Search Results (30)

The corrosion behavior was investigated for three Al-Mg aluminum alloys (i.e., 5052, 5083 and 5182 aluminum alloys) with different alloying contents in 3.5 wt.% NaCl solution at 35 °C by means of potentiodynamic polarization, electrochemical impedance spectroscopy, immersion test, X-ray photoelectron spectroscopy and microscopy techniques. All alloys spontaneously passivate in the test solution, but the pitting corrosion takes place at the intermetallic phases during the long-term immersion test. The comparative analyses indicate that more Mg and less Cr in aluminum alloys result in increases in the passive current density and the pit depth and decreases in the polarization resistance, the pitting potential and the ratio of Al₂O₃/Al(OH)₃ in the product film. However, the differences in the pitting potentials of the three aluminum alloys are smaller than approximately 22 mV. Their pit depth values are less than 110 μm after 120 days of immersion. The three aluminum alloys have relatively high corrosion resistance in the simulated seawater solution. Full article

This investigation employed different laser powers to conduct the laser welding–brazing process of 5052 aluminum alloy to both Al-Si coated and uncoated 22MnB5 steel. The flux-cored Zn-Al22 filler metal was employed during the procedure. The influence of Al-Si coatings on the microstructure and corrosion resistance of Al/Steel welded joints was investigated using microstructural characterization and electrochemical tests. It was noted that the interfacial microstructure of the laser Al/steel joints was significantly altered by the Al-Si coating. Moreover, the Al-Si coating suppressed the formation and growth of the interfacial reaction layer. Electrochemical corrosion tests showed that the impact of Al-Si coating on the corrosion resistance of laser joints depended on the laser powers and thickness of the interfacial intermetallic compound (IMC) layer. The research suggests that galvanic corrosion occurs due to the differences in corrosion potential between fusion zone (FZ), steel, and Fe-Al-Zn IMCs, which accelerate the corrosion of the joint. The IMC layer acts as a cathode to accelerate the corrosion of the FZ and as an anode to protect the steel from corrosion. Full article

Wear performance is integral to component longevity, minimizing industrial waste and excess energy costs in a wide variety of applications. Anodized aluminum oxide (AAO) has many beneficial properties leading to its wide use across industries as a surface treatment for many aluminum components, but the wear properties of the coating could be improved significantly. Here, we used an electrochemical method to incorporate molybdenum disulfide (MoS₂), a nanomaterial used as a dry lubricant, to modify alloys of aluminum during AAO preparation. Using Raman spectroscopy and tribological scratch measurements, we thoroughly characterized the structure and wear behavior of the films. The MoS₂ deposition procedure was optimal on aluminum 5052 anodized in higher acid concentrations, with friction coefficients at around 0.05 (~10× better than unmodified AAO). Changing anodization conditions to produce harder films with smaller pores led to worsened wear properties, likely because of lower MoS₂ content. Studying a commercial MoS₂/AAO film of a different Al alloy (7075) showed that a heat treatment step intended to fully convert all deposited MoS_x species to MoS₂ can adversely affect wear in some alloys. While Al 6061 and 1100 produced films with worse wear performance compared to Al 5052 or 7075, our results show evidence that acid cleaning after initial anodization likely removes residual alloying elements, affecting MoS₂ incorporation. This study demonstrates a nanomaterial modified AAO film with superior wear characteristics to unmodified AAO and relates fabrication procedure, film structure, and practical performance. Full article

The formability at room temperature and low speed limits the application of aluminum alloy, while high strain rates positively improve the formability of materials. The constitutive behaviors of materials under high strain rates or impact loadings are significantly different from those under quasi-static conditions, while few constitutive models consider the effect of the mobile dislocation and forest dislocation evolution on the dynamic strain aging (DSA) over a wide strain-rate range. The 5052 aluminum alloy, of which the primary source of strain-hardening is dislocation–dislocation interaction, is widely used in manufacturing automotive covering parts and is considered one of the most promising alloys. Therefore, this study conducts uniaxial tensile tests on AA5052-O under conditions of temperatures ranging from 293 K to 473 K and strain rates ranging from 0.001 ${\mathrm{s}}^{-1}$ to 3000 ${\mathrm{s}}^{-1}$, and compares the stress–strain relationships of AA5052-O under different conditions to illustrate the constitutive relationship affected by the dislocation evolution over a wide strain-rate range. The Arrhenius model based on the thermal activation mechanism is modified and extended by considering the effects of dynamic strain aging (DSA), drag stress, and the evolution of mobile dislocation and forest dislocation. Thus, a new physics-based constitutive model for AA5052-O is proposed, which can well reflect the change in strain-rate sensitivity with the strain rate increasing. The mobile dislocation density and total dislocation density are predicted with a modified Kubin–Estrin (KE) model, and the influences of variable mobile dislocation on DSA and dislocation drag are discussed as well. In order to verify the reliability of the new constitutive model, the dislocation densities of the specimens before and after deformation are obtained with TEM and XRD, which are in good agreement with the predicted values. This study also compares the newly proposed model with classic constitutive models using multiple statistical evaluation methods, which shows that the new physics-based constitutive model has not only more clear physical meanings for its parameters but also has a higher prediction accuracy. Full article

Non-destructive and reliable radiation-based gauges have been routinely used in industry to determine the thickness of metal layers. When the material’s composition is understood in advance, only then can the standard radiation thickness meter be relied upon. Errors in thickness measurements are to be expected in settings where the actual composition of the material may deviate significantly from the nominal composition, such as rolled metal manufacturers. In this research, an X-ray-based system is proposed to determine the thickness of an aluminum sheet regardless of its alloy type. In the presented detection system, an X-ray tube with a voltage of 150 kV and two sodium iodide detectors, a transmission detector and a backscattering detector, were used. Between the X-ray tube and the transmission detector, an aluminum plate with different thicknesses, ranging from 2 to 45 mm, and with four alloys named 1050, 3050, 5052, and 6061 were simulated. The MCNP code was used as a very powerful platform in the implementation of radiation-based systems in this research to simulate the detection structure and the spectra recorded using the detectors. From the spectra recorded using two detectors, three features of the total count of both detectors and the maximum value of the transmission detector were extracted. These characteristics were applied to the inputs of an RBF neural network to obtain the relationship between the inputs and the thickness of the aluminum plate. The trained neural network was able to determine the thickness of the aluminum with an MRE of 2.11%. Although the presented methodology is used to determine the thickness of the aluminum plate independent of the type of alloy, it can be used to determine the thickness of other metals as well. Full article

Aluminum (Al) alloys are lightweight and machinable and have been widely used in industrial applications, particularly the formation of complex mechanical parts. However, the 5052 Al alloy frequently encounters problems like corrosion and wear during its service life, significantly impacting the equipment’s longevity. This study investigated the effects of pulse voltage (320 to 400 V) and frequency (50 to 200 Hz) on the growth and surface morphology of 5052 Al alloy films formed through micro-arc oxidation (MAO) to improve their corrosion and wear resistance while maintaining a surface roughness of less than 1 μm. The results indicate that higher operating voltages and frequencies correlated with increased thickness in the resulting ceramic oxide films formed using MAO. In addition, as the pulse frequency increased, the distribution of the holes became more uniform across the surface. We examined the surface and cross-sectional morphology, as well as the thickness of the MAO coatings, through scanning electron microscopy (SEM). The corrosion and wear resistance of the MAO coatings formed under different electrical parameters were analyzed using electrochemical corrosion tests and scratch tests. The MAO coatings produced at 400 V and 200 Hz were the thickest, at approximately 4.8 μm, and demonstrated superior corrosion and wear resistance. These coatings demonstrate significantly reduced wear width, highlighting their exceptional resistance to corrosion and wear. Hole cracking occurred only above the top layer of the coating and not beneath the mid-layer, which protected the substrate from damage due to the direct passage of Cl ions through the holes. Full article

The bonding properties of BFRP composites have been demonstrated in previous studies, satisfying the strength and durability criteria. In this paper, a further in-depth study is carried out to bond Basalt Fibre Reinforced Polymer (BFRP) to Aluminum Alloy 5052 using two bonding agents, Aralite^® 2012 and Aralite^® 2015, respectively. The salt sprays under 80 °C, 3.5% NaCl environment; 80 °C, 5% NaCl environment; and pure water environment are also considered for comparison. Experimental results show that joints created with Araldite^® 2012 adhesives show higher average breaking strength (10.66 MPa at 720 h) and better ductility in a 5% NaCl environment. While the Araldite^® 2015 adhesive joint exhibits a combination of tear failure and interface failure, along with thin-layer cohesion failure. In the SEM images of the two adhesive joints’ failure, fiber pullout due to tension and damage at the interface between fiber and resin is apparent. To validate the experimental outcomes, water absorption testing, DSC, TGA-DTG, and FTIR experiments were conducted on dog-bone-shaped adhesive specimens to elucidate the results. Full article

In this paper, the influence of ultrasonic vibration on the forming forces and surface quality of products formed using an ultrasonic-assisted incremental sheet forming (UISF) method was investigated and compared with an incremental sheet forming (ISF) method. The elements and parameters used for research include a sheet of Al 5052 aluminum alloy with thickness of 1.0 mm, a lathe with a feed rate of 70–130–225 rpm, and step size of 1.0–1.5–2.0 mm. The results show that ultrasonic vibration significantly reduces the forming forces, of which the main forming force F_zmax is reduced by about 20%. Besides, the results also show that the surface quality of products formed via UISF is significantly improved compared to that formed by ISF. Full article

Aiming at the enhancement of the lightweight formability potential of aluminum alloy, the bulging and tensile properties of a 5052 Aluminum alloy sheet were tested on a microcomputer controlled sheet metal forming tester and tensile testing machine. The effects of different blank holder force, punch velocity and lubrication conditions were investigated on bulging properties by the experimental analysis. The cupping values (Erichsen Cupping Index: IE) of sheets with a thickness of 1.2 mm at room temperature were obtained under different process parameters. Meanwhile, the anisotropic property of the material was analyzed in different rolling directions. The results show that the sheet cupping values increase with the increase of blank holder force and punch velocity, and the stress state was changed due to the changing of the blank holder force and strain rate. Moreover, the use of lubricating conditions with a lower coefficient of friction allows the sheet to exhibit a larger cupping value. The effect of rolling direction on the anisotropy of 5052 aluminum alloy sheet is distinct, which means in the aluminum alloy sheet forming process the anisotropy factor should be carefully considered. Full article

Manufacturing aircraft components through 3D printing has become a widespread concept with proven applicability for serial production of certain structural parts. The main objective of the research study is to determine whether a chlorinated polyethylene material reinforced with milled carbon fibers has the potential of replacing the current 5052 NIDA aluminum alloy core of the IAR330 helicopter tail rotor blade, under the form of a honeycomb structure with hexagonal cells. Achieving this purpose implied determining the tensile and compression mechanical properties of the material realized by fused deposition modeling. The tensile tests have been conducted on specimens manufactured on three printing directions, so that the orthotropic nature of the material may be taken into account. The bare compression tests were realized on specimens manufactured from both materials, with similar honeycomb characteristics. All the mechanical tests have been performed on the Instron 8872 servo hydraulic testing system and the results have been evaluated with the Dantec Q400 Digital Image Correlation system. The experimental tests have been reproduced as finite element analyses which have been validated by results comparison, in order to determine if the compression model is viable for more complex numerical analysis. Full article

In order to reduce the elemental species produced in the recycling and melting of aluminum scrap and to improve the quality of pure aluminum and aluminum alloys, it is necessary to classify the different grades of aluminum scrap before melting. For the problem of classifying different grades of aluminum scrap, most existing studies are conducted using laser-induced breakdown spectroscopy for identification and classification, which requires a clean and flat metal surface and enormous equipment costs. In this study, we propose a new classification and identification method for different grades of aluminum scrap based on the ResNet18 network model, which improves the identification efficiency and reduces the equipment cost. The objects of this research are three grades of aluminum scrap: 1060, 5052, and 6061. The surface features of the three grades were compared using a machine vision algorithm; three different datasets, using RGB, HSV, and LBP, were built for comparison to find the best training dataset for subsequent datasets, and the hyperparameters of learning rate and batch size were tuned for the ResNet18 model. The results show that there was a differentiation threshold between different grades through the comparison of surface features; the ResNet18 network model trained the three datasets, and the results showed that RGB was the best dataset. With hyperparameter optimization of the ResNet18 model, the accuracy of final classification and recognition could reach 100% and effectively achieve the classification of different grades of aluminum scrap. Full article

Previous studies have yet to show a consistent effect of severe plastic deformation (SPD) processing on the wear behavior of different metals and alloys. To fill this scientific gap, this study investigated the effect of the cyclic extrusion compression (CEC) process, as one of the prominent SPD techniques, on the wear behavior of AA5052. In addition, the microstructure evolution and mechanical properties of the sample before and after the process were experimentally examined and studied. It was found that the yield and ultimate tensile strength of the AA5052 improved significantly after the first pass, while the elongation-to-failure decreased considerably. Further, the subsequent passes mildly changed the trend of increasing strength and reducing elongation-to-failure. SEM morphology indicated that the ductile mode of the initial annealed alloy changed to a combination of ductile and brittle failure modes, in which the level of the brittle failure mode increased with the addition of passes. TEM observations showed that the grain refinement during the CEC process included the formation of dislocation cell structures, subgrain boundaries, and low-angle grain boundaries, with the subgrain boundaries initially evolving into low-angle grain boundaries and, eventually, due to the imposition of additional plastic strain, into high-angle grain boundaries. Furthermore, the CEC process and its increased number of passes led to a significant improvement in wear resistance due to the enhanced tensile strength achieved through grain refinement. In this regard, the wear mechanism of the initial alloy was a combination of adhesion and delamination, with the plastic deformation bands changing to plowing bands with decreased adhesive wear during the process. Eventually, oxidization was found to be a mechanism contributing to wear under all conditions. Full article

Background The severe plastic deformation approach and its well-known cyclic extrusion compression (CEC) method have been established as a powerful tool for fabricating bulk ultrafine-grained metals and alloys with improved properties. Objective This study focused on the microstructure evolution, hardness behavior, and corrosion properties of the CEC-processed Al5052 up to four passes compared to the initial annealed state. Methods The initial and CEC-processed Al5052 samples at different pass numbers were examined experimentally by EBSD analyses, hardness measurements, and corrosion resistance. Results Substantial grain refinement was attained from ~23 μm for the annealed sample to ~0.8 μm in the four passes sample. In addition, the hardness values considerably increased up to 75.7% after four passes from the initial value of 80 HV. In addition, the increment of pass numbers led to a more uniform dispersion of hardness values. Furthermore, the production of more stable protective oxide layers on the UFG structure of the CEC-processed sample led to the improvement in electrochemical response with a corrosion rate reduction from 1.49 to 1.02 mpy, respectively, in the annealed and final pass CEC-processed samples. In fact, the annealed sample manifested more large-sized and deeper pits than the CECed samples due to the increment of potential values and electrochemical attack of chlorine ions that finally deteriorates the corrosion performance. Conclusions CEC is an efficient method to improve the mechanical properties of materials due to substantial microstructural changes along with enhancement of electrochemical behavior because of the presence of small-sized and shallow pits. Full article

Micro-arc oxidation (MAO) treatment can effectively improve the wear resistance, corrosion resistance, and mechanical strength of aluminum alloy substrates. Improving the porous structure of MAO film and effectively sealing the pores is a significant research issue. In this study, the MAO treatment of 5052 aluminum alloy was carried out in silicate electrolytes. The MAO films were sealed with different concentrations of SiO₂ nanoparticles. The effects of SiO₂ nanoparticle content on the MAO films’ microstructure, mechanical properties, and corrosion performance were systematically investigated. When adding SiO₂ nanoparticles to electrolytes, the particles were deposited at the micropores of the film, which could effectively seal the porous MAO film and significantly improve its corrosion and wear resistance. The corrosion resistance and wear resistance properties were optimal with 5.0 g/L SiO₂ addition. Compared to the unsealed film, the corrosion current density and corrosion rate decreased from 1.24 × 10⁻⁹ A/cm² and 1.47 × 10⁻⁵ mm/a to 7.78 × 10⁻¹⁰ A/cm² and 9.15 × 10⁻⁶ mm/a, respectively. Moreover, the average friction coefficient of the sealed film was 0.606, which was ~19.3% lower than that of the substrate and 3.3% lower than for the unsealed film. Full article

Self-pierce riveting of three thin sheets of 980 MPa steel and 5052 aluminum alloy was performed to investigate the effect of sheet configuration on the deforming behaviors of the sheets and the rivet and joint strength. When the lower sheet was aluminum alloy, the joining range was relatively wide, i.e., the interlock hooking the rivet leg tended to be large. In the sheet configuration in which the upper and lower sheets were A5052 and the middle sheet was 980 MPa steel, the rivet leg spread out moderately and the joint without defects was obtained. In the lower 980 MPa steel sheet, fracture tended to occur due to the low ductility of the lower sheet, and the joining range was narrow with the small interlock although the three sheets were joined by an appropriate die shape. In joint strength of joined three sheets, fracture occurred in the lower-strength aluminum alloy sheet if interlocks of about 300 μm and 150 μm could be formed in the lower aluminum alloy sheet and 980 MPa steel sheet, respectively. Full article