Aluminum Alloy Sheets Research Articles

Analytical Approach for Forecasting the Load Capacity of the EN AW-7075-T6 Aluminum Alloy Joints Created Using RFSSW Technology.

To ensure the high reliability of aircraft structures, the Refill Friction Stir Spot Welding (RFSSW) process must be characterized by a high load capacity of the welds and a small standard deviation of the load capacity spread. This allows us to obtain uniform functional properties in the connections, ensuring the high quality of the process. This work aims to select the most favorable technological parameters for the welding process of EN AW-7075-T6 Alclad aluminum alloy sheets, which are used for the production of aircraft structures. The best networks were calculated using the Statistica 13.3 program. The obtained results were compared with the results of previous investigations. It has been shown that a model using neural networks allows for the determination of connection parameters with much greater accuracy than the classical model. The maximum error in estimating the load capacity of the connection for the mathematical model was 6.13%, and the standard deviation was 14.51%. In the case of neural networks, the maximum error value did not exceed 1.55%, and the standard deviation was 3.74%. It was shown that, based on the neural model, it is possible to determine the process parameters that ensure the required quality capacity of the process, ensuring a probability of obtaining the required load capacity of the connections amounting to P = 0.999935 with a defect rate of 0.0065%. This possibility is not provided by the classical model due to its large error in estimating the process spread and the high sensitivity of the process input parameters to the output parameters.

Optimization of 2024-T3 Aluminum Alloy Friction Stir Welding Using Random Forest, XGBoost, and MLP Machine Learning Techniques.

This study optimized friction stir welding (FSW) parameters for 1.6 mm thick 2024T3 aluminum alloy sheets. A 3 × 3 factorial design was employed to explore tool rotation speeds (1100 to 1300 rpm) and welding speeds (140 to 180 mm/min). Static tensile tests revealed the joints' maximum strength at 87% relative to the base material. Hyperparameter optimization was conducted for machine learning (ML) models, including random forest and XGBoost, and multilayer perceptron artificial neural network (MLP-ANN) models, using grid search. Welding parameter optimization and extrapolation were then carried out, with final strength predictions analyzed using response surface methodology (RSM). The ML models achieved over 98% accuracy in parameter regression, demonstrating significant effectiveness in FSW process enhancement. Experimentally validated, optimized parameters resulted in an FSW joint efficiency of 93% relative to the base material. This outcome highlights the critical role of advanced analytical techniques in improving welding quality and efficiency.

Characteristics of 2D Ultrasonic Vibration Incremental Forming of a 1060 Aluminum Alloy Sheet.

Currently, 1060 aluminum alloy is widely applied in the electronics industry, construction, the aerospace field, traffic engineering, decorations, and the consumer goods market for its good chemical, physical, and mechanical properties. In general, excellent processing property is necessary and important for the manufacturing of complicated panels. In this paper, a special 2D ultrasonic vibration incremental forming method is designed to improve its plasticity and mechanical properties. Three kind of processing methods, including traditional single-point incremental forming, longitudinal ultrasonic vibration incremental forming, and 2D ultrasonic vibration incremental forming, are used for the flexible manufacturing of cones and cylindrical cups of 1060 aluminum alloy sheet. Then, micro-hardness tests, residual stress tests, and scanning electron microscopy tests are carried out to probe the changes in micro-structure and mechanical properties and to analyze the effects of different types of ultrasonic vibration on the plasticity and fracture characteristic of 1060 aluminum alloy. It is proven that 2D ultrasonic vibration facilitates the improvement of plasticity and surface qualities of 1060 aluminum alloy better than the other two processing methods. Therefore, the novel 2D ultrasonic vibration incremental forming process possesses substantial application value for the flexible and rapid manufacturing of complicated thin-walled component of aluminum alloy.

Microstructure and Properties of Multilayer 5052 Aluminum Alloy Sheet by Laser Welding

Microstructure and Properties of Multilayer 5052 Aluminum Alloy Sheet by Laser Welding

Applying punching without die to micro-hole array processing

Aluminum alloy (Al6061) sheet micro-hole processing is extensively used in smartphones, tablet PC, and smart wearable devices. The micro-hole processing is commonly performed using laser, micro drilling, micropunching, micro discharge, and chemical etching technologies. Micro-punching technology is characterized by precision and rapid processing, but the precision positioning of the punch head and lower die is one of the major difficulties in micro-hole punching, especially in manufacturing array micro-holes. This study used punching without die technology. This technology uses an array punch head to punch the lower die holes on the base, then performs array micro-hole punching. The experimental results show that a micro-hole array with 37 micro-holes were successfully manufactured and can be reproduced many times. Tapered array micro-holes with a high aspect ratio can be manufactured using this punching without die technology; the micro-hole depth can be 260 μm, the inlet diameter is 116 μm, and the outlet diameter is 25 μm. This study has successfully developed the feasibility of array micro-hole punching technology.

Research on Surface Protection Technology of Aluminum Alloy Heat Sinks in Lithium Battery with Composite Anodic Oxide Film

Aluminum alloy sheets are immersed in a mixed acid electrolyte for anodic oxidation to prepare different types of anodic oxide films. The mass concentration of TiO2 nanoparticles in the electrolyte is appropriately increased, and under the action of liquid flow disturbance, the number of nanoparticles adsorbed on the surface of aluminum alloy specimens increases, which plays a good role in homogenizing current and filling, promoting more uniform film formation and inhibiting local excessive corrosion and dissolution of the anodic oxide film, Gradually generate a composite anodized film with good density. The composite anodized film constructs a protective barrier on the surface of the aluminum alloy heat sink in lithium batteries, which can effectively block corrosive media and has a better protective effect on the heat sink than conventional anodized film and mixed acid anodized film, thereby significantly improving the corrosion resistance of the heat sink.

Evolution of Fe-bearing phases during the fabrication and its effect on the mechanical properties of AA8014 aluminum alloy

The morphology of Fe-bearing phase particles has significant influences on the mechanical properties of AA8014 aluminum alloy sheets. This study aims to investigate the evolution of the morphology, size, and distribution of Fe-bearing phases during casting, homogenization, and rolling. In the paper, the effects of thermal treatment and deformation on the evolution of the Fe-bearing phases, and the mechanical properties of AA8014 aluminum alloy annealing sheet have been studied quantitatively. The main phase components in the ingot are α-Al matrix, Al6(Fe,Mn), and a small amount of Al3(Fe,Mn) and α-Al(Fe,Mn)Si. Homogenization at 630℃ for 12 h leads to the transformation of the metastable Al6(Fe,Mn) particles into stable α-Al(Fe,Mn)Si with “pore structures”. Subsequent hot rolling (75.0 mm to 7.0 mm, deformation rate of 91%) results in a significant increase in the area number density of Fe-bearing particles, accompanied by a notable decrease in average length and aspect ratio, leading to a more uniform distribution of Fe-bearing phases. Cold rolling (7.0 mm to 0.7 mm, deformation rate of 90%) or further annealing causes slight changes in the area number density and size of Fe-bearing phases. Notably, the content of α-Al(Fe,Mn)Si is minimal in the non-homogenized ingot. After hot rolling and cold rolling, the coarse Fe-bearing particles are observed in the non-homogenized sheets with 7.0 mm and 0.7 mm thickness, with a non-uniform distribution of the Fe-bearing phases. A comparative study was conducted on the mechanical properties and microstructure in final sheets with 0.7 mm thickness fabricated from homogenization and non-homogenization. The yield strength, ultimate tensile strength, elongation, and work hardening exponent in sheet with homogenization are higher due to smaller grain and Fe-bearing phase particles.

Research on incremental forming simulation based on an improved constitutive model

The incremental sheet metal forming process, characterized by the step-by-step deformation of sheet metal using a simple die, is classified as a type of plastic deformation technology. This method allows for the formation of complex-shaped parts even without the use of a specialized die. Its notable characteristic lies in its low forming load and high flexibility. To accurately forecast finite element simulation outcomes for the incremental sheet forming of 2024-O aluminum alloy sheets, constructing a precise constitutive model is essential. Typically, the uniform strain range in traditional unidirectional tensile tests does not surpass 0.3, primarily due to the necking phenomenon. This limitation hampers the accurate prediction of the actual large plastic deformation process. To address this issue, a theoretical model describing the stress-strain relationship in metal plastic deformation processes is developed using crystal plasticity theory. The constitutive model for the forming of 2024-O aluminum alloy is then constructed by adjusting the hardening coefficient and hardening index. Utilizing the improved constitutive model, the incremental sheet forming process is simulated using ABAQUS software. Upon comparison with experimental results, it is observed that the Thickness Average Absolute Relative Errors (TAARE) of the adjusted constitutive model at forming angles of 60°, 55°, and 50° are 0.414%, 0.467%, and 0.256%, and The Thickness Root Mean Square Errors (TRMSE) are determined as 0.0121, 0.0116, and 0.0094, respectively. These results indicate that the constitutive model and parameters established in this study can adequately capture the mechanical behavior of 2024-O aluminum alloy during the incremental sheet forming process.

Performance and Interfacial Microstructure of Al/Steel Joints Welded by Resistance Element Welding.

In this study, an upper sheet of an A6061 aluminum alloy and a lower sheet of Q235 steel were welded by resistance element welding with a steel rivet. The temperature field during welding was calculated using ABAQUS numerical simulation software, and the interfacial microstructure was observed. A nugget was formed between the rivet shank and the lower sheet. With increases in welding current and welding time, the tensile shear load of the joint increased first and then decreased slightly. When the welding current was 14 kA and the welding time was 300 ms, the tensile shear load of the joint reached a maximum of 7.93 kN. The smaller the distance from the position to the lower sheet along the interface between the rivet shank and upper sheet, the longer the high-temperature duration and the higher the peak temperature during welding. At the junction of the rivet shank, upper sheet, and lower sheet in the joint, the high-temperature duration was the longest, at about 392 ms, and the peak temperature was the highest, at about 1237 °C. The results show that the smaller the distance from the position to the lower sheet along the interface between the rivet shank and the upper sheet in the joint, the thicker the reaction layer generated there, and that the thickness of the reaction layer was about 2.0 μm at the junction of the rivet shank, upper sheet, and lower sheet in the joint.

Predicting the in-plane mechanical anisotropy of 7085 aluminum alloys through crystal plasticity simulations and machine learning

The crystallographic texture of rolled 7xxx series aluminum alloys may lead to mechanical properties anisotropy which undermines the formability and performance of the material. This article aims to explore the quantitative relationship between texture and the in-plane anisotropy of 7085 aluminum alloy. A comprehensive computational method combining crystal plasticity simulation with machine learning and experiment was used to establish an analytical model and train a machine learning model to predict the anisotropy of 7085 aluminum alloys. We first performed a full-field crystal plasticity spectral simulations using fast Fourier transformation (CPFFT) to predict the anisotropy of 7085 aluminum alloy at different annealing times. Then, based on the CPFFT simulation data, the quantitative relationship between texture and the in-plane anisotropy of the r-value was established by using the multiple linear regression and gradient boosting regressor model. The results indicate that CPFFT simulation can effectively capture the influence of texture changes on anisotropy, and the model established through the gradient boosting regressor model is in good agreement with experimental results, providing effective guidance for improving the performance of 7085 aluminum alloy sheets.

Numerical simulation and defect prediction of forming process for aluminum alloy sheets considering the effect of both anisotropy and lode parameter

Traditional GTN meso-damage model, neglecting the effect of anisotropy or shearing on the evolution of microvoid, leads to the lower predictive capabilities of forming defects for aluminum alloy sheets. In this paper, a modified constitutive model of aluminum alloy sheet considering the effect of both anisotropy and shearing is proposed, and the corresponding model parameters are calibrated by inverse finite element method and uniaxial tensile test of the smooth strip sheet without hole. Then, the constitutive equation of the modified model is compiled into a VUMAT subroutine using backward Euler integration algorithm and FORTRAN language to perform subsequent numerical simulation in ABAQUS/Explicit, the validity of the proposed shear-corrected GTN model is also verified through the uniaxial tensile experiment of the strip sheet with a hole in the middle. Finally, finite element (FE) model of the mould-sheet coupling system is developed based on the modified GTN model, and the influence of punching speed, blank holder force, friction coefficient and dwell time on the forming performance of AA5052 aluminum alloy sheet is investigated. The results show that ductile fracture of aluminum alloy sheet is most prone to exist on the upper fillet of part.

Investigation on the Effect of Blank Holder Force and Initial Blank Size on the Thinning Problem of the Fuel Tank Part Made from Aluminum Alloy Sheet 5754-O under Deep Drawing Process

Deep drawing process is a common sheet metal forming technique in motor vehicle manufacturing. There are three primary defects that could be occur in deep-drawn parts: tearing, wrinkling, and thinning. When the thinning is difficulty detected by visual inspection. As a result, this study aims to address the thinning issue in a fuel tank part made from an aluminum alloy sheet AA5754-O 1.5 mm thick under cold working deep drawing process, while the manufacturer's desired upper limit for thinning is 20%. Two influential parameters viz. blank holder force and initial size of blank, were investigated and optimized by using Finite Element Analysis (FEA) through PAM-STAMP simulation software with the validated material model was based on Hill’s 1948 anisotropic yield criterion with Swift hardening law. The mechanical parameters in the mentioned model were derived from the results of uniaxial tensile tests. In conclusion, both the hydraulic cushion's blank holder pressure and the initial size of the blank were found to influence the thinning of the part, either individually or in combination. Despite optimizing both parameters, they were unable to consistently achieve the desired limit.

A NEW TYPE OF PLUG-IN FRICTION-STIR LAP WELDING BASED ON THE 6061-T6 ALUMINUM ALLOY

In this study a new type of plug-in friction-stir lap welding (PFSLW) is proposed to prepare welded joints based on 4-mm-thick 6061-T6 aluminum alloy sheet. The differences in the cross-sectional morphology, microstructure, cross-sectional hardness and shear properties between the PFSLW joint and the normal friction-stir lap-welding (FSLW) joint are discussed. The results show that the cross-sectional morphology of the PFSLW joint has undergone changes. The PFSLW joint has a mechanical interlocking structure on the advancing side that is beneficial to the connection strength of the joint. The grain structure differs at the boundary between the thermo-mechanically affected zone (TMAZ) and the heat-affected zone (HAZ), and the PFSLW joints show a more pronounced bending deformation of the grain organization near the boundary. The microhardness of PFSLW joints was increased in the TMAZ and HAZ areas, and the lowest hardness is further away from the center of the weld. The failure load of the PFSLW joint has been improved, the microcracks part of the PFSLW joint has a ridge-like structure. In addition, the actual welding width of PFSLW joints was improved.

Expression of concern “An investigation on fatigue behavior of AA2024 aluminum alloy sheets in fuselage lap joints” [Eng. Fail. Anal. 126 (2021) 105457

Expression of concern “An investigation on fatigue behavior of AA2024 aluminum alloy sheets in fuselage lap joints” [Eng. Fail. Anal. 126 (2021) 105457

Development of FSW Process Parameters for Lap Joints Made of Thin 7075 Aluminum Alloy Sheets.

The article describes machine learning using artificial neural networks (ANNs) to develop the parameters of the friction stir welding (FSW) process for three types of aluminum joints (EN AW 7075). The ANNs were built using a total of 608 experimental data. Two types of networks were built. The first one was used to classify good/bad joints with MLP 7-19-2 topology (one input layer with 7 neurons, one hidden layer with 19 neurons, and one output layer with 2 neurons), and the second one was used to regress the tensile load-bearing capacity with MLP 7-19-1 topology (one input layer with 7 neurons, one hidden layer with 19 neurons, and one output layer with 1 neuron). FSW parameters, such as rotational speed, welding speed, and joint and tool geometry, were used as input data for ANN training. The quality of the FSW joint was assessed in terms of microstructure and mechanical properties based on a case study. The usefulness of both trained neural networks has been demonstrated. The quality of the validation set for the regression network was approximately 93.6%, while the errors for the confusion matrix of the test set never exceeded 6%. Only 184 epochs were needed to train the regression network. The quality of the validation set was approximately 87.1%. Predictive maps were developed and presented in the work, allowing for the selection of optimal parameters of the FSW process for three types of joints.

Portevin-Le Chatelier characterization of annealed Al-Mg alloy sheets with different Mg contents

The stress-strain flow curves of solid solution treated and annealed Al-(2.86-9.41)Mg aluminum alloy sheets were investigated during tensile process at room temperature at a strain rate of 1 × 10−3 s−1, in order to reveal the effect of solute Mg atoms and β-phase nanoparticles in the α-Al matrix on their Portevin-Le Chatelier (PLC) characteristics. The results show that with the increase of Mg contents of alloys, the concentration of solute Mg atoms and the volume fraction of β-phase nanoparticles in the α-Al matrix of the annealed alloy sheets increase. The β-phase nanoparticles promote the PLC effect during the tensile process, causing the increase of stress drop amplitude Δσ of the tensile curves of the alloy sheets. However, the β-phase nanoparticles have little influence on the strain period ΔεTmax of rectangular waves. The flow strain difference Δεc−σ between the yield point and the beginning of PLC effect decreases monotonically from 5.4 × 10−4 to 5 × 10−5 as the Mg contents of alloy sheets increase from 2.86 wt.% to 9.41 wt.%. The strain period ΔεTmax of the rectangular waves corresponding to the high flow stress and stress drop amplitude Δσ obtained for the serrated stress-strain curves of the alloy sheets gradually increase with the increasing Mg contents of alloy sheets.

Investigation of structure–flexural response relations in thermoplastic carbon/glass fiber‐metal laminates

AbstractIn the current work, fiber‐metal laminates (FMLs) consisting of alternated continuous fiber‐reinforced thermoplastic composite layers and aluminum alloy sheets were proposed by the hot‐pressing method. Carbon fiber‐reinforced polyamide 6 (PA6/CF) and glass fiber‐reinforced polypropylene (PP/GF) prepregs were selected as composite layers. The effect of the assembly method between composite prepreg and aluminum sheets as well as the stacking configurations on the flexural response of FMLs were investigated. Meanwhile, the macro and micro‐structural observations were performed to characterize failure mechanisms in these structures. Experimental results revealed that the strength and stiffness of hybrid FLMs depended on the material property on the surface layer. With the stacking sequence of aluminum sandwiched by PA6/CF achieved the highest flexural strength of 535.3 MPa and modulus of 63.6 GPa in the series of FMLs, which could achieve satisfied lightweight and strength‐stiffness properties. The ductile deformation of aluminum sheets and fracturing and pulling out of the fibers were the main characterized failure mechanisms of thermoplastic FMLs. For glass fiber‐metal laminates, stacking configurations of three aluminum sheets alternation with four PP/GF intermediate layers achieved a favorable flexural property. Above all, the proposed thermoplastic FMLs have great potential in civil applications especially in the automobile industry as structural parts.Highlights Thermoplastic fiber‐metal laminates are designed and fabricated. The assembly method and stacking sequences influence the flexural property. FMLs with PA6/CF and aluminum achieve satisfied strength stiffness. PP/GF prepreg and aluminum layer display ductile deformation mode.

Cut surface characteristics of aluminum alloy sheet in cryogenic shearing process

Die cutting is a well-known process of sheet metal forming for separating sheet metal into the required shape. Compared with other cutting processes such as machining, this process has the advantages of a high production rate and low production cost. Currently, as a necessary process in sheet metal manufacturing, this process has been researched to improve the efficiency of the process and quality of cut components. In this study, the application of cryogenics in the die-cutting process was investigated, and the characteristics of the cut surfaces were examined. The shearing process was investigated using a die-cutting model. An aluminum alloy grade A5083 (JIS standard) was used as the workpiece. After shearing, the physical characteristics of the cut surfaces were examined using a 3-D laser scanner. Shear forces were also reported. The grain evolution in the shearing zone was also investigated. The results revealed that compared with the shearing process at room temperature, the ratio of clean cut to workpiece thickness was slightly increased. However, they showed differences in fracture characteristics. A concave feature in the fracture zone was generated at the cryogenic temperature, particularly for small clearances. These results were clearly explained based on the initial fracture angle and its propagation, and grain evolution. Based on the changes in the material properties at cryogenic temperatures, an elongated grain structure was easily generated, resulting in a larger initial fracture compared with that of the shearing process at room temperature. This is important when using the cut component, as the strength of the cut part decreases owing to the larger concave features. In addition, it provides helpful information on cut components that may require additional operations.

Research on joint strength and energy absorption of CFRP and Al sheets bonded-FDS hybrid joining

The application of a composite-metal alloy lightweight body structure is one of the ways to achieve lightweight in an automobile. Materials such as carbon fiber reinforced polymer (CFRP) and aluminum alloys are widely used in the automotive industry due to their excellent performance. However, the significant differences in performance parameters between CFRP and aluminum alloy materials make joining heterogeneous materials challenging. Therefore, a rational joining process is crucial for the development of CFRP–aluminum alloy structures. This study proposes a hybrid joining method that combines flow drill screw (FDS) and adhesive bonding to join commonly used aluminum alloy sheets with CFRP sheets in automotive body manufacturing. Finite element analysis simulations were used to compare and characterize the failure modes of the bonded-FDS hybrid joints in tensile tests. The results were verified for accuracy. Tensile tests were conducted to compare the mechanical performance and failure modes of bonded joints, FDS joints, and hybrid joints. By analyzing the load–displacement curve, it was found that the FDS process in the hybrid joining damages the internal structure of the adhesive layer. However, the joint strength is still higher than that of the single joint strength, and the energy absorption value is about 4.7 times that of the adhesive and 1.6 times that of the FDS. This study provides a new industrial solution and serves as a reference for failure performance in composite material structures in the automotive industry, especially in cases involving one-sided access joining points.

Effect of Process Parameters on Joint Performance in Hot Pressure Welding of 6061 Aluminum Alloy to CF/PA66.

Polymer-metal hybrid structures combine the merits of polymer and metal materials, making them widely applicable in fields such as aerospace and automotive industries. However, the main challenge lies in achieving efficient and strong connections between the metal and polymer components. This paper uses the jet electrochemical machining (Jet-ECM) method to customize the surface morphologies on 6061 aluminum alloy (AA6061) sheets. The connection between AA6061 and carbon fiber-reinforced PA66 (CF/PA66) is then achieved through hot pressure welding (HPW). The effects of aluminum alloy surface morphology, welding force, and welding time on the mechanical properties and microstructure of the joint are investigated. The optimal process parameters are determined by the design of the experiment. The results show that the aluminum alloy surface morphology has the greatest impact on the mechanical property of the welded joint. The optimal process parameters are surface morphology with wider, shallower, and sparsely distributed grooves on the aluminum alloy surface, the welding force is 720 N, the welding time is 12 s, the welding temperature is 360 °C, the cooling time is 16 s, and the optimal peak load of the joint is 6690 N. Under the optimal parameters, the fracture morphology in the AA6061 side is almost entirely covered with CF/PA66. The joint experiences cohesive failure in most areas and fiber-matrix debonding in a small area.