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This study compares the fatigue life of a 7475-T7351 aluminum alloy lower wall plate in an aircraft beam structure under alternating corrosion and fatigue conditions to universal fatigue life. It incorporates a corrosive environment and variable amplitude fatigue loads. The current study uses the "beach marking" technique and visual inspection to monitor crack propagation and evaluate the corrosive environment's impact on fatigue life and damage tolerance. The experimental results indicate that during the fatigue crack initiation and penetration stages, the corrosion environment does not significantly impact the fatigue life of the beam structure because of the protection from uniform oxide films, epoxy primer, and sealants at joints. In the crack propagation stage, the corrosive environment speeds up crack growth compared to universal fatigue tests. Additionally, a "hysteresis effect" in alternating corrosion and fatigue tests shows the fatigue crack growth rate changing discontinuously, caused mainly by corrosion dissolving slip bands at the crack tip. Altogether, this study provides new insights into the influence of alternating corrosion and variable amplitude load on an aircraft beam structure's fatigue life and damage tolerance. [ABSTRACT FROM AUTHOR]

Bifunctional polymers have been studied as bonding layers (BL) on aluminum surfaces to promote adhesion of adhesives for structural bonding applications. The BL are located at the interface between the aluminum substrate and the adhesive. The mechanical performances of the BL in a bonded assembly were evaluated via several complementary mechanical tests, before and after ageing cycle: single lap shear, Arcan test, three-point bending test, and micro-scratch. The results of these four mechanical tests were compared with those of a raw reference (without any treatment) and a reference that had undergone standard surface preparation (cleaning and etching), in order to assess the mechanical performances of the surface treatment products (BL), and to value these products on the surface treatment market. In order to follow a methodology for selecting the best surface treatments, the mechanical results were compared with each other, and even correlated for samples with bonding layers (containing phosphorus and carboxylic acid functions). The correlation of the results obtained from the four mechanical tests (single lap shear, Arcan, three-point bending, and micro-scratch tests) therefore makes it possible to validate the methodology for evaluating these surface treatments. [ABSTRACT FROM AUTHOR]

The corrosion products formed on the internal surfaces of the primary system are the major factor that generates radioactive contaminants such as oxide films and cruds during decommissioning, causing radiation exposure to workers. Thus, decontamination of nuclear facility surfaces is crucial to ensure the safe completion of decommissioning work. This study applied laser decontamination, which enables precise work while minimizing the deformation of the material surface through the control of process parameters, and investigated the characteristics of the decontaminated area. Specimens coated with Ni-ferrite on an aluminum alloy (A6061) substrate were fabricated and used in this experiment. Laser decontamination was performed using a low-power Q’switching fiber laser while varying the laser beam overlap rate and number of scans. The results of laser decontamination differed by the process parameters and material characteristics. It is determined that high decontamination efficiency can be achieved if appropriate conditions are applied. [ABSTRACT FROM AUTHOR]

The heat treatment of aluminum alloys is very important in industries where low weight in combination with high wear resistance, good strength, and hardness are important. However, depending on their chemical composition, aluminum alloys are subjected to different mechanical and thermal treatments to achieve the most favorable properties. In this study, an Al-Zn-Mg alloy was heat-treated including solution annealing at 490 °C for 1 h with subsequent artificial aging at 130, 160, and 190 °C for 1, 5, and 9 h. The hardness (HV1) and abrasive wear resistance with three different abrasive grain sizes were measured for all samples. The highest hardness was measured for the samples artificially aged at 130 °C/5 h, 227 HV1, while the lowest hardness was measured for the samples aged at 190 °C/9 h. The highest and the lowest wear resistance was also observed for the same state, i.e., artificially aged at 130 °C/5 h and 190 °C/9 h, respectively. The critical abrasive grain size was detected for some samples, where a decrease in wear rate was observed with an increase in the abrasive grain size from the medium value to the largest. The Response Surface Methodology (RSM) was applied to demonstrate the influence of the input parameters on the material wear rate. [ABSTRACT FROM AUTHOR]

The high-temperature stability of RuAl-based electrodes for application in microelectronic devices is analyzed for long-term duration. The electrodes are prepared on Ca3TaGa3Si2O14 (CTGS) substrates using SiO2 and Al-N-O cover and barrier layers as oxidation protection. The samples are annealed at 600, 700, or 800 °C in air for 192 h. Minor degradation is observed after thermal loading at 700 °C. The annealing at 800 °C for 192 h leads to a partial oxidation of the Al in the extended contact pad and to a complete oxidation of the Al within the structured interconnect electrodes. The different degradation of the interconnect electrodes and the contact pads is caused by their different lateral dimensions. In summary, long-term high-temperature stability is demonstrated up to at least 700 °C in air. Less oxidizing atmospheres should allow the application at higher temperatures and for a significantly longer duration. [ABSTRACT FROM AUTHOR]

AbstractDismantling behavior of aluminum/carbon fiber-reinforced plastic (aluminum/CFRP) bonded assemblies using dismantlable adhesives was investigated. These adhesives contained expanded graphite (EG) to facilitate the dismantling process by inducing volume expansion during heating. Our objective was to identify the optimal additive conditions of EG, which would allow for easy dismantling while maintaining adequate adhesive strength in aluminum/CFRP bonded assemblies during regular operation. To achieve this, various experiments with adhesives containing EG of different flake sizes and volume fractions were conducted. The experimental results demonstrated that a moderate addition of fine-flake sized (140 μm) EG (5 vol%) tended to provide the desired combination of sufficient adhesive strength and ease of dismantling. [ABSTRACT FROM AUTHOR]

The utilization of Aluminum hollow panels enhances structural strength while simultaneously ensuring a lightweight and efficient use of materials. During their application, these panels necessitate a welding process that is susceptible to porosity due to the disparity in hydrogen gas solubility between liquid and solid aluminum. Solid-state welding techniques, such as Friction Stir Welding (FSW), have proven to be effective and appropriate solutions for overcoming this issue. However, due to the thickness of the hollow panels, FSW process is unfeasible as it requires welding on both sides, resulting in prolonged production times. Consequently, the development of a one-step double-acting FSW technique becomes necessary, involving the simultaneous utilization of two tools. The usage of two tools introduces two sources of friction-stir forces, heat, and axial forces, demanding an assessment of the novel response from the specimens. This research aims to analyze the effect of a specific parameter, namely the tool rotation speed, within the one-step double-acting FSW process on the physical and mechanical properties of the AA6061 hollow panels. The One-Step Double-Acting FSW process involved conducting variations in the tool rotation speed on both sides of the welds. Specifically, for the 4G weld position (underside of the workpiece with an overhead weld position), speeds of 1200, 1500, and 1800 rpm were employed. Meanwhile, a consistent rotation speed of 1500 rpm was maintained for the 1G weld position (overside of the material with a flat weld position). The transverse speed and tilt angle are set at 30 mm/min and 2°, respectively. Elevating the tool rotation speed results in increased hardness, load capacity, and bending strength of the weld joints. The specimen subjected to the highest rotational speed (1800 rpm) exhibits the most exceptional mechanical properties, including a hardness of 73.46 HVN, load capacity of 18.47 kN, and bending strength of 60.56 MPa. [ABSTRACT FROM AUTHOR]

Friction stir lap welding experiments between 6061 aluminum alloy plate and DP590 dual-phase steel plate were carried out. The effects of welding parameters and addition of Ni foil interlayers with different thickness on the microstructures and mechanical properties of the lap joints were investigated. The shear strength of the joint reached the maximum value of 6597 N and showed a mixed ductile-brittle fracture mode when the welding speed, the rotating speed and the thickness of the Ni foil intermediate layer were set to 100 mm/min, 900 rpm and 0.3 mm, respectively. A certain amount of beneficial plastic AlNi and FeNi3 intermetallic compounds are formed through the reaction of Al, Fe and Ni at the aluminum alloy/steel interface. [ABSTRACT FROM AUTHOR]

Acoustic emission (AE) signals are thought to contain crucial information for identifying defects and monitoring processes. It is crucial to have a comprehensive understanding of how AE signal parameters behave under different experimental conditions. However, based on current research, there appears to be a lack of knowledge on the impact of machining parameters, especially in milling operations, where complex chip formation patterns, interaction effects, and directional pressures and forces are present. To bridge this informational void, analyzing how various cutting conditions impact the AE signal characteristics derived from milling operations is crucial. This research predominantly focuses on the impact of cutting conditions, material attributes, insert coatings, and nose radius on AE signal attributes in the time domain. The proposed innovative method suggests segmenting acquired AE signals correlated with the cutting tool's trajectory through the material into three distinct phases: entry, active cutting, and exit, each marked by a particular signal timeframe for effective signal processing and characteristic derivation. Furthermore, advanced signal processing techniques and statistical analysis are utilized to determine which AE parameters are sensitive to changes in cutting parameters. This research identifies cutting speed and feed rate as the primary variables affecting AE signal characteristics. The study's outcomes can enhance sophisticated classifications and AI techniques for monitoring machining operations. [ABSTRACT FROM AUTHOR]

The prerequisite of the weld bead finishing is intricately linked to the quality of the welded joint. It constitutes the final, yet pivotal, stage in its formation, significantly influencing the reliability of structural components and machines. This article delineates an innovative post-weld surface finishing method, distinguished by the movement of a specialized cutting tool along a butt weld. This method stands out due to its singular approach to machining allowance, wherein the weld bead height is considered and eradicated in a single pass of the cutting tool. Test samples were made of AISI 304L, AISI 316L stainless steels and EN AW-5058 H321, EN AW-7075 T651 aluminum alloys butt-welded with TIG methods. Following the welding process, the weld bead was finished in accordance with the innovative method to flush the bead and the base metal's surface. For the quality control of welded joints before and after the weld finishing, two non-destructive testing methods were chosen: Penetrant Testing (PT) and Radiographic Testing (RT). This article provides results from the examination of 2D profile parameters and 3D stereometric characteristics of surface roughness using the optical method. Additionally, metallographic results are presented to assess changes in the microstructure, the microhardness, and the degree of hardening within the surface layer induced by the application of the innovative post-weld finishing method. [ABSTRACT FROM AUTHOR]

The manuscript presents the results of butt joining of 3-millimeter-thick AlCu4Mg1 alloy sheets using the FSW (friction stir welding) and UWFSW (underwater friction stir welding) methods. The aim of the research is to verify the influence of the water environment on the FSW friction welding process. The article checked three sets of joint parameters. The parameters differed in tool rotation speed and feed rate. The same sets of parameters were used for the FSW and UWFSW fusion techniques. With the supplied devices, metallographic sections are cross-sectioned, and the power supplies are subjected to a light microscope. Microhardness tests and the influence of the heat-affected zone were carried out. A monotonic test was performed. A monotonic test is available, extended with a visual correlation test. The obtained cracked fracture surfaces were examined using a scanning microscope. An analysis of the microfractographic cracking process was carried out. The obtained results did not show any improvement in the strength properties of the obtained joints made using the UWFSW technique when using a scanning microscope. [ABSTRACT FROM AUTHOR]

Different anodized coatings are prepared on the surface of 2024 aluminum alloy from different solutions by pulse anodizing to improve corrosion resistance and hardness. The thickness, roughness, structure, hardness, surface morphology, and corrosion resistance of different anodized coatings are studied. It is found that the anodized coating is composed of a porous layer on the surface and a nonporous barrier layer inside, showing the structure of γ-Al2O3 and α-Al2O3. The anodized coating prepared from sulfuric acid solution mixed with oxalic acid and glycerol has a larger thickness and higher hardness. The surface morphology of the anodized coatings is porous. The thickness of the anodized coating prepared from oxalic acid solution is small and the pore distribution is not uniform. However, the anodized coating obtained from sulfuric acid solution mixed with oxalic acid and glycerol has the smallest average pore size of 6.38nm and ordered pore distribution, resulting in the best corrosion resistance. [ABSTRACT FROM AUTHOR]

Aluminum alloy parts are widely used in aerospace and other fields due to their light weight and good corrosion resistance. However, during the forming process, uneven deformation can lead to high residual stresses and low forming accuracy in the parts, ultimately seriously affecting the subsequent service performance. In this study, the influence of the cryogenic–vibration compound field on the residual stresses, microstructural evolution, and forming accuracy were investigated based on the deep drawing experiment of aluminum alloy cylindrical parts. The results indicate that when compared to the absence of cryogenic and vibration, the compound field can reduce residual stresses in the parts by 22%, which is attributed to lower dislocation density and more uniform distribution of low-angle grain boundaries. The cryogenic environment can weaken the degree of dislocation entanglement in low-angle grain boundaries, meanwhile, the dislocations are easily dissociated and released under the vibration. The maximum sidewall thickness difference, the sidewall height difference, and the surface roughness decrease by 68, 69, and 52%, respectively, which is due to the uniform distribution of microstructure and the reduction of frictional resistance caused by the boiling liquid nitrogen. This study provides a new method for the forming of high-quality aluminum alloy parts. [ABSTRACT FROM AUTHOR]

Previous research revealed that the quality of the ingots produced by different primary or secondary alloy suppliers can differ remarkably. In this way, the quality of the liquid metal and the castings produced from it can be affected by the impurity content of the ingots used as charge material. In this work, a modified reduced pressure test (RPT) technique, which is based on the remelting of samples extracted from ingots, was applied to investigate the quality of primary AlSi9Mn ingots made by horizontal direct-chill (HDC) casting and gravity casting techniques. For the evaluation of metal quality, image analysis of the cross sections was applied. Pore area fraction, number density, normalized bifilm index, and normalized total pore perimeter were determined, and the relationships between the different metrics were analyzed. The results were compared with the melt quality assessment of the as-melted batches made from the ingots. Solidification simulations, thermal analysis, and microstructural investigations were conducted to investigate the solidification conditions of traditional and remelted RPT samples. Based on the results, the HDC cast ingots possess lower oxide and gas concentrations, which can be traced back to the differences in the melt preparation and casting technologies of the ingots. The comparison of the parameters evaluated by image analysis revealed that there is a strong linear relationship between normalized bifilm index and normalized total pore perimeter. The possible sources of error in ingot quality evaluation are highlighted. [ABSTRACT FROM AUTHOR]

This research paper examines the effect of different solution heat treatments parameters (temperature and time) on Al–3.39%Cu–2.26%Mg (wt%) alloy's microstructure, thermal, mechanical and corrosion properties. 5754 alloy and Al–Cu alloy are used to make Al–3.39%Cu–2.26%Mg (wt%) by gravity die casting. Solution heat treatment at different temperature and time (500 °C-10 min, 500 °C-4h, 530 °C-10 min and 530 °C-2h). As-cast Al–Cu–Mg alloy have α-phase and eutectic phase. After solution heat treatment and aging, precipitates phases is observed in microstructure. X-ray diffraction analysis results have shown that a precipitate phase [S phase (Al2CuMg)] gets formed in as-cast conditions but undergoes dissolution during the solution heat treatment process. As-cast Al–Cu–Mg alloy has a Brinell hardness value of 77.2 HB. As-cast alloy has S (Al2CuMg) precipitate phase increases hardness by precipitation strengthening. After solution heat treatment and aging, Brinell hardness reduces. After solution heat treatment (500 °C for 4 h) and aging (200 °C for 5 h), Brinell hardness values becomes 63.6 HB (− 17.6% decrease). Corrosion resistance improves after the solution heat treatment due to the dissolution of the precipitate phase, forming an almost single-phase solid solution. The as-cast alloy exhibits a peak compressive stress of 494.2 MPa, which increases after solution heat treatment and water quenching to 572.7 MPa (without aging). After aging, peak compressive stress decreases to 508.4 MPa. Failure strain for the as-cast alloy is 39.6%, reducing to 31.1% after solution heat treatment and water quenching. It again increases to 43.1% after aging. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aluminum alloys have received substantial interest for the fabrication of complex and large size components for the aerospace industry via additive manufacturing processes. This work explores the fatigue performance of aluminum alloy 2319 fabricated by wire-based Directed Energy Deposition (DED) with Cold Metal Transfer (CMT) process, i.e., wire arc additive manufacturing (WAAM) technology. The as-deposited 2319 wall microstructure was composed by both columnar dendrites and equiaxed grains along the build direction (BD). Also, fine and coarse θ and θ′ precipitates were noticed in the WAAM printed 2319 wall due to repeated thermal cycles while fine precipitates were observed in wrought alloy. The microhardness measurements revealed a gradual decrease from the bottom to the top layers and varied between 65 and 86 HV. Tensile properties (yield strength, ultimate tensile strength, and elongation) measured in the horizontal and vertical directions were 99 ± 4 MPa, 268 ± 11 MPa 14.8 ± 1.5% and 96 ± 3 MPa, 257 ± 9 MPa, and 15.6 ± 2%, respectively. The WAAM 2319 fabricated in this work retained 72% of the strength of their AA2219-T62 wrought counterparts, which can be attributed to the large columnar grains that developed during the additive manufacturing process. The fatigue strength of WAAM 2319 specimen was 67 MPa, corresponding to 65% of the fatigue strength of AA2219-T62. Fracture surface analysis revealed the presence of small and large dimples, secondary micro-cracks, broken intermetallics, and inclusions. This work will provide novel insights and guidance for manufacturing near-net shape aluminum alloys by wire-based DED with improved tensile and fatigue properties. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure, mechanical properties, and corrosion behavior of friction stir welded (FSW) joints of the two aluminum alloys 6005A‐5083 were investigated and their correlation was discussed. In contrast to FSW joints of the same aluminum material, this results in a "V" shape curve of hardness distributed nonsymmetrically along the weld. The lowest hardness area occurs at the interface between the heat‐affected zone and the thermo‐mechanically affected zone of 6005A (6‐HAZ and 6‐TMAZ) due to the transformation of the β" phase under the influence of heat input during the stir friction process. This also leads to all tensile specimens fracturing in this area. The corrosion behavior of the FSW joint in acidic solution containing Cl− was determined by an exfoliation corrosion (EXCO) test, an intergranular corrosion (IGC) test, and potentiodynamic polarization measurements, based on the potential application in acid rain environment. The results showed that the corrosion resistance order in the acidic solution is: 6‐HAZ > NZ > 6‐BM > 5‐HAZ > 5‐BM. The 5‐BM has the worst corrosion resistance due to the high corrosion sensitivity of Al3Mg2 in acidic solution. However, good corrosion resistances are shown in NZ and 6‐HAZ, which is related to a relatively homogeneous microstructure in NZ and a dissolution or coarsening of β" phases in 6‐HAZ because of frictional heat input. [ABSTRACT FROM AUTHOR]

This paper prepared cerium myristate coating on a 6061 aluminum alloy surface using a one-step cathode electrodeposition method under different deposition times and deposition current densities. The results show that the corrosion resistance of the aluminum alloy covered with the obtained coating is higher than that of the blank aluminum alloy. Moreover, the corrosion resistance of the coatings obtained at different deposition current densities increases first and then gradually stabilizes with the deposition time and finally shows a similar protection effect to the aluminum alloy. Then, the coating obtained at a lower deposition current density (0.5 mA/cm2) was systematically studied from an energy-saving perspective. Potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) results show that the aluminum alloy's corrosion rate and corrosion trend in 3.5 wt% NaCl solution are reduced after the coating is covered. The protective effect of the coating on aluminum alloy reaches its maximum when the deposition time is 15 min. At this time, the corrosion current density of aluminum alloy is three majority orders lower than that of blank aluminum alloy, and the total corrosion resistance is two majority orders higher. Corrosion and pitting potential are about 140 mV more positive than blank aluminum alloy. The SEM and water contact angle (WCA) results show that the coating gradually transforms from a smooth and dense layer into a rough and loose porous layer with the extension of deposition time. When the deposition time reaches 15 min, the WCA of the coating can be 157.5°, showing superhydrophobicity. The stability test also found that the obtained coating has good mechanical wear resistance, UV light resistance stability, and anti-corrosion durability. Finally, based on the changes in morphology and corrosion resistance of the coatings obtained at the deposition current density of 0.5 mA/cm2 under different deposition times, it is speculated that the superhydrophobic coatings obtained by electrodeposition may consist of a dense inner layer and a loose porous outer layer. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates ultrasonic plastic welding to join the carbon fiber-reinforced thermoplastics and 6061Al alloy in a lap-type joint configuration. An interfacial polymer coating through a fluidized bed on aluminum alloy was considered an energy director, as it was essential for concentrating heat at the interface during welding. The significant ultrasonic process setting (weld pressure: 0.5 MPa, weld time: 600 ms, hold time: 1000 ms) was statistically realized for a maximum lap shear strength of the joint that showed the interlaminar shear (first-layer ply) failure of the composite, while the welding interface morphology revealed interdiffusion of thermoplastics with the load-bearing carbon fibers attached to the composite-coating resin mixtures, whereas the coating interface offered a strong adhesion of polymer on the aluminum surface asperities through mechanical interlocking. An efficient multi-material joint was obtained within 1.6 s in comparison to the adhesive bonding technology that required at least 20 min. Additionally, the interfacial coating serves as an insulator, avoiding galvanic corrosion in joints as well as fretting damage. The encouraging findings of this research provide deeper insight into joining thermoplastic composites to metals by ultrasonic plastic welding without the use of a separate energy director, which simplifies the process of industrialization. [ABSTRACT FROM AUTHOR]

The effect of time-periodic two-frequency rotation modulation on Rayleigh–Bénard convection in water with either AA7072 or AA7075 nanoparticles is investigated. The single-phase description of the Khanafer–Vafai–Lightstone model is used for modeling the nanoliquids. An asymptotic expansion procedure is adopted in the case of the linear stability to obtain the correction (due to modulation) to the Rayleigh number at marginal stability of unmodulated convection. A nonlinear regime of convection is considered with a nonautonomous generalized Lorenz model as the governing equation. The method of multiscales is then employed to obtain the coupled nonautonomous Ginzburg–Landau equations with cubic nonlinearity from the Lorenz model. These equations are presented in the phase-amplitude form and the amplitude is used to quantify the heat transport. The modulation amplitude is considered to be small (of order less than unity) and moderate frequencies of modulation are considered. We found that there is a threshold frequency beyond which the system behavior reverses. At frequencies below the threshold, the mean Nusselt number increases with an increase in the amplitude of modulation while an opposite influence is seen for values above the threshold. Such a behavior is a consequence of what is analogously seen in the case of the critical Rayleigh number. The influence of two-frequency modulation is more pronounced on the results of the linear and nonlinear regimes compared to that of the single-frequency one. The heat transport is enhanced due to the presence of dilute concentration of suspended nanoparticles (either AA7072 or AA7075 nanoalloys) in water. The influence of nanoparticles is to modify the threshold values generating chaos but it does not qualitatively alter the dynamical behavior of the system. The plots of Lyapunov exponents reveal that there is no possibility of hyper-chaos in the generalized Lorenz model when there is a rotational modulation. [ABSTRACT FROM AUTHOR]

Aluminum alloy has the characteristics of good corrosion resistance and high strength, so aluminum alloy workpiece is widely used in the aerospace field. However, in milling, the surface of the aluminum alloy workpiece generates residual stress due to the coupling of force and heat, which seriously affects the fatigue performance of the workpiece. To investigate the residual stress formation mechanism, an analyzed model of machining-induced residual stress considering energy conversion in milling process was proposed. In this process, the milling force prediction model is established. Then, an effective cutting work model is established based on the milling force model. After that, the strain energy density of the machined surface layer was analyzed and the strain energy solution model was established. Subsequently, the prediction models of mechanical stress, thermal stress, and residual stress are established respectively, and the residual stress values are brought into the strain energy model to obtain the strain energy. Afterwards, the functional transformation relationship between effective cutting work and strain energy storage per unit time is analyzed. Finally, several milling experiments were carried out to verify the predicted milling force and residual stress values. Experimental results show that errors between the predicted values and the experimental values are about 5% and 15%, respectively, and the conversion relationship between work and energy show that the stored strain energy per unit time increases with the increase of the effective cutting work. [ABSTRACT FROM AUTHOR]

Electron beam additive manufacturing (EBAM) has broad application prospects in the preparation of large structural components such as those in aerospace structures. It is of great significance to have a deep understanding of the residual stress distribution and deformation of EBAM. A three-dimensional transient thermal–mechanical coupling model was established for the comprehensive investigation of the deformation and residual stress of aluminum alloy components prepared by wire-feed EBAM for the first time. The reliability of the simulation model was verified by comparing the predicted temperature, stress and deformation with experimentally measured values. The influence of heat input on residual stress distribution and deformation was studied using the verified model. The simulation results indicate that reducing heat input is an efficient approach to reducing deformation and residual stress. The developed model can be a powerful tool to optimize process parameters to reduce the residual stress and deformation of EBAM aluminum alloy components. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] Aluminum alloy (Al alloy) suffers from severe corrosion in acidic solution. Two-dimensional (2D) MXene-based composite coatings show great prospects for corrosion protection on metals used in special conditions. The composite coatings still face challenges in complex functionalization and orientation control. In harsh conditions, the long-term ability and roles of MXene in corrosion protection are still not clear. Here, a bio-inspired myristic-calcium chloride-Ti 3 C 2 T x MXene (MA + CaCl 2 + MXene) composite coating is successfully prepared on aluminum alloy (Al alloy) by electrodeposition process. Electrochemical tests, surface morphology, and chemical composition are analyzed to investigate the corrosion resistance and protection mechanism of the MXene coating in acidic solution (0.5 M H 2 SO 4 + 2 ppm HF). As a result, the incorporation of MXene can significantly reduce corrosion current density (7.498 × 10-8 A/cm2) by ∼ 5 orders of magnitude and impedance modulus at 0.01 Hz (|Z| 0.01 Hz) value of the composite coating is 196.8 Ω·cm2, which is over 4 times higher than that of bare Al alloy (40.74 Ω·cm2) after immersion test for 72 h. Furthermore, the in-situ corrosion test confirms the enhanced corrosion resistance of the MA + CaCl 2 + MXene composite coating. The MXene can increase coating thickness to 23.6 ± 0.4 μm, reduce porosity to (5.845 ± 1) × 10-5, decrease the diffusion coefficients of H+ to (1.587 ± 0.3) × 10-9 cm2/s, and enhance the adhesion of the coating to the substrate (the delamination time exceeds 5 h), thus providing improved anti-corrosion ability. This strategy opens up new prospects for construction of 2D MXene-based anti-corrosion coatings. [ABSTRACT FROM AUTHOR]

The effects of different anodic oxidation voltages on micromorphology, composition, porosity, microhardness and corrosion resistance of anodic oxide film were studied by using 2A12 aluminum alloy as the matrix. The results show that the oxide films generated under different anodic oxidation voltages are porous. At 20 V, the surface porosity of the sample is the largest(4. 394%) and the oxygen content the highest(35. 76%). The surface roughness is the largest(34. 9) at 30 V. With the increase of anodic oxidation voltage, the corrosion resistance of the sample surface shows a trend of increasing first and then decreasing, and the corrosion resistance is strongest at 20 V. After the optimal anodized aluminum alloy matrix is coated with epoxy coating, the mechanical properties and corrosion resistance of the aluminum alloy matrix are analyzed, and the results show that the anodizing process can greatly improve the adhesion and corrosion resistance of the coating sample. [ABSTRACT FROM AUTHOR]

The production of thin-walled elements, especially those with large overall dimensions, poses numerous technological and operational problems. One of these problems relates to the machining-induced strain of such elements resulting from residual stress generated during the machining process. This study investigates the effect of the technological parameters of milling on residual stress in the surface layer of thin-walled plates made of aluminum alloy EN AW-2024 T351 for aerospace applications. The results have shown that residual stress increases with the cutting speed only to a certain point, reaching the maximum value at vc = 750 m/min. At a cutting speed vc = 900 m/min, residual stress significantly decreases, which probably results from the fact that the milling process has entered the High-Speed Cutting range, and this inference agrees with the results obtained for the cutting force component. Residual stress increases with the feed per tooth, while the relationship between residual stress and milling width is the same as that established for residual stress and variable cutting speed. Positive tensile stress is obtained in every tested case of the milling process. The results have also shown that the induced residual stress affects the strain of machined thin-walled parts, as proved by the strain results obtained for milled thin walls. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to study the effect of current-carrying condition on the electrochemical process and atmospheric corrosion behavior of the commercial aluminum alloys. Design/methodology/approach: Potentiodynamic polarization tests were performed to study the electrochemical process of the aluminum alloys. Salt spray tests and weight loss tests were carried out to study the atmospheric corrosion behavior. The corrosion morphology of the alloys was observed, and the products were analyzed. Findings: The corrosion process of four aluminum alloys was accelerated in the current-carrying condition. Moreover, the acceleration effect on A2024 and A7075 was much stronger than that on A1050 and A5052. The main factors would be the differences in microstructure and corrosion resistance between these alloys. As the carried current increased, the corrosion rate and corrosion current density of the aluminum alloys gradually increased, with the protection of the corrosion product film decreasing linearly. Originality/value: This is a recent study on the corrosion behavior of conductors under current-carrying condition, which truly understands the corrosion status of power grid materials. Relevant results provide support for the corrosion protection and safe service of aluminum alloy in power systems. [ABSTRACT FROM AUTHOR]

Aluminium alloy AA2519 has been successfully utilized in military vehicles, including advanced amphibious assault vehicles (AAAV), for the purpose of achieving weight reductions, superior ballistic properties, and excellent stress corrosion cracking (SCC) resistance. Friction stir welding (FSW) is exclusively utilized for joining different parts of this material to manufacture desired components for the targeted applications. On the other hand, studies on the corrosion behavior of the FS-welded material are scarce. In this work, using indigenous AA2519-T87 plates, friction stir welding was carried out to evaluate and compare the electrochemical behavior of the base alloy with that of the welded joint. The results showed significant improvement in the pitting corrosion resistance of the welded joints. These results were correlated with the considerable changes in the microstructure of the welded joints produced during the FSW process. [ABSTRACT FROM AUTHOR]

Recently, a new dissimilar mechanical joining method, dimple spot welding (DSW), has been developed for joining steel sheets and aluminum alloys. In this study, tensile shear tests and fatigue tests were conducted on four types of dissimilar lap joints, with two types of steel sheets and two types of Al alloys joined by DSW. Both the tensile shear strength and fatigue strength of DSW joints were found equal to or greater than those of a self‐piercing riveting (SPR) joint. In all four types of DSW joints, fatigue cracks were initiated from the Al alloy and were associated with fretting induced by repeated contact and friction. A finite element analysis showed that the tangential stress was mainly governed by the friction coefficient and also affected by the steel sheet strength. Higher‐strength steel led to lower tangential stress, resulting in a longer fatigue life for the DSW joint. Highlights: A dimple spot welding (DSW) is developed for joining steel sheets and aluminum alloys.Tensile shear tests and fatigue tests are conducted on DSW joints and SPR joint.DSW joints shows greater tensile shear strength and longer fatigue lives than SPR joint.Fatigue cracks in DSW joints were initiated associated with fretting. [ABSTRACT FROM AUTHOR]

The application of the Factor of Intensity of Constraint (FIC) criteria becomes instrumental in quantifying effectiveness by measuring the reduction in mechanical energy at the fracture tip, thereby extending the structural life. The robust mechanical properties offered by bonded composite patch repair technology, including enhanced fatigue resistance, mass gain, adaptability to complex sections, and corrosion resistance, play a pivotal role in fortifying damaged structures. Our findings highlight the interdependence of geometric and mechanical properties among the composite patch, adhesive, and damaged structure. Our investigation centers on M(T) aluminum alloy 6061 T6 centrally fissured samples from the 6000 series. We present a comprehensive examination of the effect of composite patch repairs on fatigue deterioration in aeronautical structures. Significantly, our study introduces novel insights by examining the effects of both constant and varying amplitude loads, emphasizing the contribution to comprehensive exploration that highlights the practical implications and benefits of composite patch repairs in enhancing fatigue resistance and longevity in aeronautical structures. Additionally, a detailed exploration is conducted to understand the effects of various parameter settings and service terms. This study contributes significant insights into the field, shedding light on the practical implications of composite patch repairs in enhancing the fatigue resistance and longevity of aeronautical structures. [ABSTRACT FROM AUTHOR]

In this paper, a novel friction stir welding tool with large diameter disc at the tip of the pin was developed to solve the problems in aluminum/magnesium friction stir lap welding. Based on the structural design of the shoulder at the tip of the pin, the temperature difference in the thickness direction of the joint was coordinated, and the aluminum-magnesium dissimilar lap joint was successfully prepared in two kinds of lap configuration. Taking AZ31B magnesium alloy and 6061 aluminum alloy as the research object, the defects and microstructure of weld joint were observed and analyzed by optical microscope and scanning electron microscope. Additionally, their mechanical properties were also evaluated. The results show that an excellent metallurgical bonding was formed between aluminum and magnesium. With the increase of the effective plate thickness and the decrease of the effective lap width, the unique hook defect shape of lap welding joint was optimized, which also promoted the improvement of the mechanical properties of the weld. In the tensile-shear test, it was found that the tensile shear strength was improved, and the joint fractured in a mixed mode of toughness and brittleness due to the change of the shape of the hook defect, and it is a mixed fracture of toughness and brittleness. [ABSTRACT FROM AUTHOR]

In this work, a bright white oxide coating was successfully prepared on 6061 Al alloy by PEO process from an environmentally friendly and low-cost concentrated silicate electrolyte as an alternative for commonly used fluozirconate electrolyte. The characteristics of PEO processes and resulting coatings both in diluted and concentrated silicate electrolytes were investigated by using Optical Emission Spectrometer (OES), Scanning Electron Microscope (SEM), X-ray Energy Dispersive Spectrometer (EDS) and X-ray Diffraction Spectrometer (XRD). The thermal control properties of the coatings were evaluated by UV-VIS-NIR spectrophotometer and infrared emissivity spectrometer, respectively. The corrosion protection performances of the coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. Results show that the discharges in diluted silicate electrolyte are more pronounced than those in concentrated silicate electrolyte. The more intensive discharges in diluted silicate electrolyte are related to plasma electrochemical reactions at the material surface or at the metal-oxide interface, facilitating to a relatively dense structure and complex oxides including α -Al 2 O 3 , γ -Al 2 O 3 and mullite. The weaker discharges in concentrated silicate are associated with the fast silicate anions deposition process, resulting in the formation of amorphous SiO 2 with a porous microstructure and high thickness. The coating prepared in concentrated silicate electrolyte is characterized by a bright white color in appearance and has much lower solar absorptance (α s) of 0.159 and higher emissivity (ε) of 0.90 than the coating prepared in diluted silicate electrolyte with α s of 0.429 and ε of 0.79. However, the coating prepared in concentrated silicate electrolyte has a little inferior corrosion protection performance compared with that prepared in diluted silicate electrolyte due to the more porous microstructure. [ABSTRACT FROM AUTHOR]

Aluminum foam is a lightweight material and has excellent shock-absorbing properties. Various properties of aluminum foam can be obtained by changing the base aluminum alloy. Multi-layer aluminum foam can be fabricated by varying the alloy type of the base aluminum alloy, but with different foaming temperatures, within a single aluminum foam to achieve multiple properties. In this study, we attempted to fabricate a two-layer aluminum foam with the upper layer of a commercially pure aluminum A1050 foam and the lower layer of an Al-Si-Cu aluminum alloy ADC12 foam by using an optical heating device that can heat from both the upper and lower sides. Two types of heating methods were investigated. One is to directly stack the A1050 precursor coated with black toner on top of the ADC12 precursor and to foam it from the top and bottom by optical heating. The other is to place a wire mesh between the ADC12 precursor and the A1050 precursor and place the A1050 precursor on the wire mesh, thereby creating a space between the precursors, which is then foamed by optical heating from the top and bottom. It was shown that both precursors can be foamed and joined, and a two-layer A1050/ADC12 foam can be fabricated for both types of heating methods. In the method in which two precursors were stacked and foamed, even if the light intensity of the halogen lamps on the top and bottom were adjusted, heat conduction occurred between the stacked precursors, and the foaming of each precursor could not be controlled, resulting in tilting of the joining interface. In the method of foaming using a wire mesh with a gap between two precursors, it was found that by adjusting the light intensity, the two precursors can be foamed almost simultaneously and achieve similar pore structures. The joining interface can also be maintained horizontally. [ABSTRACT FROM AUTHOR]

Cathodic protection is widely used for metal corrosion protection. To improve their performance, it is necessary and urgent to study the influence of metal oxides on the microstructure and performance of aluminum alloy sacrificial anodes. Taking an Al-Ga-In sacrificial anode as the research object, the dissolution morphology and current efficiency characteristics were studied by means of electrochemical testing and microstructural observation, and the influence of varying Pb and Bi contents on the performance of an aluminum alloy sacrificial anode was investigated. The test results reveal that: (1) The Al-Ga-In sacrificial anode with 4% Pb and 1% Bi contents exhibits the best sacrificial anode performance. (2) The inclusion of an appropriate Bi element content shifts the open-circuit potential in a negative direction and promotes activation dissolution. Conversely, excessive Bi content leads to uneven dissolution, resulting in the shedding of anode grains and greatly reducing the current efficiency. (3) During the activation dissolution of the aluminum alloy, the second phase preferentially dissolves, and the activation point destroys the oxide film, resulting in the dissolution of the exposed aluminum matrix. Consequently, the concentration of dissolved metal ions is reduced and deposited back on the surface of the anode sample, promoting the continuous dissolution of the anode. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) based on cold metal transfer (CMT) technology is very suitable for additive manufacturing of light metals such as aluminum and magnesium alloys due to its low heat input. The temperature field in CMT additive manufacturing determines the microstructure evolution and mechanical properties. However, the mechanism of CMT-related process parameters affecting the thermal process and molten pool geometry in additive manufacturing is still unclear. The finite element analysis model of the CMT additive manufacturing process was established based on element birth and death technology, and the temperature field and molten pool shape in the CMT additive manufacturing process were quantitatively studied. The results show that with the increase in welding speed, the maximum temperature of the molten pool decreases, the length of the molten pool decreases, and the depth of the molten pool changes little. The effect of interlayer cooling on the temperature field of CMT additive manufacturing was quantitatively analyzed. The study found that without cooling between the deposited layers, heat accumulation will occur in the component of additive manufacturing, and the peak temperature will be higher. With the increase of the additive manufacturing layer number, the peak temperature of the additive manufacturing layer increases. With the increase of additive layer number and no cooling between sedimentary layers, the length of the molten pool increases obviously. The correctness of the model is verified by the experimental measurement of weld geometry in CMT additive manufacturing of AA5356 aluminum alloy. This study provides a theoretical basis for the optimization of the CMT additive manufacturing process of aluminum alloy. [ABSTRACT FROM AUTHOR]

AbstractIn this study, 6061-Al and AZ31-Mg were successfully joined using the contact reaction brazing process without an interlayer under a pressure of 2 MPa and a vacuum of 1 Pa. The study examined the microstructure and mechanical properties of 6061/AZ31 joints, as well as the impact of process parameters including heating mode, cooling rate, heating temperature, and holding time on the joints. The results show that the 6061/AZ31 brazing seam can be divided into two zones: the liquid-phase solidification zone and the diffusion reaction zone. The liquid-phase solidification zone consists of the (α-Mg + Al12Mg17) eutectic organization and precipitation phases distributed therein. The diffusion reaction zone mainly consists of the Al3Mg2 layer in the brazing seam close to the 6061. Fractures in joints mainly occur in the diffusion reaction zone, where the hard and brittle Al3Mg2 layer is located and extends into the liquid-phase solidification zone. Brazing joint quality was better with a cooling rate of 5 °C/s and heating without pre-weld and post-weld holding processes. The highest joint shear strength of 37 MPa was achieved at 445 °C with a holding time of 5 s. The joint exhibited no obvious defects, and the axial shrinkage of the specimen was 0.414 mm, with minimal deformation. [ABSTRACT FROM AUTHOR]

The welding process of aluminum (Al) alloy car body has problems such as poor weld quality, low welding coefficient, and large welding deformation. This paper mainly focuses on material accuracy design, lap structure design, simulation, and process manufacturing to break through the precision control problems caused by welding deformation of battery electric vehicle Al alloy car body. First, the 209 key functional dimensional chains of Al body-in-white are analyzed and decomposed to component and profile tolerance dimensions step by step. Moreover, the differences of vertical butt, bevel butt, and plug structures are studied and joint matching is implemented in a targeted manner. Subsequently, through welding deformation simulation analysis and welding sequence optimization, the body-in-white welding process and tooling fixtures are guided and designed to ensure that the dimensional accuracy of the Al body is controlled to ±2 ​mm in all aspects. Finally, the design of the whole vehicle arrangement of mechanical, human-machine, and major components is carried out, and an all-Al framed battery electric vehicle lightweight platform with different sizes and ranges is innovatively created. The difficulties such as the contradiction between power battery size and arrangement space, unreasonable arrangement position, and load distribution are solved. [ABSTRACT FROM AUTHOR]

A large passenger airplane experienced an inflight rapid decompression and was forced to make an emergency landing. Post-accident inspection revealed that a section of the fuselage skin on the top portion of the airplane (crown) had fractured and flapped open during the flight. The National Transportation Safety Board (NTSB) Materials Laboratory examination of the fuselage structure determined that multiple-site damage (fatigue cracking) originated at the skin panel of a lap joint from areas of improperly drilled rivet holes. Fatigue crack growth analysis on the fracture face of the skin panel via quantitative fractography was performed by scanning electron microscopy revealed that cracking started approximately when the airplane entered service. [ABSTRACT FROM AUTHOR]

This research investigates the Al-4wt%Cu alloy, renowned for its significant mechanical properties, using both numerical simulations and experimental methods. The study focuses on the heat treatment process of the alloy, involving an extended duration ranging from 8 to 30 hours at a temperature of 500℃, followed by a reduction to 195℃ to alleviate residual stresses. Key to this process is the utilization of Brunel hardness equipment and a fatigue testing apparatus employing a bending load. The investigation extends to a mathematical simulation, elucidating the process of copper separation via deposition in aluminum and the subsequent phase transformation, which results in optimal mechanical properties. Further, the fatigue testing procedure for the alloy is simulated using the Auto Desk Inventor program. Results from the experimental phase indicate that a 12-hour treatment duration yields superior mechanical properties, with a recorded hardness of 260 Brunel and a strength of 200 MPa. In parallel, the numerical simulation results, exhibiting a strength of 195.7 MPa, demonstrate a notable convergence with the experimental findings, factoring in a correction factor of 0.96. This study not only underscores the efficacy of the optimized aging process in enhancing the alloy's mechanical attributes but also bridges the gap between theoretical predictions and experimental outcomes, providing a comprehensive understanding of the alloy's behavior under varied treatment conditions. [ABSTRACT FROM AUTHOR]

This research investigates the impact of varying the slope of the top mold in the gravity casting process of aluminum alloy (A356). The casting mold slopes were adjusted to 7°, 12°, and 17° angles, and the study integrates software analysis (Altair, 2021.2) with physical examinations to assess potential defects in the casted products. The findings from both approaches exhibit a consistent pattern, revealing notable defect porosities in molds with slopes of 7° and 12°. Radiography examinations provide insights into defect distribution within the hub wheel rim, particularly pronounced in molds with slopes of 7° and 12°. This observation suggests that disturbances in air and heat distribution impede the solidification process within the mold. Metallography profiles further highlight the presence of phases a (Al), ß (Si), and the eutectic region in the casted product. Defect severity is prominently manifested in a fractured profile, particularly for products cast with a 7° slope. In contrast, a higher slope of 12° results in localized porosities and effectively mitigates defect distribution. The most favorable outcome, devoid of substantial defects, is achieved with a 17° mold slope, successfully passing stringent quality checks. [ABSTRACT FROM AUTHOR]

This study is a multiscale experimental investigation into the embrittlement of Al-Zn-Mg aluminum alloy (7075-T6) caused by liquid metal gallium. The results of the experiment demonstrate that the tensile strength of the 7075-T6 aluminum alloy significantly weakens with an increase in the embrittlement temperature and a prolonged embrittlement time, whereas it improves with an increase in the strain rate. On the basis of the analysis of the experimental data, the sensitivity of the embrittlement of 7075-T6 aluminum alloy by liquid gallium to the loading strain rate is significantly higher compared to other environmental factors. In addition, this study also includes several experiments for microscopic observation, such as Scanning Electron Microscope (SEM) observation, Energy-Dispersive Spectrometer (EDS) spectroscopy, and Electron Back Scatter Diffraction (EBSD) analysis. The experimental observations confirmed the following: (1) gallium is enriched in the intergranular space of aluminum; (2) the fracture mode of 7075-T6 aluminum alloy changes from ductile to brittle fracture; and (3) the infiltration of liquid gallium into aluminum alloys and its enrichment in the intergranular space result in the formation of new dislocation nucleation sites, in addition to the original dislocations cutting and entanglement. This reduces the material's ability to undergo plastic deformation, intensifies stress concentration at the dislocation nucleation point, and, ultimately, leads to the evolution of dislocations into cracks. [ABSTRACT FROM AUTHOR]

This paper presents an investigation on the forming characteristics of the tailor rolled blank of an aluminum alloy (Al-TRB) during three-point bending at room temperature through experiments and finite element simulations. The strain distribution, spring-back characteristics, and metal flow law of 6000 series Al-TRB during three-point bending are explored. The prepared Al-TRB has good bending properties, and no surface cracks appear in the bending region of the Al-TRB when bent to 180°. Surface roughening occurs on the outside of the bending region. Since the strain in the thick zone is greater than that in the thin zone, the surface roughening in the thick zone is more obvious than that in the thin zone. The spring-back angle in the thin zone is higher than that in the thick zone after three-point bending, and the overall spring-back angle of Al-TRB becomes larger with an increasing bending angle. When the transition zone of Al-TRB is centered and the length of the transition zone is certain, as the length of the equal-thickness zone increases, the spring-back angle of the thin zone is larger, while the spring-back angle of the thick zone is smaller. Under the premise of a certain total length of Al-TRB and the length of the transition zone, the larger the length proportion of the thin zone, the larger the overall spring-back angle of Al-TRB, and the larger the length proportion of the thick zone, the smaller the overall spring-back angle of Al-TRB. In addition, a slight metal flow phenomenon exists during three-point bending, which shows that the metal in the bending region will flow to the thick zone, and the metal at the edge will flow to the thin zone. At the same time, there are localized thickening and thinning phenomena in Al-TRB. This study is helpful because it provides theoretical guidance for designing molds for the actual production of Al-TRB parts for automotives. [ABSTRACT FROM AUTHOR]

AA5052 is a widely used aluminum alloy in the automotive industry due to its excellent weldability, mechanical properties, and corrosion resistance. This study aims to optimize the parameters for wobbling overlap laser welding of dissimilar thickness aluminum AA5052-H32 sheets. The investigated parameters include laser power, travel speed, focal position, oscillation shape, and oscillation amplitude. The results reveal that the oscillation pattern has a minimal effect on mechanical strength. Additionally, the power intensity range of 13.2–20 J/mm2 has been identified to ensure that weld efficiency remains above 89.9%. However, considering the significance of the undercut value for achieving a smoother weld line, it is necessary to maintain the oscillation amplitude at a minimum value of 1.5 mm. The microhardness pattern proves to be a valuable method for detecting defects such as underlying porosities and deflection caused by excessive thermal input on the top sheet. The optimized processing parameters for 1–1.5 mm thickness aluminum AA5052-H32 are determined as 2500 W, 5 m/min, 6.0 mm, and 1.5 mm for laser power, travel speed, focal position, and oscillation amplitude, respectively. [ABSTRACT FROM AUTHOR]

Microbially influenced corrosion is one of the main issues of concern in industries due to its significant economic impact. In this work, we focused on Lacticaseibacillus paracasei, a typical microorganism identified in the corrosion products of aircraft fuel systems. The corrosion behavior of the 7B04 aluminum alloy was investigated using electrochemical measurements. The surface morphology was examined using stereomicroscopy and scanning electron microscopy. It was observed that when the Al alloy was immersed in the bacterial system, the impedance value decreased and the corrosion current density increased compared to the sterile system. Furthermore, with increasing immersion time, the pH value was found to be smaller than that in the sterile system, indicating that the acidic metabolic products of the bacteria exacerbated the corrosion. These findings were further supported by surface analyses, and the corrosion mechanism was discussed. [ABSTRACT FROM AUTHOR]

In this study, a magneto‐thermo‐structural coupling finite element method was proposed to calculate the electromagnetic field, temperature field, stress field, and strain field of an aluminum alloy piston during thermal shock process. The computed temperature results at the measurement points of T3 and T4 agree well with the measured data. The concept of tensile strain energy density was proposed as a thermal fatigue damage parameter, and the thermal fatigue life of the piston was predicted on the basis of the calculated results by magneto‐thermo‐structural coupling analysis and tensile strain energy density‐life equation; the discrepancy between the predicted life and the experimental one is 16%. The thermal fatigue failure mechanism of the piston was also clarified. High cyclic stresses occur on the edge of Si due to the difference in thermal expansion coefficient of Al and Si; micro cracks first originate on the edge of Si, then grow through combining other micro cracks, and eventually form macro cracks. Highlights: A magneto‐thermo‐structural coupling finite element method was developed.A novel thermal fatigue life prediction method was proposed.The thermal fatigue failure mechanism of the piston was clarified. [ABSTRACT FROM AUTHOR]

An advanced plasma-MIG hybrid welding was employed for the butt-joint of titanium (Ti) alloy and aluminum (Al) alloy sheets in this study. First, the weld bead appearance and geometry of 3 mm thick Ti/Al butt-joint specimens under different hybrid welding parameters were investigated. Then, the effects of hybrid welding parameters on the mechanical properties, fracture surface, and weld bead microstructure of the specimen were researched. In addition, the fracture mechanism between weld bead geometry and failure load of specimen was further discussed. This study selected the plasma arc current, MIG welding current, and the central gas flow rate of plasma arc as the hybrid welding parameters. The results demonstrate that Ti/Al butt-joints produced at a higher MIG welding current of 110 A or a higher central gas flow rate of 0.3 L/min increase both the height of reinforcement and porosity of fusion zone. When the MIG welding current is set to 100 A and the central gas flow rate is set to 0.2 L/min, increasing the plasma arc current to 60 A improves both weld bead geometry and tensile strength. [ABSTRACT FROM AUTHOR]

In this paper, the effects of welding speed and ultrasound on the structure and strength of aluminum-steel bimetals produced by friction stir welding have been investigated. It is shown that the strength of joints in the range of the selected technological ultrasonic impact parameters, as a rule, reduces. This is attributed to the antifriction effect, since ultrasound leads to a decrease in the dissimilar layer interface complexity and the strain of the lower steel layer. A reduction in the welding speed also led to a similar effect. It is noted that the antifriction effect is most strongly exhibited in modes with higher heat generation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Currently, drilling of directional oil and gas wells under complex technical-technological and mining-geological conditions requires the use of drill pipes made of various materials. In turn, to choose rational modes of strengthening drill pipes and drill string layouts, information on the contact forces and friction forces of the drill string pipes on boreholes is necessary. Drill pipe curved sections friction with boreholes and drill bit resistance moment changes are the main causes of uneven rotation of a drill string during rotary or combined drilling methods and the occurrence of parametric oscillations. To reduce the cost of mechanical energy for well wiring, it is necessary to take into account the "drill string–borehole rocks" force interaction to estimate the magnitude of the frictional forces and their influence on the technological parameters of the drilling process. To solve this problem, mathematical models of "conventionally vertical and inclined drill string sections–borehole" were built. Based on the industrial data, an analysis of the force interaction of a deformed drill string composed of pipes made of different materials (aluminum, titanium, steel) was carried out. Analytical dependences were obtained for determining the contact forces and friction of the pipes on boreholes. A numerical study of the change of these power factors depending on the depth of the well under conditions of intensive vibration loading was carried out. The amplitude values of these forces, the frequency of their change for good sections, as well as the places for the most rational installation of drill pipes in the layout of the drill string were estimated. It was established that the intensity of contact and friction forces for steel drill pipes is greater than for titanium or aluminum ones. It is shown that the greater impact of a solid steel string on contact forces and frictional forces compared to a layout with sections of titanium or aluminum pipes in the range of vibration frequencies of 8–22 Hz corresponds to a bit rotation frequency of 70–80 rpm. The practical application of the obtained research results will contribute to the improvement of technical and economic indicators of the well drilling process. [ABSTRACT FROM AUTHOR]