Aluminum Strips Research Articles

Generalisation of the hydrodynamics model method for hot and cold strip rolling application

The present work constitutes a generalization of the hydrodynamic model used to predict the pressures and the rolling speeds during the hot rolling of aluminum and copper strips. The hydrodynamic model with a linear behavior (Newton viscous) of the materials shows good predictions in the literature but its applicability is questionable in non-linear cases, when the materials exhibit viscoplastic or plastic behavior. This work extends the model to accommodate non-linear cases commonly encountered in rolling models (viscoplastic and plastic behaviors). The obtained results are in good agreement with experimental data from the literature. The validated model can, therefore, be considered an enhanced hydrodynamic model for predicting pressures and velocities during both hot and cold rolling of thin strips.

Controlling Aluminum Strip Thickness by Clustered Reinforcement Learning With Real-World Dataset

Controlling Aluminum Strip Thickness by Clustered Reinforcement Learning With Real-World Dataset

Phase and group speeds of airborne surface waves over porous layers and periodically rough hard surfaces.

Sound fields above porous layers or rough acoustically hard boundaries may include airborne surface waves. The surface wave properties depend on the effective surface admittance. Analytical expressions for surface wave speeds are derived from models for the acoustical properties of rigid porous media. Surface wave effects on measurements of level difference spectra over porous asphalt are investigated and predictions of phase, group speeds, and vertical attenuation of the surface waves over externally reacting hard backed layers corresponding to a porous asphalt are compared. Predictions of surface wave characteristics above an identical vertical slit medium are compared with data obtained over arrays of parallel aluminum strips on an acoustically hard surface. Group speeds of surface waves over lattices, parallel regularly spaced strips, and snow obtained by numerical differentiation of the phase speed spectra corresponding to admittance spectra deduced from complex excess attenuation are found to compare well with those estimated from time domain data. An effective admittance, deduced from a boundary element method simulation of the excess attenuation spectrum over regularly spaced ribs so that the frequency of the peak corresponds with that in the measured spectrum, is used to estimate the group speed of the associated surface wave.

Sub-rapid solidification microstructure characteristics and control mechanisms of twin-roll cast aluminum alloys: A review

Rapid growth in industrial sectors such as automotive and shipbuilding has highlighted the significance of strip casting technology to produce lightweight alloys, particularly aluminum alloys widely used in both industrial production and daily life. Twin-roll casting (TRC), as an economically and environmentally friendly method for slab/strip production and processing, has attracted significant interest from researchers. However, the development of TRC aluminum alloys faces many challenges due to limited understanding of microstructural characteristics and control mechanisms. To further enhance comprehension of TRC aluminum alloys, this article reviews the influencing parameters, control methods, and existing issues related to TRC sub-rapid solidification (SRS) microstructure. It firstly summarizes TRC equipment types and their solidification characteristics, followed by a detailed analysis on key parameters affecting the evolution of TRC microstructure including rolling speed, roll separation force (RSF), and heat transfer coefficient (HTC). Finally, solutions to TRC defects are summarized and evaluated alongside their underlying mechanisms. This article provides a comprehensive review of the characteristics and control mechanisms of TRC microstructure while offering valuable insights for the future production of high-quality TRC aluminum strips.

Microstructural Evolution and Mechanical Behavior of Pure Aluminum Ultra-Thin Strip under Roller Vibration

As the demand for lithium-ion batteries increases, higher quality requirements are being placed on pure aluminum ultra-thin strips, one of the main materials used in lithium-ion battery current collectors. Roller vibration during the rolling process of pure aluminum ultra-thin strips is unavoidable and significantly affects the quality of the strips. This paper uses 1A99 pure aluminum ultra-thin strips as raw materials and employs a controlled vibration method during the rolling process to obtain products under two conditions: stable rolling and vibrational rolling. The surface and cross-section of the aluminum strips were characterized using scanning electron microscopy (SEM), and the microstructure of the surface and cross-section was studied using electron backscatter diffraction (EBSD) technology. The results show that, during stable rolling, the surface quality of the aluminum strip is good without defects. Under vibration, obvious vibration marks appear on the surface of the aluminum strip, showing characteristics of peaks and troughs. With the increase in strain at the trough position, there is a transition from low-angle grain boundaries to high-angle grain boundaries, and the grain size is uneven at the peak and trough positions, with noticeable grain refinement at the troughs. At the same time, under the influence of vibration, the aluminum strip induces a different texture morphology from conventional rolling. Due to the different plastic strains at the peak and trough positions, a texture alternation phenomenon occurs at these positions. The tensile test results indicate that aluminum strips exhibit poor mechanical properties under roller vibration, with the reduction in mechanical performance primarily attributed to the uneven microstructure distribution caused by roller vibration.

Friction stir seam- and spot-welded aluminium honeycombs: Enhanced structural integrity eliminating adhesive bonding challenges

Aluminium honeycombs serve as a primary core material for energy absorption in various transportation and structural applications, with particular emphasis on their superior strength in the out-of-plane direction. However, conventional fabrication methods rely on adhesive bonding of aluminium strips, revealing poor bond strength under collapse stress. Premature structural failure arises from adhesive failure and subsequent debonding of cell walls, occurring before the aluminium strips fail. Addressing this, an innovative approach utilizing friction stir seam, and spot welding has been introduced to overcome adhesive bonding limitations. Welded joints exhibit a remarkable tenfold increase in strength compared to adhesive bonds. Notably, welded honeycombs demonstrate 32–37% higher crushing strength and an 80–84% increase in specific energy absorption capacity over adhesive-bonded variants. Collapse mechanisms involve pure buckling in seam-welded honeycombs without weld region failure, while spot-welded honeycombs display a combination of bending-shear and spot tearing, particularly evident with wider weld spacing. Obtaining longitudinal loading on seam-welded honeycomb walls is advantageous because of its 57% higher normalized maximum load capacity compared to the shear-tensile strength obtained for spot-welded walls. This study marks a significant advancement in the existing manufacturing route for honeycombs in achieving superior crushing performance.

Simulation and Study of Influencing Factors on the Solidification Microstructure of Hazelett Continuous Casting Slabs Using CAFE Model.

The Hazelett continuous casting and rolling process represents a leading-edge production method for cold-rolled aluminum sheet and strip billets in the world. Its solidification microstructure significantly influences the quality of billets produced for cold rolling of aluminum sheets and strips. In this study, employing the CAFE (Cellular Automaton-Finite Element) method, we developed a coupled computational model to simulate the solidification microstructure in the Hazelett continuous casting process. We investigated the impact of nucleation parameters, casting temperature, and continuous casting speed on the microstructural evolution of the continuous casting billet. Through integrated metallographic analyses, we aimed to elucidate the controlling mechanisms underlying the Hazelett continuous casting process and its resultant microstructure. The results demonstrate that the equiaxed rate of grains increases with an increase in nucleation density, and the grain size decreases under constant cooling strength. With other nucleation parameters held constant, the grain size decreases as undercooling increases, and the columnar crystal zone expands. The nucleation density of the Hazelett continuous casting aluminum alloy has been determined to range between 1011 m-3 and 1013 m-3, and the undercooling ranges between 1 °C and 2.5 °C. The solidified grain structure can be controlled between 35 μm and 72 μm. The grain size of the continuous casting billet increases with an increase in pouring temperature and decreases as the casting speed increases. Elevating the pouring temperature positively impacts the fraction of high-angle grain boundaries and promotes the dendritic to equiaxed grain transition. Moreover, there exists potential for further optimization of continuous casting process parameters.

Union channel pruning-based U2Net for online surface defect segmentation of aluminum strips in production processes

Union channel pruning-based U2Net for online surface defect segmentation of aluminum strips in production processes

Bonding characteristics of aluminium laminates and aluminium–graphite composites processed by roll bonding

Roll bonding is a solid-state welding process, employed to join similar and dissimilar metals. Roll bonding with secondary particles in-between and accumulating the roll bonded material multiple times is an alternative method for manufacturing high-strength composites. In the current work, commercially pure aluminium strips are roll bonded at room temperature to 400 °C. The percent reduction varied from 10% to 70%, with an increment of 10%. Moreover, the aluminium strips are roll bonded with graphite particles dispersed in between (Al–Gr–Al). The aim is to study the effect of graphite particles on bonding behaviour. The critical process parameters such as the effect of temperature and percentage reduction on the bond strength are determined. The lap shear test is used to evaluate the bond strength. It is observed that the dispersion of graphite particles in between aluminium significantly increased the threshold reduction required for bond establishment. The threshold reduction decreases for roll-bonding aluminium with increasing temperature. Furthermore, it is observed that the bond strength significantly increases with increasing processing temperature. However, roll bonding with the graphite particles dispersed in between reduced the bond strength, and the effect was significant with increasing temperature. The bond strength of both Al and the Al–Gr–Al composites increases by increasing the reduction percentage. The de-bonded sample surfaces are analyzed using a scanning electron microscope. It is worth mentioning that the experimental outcomes of the current study predict the roll bonding parameters for the successful fabrication of an Al/Gr composite by accumulative roll bonding.

Electro-mechanical performance of double-flushed riveted joints

This paper revisits double-flush riveting to compare the static and fatigue performance of the resulting joints with those fabricated by conventional bolting. Experimental measurements of electrical resistance, combined with finite element analysis of electric current flow, serve a dual structural and electrical purpose of validating the number of cycles after which the loss of contact between the overlapping sheets becomes significant, and evaluating the relative performance of both types of joints in electric energy distribution systems built upon aluminum strips. The first of these purposes is a novelty in fatigue testing while the second paves the way for improving the efficiency of electric power grids.

Expanding the technological capabilities of the twin roll casting machine.

urrently, one of the most promising areas of metallurgy development is the creation of foundry and rolling complexes based on twin roll casting machines. Their application makes it possible to organize the economical production of high-quality strips of stainless and alloy steels for critical purposes. Despite the existing experience in the creation and development of such equipment in Russia, domestic developments are still inferior to the foreign level. Thus, there is an urgent need to continue work on this topic and to create domestic industrial equipment, taking into account the latest technical solutions. At the same time, the technological capabilities of twin-roll casting machines both here and abroad are not fully used. The specialists of JSC AHK VNIIMETMASH have developed a number of the latest versions of the twin-roller casting machine with advanced technological capabilities. Due to the dosed supply of various reagents into the gap between the casting rolls-crystallizers it is possible to produce steel strips with improved properties, as well as porous aluminium strips, and also composite strips for critical applications. The article discusses the design and technological features of the proposed options for two-roller casting machines.

A combination of aluminium strip and brass mesh to process a refined structure composite via accumulative roll bonding: A characterization study

In the present study, a dissimilar composite consisting of commercially pure aluminium and 70–30 brass alloy was manufactured using the accumulative roll bonding process. For microstructural evaluations, optical microscopy, scanning electron microscopy, and electron back-scattered diffraction were employed. It is indicated that after the 3rd ARB pass, the bonding between the reinforcements and matrix strengthened. However, after the 5th pass, the formation of micro-cracks along the Al/brass interface was observed. These cracks accompanied by the separation of matrix/particle led to fracture of the composite from the base metal as confirmed by fractography of the failed specimen. Also, the average diameter of Al grains was estimated to range from 1.2 μm (between brass particles) to 850 nm (near brass fragments). The micro-texture study of the selected areas indicated the evolution of P and Q components known as recrystallization texture near the brass particles. Above all, mechanical evaluations were conducted using Vickers microhardness and tensile tests. Results revealed a dramatic increase in the composite ultimate strength and hardness and then saturation as compared to that of Al without brass fragments. However, a sudden drop in hardness occurred for the composite at the 3rd pass.

Online surface defect segmentation on aluminum strip production line using a lightweight and efficient model

A significant challenge in automated defect inspection (ADI) of aluminum strip surfaces is improving segmentation speed to satisfy the online inspection requirements of the production line while maintaining the precision of defect identification. This study proposes a lightweight and efficient defect segmentation model that can be applied in aluminum processing enterprises for fast and precise segmentation of aluminum strip surface defects. A novel fusion attention (FA) mechanism is first established to enhance the focus on critical characteristics along the spatial and channel dimensions. This mechanism adopts continuous dilated convolutions with appropriate dilation rates to effectively increase the range of the receptive field and improve defect localization accuracy. Subsequently, a lightweight MobileViTv2 with an embedded FA mechanism is employed as a multi-scale feature extractor to learn comprehensive representations from defect images. Next, a novel feature fusion method, named large-scale feature pyramid network (LSFPN), is introduced to enhance the focus on details within large-scale features. LSFPN establishes four progressively shallower top-down pathways with fast normalized fusion weights and incorporates lightweight aggregation nodes based on the MoblieNetv2 block. Surface images of straightened aluminum strips with five universal defects were collected, whereby a new dataset was established. The experimental outcomes demonstrate the proposed model outperforms other state-of-the-art techniques synthetically, achieving a mean Intersection over Union (mIoU) of 87.01%, a segmentation speed of 61.67 fps, and a model size of 16.23 MB. This model may serve as a valuable theoretical foundation for the online segmentation of aluminum strip surface defects in embedded devices.

Online visual end-to-end detection monitoring on surface defect of aluminum strip under the industrial few-shot condition

Surface defect detection systems based on deep learning are employed in the manufacturing system, and their good detection performance largely relies on abundant annotated data. Nevertheless, industrial datasets are often difficult to obtain, which hinders the development of defect detection systems to some extent. In an effort to address the issue that the scarcity of training data leads to poor performance, this paper proposes a novel end to end few-shot detection method for industrial real-time detection on aluminum strips. The meta-learning theory is introduced into the multi-scale structure of the YOLOv4 framework, which means that multi-scale meta-feature maps are extracted through the backbone network and each meta-feature map is recalibrated by reweighted vectors to strengthen class-specific features. Subsequently, a multi-scale prediction module with a new parsing strategy is designed to locate and classify the defects at different scales for the reweighted meta-features. All experiments are performed using data collected from the aluminum strip production line in a cold rolling workshop. In addition, the dataset required for training is constructed based on the few-shot training strategy. Pre-training is conducted on a large amount of labeled data from base classes in advance, and the pre-trained weights are then loaded to train the model on a small amount of labeled data from all classes to rapidly deploy the model in multi-task scenarios. The proposed method shows excellent performance, improving the accuracy for novel classes by more than 14.6%, which enhances the industrial practicality of detection systems.

Superconducting detector magnets for high energy physics

Various superconducting detector solenoids for particle physics have been developed in the world. The key technology is the aluminum-stabilized superconductor for almost all the detector magnets in particle physics experiments. The coil fabrication technology is also important and it has advanced along with the conductor technology, such as the inner coil winding technique, indirect cooling, transparent vacuum vessel, quench protection scheme using pure aluminum strips and so on. The detector solenoids design study is in progress for future big projects in Japan and Europe, that is, ILC (International Linear Collider), FCC (Future Circular Collider) and CLIC (Compact LInear Collider), based on the technologies established over many years. The combination of good mechanical properties and keeping a high RRR is a key point for the development of Al-stabilized conductor. The present concern for the detector solenoid development is to have been nearly losing the key technologies and experiences. Nowadays, there are no industrial companies having the capacity to manufacture such aluminum stabilized superconductor. Complementary efforts are seriously required to re-realize and validate the performance required in the future projects in collaboration with worldwide institutes and industries. Some mid-scale physics experiments required detector solenoids wound with not aluminum stabilized conductor but conventional copper stabilized conductor. The specific requirement is to control the magnetic field distribution precisely, and the efforts to realize the requirement are on going with regard to the magnetic field design technology with high precision simulation, coil fabrication technology and so on.

Simulation of Gas Jet Impingement Cooling in Continuous Heat Treatment Lines with the ANSYS GEKO Turbulence Model*

Abstract Gas impingement jets are widely applied in industrial cooling processes. In continuous heat treatment lines of steel, aluminium and copper strips, impingement jet nozzle systems are utilised to achieve rapid cooling or heating. The heat transfer depends on the flow but also on the geometric parameters such as nozzle to strip distance and the nozzle shape. The key challenge while designing cooling sections is to determine the performance of those nozzle systems or their Nusselt number respectively. Jet cooling sections are challenging to model with computational fluid dynamics or in an experimental set up. Yet, RANS-turbulence models are a cost-effective way to predict Nusselt numbers. In this work the capability of the ANSYS generalized k-omega (GEKO) two-equation turbulence model to determine the local and integral Nusselt number of an impinging air jet is evaluated. The results are contrasted to experimental investigations.

Real-time and accurate defect segmentation of aluminum strip surface via a lightweight network

Real-time and accurate defect segmentation of aluminum strip surface via a lightweight network

Effect of Cu content on central-segregation composition and mechanical properties of Al–Mg–Si alloys produced by twin-roll casting

Dissolving the inherent central segregation is critical to improve the performance of twin-roll casting (TRC) aluminum strips. In this study, we investigated the effects of Cu content (0.8, 1.2, and 1.6 wt%) on the central-segregation composition and mechanical properties of TRC Al–0.8Mg–1.0Si alloys. Cu promoted the segregation-phase transformation from the higher-melting-temperature Mg2Si phase to the lower-melting-temperature Cu-containing phases (Q-AlCuMgSi and θ-Al2Cu), resulting in an easier dissolution of central segregation. Therefore, the segregation of 0.8 and 1.2 wt% Cu alloys was almost dissolved following cold rolling and solution treatment compared to Cu-free alloys. However, after a higher content of Cu (1.6 wt%) was added, the segregation became too severe to dissolve. After modifying with 1.2 wt% Cu, the yield strength (YS) of the TRC alloy increased from ∼306 to 335 MPa, and the elongation was increased from ∼13 to 17%. The contribution of solution strengthening and increasing volume fraction of precipitates results in the strengthening effect of Cu. Meanwhile, the dissolution of segregated phases is also advantageous for solution and precipitation strengthening. This study could lead to the development of a simple method to dissolve TRC central segregation and produce TRC Al–Mg–Si alloys with excellent performance.

Audio-frequency surface wave characteristics above porous and comb-like surfaces

Part of the solution for the sound field due to a point source in air over a porous boundary has the form of an airborne surface wave. Analytical expressions for the surface wave characteristics are reviewed and corresponding analytical expressions for group speed are obtained from a thin air layer approximation for the impedance of a comb-like surface, from two approximate models for the acoustical properties of porous media and from a model for identical slanted slit pores. Predictions of absorption coefficient spectra for a hard-backed porous layer with flow resistivity sufficiently low that there is extended reaction are made using two of the approximate models and compared with those of a relatively exact slanted slit pore model. The model derived specifically to predict the acoustical properties of porous asphalt is found to be the least satisfactory. The various models are used to obtain analytic expressions for the surface wave group speed. Predictions of surface wave characteristics including group velocity are compared with data obtained over arrays of parallel aluminium strips.

Improved Method Based on Retinex and Gabor for the Surface Defect Enhancement of Aluminum Strips

Aiming at the problems of the blurred image defect contour and the surface texture of the aluminum strip suppressing defect feature extraction when collecting photos online in the air cushion furnace production line, we propose an algorithm for the surface defect enhancement and detection of aluminum strips based on the Retinex theory and Gobar filter. The Retinex algorithm can enhance the information and detail part of the image, while the Gobar algorithm can maintain the integrity of the defect edges well. The method first improves the high-frequency information of the image using a multi-scale Retinex based on a Laplacian filter, scales the original image and the enhanced image, and enhances the contrast of the image by adaptive histogram equalization. Then, the image is denoised, and texture suppressed using median filtering and morphological operations. Finally, Gobar edge detection is performed on the obtained sample images by convolving the sinusoidal plane wave and the Gaussian kernel function in the null domain and performing double-threshold segmentation to extract and refine the edges. The algorithm in this paper is compared with histogram equalization and the Gaussian filter-based MSR algorithm, and the surface defects of aluminum strips are significantly enhanced for the background. The experimental results show that the information entropy of the aluminum strip material defect image is improved from 5.03 to 7.85 in the original image, the average gradient of the image is improved from 3.51 to 9.51 in the original image, the contrast between the foreground and background is improved from 16.66 to 117.53 in the original image, the peak signal-to-noise ratio index is improved to 24.50 dB, and the integrity of the edges is well maintained while denoising. This paper’s algorithm effectively enhances and detects the surface defects of aluminum strips, and the edges of defect contours are clearer and more complete.