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The role of ambient oxygen gas (O2) on molecular and nanoparticle formation and agglomeration was studied in laser ablation plumes. As a lab-scale surrogate to a high explosion detonation event, nanosecond laser ablation of an aluminum alloy (AA6061) target was performed in atmospheric pressure conditions. Optical emission spectroscopy and two mass spectrometry techniques were used to monitor the early to late stages of plasma generation to track the evolution of atoms, molecules, clusters, nanoparticles, and agglomerates. The experiments were performed under atmospheric pressure air, atmospheric pressure nitrogen, and 20% and 5% O2 (balance N2), the latter specifically with in situ mass spectrometry. Electron microscopy was performed ex situ to identify crystal structure and elemental distributions in individual nanoparticles. We find that the presence of ≈20% O2 leads to strong AlO emission, whereas in a flowing N2 environment (with trace O2), AlN and strong, unreacted Al emissions are present. In situ mass spectrometry reveals that as O2 availability increases, Al oxide cluster size increases. Nanoparticle agglomerates formed in air are found to be larger than those formed under N2 gas. High-resolution transmission electron microscopy demonstrates that Al2O3 and AlN nanoparticle agglomerates are formed in both environments; indicating that the presence of trace O2 can lead to Al2O3 nanoparticle formation. The present results highlight that the availability of O2 in the ambient gas significantly impacts spectral signatures, cluster size, and nanoparticle agglomeration behavior. These results are relevant to understanding debris formation in an explosion event, and interpreting data from forensic investigations. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a promising joining technique with low environmental impact. Considering the importance of adequate selection of FSW parameters for weld quality and energy consumption, this study presents an optimization of specific energy considering constraints. The Newton optimization method is used to find the optimal values of process parameters. The specific energy consumed during the FSW is calculated from the expression for the torque variation as a function of the process velocities and tool geometry. The constraints are imposed to ensure selected parameters produce defect-free welds and are defined based on the literature review. The specific energy is optimized to find the optimal values of welding speed, rotational speed, shoulder radius, and pin radius of the tool. Additionally, the power is analyzed at the minimum specific energy condition. The results show that a welding speed of 200 mm/min and a tool rotational speed of 400 rpm minimize the specific energy consumed. Moreover, for plates with a thickness between 3 and 6 mm, the optimal values of shoulder radius and pin radius for the minimum specific energy are 10 mm and 3.8 mm, respectively. In the same way, for plates with a thickness between 7 and 9 mm, the minimum specific energy is obtained for a shoulder radius of 13.90 mm and a pin radius of 5.08 mm. [ABSTRACT FROM AUTHOR]

The machining of monolithic components is prone to deformation, which causes a large amount of production resources to be wasted. Therefore, studying the process of initial configuration optimization method to reduce machining deformation is of great significance for the precision machining of monolithic components. In this paper, the concept and mathematical expression of the initial process configuration are proposed for aluminum alloy U-shaped cross-section stringer structural components. The initial configuration optimization problem is formulated with the initial process configuration as the variable and the objective of minimizing machining deformation. An iterative method is used to optimize the initial process configuration. The machining deformation after the optimized configuration was analyzed by finite element simulation and theoretical calculation, and the deformation data error of the two was less than 20%, which verified the correctness of the method proposed in this paper. Machining tests were carried out, and the results show that the proposed initial configuration optimization method can control the deformation of the U-shaped long truss parts within ± 0.06 mm/m, which is 80–90% less than that before optimization. This initial configuration optimization method has a positive effect on controlling machining deformation. [ABSTRACT FROM AUTHOR]

This study aims to explore the influence of control parameters from the perspective of the amorphous ceramic coating formation process. Three preparation processes were preferred based on the thickness, appearance and corrosion resistance of the coatings by orthogonal experiment. The surface morphology, cross-sectional structure, phase composition and micro-hardness of PEO coatings were examined using scanning electron microscopy (SEM)/Energy dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD) and hardness measurement techniques. Findings indicate that voltage exerts the most significant impact on coating thickness and appearance, whereas the influence of other parameters becomes more pronounced as the voltage increases. Three amorphous ceramic coatings prepared in 20 min with thicknesses of 27.4 μm, 83.2 μm and 193.3 μm increased the surface hardness of 6061 aluminium alloy by 6–8 times, and decreased the corrosion current density of 6061 aluminium alloy by 3 orders of magnitude in 1 mol L−1 HCl solution. Moreover, the thickening of the coating primarily occurs within a few minutes after the voltage reaches its peak, and high frequency and low duty ratio are prerequisites for better appearance under higher voltage conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

This work reported the influence of laser surface melting (LSM) pretreatment on the growth behavior, electrical insulation and corrosion resistance of plasma electrolytic oxidation (PEO) film on 6061 aluminum alloy. It is found that the LSM pretreatment refines the surface structure of original Al metal, generating defects that store excessive energy, thereby enhancing reaction kinetics and phase transition during the PEO process. By LSM pretreatment, uniform electrical discharge and film growth can be obtained, resulting in fewer defects and lower porosity in PEO layers. Additionally, a large amount of columnar crystals comprising of SiO 2 phase are observed, which transformed from the SiO 3 2− deposited on the surface, and the LSM pretreatment significantly improves the electrical insulation, corrosion resistance, and substrate adhesion of following PEO layer. Under the same PEO treatment duration, the breakdown voltage of coating increased by 100 V, and icorr decreased from 3.26 × 10−4 to 9.13 × 10−6 A cm−2. It is expected that the combination of LSM and PEO processes can not only enhance the surface properties of Al metal, but also expand the practical application of aluminum alloy in high-power electronic devices and related fields. [Display omitted] [ABSTRACT FROM AUTHOR]

Aluminum alloys are widely used in lightweight automotive structures due to their excellent properties. To deeply explore the development of surface bonding technology, aluminum alloy is selected as the object, and current research status of aluminum alloy surface treatment methods is reviewed. The adhesion mechanism during joint preparation, the method of adhesive selection, and the bonding process are summarized. This overview discusses the impact of different surface treatment processes on aluminum alloy joints from two perspectives: substrate characteristics and joint failure modes. It examines how these processes affect surface roughness, surface morphology, surface contact angle, surface free energy, surface chemical composition, and bonding performance. Additionally, it looks ahead to key directions for future research on adhesive joint performance. The results indicate that surface treatment increases the surface roughness of aluminum alloys, reduces the contact angle, and improves surface wettability. Moreover, chemical elements or functional groups that enhance adhesion are introduced on the surface, improving the bonding capability between the adhesive and the substrate. Compared to single‐surface treatment methods, hybrid treatment methods significantly enhance the surface characteristics of aluminum alloys and are expected to become a primary focus for future research on bonded joint performance. [ABSTRACT FROM AUTHOR]

Micro-arc oxidation (MAO) coatings can enhance the wear and corrosion resistance of aluminum alloys, but the high coefficient of friction and surface pores can lead to failure in the field. In this study, zinc acetate and graphite particles are introduced to the electrolyte to form corrosion-resistant and lubricating MAO coatings on the LY12 aluminum alloy. Zinc phosphate nanocrystals formed in situ are uniformly distributed in the amorphous coating, while the extrinsic graphite is mainly located in the amorphous structure. Compared to the aluminum alloy substrate, the friction coefficient of the optimal MAO coating decreases to ∼0.2, and the wear rate decreases by nearly 10 times. Zinc phosphate nanocrystals generated in situ in the coatings release Zn2+ during corrosion attack to cover the vulnerable weak corrosion areas around the pores. The corrosion resistance is improved significantly, as manifested by the increase of the corrosion potential from −1.290 V to −0.811 V and the decrease of the corrosion current density from 3.172 × 10−6 A cm−2 to 4.320 × 10−10 A cm−2. The co-doped MAO coatings have better wear and corrosion resistance and are more suitable than the LY12 alloy in many engineering applications. [ABSTRACT FROM AUTHOR]

This study investigated the preparation of SiC porous ceramics using an organic foam impregnation-high temperature sintering process. To address the poor wettability of SiC ceramics when used as the reinforcement phase, the surface of SiC porous ceramics was modified with Al 2 O 3. SiC-Al 2 O 3 /2A50 co-continuous composites were then fabricated by infiltrating 2A50 aluminum alloy into the SiC-Al 2 O 3 porous ceramics under pressure. Microstructural observations, along with friction, wear performance, and thermal stability test, demonstrated that Al 2 O 3 surface modification significantly enhances the friction and wear performance as well as the thermal stability of the co-continuous composites. The prepared SiC-Al 2 O 3 /2A50 co-continuous composite exhibited excellent wear resistance, good thermal stability and stable bonding at heterogeneous interfaces. Compared to 38CrSi steel, the SiC-Al 2 O 3 /2A50 co-continuous composite not only offers the advantage of reduced weight but also shows a significantly lower wear rate of 9.3 × 10−5 mm3/N·min under a 50 N load. These findings suggest that the SiC-Al 2 O 3 /2A50 co-continuous composite has the potential to replace 38CrSi steel as a wear-resistant material. [ABSTRACT FROM AUTHOR]

5356 aluminum alloy welding wire is widely used in automotive, aerospace, and marine, due to its excellent corrosion resistance, high strength-to-weight ratio, and excellent weldability. The properties of aluminum alloys are primarily determined by their microstructure. This study investigates the microstructure evolution, mechanical properties, and texture of 5356 aluminum alloy welding wire produced using the continuous casting direct rolling (CCDR) method. The results show that continuous rolling led to an increased generation of dislocations in the matrix, and dynamic recovery plays an important role in reducing dislocation density. As a result of dynamic recovery, the microstructures of 3RPs consist of extensive deformed grains and numerous substructures. The continuous casting direct rolling textures are characterized to be cube and shear textures. After 10 rolling processes, the 5356 aluminum alloy welding wire shows a highest tensile strength of 365 MPa with a lowest elongation of 8.8%. This research provides theoretical guidance to produce high-performance 5356 aluminum alloy welding wires, paving the way for their more efficient and reliable applications. [ABSTRACT FROM AUTHOR]

Technologies that facilitate recycling are attracting considerable interest from the perspective of resource constraints. In the present study, degradable primer films are to facilitate the removal of strongly bonded joints. This film consists of a light‐cured trifunctional anthracene compound that thermally decomposes to its original liquid state. To demonstrate its function as a degradable primer film and verify its range of applications, various substrates, such as aluminum alloys, stainless steel, carbon fiber‐reinforced plastics, carbon fiber‐reinforced thermoplastics, and polyetheretherketone, are bonded through the primer film using a two‐component epoxy adhesive. All the single‐lap specimens exhibit strengths above 10 MPa, which is sufficient, or base material fracture. When adhesive bonding specimens prepared using the same procedure are heated at 180 °C to transform the coating film to a liquid state, the bond strength is significantly reduced. The primer film is expected to exhibit long‐term stability of more than one year at ≈60 °C. [ABSTRACT FROM AUTHOR]

• A space harpoon device based on aluminum honeycomb buffer has been designed for space debris. • The feasibility of the harpoon capture scheme was verified through ground experiments. • Aluminum honeycomb reduces the impact force and rebound speed during operation. • The adaptability of space harpoons can capture target states of different postures and materials. To address the issues of high impact and limited adaptability in capturing space debris with space harpoons, a novel harpoon capture device based on aluminum honeycomb buffering was proposed. The issue of excessive impact force for harpoons could be effectively addressed by the excellent energy-absorbing characteristics of aluminum honeycomb. A simulation model was established to analyze the penetration of space harpoons into aluminum alloy target plates using Johnson-Cook's dynamic constitutive model and fracture failure criteria. Ground experiments were conducted to validate the correctness of the simulation model. The impact of aluminum honeycomb was investigated by analyzing the simulation results of harpoons with and without aluminum honeycomb. With the introduction of aluminum honeycomb as a buffering component, the rebound velocity of the harpoon decreased by 76.2 %, and the impact force reduced by 78.6 %. Then the model was used to study the influence of different launching angles and different targets on the penetration characteristics of the space harpoon. The research findings indicate that space harpoons could successfully penetrate and capture aluminum alloy targets at a launch velocity of 53.1 m/s to 58.5 m/s, as determined through ground experiments and simulation analysis. The error in the crushing height of the aluminum honeycomb was found to be 2.19 %, while the error in the harpoon penetration depth was 9.02 %. Moreover, within a launch angle error of 10°, space harpoons also demonstrate the capability for adaptive capture of both aluminum alloy plates and aluminum honeycomb sandwich panels, with average correction capabilities of 92.5 % and 95.5 %. In conclusion, the analysis of the adaptive penetration characteristics of space harpoons provides a solid theoretical foundation and technical support for the design of harpoon capture systems. [ABSTRACT FROM AUTHOR]

The aeronautical industry widely uses the riveting process for metallic sheet metal structure joining processes, mainly when manufactured using aluminum alloys. During riveting operations, some level of geometrical deformation is induced in the airframe structure and such an effect may impact the manufacturing cycle and the product shape. It is important to identify the induced-deformation mechanisms associated with such phenomena and simulation methods capable of foreseeing them numerically or algebraically. The development of simulation methods, even if approximated methodologies, is necessary to assess possible geometrical variations in riveted airframes. Those structures are usually part of wing and fuselage panels. This work presents a general literature review of the riveting process and current modeling techniques aiming to identify modeling methods that could become an adequate baseline approach for riveting-induced deformations. Riveted geometry distortions may produce undesired consequences on manufacturing cycles, aerodynamics performance, and structural efficiency. [ABSTRACT FROM AUTHOR]

The behavior of materials under high strain rates is pivotal to their deformation during machining processes. This research focuses on numerical modeling of the dynamic behavior of aluminum alloys (AA) 7075-T6 in dry turning operation. The Johnson–Cook (J-C) constitutive equation and coefficients derived from the split-Hopkinson pressure bar (SHPB) and uniaxial tensile tests were used in numerical simulations based on finite element (FE). Numerical models were validated under different machining conditions. The numerical and experimental studies revealed the significant impact of the feed rate on the alloy's behavior, chip thickness, and chip morphology. The work confirmed that increasing the cutting speed and feed rate led to higher machining temperatures. The lowest amounts of built-up layer (BUL) and built-up edge (BUE) were observed at high cutting speed and feed rate levels. The minimum surface roughness was recorded at low feed rates and high cutting speeds. The experimental results adequately confirmed the accuracy of the FE simulations. This research indicates that strain rate hardening significantly affects AA 7075-T6 and substantially increases strength as the strain rate increases. The results of the machining simulation validated the appropriateness of the J-C damage parameters used for the material. [ABSTRACT FROM AUTHOR]

The unsatisfactory mechanical performance at high temperatures limits the broad application of 3D‐printed aluminum alloy structures in extreme environments. This study investigates the mechanical behavior of 4 different lattice cell structures in high‐temperature environments using AlSi12Fe2.5Ni3Mn4, a newly developed, heat‐resistant, high‐strength, and printable alloy. A novel Antisymmetric anti‐Buckling Lattice Cell (ASLC‐B) based on a unique rotation reflection multistage design is developed. Micro‐CT (Computed Tomography) and SEM (Scanning Electron Microscope) analyses revealed a smooth surface and dense interior with an average porosity of less than 0.454%. Quasi‐static compression tests at 25, 100, and 200 °C showed that ASLC‐B outperformed the other 3 lattice types in load‐bearing capacity, energy absorption, and heat transfer efficiency. Specifically, the ASLC‐B demonstrated a 51.56% and 44.14% increase in compression load‐bearing capacity at 100 and 200 °C compared to ASLC‐B(AlSi10Mg), highlighting its excellent high‐temperature mechanical properties. A numerical model based on the Johnson‐Cook constitutive relationship revealed the damage failure mechanisms, showing ASLC‐B's effectiveness in preventing buckling, enhancing load‐transfer efficiency, and reducing stress concentrations. This study emphasizes the importance of improving energy absorption and mechanical performance for structural optimization in extreme conditions. The ASLC‐B design offers significant advancements in maintaining structural integrity and performance under high temperatures. [ABSTRACT FROM AUTHOR]

The surface quality of aluminium alloy castings is crucial to quality control. Aiming to address the challenges of limited samples and extensive computation in deep learning‐based surface defect detection for aluminium alloy castings, this paper proposes a surface defect detection method based on data enhancement and the Casting Real‐Time DEtection TRansformer. First, to tackle the issue of small sample sizes and uneven distribution in surface defect data sets of aluminium alloy castings, ECA‐MetaAconC Deep Convolution Generative Adversarial Networks is proposed for generating defects with fewer samples and employ the image augmentation (IMGAUG) library for sample enhancement. Second, building upon the Real‐Time DEtection TRansformer (RT‐DETR), a lightweight partial‐rep convolution is designed to decrease the network's parameter count. Simultaneously, the Deformable attention module and the DRBC3 module are introduced to enhance the neck network, thereby improving the model's capability to capture information and enhancing its detection performance. Compared to RT‐DETR, this method reduces the number of model parameters by 38.7%, increases mAP by 1.5%, and achieves a frame rate that is 1.58 times higher than the original model. The experimental results demonstrate that this method can effectively and accurately detect surface defects in aluminium alloy castings, satisfying industrial requirements. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) of rare‐earth‐modified high‐strength aluminum alloys presents a novel approach for manufacturing complex components with enhanced structural performance, particularly in aerospace applications. This study fabricates Al–Mg–Sc–Zr specimens using various powder spreading parameters to explore their impact on laser processability. The investigation reveals that varying the powder layer thickness from 30 to 70 μm yields the smallest irradiation diameter of 135 μm at an optimal thickness of 50 μm, attributable to effective multiple reflections, high laser absorption rates, and stability. With an optimal laser power of 400 W, a scanning speed of 600 mm s−1, and a hatching spacing of 60 μm, the sample produced at 50 μm layer thickness achieves a relative density of 99.23%, a top surface roughness of 15.42 μm, and a refined grain size of 1.67 μm. Following aging at 325 °C for 4 h, this sample exhibits a tensile strength of 518 MPa and an elongation of 15.6%. The findings establish a theoretical basis for controlling the morphology and properties of high‐strength aluminum alloys in laser additive manufacturing. [ABSTRACT FROM AUTHOR]

Cold expansion is a mechanical method for creating residual stresses. This method is a proven technique to increase the fatigue life, and checking the residual stress on it, is of particular importance. A cold expansion process is widely used to generate beneficial residual stresses into an annular region around the hole. In the present research work, AA 6016-T6 and AA 1100 aluminum alloys which are two strain rate sensitive materials, were subjected to cold expansion process with different mandrel velocities. In fact, the effect of mandrel velocity on the created residual stresses has been investigated. The constants of the Johnson-Cook material model have been determined for them and the process has been investigated, experimentally and numerically. The obtained results revealed that the values of the residual stresses created in the sheets depend on the velocity of the process especially at the edge of the sheets holes. By increasing the mandrel velocity from 5 to 500 mm/min, depending on the distance from the hole to the edge of the sheet, it is possible to enhance the hoop residual stress by 37.3–41.2% in AA 1100 aluminum alloy and by 37.6–38.1% in AA 6016-T6 aluminum alloy. This research showed that in all cases, the radial residual stresses created around the holes are negative. Also, it was cleared that due to the existence of material constraints and the movement of the sheet material, the amount of hoop residual stress created in the mid-thickness is more than the exit face and in the exit face is also more than the entrance face, exactly unlike the size of their zones. [ABSTRACT FROM AUTHOR]

This study presents the development of a material selection decision support system for an automotive rooftop tent. The system uses five parameters of material cost, formability, corrosion resistance, tensile strength and hardness to optimize material choice from a list of aluminium alloy options. This was done before production via the deep drawing process can commence. The parameters were quantified using the average market prices for each alloy, product requirements obtained from the case study and the performance data that was obtained from the uniaxial tensile and hardness tests. These inputs were combined with the developed material selection framework and then programmed into a web-based decision support system for automated, data-driven material selection. The output presents the recommendation for the optimum material that balances cost-effectiveness and performance. The decision support system was successfully used to select the optimum alloy for the rooftop tent. Results show that AA1050 is the optimum material, providing weight reduction at the minimum achievable cost without compromising the product requirements for the rooftop tent. The decision support system is also scalable, and this allows it to be used with larger datasets for different products and processes in the future. [ABSTRACT FROM AUTHOR]

2024 aluminum alloy has high strength, processing performance, and good damage tolerance performance, but it is prone to intergranular corrosion and pitting. Therefore, the development of corrosion protective coatings is essential for the aluminum alloy. In this paper, cerium ion (Ce3+) was doped into chitosan‐modified montmorillonite (Ce‐CS‐MMT) by ion exchange method, and the corrosion protective performance of Ce‐CS‐MMT epoxy coating (Ce‐CS‐MMT/EP) was investigated. The electrochemical analysis of aluminum alloy in cerium‐containing solution showed the corrosion inhibition efficiency reached 95.52%. The result indicates the corrosion inhibition effect of cerium‐containing solution was better than pure NaCl solution and MMT solution. The corrosion study of the coating illustrates that the protection rate of Ce‐CS‐MMT/EP reached 95.82%, which was higher than that 91.83% of Ce‐MMT/EP. The result indicates the resistance of charge transfer was greater and the better shielding effect for electrolyte corrosion ions than MMT and Ce‐MMT epoxy coatings, and the corrosion protective performance was excellent. [ABSTRACT FROM AUTHOR]

Evolution of the microstructure of new Al–Cu–Mg–Y(Er)–Cr alloys is studied during casting, surface laser melting, simulating selective laser melting, and subsequent homogenization annealing. A structure of surface laser melting tracks without defects of crystallization origin, in particular, hot cracks, is obtained. At the same time the track zone does not have a shrinkage cavity and porosity. The grain structure of tracks is represented by a narrow zone of columnar crystals and a zone of equiaxed crystals about 5 μm in size. During homogenization of the AlCuYMgCr–L alloy particles grow in size to approximately 500 nm, while in AlCuErMgCr–L alloy they grow to a significantly larger size of 2 μm. A common feature for both alloys is presence within aluminum solid solution of a large number of particles less than 100 nm in size. According to studies and thermodynamic calculations conducted previously, during alloy homogenization of these alloys, heterogenization should occur with nucleation of L12–Al3(Zr,Y)/L12–Al3(Zr,Er) and Al45Cr7 phases dispersoids. [ABSTRACT FROM AUTHOR]

Al-based metallic glasses (MGs) effectively circumvent the longstanding tradeoff between corrosion resistance and mechanical properties inherent in commercial Al alloys due to their distinctive structural and compositional attributes. This article systematically elucidates the effects of composition and microstructure on the corrosion evolution process, particularly regarding pitting corrosion. This comprehensive examination encompasses aspects such as Cl− adsorption, passive film characteristics, and the stability of pit growth, and based on insights drawn from this exhaustive review of the literature, it advocates for further investigations aimed at advancing the development of corrosion-resistant Al-based MGs. [ABSTRACT FROM AUTHOR]

The results of modeling and research of casting, rolling, and extrusion processes for producing wire from AleZr system alloys and determining its physical and mechanical properties have been presented. When implementing combined processes for processing aluminum alloys, the number of operations is significantly reduced, productivity and yield are increased. As a result of the conducted research, the influence of alloy preparation modes and their chemical composition on the physical, mechanical and electrical properties of longish semifinished products from AleZr system alloys obtained by combined rollingextrusion (CRE) and ingotless rolling-extrusion (IRE) methods were investigated. The simulation of the CRE process for one of these alloys of the system was carried out in the DEFORM 3D software package using data on its rheological properties obtained by the hot torsion method. Based on the modeling results, the optimal modes for conducting experimental studies were selected. The features of metal forming were experimentally studied, the temperature-velocity and technological parameters of combined processing were found, as well as the properties of cast billets, including those obtained using an electromagnetic mold (EMM). The results of experimental studies of the CRE and IRE processes suggest that it is possible to obtain longish deformed semifinished products from alloys AleZr system with a level of physical, mechanical and electrical properties that meet international standards. At all technological stages, including drawing, the structure of the metal was studied, and data on the physical and mechanical properties of hot-extruded rods and wire in cold-deformed and annealed states was obtained. The heat resistance of wire made from the investigated alloys was studied and it was found that after testing at a temperature of 280 °C and a holding time of 1 h, it satisfies the requirements of the AT3 type standard with a maximum permissible long-term operating temperature of 210 °C. Recommendations are given for industrial implementation; alloys containing 0.15e0.20% zirconium and 0.10e0.15% iron are recommended for the manufacture of AT1 type wire without heat treatment, as well as 0.25e0.30% Zr and 0.2e0.25% Fe for AT3 wire type with heat treatment. [ABSTRACT FROM AUTHOR]

The high-energy ball milling process was applied to fabricate a composite material from 7075 aluminium alloy milling chips, silicon carbide, and titanium dioxide powders. Raw materials were ground, and the obtained powders were cold pressed and sintered. It was demonstrated that this method can be used in the recycling of aluminium alloy scrap characterised by a high surface-to-volume ratio, and also that chemical removal of the oxide layer from chips is not necessary. The finest particles, with 50 vol.% of their population below 36 μm, were obtained after grinding for 60 min at a 1000 rpm rotational speed. Such an intensive grinding was necessary to fabricate the compact composite material with a homogeneous microstructure and a low porosity of 0.7%. The corrosion resistance of the composites was studied in 3.5 wt.% NaCl solution using cyclic voltammetry and electrochemical impedance spectroscopy, and corrosion rates in the range of ca. 342 and 3 μA∙cm−2 were obtained. The corrosion mechanism includes aluminium alloy dissolution at the matrix/reinforcement interphase and around intermetallic particles localised within the matrix grains. [ABSTRACT FROM AUTHOR]

Soluble aluminum alloy materials used in underground operational tools are synthesized via a high-temperature smelting process. The microstructure and composition distribution of the alloy were analyzed using X-ray diffraction, metallographic microscopy, and scanning electron microscopy with energy-dispersive X-ray and electron backscatter diffraction techniques. The mechanical properties were evaluated using a universal testing machine and hardness tester, while solubility assessments were conducted in a constant-temperature water bath. This study focuses on the plasticity and dissolution characteristics of Al-Mg-Ga-Sn-In alloys with varying Mg contents. The tensile strength (σb) of the alloy was 181.99 MPa, with an elongation (δ) of 27.49% and cross-sectional shrinkage (φ) of 11.67% at a magnesium content of 3.0 wt.%. Additionally, in the compressive test, the compressive yield strength (σsc) was recorded at 188.32 MPa, while the compression rate (δ) was 27.06% and the section expansion rate (φ) was 138.66%. Furthermore, the alloy demonstrated the ability to dissolve spontaneously in water at 90 °C, exhibiting an average dissolution rate of 1.0 g·h−1cm−2 and a maximum dissolution rate of 3.25 g·h−1cm−2 after 12.0 h. Consequently, this alloy composition not only satisfies the requirements for rapid solubility but also exhibits favorable plasticity, providing a novel reference for the selection of soluble aluminum alloy materials. [ABSTRACT FROM AUTHOR]

In this article, AlSi10Mg aluminum alloy was used as the substrate to prepare aluminum alloy/diamond composite materials with laser cladding technology. The effects of the composition and laser power on the microstructure and thermal properties of the composite materials were studied. The results show that the prefabrication of tungsten carbide layer on the diamond surface enhances the wettability of diamond with aluminum alloy and reduces the laser reflection, which ensures the implementability of laser cladding technology for the preparation of aluminum alloy/diamond composites. The laser power and components determine the temperature of the molten pool and thus the state of the organization of the composite material to be formed by cladding. With the increase in the diamond content, the density, specific heat, mechanical properties, and average linear thermal expansion coefficient of the composite material gradually decrease, while the thermal conductivity first increases and then decreases. The thermal conductivity of the aluminum alloy/diamond composite material prepared by laser cladding is 200.68 W/mK, and the linear thermal expansion coefficient is 1.904 × 10−5/K, which are superior to those of the matrix AlSi10Mg aluminum alloy. [ABSTRACT FROM AUTHOR]

Wire Arc Additive Manufacturing (WAAM) technology, known for its low equipment and material costs, high material utilization, and high production efficiency, has found extensive applications in the fabrication of key components for the aerospace and aviation industries. The stability of the arc is crucial for the WAAM process as it directly affects the forming of the parts. In this study, the monitoring data of electrical signals and arc morphology during the WAAM process of 2319 aluminum alloy were investigated using a high-speed camera system and current/voltage acquisition system. By analyzing the current and voltage signals, as well as the arc imaging results, the influence of arc stability on the forming of the cladding layer was studied. The experimental results indicated that when both current and voltage exhibit regular periodic fluctuations, this manifests as a stable short-circuit droplet transition form, while sudden changes in these signals represent abnormal droplet transition forms. The adaptability of the process directly influenced the arc shape, thereby affecting the forming of the cladding layer. Under the process parameters of welding speed of 240 cm/min and wire feeding speed of 6.5 m/min, it was observed that the current signal exhibited a tight state and the variance of the arc width was minimized. This indicated that at a higher wire feeding speed, the droplet transfer frequency was increased. Under these process parameters, the arc output was more stable, resulting in a uniform metal coating. [ABSTRACT FROM AUTHOR]

To meet the application requirements of electronic connectors, a trivalent chromium process (TCP) conversion coating was prepared on the Zn–Ni alloy plating of 2024 aluminium alloy. The composition of the TCP solution was as follows: 45 g/L Cr(NO3)3, 14 g/L CoCl2, 1.3 g/L NiCl2, 10 g/L citric acid, 10 g/L succinic acid and 1 g/L sodium dodecyl sulphate. The properties of TCP were characterised by a range of techniques, including macroscopic observations, scanning electron microscope, energy‐dispersive X‐ray spectrometer, three‐dimensional (3D) morphometry, electrochemical impedance spectroscopy, polarisation curves and conductivity tests. The TCP prepared in this experiment exhibits a uniform black colour and bright appearance, predominantly composed of Zn, Ni, O, Cr and Co. The TCP enhances the impedance of Zn–Ni alloys, reduces the corrosion current to 1.99 × 10−5 A/cm2 and maintains a flatter surface 3D morphology and less surface roughness following electrochemical testing. It has better corrosion resistance. Following the preparation of the TCP on a suitably sized shell sample, the shell resistance was 1.2 mVDC with good electrical conductivity, which meets the requirements for electrical connector applications. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study is to use non-destructive testing of corrosion on coated aluminium alloys using differential eddy current detection (DECD), with the aim of elucidating the relationship between the characteristics of corrosion defects and the detection signal. Design/methodology/approach: Pitting corrosion defects of varying geometrical dimensions were fabricated on the surface of aluminium alloy plates, and their impedance signals were detected using DECD to investigate the influence of defect diameter, depth, corrosion products and coating thickness on the detection signals. Furthermore, finite element analysis was used to ascertain the eddy current distributions and detection signals under different parameters. Findings: The size of the defect is positively correlated with the strength of the detection signal, with the defect affecting the latter by modifying the distribution and magnitude of the eddy current. An increase in the diameter and depth of corrosion defects will enhance the eddy current detection (ECD) signal. The presence of corrosion products in the corrosion defects has no significant effect on the eddy current signal. The presence of a coating results in a decrease in the ECD signal, with the magnitude of this decrease increasing with the thickness of the coating. Originality/value: The objective is to provide experimental and theoretical references for the design of eddy current non-destructive testing equipment and eddy current testing applications. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to explore how graphene can improve the mechanical and anti-corrosion properties of TiO2-SiO2 sol-gel coating. This sol-gel coating has been prepared on aluminum alloy substrate using graphene as both nano-filler and corrosion inhibitor. Design/methodology/approach: To examine the effect of graphene on mechanical properties of sol-gel coating, the abrasion resistance, adhesion strength and scratch resistance of coating have been evaluated. To reveal the effect of graphene on the anti-corrosion property of coating for aluminum alloy, the electrochemical impedance spectroscopy (EIS) has been conducted in 3.5 Wt.% NaCl medium. Findings: Scanning electron microscopy images indicate that graphene nanoplatelets (GNPs) have been homogeneously dispersed into the sol-gel coating matrices (at the contents from 0.1 to 0.5 Wt.%). Mechanical tests of coatings indicate that the graphene content of 0.5 Wt.% provides highest values of adhesion strength (1.48 MPa), scratch resistance (850 N) and abrasion strength (812 L./mil.) for the sol-gel coating. The EIS data show that the higher content of GNPs improve both R1 (coating) and R2 (coating/Al interface) resistances. In addition to enhancing the coating barrier performance (graphene acts as nanofiller/nano-reinforcer for coating matrix), other mechanism can be at work to account for the role of the graphene inhibitor in improving the anticorrosive performance at the coating/Al interface. Originality/value: Application of graphene-based sol-gel coating for protection of aluminum and its alloy is very promising. [ABSTRACT FROM AUTHOR]

Purpose: As a commonly engine coolant, ethylene glycol can produce corrosive acid byproducts at high temperatures when the car is running, specifically oxalic acid (OA), which can shorten the service life of engine. At the same time, chloride ions can also be introduced during coolant preparation processes. Therefore, this paper aims to investigate the synergistic corrosion behavior of Cl− and OA on ADC12 aluminum alloy. Design/methodology/approach: The electrochemical tests, scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction and X-ray photoelectron spectroscopy) were used. Findings: The results showed that the corrosion rate of the aluminum alloy increased with the increase of OA and Cl− concentrations. After adding Cl−, the surface film of the aluminum alloy was further damaged, Cl− has a synergistic effect with OA and their interaction further accelerated the corrosion of the aluminum alloy. Nevertheless, as the immersion time increased, the corrosion rate of the aluminum alloy gradually diminished due to the formation of aluminum oxalate. Originality/value: The corrosion of ADC12 aluminum alloy was studied in OA, Cl− and their mixed solutions; the synergistic effect of OA and Cl− on the corrosion of ADC12 aluminum alloy was discussed, and aluminum oxalate formed inhibited its corrosion. [ABSTRACT FROM AUTHOR]

Purpose: This research aims to examine the impact of friction stir processing (FSP) treatment on an aluminum alloy, especially the AD31T alloy derived from the Al-Fe-Mg-Si system. The aim is to assess the influence of different processing techniques on the microstructure and physical and mechanical characteristics of the material, with a specific focus on structural and bulk imperfections inside the stir zone (SZ). Design/methodology/approach: The study demonstrates that augmenting the linear velocity of the tool within the 25–100 mm/min range results in significant enhancements. The enhancements include a decrease in the heat-affected zone (HAZ), a reduction in the extent of volume defects inside the SZ and a more uniform deformation. The microstructural analysis results are corroborated by data acquired from microhardness and electrical conductivity studies, confirming the beneficial influence of modifying the tool's linear velocity on the material parameters. Findings: This study provides significant observations on the changes in microstructure and the generation of flaws throughout the process of FSP of AD31T alloy. These results have practical implications for improving the characteristics of the alloy and optimizing the production conditions. Originality/value: All samples exhibit a distinct reduction in electrical conductivity within the initial third of the sample, aligning with the transitional region between the base metal (BM) and the HAZ. This underscores the importance of understanding the transitional zones during FSP. [ABSTRACT FROM AUTHOR]

Background: The size effect and deformation instability exhibited by materials at the micro- and nano-scale constrain the development and application of miniaturized devices. Introducing different defects in materials through different technical means to improve the deformation stability of materials has been the main research point of micro- and nano mechanics. Objective: This paper presents a novel strategy to completely eliminate the instability of microscopic deformations by the introduction of high-density precipitates in aluminum alloys by means of suitable heat treatment. Methods: A suitable heat treatment is used to introduce a high density of precipitates in the 7075 aluminum alloy. Using the Focused Ion Beam technique and in situ micropillar compression tests, micron-sized single-crystal micropillars were fabricated and the size dependence of the strength and strain-hardening behavior of 7075 aluminum alloy was systematically analyzed. Results: Compared with precipitate-free Al–Mg alloy micropillars, the micropillars fabricated from 7075 aluminum alloy exhibited more stable deformation behavior, predominantly due to the impediment of dislocation motion by precipitates. The power-law exponent for yield strength relative to pillar size was determined to approach a near-zero value, indicating a negligible dependency of yield strength on specimen size. Similarly, the smaller the size of micropillar, the higher the hardening rate, which can be rationalized by exhaustion hardening. Conclusions: The proposed method can eliminate the size effect of materials with pillar size above 0.5 μm and leads to a stabilization in deformation behavior. These are advantageous for the application of micro- and nano-sized components in advanced engineering systems. [ABSTRACT FROM AUTHOR]

Background: Reliably calibrated criteria are needed for an accurate prediction of fracture of various components. However, there is not always a sufficient amount of material available. Therefore, miniature testing provides an alternative that is researched together with the following calibration of the ductile fracture criteria and investigating the size effect. Objective: The aim is to design miniature testing equipment and specimens for tensile testing, which covers various stress states. This is supplemented by the small punch test, which has the same specimen thickness, taken from the literature to broaden the portfolio for calibration. The second part deals with conducting the finite element analysis, which provided a basis for the calibration of the phenomenological ductile fracture criterion applicable to crack-free bodies to indicate the crack initiation. Methods: The steel frame to test thin specimens is designed with optical measurement of deformations. The finite element method is used, within Abaqus and user subroutines, to simulate the tests to obtain the variables needed for the calibration. In addition, the calibration of the criterion using machine learning is explored. Results: The feasibility of the proposed experimental program is tested on the aluminium alloy 2024-T351. Moreover, the numerical simulations, which showed a good match with experiments in terms of force responses, adds to the knowledge of modelling in the scope of continuum damage mechanics. Conclusions: The presented results provide a material basis for the aluminium alloy studied on a lower scale, while they broaden the testing possibilities and analyses the calibration strategies for the best failure predictability possible. [ABSTRACT FROM AUTHOR]

In this study, Bi alloy AA1100/TiO2/AA5083 composites were produced by accumulative press bonding (APB) for the first time. In the first step, two bars of aluminum alloys 1100 and 5083 with 5 wt.% of uniformly scattered TiO2 particles were stacked together and pressed with a 50% reduction ratio. Then, this process was continued up to six steps. Corrosion properties of composites were studied by potential dynamic polarization and electrochemical impedance spectroscopy measurement in 3.5 wt.% NaCl solution. So, in this investigation and as its novelty, a considerable improvement was revealed in the main electrochemical parameters as a result of enhancing the influence of APB steps and the inert character of the particles. Moreover, using the wear test, the wear resistance of these bi alloy composites has been studied vs the APB steps. Also, the wear and electrochemical experiments showed that corrosion and wear resistance of samples were improved by the APB steps by 70% and 34%, respectively. [ABSTRACT FROM AUTHOR]

Passivity breakdown mechanism of high-strength 7068 alloy is studied. Breakdown potential varied linearly with log aCl‒, pH, and square root of scan rate in potentiodynamic polarization tests. Mott-Schottky analysis showed that the dominant defect is cation vacancy. Passive layer characteristics like cation vacancy density and defect annihilation rate are determined. Critical cation vacancy density for pitting obtained from point defect model and the theoretical values are somewhat compatible. Chloride concentration of 0.01 M is too dilute to cause severe localized corrosion, whereas beyond 0.5 M, saturation is achieved in terms of breakdown potential and the cation vacancy density. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) was employed in an attempt to gain insight into the mechanisms of ethyl 2-cyanoacrylate (ECA) curing (polymerisation) and bonding on aluminium alloy 2024 metal. EIS can detect ionic movement, adsorption processes, charge transfer and storage occurring at an adhesive/substrate interface and/or in a bulk bond line during curing. Low-frequency capacitance measurements demonstrated sensitivity to surface polymerisation reactions and were modelled using an equivalent circuit model with two time constants in series. At a frequency of 1 kHz, changes in the dielectric polymer could be readily followed with time, confirmed by employing a crown ether to accelerate the polymerisation process. Hydrolytic degradation of poly-ECA bonds at a stainless steel interface was also investigated. An equivalent circuit model containing a number of circuit components comprising pore, charge transfer and diffusional impedances, along with polymer film, double layer and diffusional capacitances (represented by constant phase elements), was developed. Three regions were identified in the frequency domain and ascribed to processes taking place at the polymer/electrolyte and polymer/metal oxide interfaces. In short, EIS can be employed to follow the rate of polymerisation of ethyl-2-cyanoacrylate and also the degradation of the resulting polymer in saline solution. [ABSTRACT FROM AUTHOR]

Additive friction stir deposition (AFSD) is a relatively new metal additive manufacturing technique with many advantages compared to fusion-based methods. Despite the recent developments, the research about AFSD is in the initial stages, and processing hard and strong materials such as Aluminum 7075 is still challenging. In this study, a set of processing parameters is introduced and optimized for the AFSD of defect-free Al 7075 parts. Microstructure, electroconductivity, and mechanical properties of the as-deposited parts are studied. Compared with feedstock, the results indicated that the conductivity of the printed specimens increased by 19.5%, and the strength and hardness experienced a significant decrease by 54.4% and 43.5%, respectively. The change in the properties was associated with the precipitation enlargement and aggregation during the AFSD process. Subsequently, heat treatment was conducted to recover the mechanical properties, and noteworthy enhancements, a 101.2% increase in hardness and a 49.1% increase in strength, were recorded compared to the as-deposited condition due to the smaller and more uniformly distributed secondary phases in the matrix. [ABSTRACT FROM AUTHOR]

Rapid investment casting (RIC) based on additive manufacturing has been widely applied in the casting industry owing to its rapid production of patterns and components of free-form and complex geometries without tooling, which is highly desirable for multiple industries. However, high-performance Al-Cu-Mg alloys like AA2024, renowned for their exceptional strength and fatigue resistance, have traditionally posed significant challenges for investment casting. These alloys are prone to hot cracking and other shrinkage defects due to the slow solidification process involved. In this study, nanoparticles are used to enable the rapid investment casting of AA2024 without any cracks or shrinkage defects. Nanotechnology-enabled RIC of AA2024 is successfully demonstrated to offer good casting quality and extraordinary mechanical performance. This work shows great potential for nanotechnology-enabled RIC of other high-strength aluminum alloys for widespread applications. [ABSTRACT FROM AUTHOR]

The Laser Directed Energy Deposition (LDED) technique in metal additive manufacturing (MAM) offers intricate geometries while maintaining material properties akin to cast and wrought components. However, challenges persist in fabricating high-strength aluminum alloys like 2xxx, 6xxx, and 7xxx series due to hot cracking during rapid solidification in LDED. This study addresses Al7075 hot cracking issue by introducing 1 wt% Zr. To evaluate this novel approach, the influence of process parameters on track geometry, porosity, microstructure, hardness, and tensile properties of both Al7075 and modified Al7075 (with 1 wt% Zr) was examined using an L27 orthogonal array of experiments. Findings indicate that increased laser power widens bead width and wetting angle. Conversely, higher scan speeds reduce bead height but marginally increase width, impacting wetting angle. Notably, the addition of Zr decreased porosity from 0.07 to 0.032%, indicating enhanced material quality. Microstructural analysis reveals Zr's role in preventing solidification cracking by enhancing molten metal fluidity during solidification, transitioning the microstructure from columnar to equiaxed fine grain due to Al3Zr precipitates, and promoting grain refinement. This addition of Zr also improved hardness and tensile strength by 11% and 10%, respectively, attributed to Al3Zr precipitates' role in grain refinement and precipitation strengthening within Al7075. In summary, incorporating 1 wt% Zr into Al7075 via LDED demonstrates promising improvements in microstructure, reducing porosity, enhancing mechanical properties, and mitigating solidification cracking, thereby offering potential enhancements in the fabrication of high-strength aluminum alloys. [ABSTRACT FROM AUTHOR]

The uniformity and efficiency of ultrasonic needle peen-forming (UNPF) cannot be achieved by a handheld single-needle peening device. Thus, a novel robotized UNPF system is designed in this paper with a multi-needle peening device. By taking the aluminum alloy 2024-T3 specimens as an example, the peening device's travel velocity and standoff distance are first determined to balance processing efficiency and safety. Thereafter, the resulting arc height for Almen-size specimens with respect to other manipulated variables (MVs), such as the vibration amplitude, the air pressure, and the number of peening passes, are fitted by the data-driven models. As the radius of curvature at the saturation state is identical for small and large specimens with similar shapes, its relationship with the arc height and at the saturation state is represented by a function of elliptic paraboloid for understanding the limit of UNPF capability. It is shown that specimens of different sizes but the same aspect ratio have a consistent radius of curvatures after being treated with the same MVs. Notably, by increasing the vibration amplitude from 21 to 35 μ m , the ratios of peening time required for achieving full coverage to its counterpart for achieving saturation state reduced from 76 to 8.3%, showing a significant improvement in forming productivity and capability. Furthermore, increasing the number of peening passes, from 1 to 32 significantly reduces surface roughness by up to 86.4%, approaching the as-received specimen's smoothness. Moreover, the maximum compressive residual stress after UNPF is - 500 MPa at a depth of 1.2 mm, and the hardness is drastically increased by 45.4% for specimens of thickness 1.5 mm, improving their fatigue life. [ABSTRACT FROM AUTHOR]

Aluminum alloy is a widely used material in railway vehicle structures. In order to accurately analyze the crack propagation mechanism of Aluminum alloy welding structures and predict their crack propagation life, this study focuses on the A7N01 Aluminum alloy and proposes a full‐field strain solution method based on the least‐squares method. For the first time, digital image correlation (DIC) experimental measurements are combined with the finite element analysis method to determine the shape and size of the plastic zone at the crack tip of the compact tension (CT) specimen. And it also calculates the crack propagation driving force parameters of the Christopher–James–Patterson (CJP) model using traditional crack propagation driving parameters. The research results revealed that the plastic zone at the crack tip captured by DIC experiments is in good agreement with the finite element simulation results. Additionally, the crack growth rate curve of the A7N01 Aluminum alloy, fitted based on the CJP model, is insensitive to the stress ratio. The results offer an effective approach to utilizing the da/dN‐∆KCJP curve in analyzing A7N01 Aluminum alloy and welded structural failures, broadening the scope of engineering applications for the CJP model. Highlights: Proposed a full‐field strain solution method based on the least‐squares method.The correlation curve between ΔK and ΔKCJP for A7N01 is established.Expanding the application of the CJP model in predicting the life of welded structures. [ABSTRACT FROM AUTHOR]

A method for improving the properties of the deposited metal in wire arc additive manufacturing of Al–Si alloy is proposed here, which introduces SiC ceramic particles into the side-axis wire feed. The effects of SiC ceramic particles on the macroscopic morphology, microstructure and mechanical properties, corrosion resistance, and wear resistance of deposited metals were studied. The results show that the introduction of SiC particles will not affect the surface-forming quality of the deposited metal; this is likely due to the stable droplet transfer and no splashing. The transverse and longitudinal tensile strengths are increased by 10.1 % and 11.3 %, respectively, while the corresponding elongations are increased by 33.1 % and 47.2 %, respectively. Further, the corrosion resistance and wear resistance of Al–Si alloy deposited metals containing SiC are improved. The (100) base surface has strong texture characteristics along the deposition direction X0, and the maximum polar density decreases to 13.63, which indicates that SiC promotes the transformation of columnar crystals to equiaxial crystals. The interface between SiC and Al is non-coherent, and the performance improvement lies in the enhanced dispersion distribution and load transfer of SiC. A ring structure was prepared using double-wire arc additive manufacturing technology, and the feasibility of side-axis wire feeding technology was verified. [ABSTRACT FROM AUTHOR]

Emerging novel composites fabricated from aluminium alloys incorporating high strength and fracture-resistant ceramics with multi-walled carbon nanotubes (MWCNTs) are used frequently in aeronautical and structural engineering fields. This research aims to examine the machinability of composites made from AA8011, consisting of 3 wt.% MWCNTs and varying weight proportions of zirconium dioxide (ZrO2) (5, 10, and 15 wt.%) fabricated via ultrasonic-assisted stir casting method. Drilling experiments are designed based on the mixed-level design (L18 21,33) of Taguchi's approach with two levels of drill point angle and three levels of % ZrO2, rotational speed (RS), and feed rate (FR). The casted micrographs show near uniform dispersal of reinforcements present in the grain boundaries, improving the dislocation density and material strength. Observation shows that with a higher addition of ZrO2, tool wear (TW) and surface roughness (SR) increase with a reduction in material removal rate (MRR), attributed to the hard ceramic reinforcements in the soft matrix. MWCNTs act as a solid lubricant, which lowers the friction between the workpiece and carbide tool. The desirability approach produces an ideal condition of 118°-point angle, 5% addition of ZrO2, 1439 rpm of RS, and 0.174 mm/rev of FR. With optimum conditions, the MRR is increased by 9.95%, and TW and SR are reduced by 6.37 and 0.69%. A machine learning approach random forest algorithm (RFA) implemented produces a near-predicted value to the experimental outputs with a correlation coefficient of 99.5, 99.56, and 98.95 for MRR, TW, and SR. [ABSTRACT FROM AUTHOR]

Conventional sheet metal forming processes have problems like low formability, non-uniform strain distribution, spring back, wrinkling, etc. High velocity processes like electrohydraulic forming can deform sheets at high strain rate and have capability to tackle such problems associated with conventional forming operations to a greater extent. Forming limit diagram (FLD) characterizes sheet deformation as measure of formability. Punch stretch test (PST) can assess formability of sheet in conventional low strain rate process, but no standard method is available to determine FLD at high strain rate. So in the present work, an experimental setup has been developed to characterize sheets at high strain rate using hydraulic forming process with a 40 kJ capacitor bank. A similar corresponding standard setup for punch stretch test is also developed for comparative study of formability with respect to dome height, forming limit curve, and strain distribution. Formability of aluminum alloy AA5754 is determined at quasi-static and high strain rates, and comparative analysis is reported for whole state of strain using dog bone samples of width ranging from 10 to 120 mm. An estimate of electrohydraulic forming parameters for high strain test of the Al alloy using the given setup is also determined. Study of comparative strain distribution behavior of samples of different widths is also carried out. Comparative analysis shows that there is an improvement in formability and strain distribution behavior of the alloy deformed using EHF as compared to PST. [ABSTRACT FROM AUTHOR]

Aluminum alloys (AAs) are potential alternative constructional materials for low-temperature infrastructures in cold regions and liquefied natural gas (LNG) storage tanks. This study investigated the mechanical properties of AA 6063-T6/7075-T6 materials through tension tests on 32 AA coupons at low temperatures ranging from 20°C to −165°C. All the AA 6063-T6 coupons exhibited ductile failure modes, and AA 7075-T6 coupons failed in brittle modes at 20°C to −165°C. The experimental results showed that decreasing the temperature from 20°C to −165°C , respectively, increased the yield, ultimate, and fracture strengths of AA 6063-T6 (or 7075-T6) by 26.8% (8.5%), 21.2% (6.5%), and 27.6% (9.7%), but their ductility was not compromised. Furthermore, regression analyses were performed to establish prediction equations for the low-temperature mechanical indexes of AAs. Finally, a full-range constitutive model was proposed to estimate the stress–strain behaviors of AA 6063-T6 and 7075-T6. The validation results confirmed that the proposed constitutive models accurately described the stress–strain behaviors of AA 6063-T6 and 7075-T6 within the temperature range of 20°C to −165°C. [ABSTRACT FROM AUTHOR]

A series of small-scale impact cratering experiments were performed on basalt at velocities of 3.5–6.0 km s−1. The formation and motion process of ejecta were observed by high-speed and ultra-high-speed cameras. The momentum transfer coefficient values and cratering size were measured. Hydrodynamic simulations in 2D were carried out to replicate the impact conditions of the basalt and calibrate model parameters. The contribution of jet, central cratering, and spalling ejection to momentum enhancement was quantitatively analyzed by simulation. Simulation results show that: the mass and the momentum of the jet are less than 1 % of the projectile mass, and the initial momentum, can be ignored. For craters in small-sized basalt, the momentum enhancement mainly comes from the spall region ejecta. The formation mechanism of ejecta at different stages was analyzed based on the shock wave and jet theory. An analytical model is developed for estimating the velocity and motion of ejecta formation at different stages. The model calculation results of the speed of the ejecta formed in different stages are consistent with the numerical results. The maximum velocity of the ejecta formed in the jet and cratering stage depends on the initial impact velocity and the Hugoniot parameters of the projectile/target material. The minimum velocity of the spallation ejecta is linearly related to the spalling strength of the target. The model provides a fast and simple method to calculate the ejecta velocity and estimate the influence range of ejecta under different impact conditions. • The speed of the jet is greater than the initial impact speed. • The contribution of jet to momentum enhancement can be ignored. • For craters in small-sized, the momentum enhancement and mass mainly come from the spall region ejecta. • A model was developed for estimating the velocity and motion of ejecta. [ABSTRACT FROM AUTHOR]

Recycling of metals is becoming crucial from an economic and environmental point of view. The solid-state recycling process Continuous Friction Stir Extrusion was used to produce wires out of A356-T6 chips. The mechanical properties of the produced wires were explored by varying the main process parameters. Characterization involved Vickers hardness tests, tensile tests, grain size measurements, and fracture surface analysis. It has been found that it is possible to achieve 77 % of the Ultimate Tensile Strength (UTS) and 92 % of Vickers hardness with respect to the as-fabricated A356 alloy. The average grain size increases with the tool rotational with values ranging from about 9 µm to about 11 µm. A 3D dedicated numerical model was used to predict the distributions and histories of primary field variables, and to calculate the Piwnik-Plata parameter, fostering a more in-depth understanding of the process mechanics. This allows for the precise prediction of unacceptable product quality of the bonding when the Plata and Piwnik parameters are low. Predicted temperature close to the rotating tool should reach 400 °C while the cochlea temperature should be below 100 °C for sound wires production thus avoiding early chip bonding and process failure. [ABSTRACT FROM AUTHOR]

The use of metal matrix composites is increasing gradually in numerous industrial applications. As a result of increased demand, accurate and precise machining of the composites in microdomains become important. Micro-electrical discharge drilling can be effectively applied for machining micro-holes in hybrid composites. The effect of micro-drilling process parameters such as pulse-on-time, pulse-off-time, peak current, tool rotation and electrode polarity on the material removal rate (MRR), radial overcut (RO) and tool wear rate (TWR) has been identified. Results reveal that the MRR, RO and TWR increase as the peak current, pulse-on-time and tool rotation increase. A copper tool with positive polarity provided better results when compared to the other combinations. Although MRR was reduced by 11.22%, RO and TWR were improved by 14.51% and 59.52%, respectively, in a grey relational analysis-based optimal parametric setting. Scanning electrode microscopic (SEM) images of the machined surface demonstrate that the machined holes have high circularity, less surface damage and negligible recast layer at the optimal setting. [ABSTRACT FROM AUTHOR]

The AA7075 alloy and AA7075/SiC/Gr hybrid composite prepared by the stir-casting method have been further thermo-mechanically processed through unidirectional hot rolling and hot cross-rolling routes to eliminate casting defects like voids, blow holes etc. Three initial sample temperatures, that is, 350℃, 400℃, and 450℃, have been considered for the hot cross-rolling. The Al alloy and its hybrid composite prepared at different rolling temperatures are studied to investigate their micro-machining behavior through micro-electric discharge machining (µ-EDM). The micro-holes are made on the rolled samples along the rolling direction of the final rolling pass using a tool with twist drill bit geometry. Further, multi-objective optimization of the µ-EDM process parameters considering the response parameters viz. material removal rate (MRR) and tool wear rate (TWR) has been carried out using the gray relational analysis (GRA) technique. The µ-EDM parameters chosen to optimize in this study are voltage, pulse on time, and tool rotation. The obtained GRA results are further analyzed through normality and equal variance tests. The R-squared values of 95.02% and 95.53% for AA7075 alloy and hybrid composite, respectively, indicate that the data fit well with the statistical model. In material removal, the different electrical and thermal characteristics of the Al matrix and the reinforcements possibly generate sparks with a different characteristic that ultimately affects the MRR of the composite. Through scanning electron microscopy (SEM), the morphological study confirmed the presence of globules and voids on the machined surface. The formation of globules and voids is more significant in the AA7075 alloy than in the composite. [ABSTRACT FROM AUTHOR]

The design of the loading path is one of the important research contents of the tube hydroforming process. Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of only finite element optimization. In this paper, the hydroforming process of 5A02 aluminum alloy variable diameter tube was as the research object. Fuzzy control was used to optimize the loading path, and the fuzzy rule base was established based on FEM. The minimum wall thickness and wall thickness reduction rate were determined as input membership functions, and the axial feeds variable value of the next step was used as output membership functions. The results show that the optimized loading path greatly improves the uniformity of wall thickness and the forming effect compared with the linear loading path. The round corner lamination rate of the tube is 91.2% under the fuzzy control optimized loading path, which was increased by 47.1% and 22.6% compared with linear loading Path 1 and Path 2, respectively. Based on the optimized loading path in the experiment, the minimum wall thickness of the variable diameter tube was 1.32 mm and the maximum thinning rate was 12.4%. The experimental results were consistent with the simulation results, which verified the accuracy of fuzzy control. The research results provide a reference for improving the forming quality of thin-walled tubes and plates. [ABSTRACT FROM AUTHOR]