermore, the buckling model of strip in symplectic space Hamiltonian system is derived, and the critical buckling stress of different strip flatness defects is directly calculated. Finally, the residual stress analytical model is combined with critical buckling stress to calculate the critical exit crown ratio to keep the strip flat. [ABSTRACT FROM AUTHOR]

Herein, the microstructure and mechanical properties of a low‐alloy Cu‐bearing transformation‐induced plasticity (TRIP) steel and their dependence on the processing history are investigated. The distributions of the retained austenite and bainite are found to be dependent on the initial cold‐rolled microstructure, which can be tailored by the preceding hot‐rolling route (unidirectional/cross rolling) and the subsequent cooling rate (furnace/air cooling). Mechanical properties and TRIP effect strongly depend on the initial microstructure, where the air‐cooled sheet shows remarkable mechanical properties; while the cross‐rolled sheet shows isotropic properties. The addition of copper results in an increase in the amount of the retained austenite, enhancement of strength‐ductility balance, and improvement of the hardening behavior of TRIP‐assisted high‐performance steel. [ABSTRACT FROM AUTHOR]

Duplex stainless steels are generally selected for applications where resistance to corrosion is the most important criteria. Several duplex stainless steel alloys are suceptible to environmental-assisted cracking and that is the subject of this invesitgation for hot-rolled alloy 2205. Duplex stainless steels (DSSs) are generally selected due to their corrosion resistance, but several environment-assisted cracking (EACs) are related to this material. Slow strain rate tests are used to evaluate the resistance to EAC, including hydrogen embrittlement and sulfide stress corrosion cracking (SSCC). In this work, a hot-rolled DSS was tested by slow strain rate tensile testing (SSRT) in two saline solutions containing H2S (10 kPa (0.1 bar) of partial pressure). Two pH levels (3.5 and 4.5) were adjusted with HCl and NaOH additions. The material was brittle in both pH levels, although the density of secondary cracks at pH 4.5 was slightly lower than at pH 3.5. This work was dedicated to analyzing the fracture surface and the secondary cracks developed in the SSRT. Lines of localized deformation of ferrite and austenite were found in the specimen tested with pH 4.5. The results were compared to the behavior of previous SSRT results and SCC failures of DSS harsh conditions. [ABSTRACT FROM AUTHOR]

Despite their complex composition, high-entropy alloys (HEAs) have a simple structure and have been extensively researched for their ability to achieve unique properties through thermo-mechanical processing (TMP). This review studies the effects of different rolling regimes and post-annealing on single and multiphase HEAs, analyzing how TMP leads to microstructural changes and improved mechanical properties. The rolling changes the shape and utilizes different mechanisms determined by the rolling temperature to strengthen the raw materials, thus affecting the HEAs' properties. The microstructural evolution of HEAs during annealing is affected by various parameters such as annealing time, annealing temperature, and heating rate, which impact the strength–ductility combination of HEAs. According to the literature, cryogenic rolling (cryo-rolling), as opposed to cold rolling, provides greater strengthening. This is due to the faster microstructural evolution kinetics in cryo-rolling. Thus, cryo-rolling enhances the strengthening by activating deformation twinning at earlier stages through the intersection of twins and more shear banding, which is preferred to microbands for HEAs with low stacking fault energy (SFE). Rolling at high temperatures is the most suitable approach for HEAs with low workability. Warm and hot rolling enable microstructure evolution through deformation mechanisms, including grain growth, recovery, recrystallization, and phase transformation based on the process temperature. The ratio of recovery to recrystallization depends on temperature and SFE, with recovery dominating in alloys with high SFE and at lower rolling temperatures, while recrystallization is more prevalent for alloys with low SFE and at higher temperatures, leading to specific ductility–strength synergy. [ABSTRACT FROM AUTHOR]

The effect of acid-soluble aluminum content on precipitates and magnetic properties of grain oriented silicon steel was researched by optical microscopy and zeiss ultra 55 Scanning Electron Microscope (SEM) technique respectively. The results show that the number of precipitates increases with the increase of acid-soluble aluminum content, and the size of precipitates is relatively large after hot rolling. Under the low hot rolling temperature, the number of precipitates in the samples is large and the size is small, moreover, the grain size of the primary recrystallized grain is small. The matching of process parameters under different production process lines is the key to obtain good magnetic performance. The effect of nitriding on magnetic properties of the samples is related to the acidsoluble aluminum content of the samples. Too much acid-soluble aluminum can deteriorate the magnetic properties. [ABSTRACT FROM AUTHOR]

The as-cast [Co40Cr25(FeNi)35−yMoy]100−xCx (x = 0, 0.5, y = 3, 4, 5 at.%) HEAs (high-entropy alloys) were prepared by a vacuum arc melting furnace and were then hot rolled. The effect of C and Mo elements on the microstructure evolution and mechanical properties of HEAs was systematically analyzed. The results showed that when no C atoms were added, the HEAs consisted of FCC + HCP dual-phase structure. In addition, as the Mo content increased, the grain size of the alloy increased from 17 μm to 47 μm. However, only the FCC phase appeared after adding 0.5 at.% carbon in Mo microalloyed HEAs, and the grain size of the Mo4C0.5 HEA decreased significantly. Due to the Mo atom content exceeding the solid solution limit, the carbides of Mo combined with the C element appeared in the Mo5C0.5 HEA. The strength of C and Mo microalloyed HEAs significantly increased compared to HEAs with no C added. However, the Mo4C0.5 HEA exhibited excellent comprehensive mechanical properties, which was superior to a majority of reported HEAs and conventional metal alloys. Its yield strength, tensile strength, and elongation were 757 MPa, 1186 MPa, and 69%, respectively. The strengthening mechanism was a combination of fine grain strengthening, TWIP effect, and solid solution strengthening. [ABSTRACT FROM AUTHOR]

Focusing on the problem of strip shape quality control in the finishing process of hot rolling, a shape model based on metal flow and stress release with the application of varying contact rolling parameters is introduced. Combined with digital twin technology, the digital twin framework of the shape model is proposed, which realizes the deep integration between physical time–space and virtual time–space. With the utilization of the historical data, the parameters are optimized iteratively to complete the digital twin of the shape model. According to the schedule, the raw material information is taken as the input to obtain the simulation of the strip shape, which shows a variety of export shape conditions. The prediction absolute error of the crown and flatness are less than 5 μm and 5 I-unit, respectively. The results prove that the proposed shape simulation model with strong prediction performance can be effectively applied to hot rolling production. In addition, the proposed model provides operators with a reference for the parameter settings for actual production and promotes the intelligent application of a shape control strategy. [ABSTRACT FROM AUTHOR]