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Curved profiles/sections have been widely used for manufacturing lightweight structures with high stiffness and strength due to aerodynamics, structural properties, and design reasons. Structural components fabricated using curved aluminum profiles satisfy the increasing demands for products used in many high-technology industries such as aerospace, shipbuilding, high-speed rail train, and automobile, which possess the characteristics of lightweight, high strength/stiffness relative to weight, superior aerodynamics performance, and aesthetics. In this paper, the advances and trends in forming techniques of curved extrusion profiles of metal alloys have been reviewed. The curved profile forming techniques are classified into three major categories: conventional cold bending technique, stress/moment superposed cold bending technique, and extrusion-bending integrated forming technique. Processes for innovative development in the field of forming curved profiles are identified; the extrusion-bending integrated technique which can directly form the billets into curved profiles by one single extrusion operation possesses the full potential for further innovation. Due to the nature of the research to date, much of the work referred to relates to hollow circular and rectangular tube cross-sections.

Mold structure and cooling parameters are significant factors that affect the heat transfer capacity of high-speed continuous casting molds of billets. Therefore, a three-dimensional fluid flow and heat transfer model of a 160 mm × 160 mm billet mold was established, and its accuracy was verified. Thereby, the characteristics of heat transfer and influences of mold structure and cooling parameters on heat transfer in the high-speed continuous casting billet mold region were revealed. It was found that extending the effective length of a mold is the most valuable method to improve its heat transfer capability and achieve high-speed continuous casting. The total heat and the shell thickness at a mold outlet increased by 19% and 9.21% on average with every 100 mm extension. Enlarging the fillet radius could enhance the uniformity of heat transfer in the mold. Considering the loss of material, the optimal fillet radius of the mold was determined to be R = 10 mm.

A numerical simulation of tungsten bar rotary forging was conducted using Deform 3D software. The effects of hammerhead radial feed, relative rotational speed, axial feed rate of the billet, and initial billet temperature on the forging process were investigated through an orthogonal test. The optimal parameters for tungsten bar rotary forging were determined as follows: The radial feed of the hammerhead is 1.5 mm, the relative rotational speed is 880 rpm, the axial feed rate is 6.5 m/min, and the initial billet temperature is 1550°C. Subsequently, a trial production of tungsten bar forging was performed using these optimized parameters. The results demonstrated that the samples produced with the optimized conditions exhibited excellent performance.

Deform-3D software was used to analyse the forming characteristics of wear-resistant steel balls, material fluidity, stress-strain distribution, load-time curve, and break coefficient of three kinds of forging billets in the forging process. It was concluded that with the reduction of the height of the original billet, the damage coefficient of the middle position of the billet decreased during the final stage of billet forming. The forging ratio of the blank should be appropriately reduced to reduce the risk of forming defects in the forging process.

High precision copper tubular components are generally manufactured by integrating the casting and rolling processes. The performance of these parts depends largely on the precision and quality of the tubular billet, which is produced via horizontal continuous casting (HCC). One of the main critical aspects of the HCC process is the crystallization zone within the graphite mold. This zone significantly influences the quality of the cast billets, the operational lifespan of the graphite mold, and the safety of the manufacturing process. However, this zone has not been thoroughly investigated due to experimental constraints. To overcome such a limitation, a fast calculation system of temperature (FCST) was employed to model the temperature field of the copper solidification process using the finite difference method. On this foundation, a machine learning approach—namely, an artificial neural network (ANN)—was used to establish the relationships between the process parameters and the crystallization position, defined as the outer and inner solidification positions. Additionally, the particle swarm optimization (PSO) algorithm was integrated with the ANN model to optimize the number of hidden layers and neurons, thereby enhancing the accuracy and the efficiency of the prediction. The coupled PSO-ANN-FCST framework effectively establishes the relationship between solidification and controllable process parameters. The proposed framework, when validated, shows a high predictive capability, with a discrepancy between the predicted and actual crystallization positions less than 3%. Through this method, a set of controllable parameters can be provided by the PSO-ANN-FCST model if appropriate objectives for the solidification parameters are determined. This investigation lays the foundation for intelligent control of process parameters in HCC, thereby improving the intelligent manufacturing of high-quality copper components.

The increasing casting speed of billets is beneficial for improving single-machine production efficiency, reducing refractory material consumption, and achieving energy conservation and consumption reduction. However, as the casting speed increases, the probability of steel leakage also increases. An analysis of the thickness of the billet shell under high casting speed allows us to analyze the reasons for steel leakage and propose targeted solutions. This article analyzes the steel leakage billet shell of grade 40 steel and concludes that the thickness of the billet shell is between 8-20 mm at the upper of the mold, and only 5-10 mm at the lower of the mold. At the beginning of its formation, the shell of the cast billet is not uniform, with a maximum difference of up to 8 mm. As the casting progresses, the shell of the billet actually becomes thinner. At a distance of 100-200 mm from the mold, the maximum air gap between the billet shell and the copper tube reaches about 5.5 mm. The air gap reduces the uniformity of heat transfer, resulting in an uneven billet shell. After the liquid steel is injected into the shell, it will cause remelting of the solidification shell, resulting in thinning of the casting shell and causing steel leakage at the outlet of the mold.

Carbon segregation is the major and classical internal defect in the continuous casting process of carbon steel. Based on the combined electromagnetic stirring equipment for new billet in a steel plant, China, the influence of combined electromagnetic stirring (M-EMS + F-EMS) on the carbon segregation of 300 mm × 340 mm special-shaped billet was studied via numerical simulation and on-site industrialization tests. The Lorentz force and carbon solute distribution were simulated under different EMS parameters. The formation mechanism of the carbon segregation of medium carbon steel with different combined electromagnetic stirring processes was analyzed. The results show that: (1) with the combined action of “solute flushing” effect and gravity, the carbon concentration in the loose side of the medium carbon steel casting billet is gradually lower than the fixed side, while the carbon concentration on the fixed side gradually accumulates more; and (2) under the action of combined electromagnetic stirring, the segregation index of casting billet could be controlled to remain between 0.96–1.05 and shows an increasing change in solidification from the skin to the center. When the current and frequency of M-EMS are 250 A and 2.0 Hz and the F-EMS are 180 A and 8.0 Hz, the carbon segregation defects in the special-shaped (300 mm × 340 mm) casting billet can be significantly improved.

Surface defects in high-temperature continuous cast billets are critical factors affecting the quality of steel products. Owing to high-temperature radiation, heavy dust contamination, varying billet specifications, and background interference from oxide scales and water stains, existing online surface defect detection technologies for high-temperature continuous cast billets still suffer from limitations including high false-positive rates, inefficient identification of pseudo-defects, and the inability to simultaneously detect three-dimensional (3D) depth information alongside two-dimensional (2D) features. To solve these problems, this paper proposes a multi-dimensional online detection technology for surface defects in high-temperature continuous cast billets based on multi-information fusion. A four-channel multispectral image sensor and a corresponding three-light-source imaging system were developed. Furthermore, a defect sample augmentation method, a deep learning-based 2D recognition method, and a photometric stereo-based 3D reconstruction method were designed to mitigate problems of low detection accuracy and poor robustness caused by sample imbalance among different defect types. Finally, industrial applications were conducted on large-section continuous cast billets, beam blanks, and billets during the grinding process. According to the surface defect detection requirements of different continuous cast billets, multispectral multi-information fusion and traditional 2D defect imaging methods were adopted respectively. The results demonstrate high-precision online detection of surface defects in continuous cast billets, with favorable practical application effects.

Electromagnetic stirring (M-EMS) has been extensively applied in continuous casting production to reduce the quality defects of casting billets. To investigate the effect of continuous casting electromagnetic stirring on billet segregation, a 3D multi-physics coupling model was established to simulate the internal heat, momentum, and solute transfer behavior, to identify the effect of M-EMS on the carbon segregation of a continuous casting square billet of 200 mm × 200 mm. The results show that M-EMS can move the high-temperature zone upward, which is favorable for the rapid solidification of the billet, and can promote the rotational flow of the molten steel in the horizontal direction. When the electromagnetic stirring current is varied in the range of 0–500 A, the degree of carbon segregation first decreases and then increases, with the best control of segregation at 300 A. In the frequency range of 3–5 Hz, the degree of carbon segregation degree increases with frequency. Meanwhile, the simulation and experimental results show that 3 Hz + 300 A is the best electromagnetic stirring parameter for improving the carbon segregation of casting billets with a size of 200 mm × 200 mm. So, a reasonable choice of the M-EMS parameters is crucial for the quality of the billet.

The horizontal continuous casting process, the initial step in TP2 copper tubular processing, directly determines the microstructure and properties of copper tubular. However, the process parameters of the continuous casting characterize time variation, multiple disturbances and strong coupling. As a consequence, their influence on a casting billet is difficult to be determined. Due to the above issues, the common factor and special factor analysis of the factor analysis model were used in this study, and the casting experiment and billet metallographic experiment were carried out to diagnose and analyze the reason of the microstructure inhomogeneity. The multiple process parameters were studied and classified using common factor analysis, the cast billets with abnormal microstructures were identified by GT 2 statistics, and the most important factors affecting the microstructural homogeneity were found by special factor analysis. The calculated and experimental results show that the principal parameters influencing the inhomogeneity of solidified microstructure are the primary inlet water pressure and the primary outlet water temperature. According to the consequence of the above investigation, the inhomogeneity of the copper billet microstructure can be effectively improved when the process parameters are controlled and adjusted.