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This paper presents a numerical study of topology-optimised pin-end aluminium alloy columns using finite element analysis (FEA). The FEA models integrate geometric imperfections and material nonlinearity, and are validated against experimental findings from the existing literature. ABAQUS v.6.15 (release 2020) is used in preparing the FEA models and obtaining the analysis results. Furthermore, modern design methodologies including Eurocode 9, the direct strength method (DSM), and the continuous strength method (CSM) are employed to assess the maximum load capacity of such columns. Parametric investigations encompass diverse parameters such as varied cross-sections, column lengths, and global and local imperfections. By analysing a total of 288 FE models, incorporating 16 column cross-sections across two lengths with nine distinct imperfections, this study compares results with those derived from modern design methodologies. Thus, this research elucidates the behaviour of novel cross-sections and the application of contemporary design techniques in their analysis. [ABSTRACT FROM AUTHOR]

The inherent instability of laser welding, particularly keyhole instability, poses significant challenges in industrial applications, leading to defects such as porosities that compromise weld quality. Various forces act on the keyhole and molten pool during laser welding, influencing process stability. These forces are categorized into those promoting keyhole opening and penetration (e.g., recoil pressure) and those promoting keyhole collapse (e.g., surface tension, Darcy's damping forces), increasing instability and defect likelihood. This paper provides a comprehensive instability analysis to uncover key factors affecting keyhole and process instability, presenting future avenues for improving laser welding stability. Using a novel numerical method for simulating laser spot welding on aluminum with COMSOL Multiphysics 5.6, we investigated the effect of laser pulse shaping on keyhole and process instability. Our analysis focused on keyhole morphology, fluid flow behaviour, and force analysis. The results indicated that the curvature effect, Marangoni effect, and Darcy's damping force are primary contributors to instability, with the curvature effect and Darcy's damping force being the most dominant. Additionally, erratic and high-velocity magnitudes induce intense fluid flow behaviour, exacerbating keyhole instability. Moreover, single/quadruple peak triangular and variant rectangular ramp-down pulse shapes produced the least instability, while multi-pulse rectangular shapes exhibited intense instability. It was found that combining triangular/rectangular pulse shapes can reduce force and keyhole instability by smoothing spontaneous force spikes, resulting in a more stabilized welding process. Controlling fluid flow and abrupt force changes with appropriate pulse shaping is key to defect-free welded products. [ABSTRACT FROM AUTHOR]

In the impact application, the impactor doesn't have to be perpendicular to the structure. This study mainly focuses on numerical low velocity oblique impact analysis performed on silicon aluminum composite foam using ABAQUS®. In this paper, the shear failure model is used to estimate damages in silicon aluminum composite foam model for different angles of the impactor. Here, dissipation energies, impact load histories and load displacement curves for damages under different angles of impactor have been characterized. From the study, it is found that the contact force intensity and penetration time decrease as the angle of the impactor increases. In the study of energy time histories, it is seen that energy increases and penetration time decreases as the angle of the impactor increases. From the contact force study, it is found that the contact force decreases, and contact time increases as the angle of the impactor decreases. The studies for displacement show that oblique impactor displacement increases as the angle of the impactor increases. [ABSTRACT FROM AUTHOR]

In this study, we successfully obtained crystalline silicon from silica powder using a metal-induced crystallization method. For this purpose, powders were first prepared from organosilicon compounds and finely dispersed aluminum particles, then their metal-induced crystallization was carried out by annealing at the temperature of 570 °C. Powders of organosilicon compounds (tetraethoxysilane and polyethylhydrosiloxane) were prepared by different technological operations in order to determine precisely the presence of carbon in the product. The results showed that the presence of carbon in silica powder affects the production of crystalline silicon. In silica powders containing no carbon, the formation of crystalline substances does not occur at the annealing temperature of 570 °C. The results of this study are of great importance for the production of polycrystalline silicon powders obtained at reduced temperatures. [ABSTRACT FROM AUTHOR]

The shape and structure of helicopter fuselage are complex, and it is difficult for a finite element method (FEM) to investigate helicopter fuselage projectile damage in a multi-projectile environment. An efficient analysis method for helicopter fuselage projectile damage is then proposed by coupling the projectile breakdown theory, which is derived from the existing empirical formula for penetrating ductile metals, and the model of projectile impact. Then, the characteristics of the helicopter fuselage impact coordinate, residual velocity, and fuselage damage area under a multi-projectile attack are investigated. The results show that the predicted residual velocities agree with the experiments. The maximum errors of the residual velocity and the fuselage damage area are 4.7% and 9.56%, respectively. Compared with the FEM, the computational time of the proposed method is reduced by 92.1%, and its efficiency is obviously improved. As the incidence angle increases, the residual velocity decreases, and the damage area increases. When the incidence angle of the projectile body is large, the projectile body cannot penetrate the surface of the fuselage, resulting in flume skid damage and a large area of damage. [ABSTRACT FROM AUTHOR]

Aluminum metal matrix composites find applications in several industries, such as aerospace, military, cars, sports equipment, and electronics. The primary objective of this experimental study is to obtain insights into the microstructural properties of an Al-Zn alloy that has been strengthened with copper. This investigation involved the preparation of an alloy including aluminum and zinc, which was afterward reinforced with varying quantities (0%, 0.4%, 1.2%, and 2%) of copper. In addition to conducting XRD tests to investigate the crystallite structure, particle size, and microscopic strain of the samples using the Scherrer and Williamson-Hall models, structural examinations were carried out using the EDS test to ascertain the elemental composition proportions. It was observed that the alloy (A-Zn-0.4%Cu) has smaller particle sizes than the other alloys under consideration. [ABSTRACT FROM AUTHOR]

The simultaneous increase in strength and plasticity of aluminum and its alloys at cryogenic temperatures has been shown in previous research, but the deformation mechanism was still unclear. Therefore, the purpose of this investigation was to reveal the relationship between slip behavior and mechanical response at low temperatures. A quasi-in situ scanning electron microscope was used to observe the evolution of slip bands in the selected aluminum single crystals with two typical orientations at 25 °C, −100 °C, and −180 °C. The results showed that irrespective of orientation, the density of the slip plane was increased with the decline in temperature, which inhibited slip localization and significantly improved plasticity and work hardening. In detail, at RT, the slip bands were widening until the micro-cracks were generated, causing early failure during deformation. When the temperature was decreased to −180 °C, the slip plane density was increased, and the deformation was more homogenous. Moreover, the slip mode was influenced by orientation and temperature. In particular, a single slip system was activated in the sample with the [112] orientation at all the temperatures investigated. Multiple slip systems were found to activate at 25 °C and −100 °C, and only the primary slip system was activated in the sample with [114] orientation at −180 °C. These findings deepen the understanding of slip behavior at cryogenic temperatures, providing new insights into the deformation mechanism of aluminum and its alloys. [ABSTRACT FROM AUTHOR]

Due to the coexistence of Al3+ and RE3+ and their similar properties, the separation of aluminum from rare earths is difficult. In this study, selective precipitation was used to separate aluminum from rare earth chloride solution via electrochemical regulated hydrolysis. By controlling the current density and electrolytic time, the rate of hydroxyl ion production was regulated, and the selective separation of rare earth and aluminum was realized according to the different precipitation sequences. By altering the temperature, current density, pH value, and other parameters, the separation performance of aluminum from rare earth in mixed rare earth chloride systems was systematically investigated. The removal rate of aluminum reached 88.35%, and the loss rate of rare earth was only 5.99% under optimized conditions. Compared with traditional neutralization hydrolysis, the new process showed higher efficiency and lower rare earth loss rate. Furthermore, a kinetic analysis of aluminum precipitation revealed that the reaction adhered to pseudo-first order kinetics. Additionally, the precipitate obtained via separation and filtration was amorphous alumina hydroxide with a small amount of rare earth attached. No reagent was consumed for the new process, which was more efficient and cleaner, providing a new idea for removing aluminum impurities from rare earth solutions. [ABSTRACT FROM AUTHOR]

Aluminum alloy offers the advantages of being lightweight, high in strength, corrosion-resistant, and easy to process. It has a promising application prospect in large-span space structures, with its primary application form being single-layer reticulated shells. In this study, shaking table tests were conducted on a 1/25 scale aluminum alloy single-layer spherical reticulated shell structure. A finite element (FE) model of the reticulated shell structure was established in Ansys. Compared with the experimental results, the deviation in natural frequency, acceleration amplitude, and displacement amplitude was less than 20%, confirming the validity of the model. An extensive analysis of the various rise–span ratios and connection constraints of a single-layer spherical reticulated shell structure was carried out using the proposed FE model. The experimental and simulation results showed that as the rise–span ratio of the aluminum alloy reticulated shell increases, the natural frequency of the reticulated shell structure also increases while the dynamic performance decreases. The connection of the circumferential members changes from a rigid connection to a hinged connection. The natural frequency of the reticulated shell structure is reduced by about 40% while the acceleration and displacement response values are decreased by approximately 15%. [ABSTRACT FROM AUTHOR]

Xerogels and powders of solid solutions based on zirconium dioxide are synthesized by the method of the coprecipitation of hydroxides from aqueous solutions of nitrate salts of zirconium, yttrium, aluminum, and cerium with an aqueous solution of ammonia. The characteristics of the resulting materials are studied. The influence of stabilizers and additives on their synthesis, sintering, and properties is assessed. [ABSTRACT FROM AUTHOR]

Stearic and phenyl-phosphonic acids were applied to fine aluminum particles to understand their effect on the surface chemical composition and bulk properties of the surface-treated powders. During the solution phase deposition process, the surface composition changes chemically through a condensation reaction between the acid and particle surface hydroxyl groups, forming covalent chemical bonds. The retention of both types of acids was verified through characterization using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The presence of stearic acid on the particle surface was observed through signature absorbance peaks, including interfacial C-O bonding modes, carboxylate, and carbonyl moieties, all present on both the treated powder. Spectra using XPS showed an increase in -CH relative intensity signal on the particle surface when compared to the raw material when considering the the carbon 2p photoelectron peak. Similar findings confirmed the presence of the phenyl-phosphonic acid when comparing to the raw material. The IR spectrum confirmed the presence of P-O-Al, P-O, and phosponates as a result of the surface bonding between the reagent and particles. XPS always provided evidence through the presence of phosphorous 2p and 2s photoelecton peaks at 191.3 and 133.4 eV, respectively. The bulk properties of both surface treated powders improved, as shown through improved apparent/tap density and a decreased Hausner Ratio (Group C to Group A behavior). Rheological characterization provided additional evidence by showing a reduced specific energy, flow rate index, and cohesion. The particle packing was improved as evidenced through reduced compressibility as a function of applied normal stress. [ABSTRACT FROM AUTHOR]

Microelectromechanical systems (MEMS)-based filter with microchannels enables the removal of various microorganisms, including viruses and bacteria, from fluids. Membranes with porous channels can be used as filtration interfaces in MEMS hemofilters or mini-dialyzers. The main problems associated with the filtration process are optimization of membrane geometry and fouling. A nanoporous aluminum oxide membrane was fabricated using an optimized two-step anodization process. Computational strength modeling and analysis of the membrane with specified parameters were performed using the ANSYS structural module. A fuzzy simulation was performed for the numerical analysis of flux through the membrane. The membrane was then incorporated with the prototype for successive filtration. The fluid flux and permeation analysis of the filtration process have been studied. Scanning electron microscope (SEM) micrographs of membranes have been obtained before and after the filtration cycles. The SEM results indicate membrane fouling after multiple cycles, and thus the flux is affected. This type of fabricated membrane and setup are suitable for the separation and purification of various fluids. However, after several filtration cycles, the membrane was degraded. It requires a prolonged chemical cleaning. High-density water has been used for filtration purposes, so this MEMS-based filter can also be used as a mini-dialyzer and hemofilter in various applications for filtration. Such a demonstration also opens up a new strategy for maximizing filtration efficiency and reducing energy costs for the filtration process by using a layered membrane setup. [ABSTRACT FROM AUTHOR]

The production and study of highly dispersed aluminum-based powders represents one of contemporary science's priority fields. This is primarily driven by the practical necessity to develop new materials, a feat that, in some cases, can only be achieved through the utilization of powdered components. This article presents the results of the mechanochemical treatment method employed to obtain highly reactive aluminum particles. It also includes a comparative analysis of aluminum particles generated through various methods and their respective properties. Furthermore, the application of these highly reactive aluminum particles in energy-intensive materials is discussed. [ABSTRACT FROM AUTHOR]

Combined with the oxidizer anions and fuel cations, molecular perovskite energetic materials show a good potential. In this work, the combustion behavior and mechanism of metal fuel aluminium (Al) with molecular perovskite energetic material (H2dabco)[NH4(ClO4)3] (DAP-4) as a high-energy oxidant was investigated. The DAP-4 based composites with metal fuel Al were designed and fabricated by the different mass ratios. Results showed that DAP-4 exhibits a good oxygen-supplied capacity for enhancing the combustion performance of Al. The maximum combustion heat of DAP-4/Al-3 at the Al/O mass ratio of 38:62 is up to 10,412 J/g in the inert gas, which is higher than those of other ratios and the mixtures of other energetic materials and Al. The evolution of pressure output, pressurization rate, and flame temperature was monitored for DAP-4/Al with different mass ratios. Composites DAP-4/Al/F were characterized by burning rates. The combustion reaction mechanism of metal fuel Al with DAP-4 as a high-energy oxidant was provided. DAP-4 was ignited firstly and released acid and oxidizing gases, which corroded Al2O3 shells on Al particle surfaces and accelerated the combustion reaction with Al to release a lot of energy. This work offered a new idea that molecular perovskite energetic materials have great potential in the high-energy Al-based solid rocket propellants. [ABSTRACT FROM AUTHOR]

The charging modules of Electric vehicles (EVs) always run in a complex and variable state. As the weakness in the reliable operation of charging modules, the accurate lifetime prediction of aluminum electrolytic capacitors (Al-caps) is important for the later maintenance and reliability design. The hotspot temperature calculation method and lifetime model limit the accuracy of aluminum electrolytic capacitors lifetime prediction methods, which cannot meet the increasing requirements for reliability. In order to solve the problems above, this paper has proposed a hotspot temperature calculation method based on the ripple current with frequency characteristics and the cooling conditions on the heat generation and thermal conductivity of the capacitors. Furthermore, the lifetime model under reference voltage has been constructed with 3D surface fitting toolbox, which describes the trends of capacitor lifetime with ambient temperature and hotspot temperature under the constant voltage condition. Considering the variation of voltage, the multiple lifetime model of capacitor is established with a voltage correction coefficient. With the proposed method, it can be realized about the real-time lifetime prediction of capacitors under multiple operating profiles such as ripple current, thermal dissipation conditions, ambient temperature and operating voltage. Finally, the effectiveness of the proposed method is verified with the annual profiles of a 30 kW EV charging module. [ABSTRACT FROM AUTHOR]

This research paper presents a study and a numerical investigation on the effect of the thickness of the samples on the crack growth as well as the phenomenon of fatigue. As well as the type of alloy used to withstand these physical deformations. Types of samples were designed from aluminum alloys 2024 and 7085 and compared with each other in bearing crack growth as well as the phenomenon of fatigue. The thermal effect was also seen on it by adjusting the temperature value in two cases, 20°C and 40°C. Where an additional processor was added to the Ansys program, which worked on the growth of the crack in a manner consistent with the phenomenon of fatigue. Where a pressure value of 4.8 MPa was applied from one side of the sample and it was fixed from the other side, where a time of 8000 s was taken. Where the results showed that the maximum deformation that was reached was 0.56 mm in the case where the thickness of the sample was 5 mm and the type of metal was aluminum alloy 7085. The value of bone deformation at a thickness of 5 mm is 0.66 mm, which is the highest value of deformation compared to the other cases. Aluminum alloy 7085 has reached a crack growth of 7.5 mm during 2777 cycles. While alloy 2024 has reached the same crack growth during 32784 cycles. The true meaning of the difference in properties between alloys can only be understood by comparing the mechanical properties of different alloys. Comparison of aluminum alloy 6061 with case with 3 mm primitive crack growth and 90 degree crack angle. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) are largely used in defense, maritime, and space applications for their excellent properties. LM5 is used where very high resistance to corrosion from seawater or marine atmospheres is required, for equipment used for the manufacture of foodstuffs, cooking utensils, and chemical plants. Zirconia is preferred over other reinforcements as it shows comparatively great refractory properties, high scratch resistance, and thermal shock resistance. Utilizing the stir casting technique, an attempt was made to produce AMCs of LM5 aluminum alloy strengthened with ZrO2. The weight percentage of ZrO2 was changed to 0%, 3%, 6%, and 9%. The specimens were prepared and tested as per ASTM standards to find the density, micro and macro hardness, impact, tensile, and compressive strength. The micrographs and SEM images confirm the uniform distribution of ZrO2 particles in the aluminum matrix. LM5/9%ZrO2 AMC has the highest density value of 2.83 g/cm3 and LM5/3%ZrO2 has the least porosity of 2.55%. LM5/9% ZrO2 has the highest hardness values of 78 VHN and 72 HRE. LM5/6% ZrO2 AMC has the highest tensile strength of 220 MPa, compressive strength of 296 MPa, and toughness of 12 J. LM5/6% ZrO2 AMCs may be used for many structural applications. [ABSTRACT FROM AUTHOR]

Rapid and accurate analysis of element concentrations in aluminum alloys is crucial due to their widespread use in modern industry. This paper proposes a one-point and multiline calibration fiber-optic laser-ablation spark-induced breakdown spectroscopy (OP-MLC FO-LA-SIBS) for the quantitative analysis of elements in aluminum alloys. The experimental system utilizes a compact fiber laser as the laser-ablation source and spark discharge to enhance the atomic emission. A portable multichannel fiber spectrometer is used to quickly collect spectra in the nongated mode. The concentrations of four elements (Mg, Cr, Cu, and Mn) in four aluminum alloy samples were calculated using the simple and efficient OP-MLC method, which involves taking another sample with a similar matrix as the standard sample. The average relative errors (AREs) for Mg, Cr, Cu, and Mn were 6.38%, 28.09%, 21.92%, and 18.97%, respectively. When the certified concentrations are greater than 0.02 wt.%, the ARE is only 13.04%. The OP-MLC FO-LA-SIBS system is compact, features simple spectra processing, and offers effective measurement, providing a convenient method for rapid and efficient quantitative analysis of elements in aluminum alloys in industrial production. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to compare the radiopacity of calcium silicate cements using a digital imaging method. Methods: Four calcium silicate cements, NeoMTA 2, OrthoMTA, ProRoot MTA, and Biodentine, were used in this study. Disk-shaped samples were prepared from each material and placed on a plexiglass plate. An aluminum step-wedge was placed alongside the samples on a digital sensor and exposed to 70 kVp and 8 mA from 30 cm away for 0.32 s. The greyness values ​​of the tested materials were measured digitally with the system software and compared with those of the step-wedge to determine the equivalent aluminum thickness. Results: The radiopacity values, expressed in equivalent millimetres of aluminum, of the studied materials ProRoot MTA, OrthoMTA, NeoMTA 2, and Biodentine were 4.32 ± 0.17 mm Al, 3.92 ± 0.09 mm Al, 3.83 ± 0.07 mm Al, and 2.29 ± 0.21 mm Al, respectively. Statistically significant differences were found between the mean radiographic density values of the tested materials (p < 0.05). Conclusion: ProRoot MTA was the most radiopaque root canal filling material among the tested materials. All materials, except Biodentine, were found to be compliant with the minimum radiopacity requirements of ISO 6876 and ADA 57 standards. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) technique is employed for quantitative analysis of aluminum samples by different classical machine learning approaches. A Q-switch Nd:YAG laser at a fundamental harmonic of 1064 nm is utilized for the creation of LIBS plasma in order to predict constituent concentrations of the aluminum standard alloys. In the current research, concentration prediction is performed by linear approaches of support vector regression (SVR), multiple linear regression (MLR), principal component analysis (PCA) integrated with MLR (PCA–MLR), and SVR (PCA–SVR), as well as nonlinear algorithms of artificial neural network (ANN), kernelized support vector regression (KSVR), and the integration of traditional principal component analysis with KSVR (PCA–KSVR), and ANN (PCA–ANN). Furthermore, dimension reduction is applied to various methodologies by the PCA algorithm in order to improve the quantitative analysis. The results indicated that the combination of PCA with the KSVR algorithm model had the best efficiency in predicting most of the elements among other classical machine learning algorithms. [ABSTRACT FROM AUTHOR]

Pinus massoniana is an important timber tree species in southern China, and acid aluminum stress seriously endangers its growth. This study focuses on physiology, gene regulation and root exudates. Aluminum stress increased the activity of malondialdehyde (MDA), proline (PRO), peroxidase (POD), soluble proteins (SP), soluble sugars (SS) and superoxide dismutase (SOD) in P. massoniana seedlings, and led to changes in growth. We identified hub genes (UCHL3, TCP1, SEC27, GluRS and ACTF) responding to aluminum stress of low concentration and hub genes (RGP, MPT, RPL24, RPL7A and EC3.2.1.58) responding to aluminum stress of high concentration. Aluminum stress mainly affected phenylpropanoid biosynthesis and flavonoid biosynthesis, and it may alleviate aluminum toxicity by inducing the upregulation of genes such as CHS, COMT, DFR and LAR to enhance root exudation of catechin. These results lay the foundation for in-depth studying the molecular mechanism of P. massoniana aluminum stress. [ABSTRACT FROM AUTHOR]

Dynamic spatial distribution and evolution of three-dimensional (3D) voids/cracks in engineering materials are crucial information to predict fatigue damage and residual life. A method of fatigue damage analysis was proposed and used to estimate low-cycle fatigue damage. First, multi-stage fatigue damage defects were measured based on x-ray computed tomography (XCT). 3D voids/cracks were reconstructed and analyzed by VG Studio and Diego algorithm. Then, 3D voids/cracks were transferred into finite element model along with material domain for numerical analysis. Thirdly, the damage transformation process was achieved by means of 3D finite element analysis. And the numerical and experimental results were compared. The estimated damage variables in terms of effective elastic modulus were in agreement with experimental results. It is indicated that the proposed numerical prediction method is valid for damage evolution in low-cycle fatigue. [ABSTRACT FROM AUTHOR]

In the present work, the feasibility of using aluminum pipes for irrigation in agricultural fields for reuse on a farm as underground canalization is analyzed. Due to the need to have a group of grain mills, it is necessary to build a new electrical branch in the installation, and due to limitations it is essential that the new pipeline be buried. Therefore, the finite element method is used to analyze the behavior of three conductors within the aluminum duct. Taking into account the effects of the magnetic field in the aluminum material and the eddy currents that are formed, which increase the losses in the energy distribution. The analysis of the behavior of electrical losses within the pipeline, it was studied how the proximity of the conductors to the pipe wall affects and the changing the distribution of the conductors inside the pipe was also verified. [ABSTRACT FROM AUTHOR]

The aluminium alloy front subframe of an automobile was developed through multi-operating condition topology optimization and multi-objective optimization methods. By considering the influences of loads on the strength, static stiffness, and modal of the aluminium alloy front subframe under typical operating conditions, the performance parameters of the aluminium alloy front subframe after topology optimization were obtained. After topology optimization was performed, the parametric model of the aluminium alloy front subframe was established. Based on the Isight optimization platform, sample points were generated with the optimal Latin hypercube test method, and the response surface approximate model was constructed. The minimum mass and maximum first-order frequency were taken as the objectives, the stress under typical working conditions did not exceed the set target value, and the maximum displacement of the installation point was taken as the constraint condition. The multi-objective particle swarm optimization algorithm was used to optimize the aluminium alloy front subframe. The error of the free modal and finite element free modal analysis of the aluminium alloy front subframe samples was less than 15%. The optimized aluminium alloy front subframe was 2.4 kg lighter than the original subframe under the premise of satisfying various performance indices, and the lightweight rate was up to 12%. [ABSTRACT FROM AUTHOR]

The application potential of aluminium conductor composite core (ACCC) conductors in the 1000‐kV power transmission line project deserves to be investigated. Its economic evaluation is a contentious issue. This paper proposes a method for selecting the type of conductors based on the life cycle cost (LCC) of a transmission line, which includes the initial investments, operation costs, maintenance costs, failure costs, and discard costs. The mathematical model of electromagnetic loss differs due to the various operational circumstances surrounding a transmission line; therefore, a novel three‐dimensional electromagnetic–fluid–thermal coupling model based on the finite element method (FEM) was proposed. The simulation error of ACCC and aluminium conductor steel reinforced (ACSR) conductors is 2.56% and 0.5%, respectively, compared to the experimental value. Subsequently, the LCC model is applied in the economic analysis of a 1000‐kV transmission line, and the costs of ACCC conductors and ACSR conductors under different annual power load utilization hours are calculated. The results indicate that the overhead power transmission line with ACCC conductors saves at least 2 × 106 ¥/km compared with ACSR when annual utilization hours reach 3500 h; meanwhile, energy saving benefits are achieved. [ABSTRACT FROM AUTHOR]

This research focused to synthesize the material by the tungsten inert gas (TIG) welding process with support of appropriate flux coating material. Therefore the required amount of flux coating material was utilized to enhance the mechanical properties of the specified localized welded regions. Hence, this study concentrated to select the nano-SiO2 flux particles that were employed for TIG process. This activated TIG welding composes the flux-coated welding on the base metal of AA5083-H111, as this material was highly reactive with SiO2 by the presence of magnesium precipitates and well synthesized after the welding. The post- and preheat treatment process was achieved before and after welding. The selection of activated TIG process parameters composed of strengthened weld specimens along with constant parameters like electrode tip angle and flow rate, respectively. Initially, the process parameters were designed by the statistical analysis of Box Behnken method with support of regression formulation to determine the optimal solution. The maximum tensile strength was attained at the welding process parameters of welding speed (100 mm/min), voltage (13 V), and current (125 amps). The higher hardness was achieved at the process parameters of welding speed (80 mm/min), voltage (12 V), and current (125 amps), respectively. Finally, the neural network approach was utilized to verify the predicted responses of tensile and microhardness properties. The interaction plots, mean plots, and 3D scatter plots were influenced to enhance the process parameters. In this research, mechanical properties were enhanced by the flux-coated SiO2 and the analytical method also advances the optimal parameters. [ABSTRACT FROM AUTHOR]

Agglomeration of distributed particles is the main problem in polymer composites reinforced with such particles. It leads to a decrease in mechanical performance and its poor reproducibility. Thus, development of methods to address the agglomeration of particles is relevant. Evaluation of the size and concentration of agglomerates is required to select a method to address agglomeration. The paper analyzes aluminum oxide particles agglomeration in particles-reinforced polymethyl methacrylate (PMMA) composites. Quantitative parameters of polystyrene-coated aluminum oxide particles agglomerates are obtained for the first time in this article. Unlike uncoated aluminum oxide particles, when coated aluminum oxide particles are used, agglomerates concentration in polymer composites decreases approx. 10 times. It demonstrates that modification of submicron particles by a polymer coating decreases the number of agglomerates in the polymer composite. The use of transmittance and opacity values to estimate particles agglomerates is reasonable in this article. It is shown that the difference in optical performance of specimens reinforced with coated and the original particles is related to the number and average size of agglomerates in the specimens. For example, when the concentration exceeds 0.2%, transmittance values for the specimens reinforced with coated particles are greater than the ones for the specimens reinforced with the original particles. [ABSTRACT FROM AUTHOR]

The greenhouse gas emissions due to the energy use in production and distribution in a supply chain are of interest to industries aiming to achieve decarbonization. The industry subjected to carbon regulations require recycling and reusing materials to promote a circular economy through a closed-loop supply chain (CLSC). In this research, we propose a two-stage stochastic model to design the CLSC under a carbon trading scheme in the multi-period planning context by considering the uncertain demands and carbon prices. We also provide a four-step solution procedure with scenario reduction that enables the proposed model to be solved using popular commercial solvers efficiently. This solution makes the proposed model distinguished from the existing models that assume the firms can purchase or sell carbon credits without quantity limitation. The application of the proposed model is demonstrated via simulation-based analysis of the aluminum industry. The results that the proposed stochastic model generates a network with capacity redundancy to cope with the varying customer demands and carbon prices, while only a slight increase in cost and emission is observed compared with the deterministic model. Furthermore, using scenario reduction, the model solved with 80% of the scenarios share the same CLSC network configuration with the model with full scenarios, while the deviation of the total costs is less than 0.53% and the computational burden can be diminished by more than 40%. This research is expected to be useful to solve optimization problems facing large-scale scenarios with known occurrence probabilities aiming for energy conservation and emissions reduction. [ABSTRACT FROM AUTHOR]

The title compound, [Al4(CH3)8(C2H7N)2H2], crystallizes as eight‐membered rings with –(CH3)2Al–(CH3)2N–(CH3)2Al– moieties connected by single hydride bridges. In the X‐ray structure, the ring has a chair conformation, with the hydride H atoms being close to the plane through the four Al atoms. An optimized structure was also calculated by all‐electron density functional theory (DFT) methods, which agrees with the X‐ray structure but gives a somewhat different geometry for the hydride bridge. Charges on the individual atoms were determined by valence shell occupancy refinements using MoPro and also by DFT calculations analyzed by several different methods. All methods agree in assigning a positive charge to the Al atoms, negative charges to the C, N, and hydride H atoms, and small positive charges to the methyl H atoms. [ABSTRACT FROM AUTHOR]

Aluminum is a widely used energy-intensive material and the second largest source of carbon emissions from metal after steel. Global demand for aluminum has grown rapidly since 1970 and has shown a high correlation with population and economic growth. These factors have posed challenges to carbon reduction of aluminum industry. Therefore, it is crucial to investigate global aluminum demand and emissions to develop low carbon pathways. However, few studies have conducted a comprehensive analysis of the global aluminum industry. We develop different scenarios of joint abatement measures to explore pathways for the aluminum industry to significantly reduce carbon emissions by 2050. Three scenarios are considered, namely, moderate mitigation scenario (MMS), enhanced mitigation scenario (EMS), and deep mitigation scenario (DMS). The results show that: 1) Aluminum industry has a high potential for carbon emission reduction. The emissions in the three scenarios will be reduced by 33%, 77% and 85% by 2050 compared to 2020, respectively. 2) The carbon emission reduction effect of energy structure optimization and low carbon technology application is significant, with the use of clean energy playing a decisive role. 3) There is an inverse U-shaped curve relationship between per capita primary aluminum demand and per capita GDP. The aluminum demand in China and India is still growing at a high rate, and carbon emissions are always at the top. This study will effectively support the development of a low-carbon transition path for the global aluminum industry. • Global aluminum industry has a relatively large potential to reduce carbon emissions by 2050. • Developing countries have not yet reached the inflection point of primary aluminum demand. • China and India are the two largest carbon emitters of aluminum industry. • Energy restructuring and low-carbon technology applications provide pathways for transformation of aluminum industry. [ABSTRACT FROM AUTHOR]

While Lean production is the dominant productive system in manufacturing, recent debates over digitalization have given rise to predictions of a new wave of work reorganization with potential benefits for workers. To what extent are Lean production and digitalization making headway in corporations and workplaces, and are they doing so in tandem? The present article argues that contradictions between distinct organizational levels follow the deployment of ‘Digital Lean’ practices. At the corporate level, these principles have spread within firms and managerial beliefs, yet their integration within workplaces has been far from unilateral. An analysis of the aluminum and rubber manufacturing sectors identifies two models of work organization, Empowered Digital Lean and Taylorized Digital Lean systems. The study shows that differences between the two regimes result from differing product markets, production characteristics and levels of workers’ power, while highlighting potential points of resistance for labor. [ABSTRACT FROM AUTHOR]

The article presents the research results of current cyclic thermal tests performed on enamelled aluminium wires connections, made with the use of a new type of Shark-Al quick-connectors. In particular, the main purpose of the conducted research was to analyse the effect of cyclic heating on the contact resistance change during the tests which allows to test the stability of the connections in simulated working conditions under current flow. Tests included a total of 300 thermal cycles, of which the first 200 were carried out to the 65 °C temperature measured in the connector at above the ambient temperature, and then additional 100 cycles were performed for the temperature of the connector at 140 °C (tolerance +5 °C). During the tests, the resistance of samples was monitored, which allowed to verify the correctness of performed connections. [ABSTRACT FROM AUTHOR]

This paper studies the microstructure and mechanical properties of MIG (Melt Inert Gas) lap welded 6005 aluminum alloy plates. Microstructure analysis (OM) of the joint showed that 15~30 μm small grains were observed at the fusion line. Mechanical analysis shows that the small grains are broken by shielding gas and molten pool flow force. Hardness test shows that there is a softening zone (41~43 HV) in HAZ much lower than BM and WZ. The low cycle fatigue test showed that the performance of lap joint decreased sharply, and the fatigue strength of weld decreased significantly, which was only 27.34% of the base metal. The fatigue fracture (SEM) of the weld observed slip band cracking and a large number of brittle fracture characteristics. Using the stress concentration factor K t for analysis, it was found that the cause of brittle fracture was mostly stress concentration. Lap joint stress concentration model appears in two ways: firstly, at the weld toe, the weld is subjected to eccentric force, secondly, there is a small gap between the two plates at the weld root, which cracks along the direction of 45° of the maximum shear stress. [ABSTRACT FROM AUTHOR]

This study investigates the crashworthiness behavior of square aluminum thin-walled tubes subjected to both axial and oblique impact loading, emphasizing the effects of crushing angle and initial contact between impactor and tube on the plastic collapse initiation and energy absorption capacity. A parametric study in crushing angle is conducted until 15°, while the two examined types of initial contact between impactor and tube consist of a contact-in-edge case and a contact-in-corner one, aiming to capture the effect of initial contact on both plastic collapse and energy absorption. Both experimental quasi-static tests and numerical simulation via finite element modeling in LS-DYNA software are carried out for the evaluation of the crushing response of the tested tubes. The 5° oblique cornered crushing revealed the greatest energy absorption, reflecting the most efficient loading case as significant tearing failure occurred around the tube corners in axial crushing due to a higher peak crushing force, while the increase in crushing angle caused a drop in energy absorption and peak force regarding the oblique loading. Finally, an initial contact-in-corner case revealed higher energy absorption compared to both axial and edged oblique loading, while peak force showed a slight decrease with crushing angle in that case. [ABSTRACT FROM AUTHOR]

Copper-based alloys with the addition of Al present excellent properties and can be considered a proper choice for applications as contact materials based on their good strength and fret resistance. Cu-Al alloys are used in different systems parts as bearings, gears and worm gears. The intention is to replace steel materials with new copper-based materials for parts that work in a possible explosive environment to reduce the possibility of spark appearance. Copper-berilyum alloys are known as non-sparking alloys and are used in different tools obtaining for environments with possible explosive gaseous. Results from the obtaining and analysis of a new alloy based on CuAlBe are given. The material was melted in a vacuum induction furnace from CuBe master alloy and high purity aluminium and cast into a metallic die. The alloys obtained were analyzed using EDS - energy dispersive spectroscopy for chemical composition, OM-optical and SEM-electronic microscopy for the microstructure, and the electro-corrosion resistance was tested using linear Tafel diagram and cyclic potentiometry. [ABSTRACT FROM AUTHOR]

This paper presents a study of a model for deformation of a medium-strength weldable corrosion-resistant low-density aluminum–lithium alloy under impact loading, as well as the identification and verification of the parameters of the Johnson–Cook deformation model based on the experiment. The results on the deformation failure criterion under shear impact deformation are also presented. [ABSTRACT FROM AUTHOR]

Alzheimer's disease is associated both with imbalances in Al 3+ production and changes in viscosity in cells. Their simultaneous measurement could therefore provide valuable insights into Alzheimer's disease pathology. Their simultaneous measurement would therefore be of great value in investigating the pathological mechanism of Alzheimer's disease. We designed a fluorescent probe YM2T with AIE effect that is capable of selectively responding to Al 3+ by fluorescence colormetrics and to viscosity by fluorescence "turn on" modes. Additionally, Al 3+ and viscosity were simultaneously detected in PC12 cells using the low cytotoxic probe YM2T via blue and green fluorescence channels. More importantly, the YM2T probe was used to image mice with AD. Hence, the YM2T probe shows potential as a useful molecular instrument for studying the pathological impact of Al 3+ and viscosity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Hydrolytic nanozyme-based visual colorimetry has emerged as a promising strategy for the detection of aluminum ions. However, most studies focus on simulating the structure of natural enzymes while neglecting to regulate the rate of hydrolysis-related steps, leading to low enzyme-like activity for hydrolytic nanozymes. Herein, we constructed a ruthenium dioxide (RuO 2 ) in situ embedded cerium oxide (CeO 2 ) nanozyme (RuO 2 /CeO 2 ) with a Lewis acid-base pair (Ce-O-Ru-OH), which can simulate the catalytic behavior of phosphatase (PPase) and can be quantitatively quenched by Al 3+ to achieve accurate and sensitive Al 3+ colorimetric sensing detection. The incorporation of Ru into CeO 2 nanorods accelerates the dissociation of H 2 O, followed by subsequent combination of hydroxide species to Lewis acidic Ce-O sites. This synergistic effect facilitates substrate activation and significantly enhances the hydrolysis activity of the nanozyme. The results show that the RuO 2 /CeO 2 nanozyme exhibits a limit of detection as low as 0.5 ng/mL. We also demonstrate their efficacy in detecting Al 3+ in various practical food samples. This study offers novel insights into the advancement of highly sensitive hydrolytic nanozyme engineering for sensing applications., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Compound pollution at industrial sites impedes urban development, especially when there is a lack of understanding about the spatial variations of internal pollution in industrial areas producing light-weight materials. In this study, spatial distribution and ecological risks of potentially toxic elements (PTEs), volatile organic compounds (VOCs), and petroleum hydrocarbons (C10-40) in the soil and groundwater of an Al/Cu (aluminum/copper) industrial site have been analyzed comprehensively. Results revealed the progressive clustering of pollutants in different soil layers, which indicated varying levels of penetration and migration of pollutants from the surface downward. Furthermore, severity of pollution varied according to pollutant type, with Cu (5-10,228 mg kg -1 ) often exceeding the background levels significantly (>40). Cd (0.03-2.60 mg kg -1 ) and Hg (0.01-3.73 mg kg -1 ) were found at elevated concentrations in deeper soil layers, suggesting distinct variations of PTEs across different soil depths. Among the more hazardous VOCS, polychlorinated biphenyls (1.80-234 μg kg -1 ) were particularly prevalent in the deeper layers of soil. Petroleum hydrocarbons (C10-40) were widely detected (6-582 mg kg -1 ), showing significant migration potential from surface to deep soil. These findings suggest that prolonged industrial activities lead to deep-seated accumulation of pollutants, which also impacts the groundwater, contributing to long-term dispersion of contaminants. Furthermore, multivariate statistical analysis indicated certain positive correlations among the distribution of Cu, Pb and petroleum hydrocarbons, indicating possible coupling of these pollutants. Severe Cu pollution caused an ecological risk in the surface soil layer (covering >20 % area of high pollution site, contributing >40 % ecological risk). While the Hg and Cd posed significant risks in the deeper soil layers, showing higher risk coefficients and mobility. The study provides crucial insights into the transformation of urban areas with a history of industrial uses into community spaces and highlights the risks posed by the remaining pollutants., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

In today's scenario, composite materials play a vital role in automobile, aerospace, and defence sectors because of their higher strength, light weight and other mechanical properties. Aluminium alloy Al6082 is a medium strength alloy with good corrosion resistance properties; hence, it is used for high-stress applications, bridges, cranes, etc. The present work focuses on comparing the mechanical properties of Al6082 and Al6082 with the addition of silicon nitride, magnesium, and bio waste of eggshells. Samples of Al6082 reinforced with 2% of silicon nitride (Si3N4), 5% of eggshell, and 1% magnesium reinforcements were prepared using the crucible casting process. Mechanical properties were evaluated through hardness test, tensile test and compressive tests, which varied with the additives of reinforcement materials. The results showed that the reinforced materials could increase mechanical properties. Further, it will be analysed by the machining parameters involved through the CNC turning process. Analysis of variance from optimisation technique shows a noteworthy increment of material removal rate (MRR) and significant decrement in surface roughness (Ra) and machining time compared to standard aluminium. Additionally, the analysis of mechanical testing has been predicted with the outcomes of stresses and displacements using the ANSYS platform. [ABSTRACT FROM AUTHOR]

Because aluminium is a lightweight and low-density material, its alloys, such as Al 6061 alloy, are extensively used in numerous automobile, defense, and aviation components. This study aims to develop a predictive model to investigate the impact of tool nose radius on the CNC turning process of Al 6061 alloy and better recognize the implications of operating machining considering cutting speed, rate of feed, cutting depth, and tool nose radius. The trials were carried out by using the response surface methodology (RSM), with an Al2O3 coated carbide tool as the cutter and an Al 6061 workpiece as the material. A mathematical model of the second-order was created. The analysis of variance (ANOVA) approach was used to analyze the performance characteristics of the turning operation. Individual desirability values from the desirability function analysis for the multi-responses are used to construct a composite desirability value. The ideal parameter levels were determined by using the composite desirability value, and the significant impact of parameters was assessed by using the analysis of variance. The minimum temperature attained at the machining parameters are 98.0 m/min cutting speed, 0.26 mm/rev rate of feed, 0.893 mm cutting depth, and 0.84 mm tool nose radius. The best total desirability value is 23.615 °C, indicating that the experimental results are close to the predicted values. [ABSTRACT FROM AUTHOR]

For improving the comprehensive mechanical properties of aluminum alloys (AAs) joint, the 6063-T6 AAs with thickness of 10 mm were bonded via the double-sided (DS) friction stir welding technique. Compared with the single-sided (SS) AAs joint, the grains in various regions of DS joints were refined in various degrees. In addition, the high-angle grain boundaries frequency of nugget zone reached to approximately 55%, which could hinder crack growth. Fatigue test result indicated that fracture positions of DS joints were either at thermo-mechanically affected zone or heat-affected zone near advancing side, resulting in the fatigue strength of 92 MPa. However, the fatigue strength of SS joints those mainly fractured on welding root was 76 MPa. The approximately 20% higher fatigue strength of DS joint than that of SS joint was mainly attributed to the elimination of the weak bonding at welding root as well as the grain refinement. [ABSTRACT FROM AUTHOR]

Photothermal heating with metallic nanostructures has the unique property of generating heat at the nanoscale owing to plasmon resonances. In this study, the heat transfer of anodic aluminum oxides (AAOs) coated with plasmonic titanium nitride (TiN) of 80 nm thickness are experimentally, numerically, and analytically studied, wherein TiN photothermally generated heat. High optical absorptance and photothermal heating efficiency are observed for the samples with pore sizes in the range of 161–239 nm, and the sample with the pore size of 239 nm exhibits the highest absorptance and photothermal heating efficiency. In addition, the numerical and analytical heat transfer analyses using the effective thermal conductivities for AAO-TiN samples are in reasonable agreement with experimental results, indicating the validity of effective thermal conductivities, which consider the periodic nature. These results can be extended to design other optically absorbing periodic structures for photothermal heating applications. [ABSTRACT FROM AUTHOR]

The formability of aluminum alloy 5754-O tailor-welded blanks prepared by friction stir welding was studied experimentally. The strain evolution and deformation during limiting dome height experiments were studied using digital image correlation and the ARAMIS software. The influence of the sheet thickness of the base materials on the punch loading, fracture strain and formability were investigated experimentally. It was found that the punch loading, fracture strain and limiting dome height values increase with the increasing sheet thickness of the base materials. A linear relationship between the limiting dome height value and the sheet thickness was demonstrated. An increase of 16.8% in the fracture strain of aluminum tailor-welded blanks was observed for an increase of 36% in sheet thickness. This paper provides a methodology for experimentally determining the forming limits of aluminum alloy tailor-welded blanks accurately. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of an MMC based on AA 7075 and strengthened through silicon carbide (SiC) as well as boron carbide (B4C) elements were studied. The (SiC + B4C) combination was used in various weight percentages of 4, 8, 12, and 16% to create the hybrid composites utilizing the traditional stir casting procedure. XRD and SEM measurements were used to investigate the dispersion of the reinforced particles. For example, microhardness, impact strength, and ultimate tensile strength were measured on hybrid composites at room temperature. The density and porosity of the materials were also studied. The researchers found that increasing the weight percentage of the (SiC + B4C) mixture resulted in a small drop in % elongation. However, hybrid composites comprising 16% (SiC + B4C) weight reduction showed some decrease in hardness and tensile strength. Equated to unreinforced alloys, the hardness and tensile strength of hybrid composites rise by 8% and 21%, respectively. Reinforcement also resulted in a decrease in impact strength and density, as well as an increase in porosity. [ABSTRACT FROM AUTHOR]

The paper presents a microscopic analysis of the surface and fracture of aluminium castings produced using the lost-wax method for patterns made of a composite material, i.e. polyethylene with the addition of bentonite. Castings are made of AlSi7 aluminium alloy (silumin) in a plaster mould. A new type of polymer waxes enriched with bentonite was used to obtain new composites, minimizing the defects caused by the casting production process. The castings were made in the centrifugal casting process. The prepared plaster moulds were removed from the furnace and poured with liquid aluminium alloy (AlSi7) at 750°C. The surface and fracture of the castings was analysed using an optical digital microscope type VHX-7000 manufactured by KEYENCE. It has been proven that the studied castings feature surface defects (raw surface defects) in the form of high roughness and the presence of bentonite inclusions classified as casting contamination. During the tests, shape defects related to mechanical damage were also detected. [ABSTRACT FROM AUTHOR]

The use of lightweight materials, such as ultra-high-strength aluminium alloys, is in high demand in the automotive and aerospace industries where weight savings are critical. The tool materials used for high-speed cutting of these aluminium alloys are subjected to severe conditions that promote premature failure of cutting tools. The application of polycrystalline diamond (PCD) coatings provides cutting tools with increased mechanical and thermal fatigue resistance and improved tribological performance. Despite these good properties, their high cost remains a major limitation in this sector. Super-hard Diamond-Like Carbon (DLC) coatings offer a technologically and economically feasible alternative to PCD-coated tools for cutting and machining non-ferrous materials. In this paper, the machining performance of coated and un-coated hard metal inserts in the turning of 7075 aluminium alloy has been explored. The surface quality of machined parts, the cutting tool wear resistance and the vibrations generated during turning of un-coated, PCD and super-hard thin DLC coatings on tungsten carbide inserts were compared. The results obtained demonstrate that DLC coatings are a potentially interesting alternative to PCD coatings for machining ultra-high-strength aluminium alloys, where surface component finish is a key factor. [ABSTRACT FROM AUTHOR]

Aluminum (Al) solubilizes into trivalent ions (Al3+) on acidic soils, inhibiting root growth. Since about 13% of global rice cultivation is grown on acidic soils, improving Al tolerance in rice may significantly increase yields. In the present study, metabolome analysis under Al toxicity between the Al-tolerant variety Nipponbare and the Al-sensitive variety H570 were performed. There were 45 and 83 differential metabolites which were specifically detected in Nipponbare and H570 under Al toxicity, respectively. Furthermore, the results showed that 16 lipids out of 45 total metabolites were down-regulated, and 7 phenolic acids as well as 4 alkaloids of 45 metabolites were up-regulated in Nipponbare, while 12 amino acids and their derivatives were specifically detected in H570, of which 11 amino acids increased, including L-homoserine and L-methionine, which are involved in cysteine synthesis, L-ornithine and L-proline, which are associated with putrescine synthesis, and 1-aminocyclopropane-1-carboxylate, which is associated with ethylene synthesis. The contents of cysteine and s-(methyl) glutathione, which were reported to be related to Al detoxification in rice, decreased significantly. Meanwhile, putrescine was accumulated in H570, while there was no significant change in Nipponbare, so we speculated that it might be an intermediate product of Al detoxification in rice. The differential metabolites detected between Al-tolerant and -sensitive rice variants in the present study might play important roles in Al tolerance. These results provide new insights in the mechanisms of Al tolerance in rice. [ABSTRACT FROM AUTHOR]

• Bubbles and cracks were observed in forged pieces made from extruded bars. • Two batches with different defect incidence were compared. • Analyses of the defects revealed the presence of oxides and carbon residues. • Forging fluids trapped in the extruded bars caused the defects detected in the pieces. Defects identified as bubbles and fissures were found in aluminium components used in internal combustion engines forged from flat extruded bars. Samples exhibiting these features were sectioned and prepared for microstructural characterization using light optical and scanning electron microscopy. The analyses were also conducted in samples that did not have such defects for comparison. The bubbles revealed the presence of oxidation and carbon residues in their interior and a series of cracks that developed from them. The fractured surface of the cracked samples revealed the presence of similar residues. The study was complemented with metallographic observations on samples cut from extruded bars from which the components were forged to identify the origin of the defects in forged pieces. These studies revealed the presence of cracks and voids close to the surface of the extruded bars. Therefore, it was concluded that the bubbles and cracks originated from the lubricant used in forging trapped within the voids and cracks of the extruded bars. The lubricant will volatilize and expand in such a case, causing bubbles and cracks in the forged components. The analyses conducted to the establishment of a quality criterion for acceptance of extruded bars. [ABSTRACT FROM AUTHOR]