Aluminum Alloy AA Research Articles

Numerical Analysis of Recycled AA6061 Reinforced Alumina Oxide Undergoing Finite Strain Deformation Uniaxial Tensile and Taylor Cylinder Impact Tests

Recycling aluminum is a topic of high interest due to the global demand for aluminum-based products. This approach presents a great opportunity to address the environmental issues caused by the primary production of aluminum made from bauxite ore. In recent years, many researchers have explored the recycling of aluminum alloys, including reinforcement, to achieve better results and improve properties. However, there have been limited efforts to predict the deformation behaviour of such materials numerically. It is generally agreed that advancements in numerical analysis are important to accelerate progress and establish the application of newly developed materials. Therefore, this study aimed to numerically predict the deformation behaviour of recycled aluminum alloy AA6061 reinforced with Alumina Oxide, subjected to finite strain deformation of uniaxial tensile tests at different strain rates (6x10-1s-1 to 6x10-3s-1) and Taylor Cylinder Impact at different impact velocities (190ms-1 to 370ms-1) using the LS-DYNA simulation code. In this numerical analysis, a Simplified Johnson-Cook model is adopted and characterized. The simulation results, which were validated against published experimental data, showed good agreement, establishing appropriate numerical prediction capabilities for recycled aluminum alloys AA6061 reinforced with Alumina Oxide.

Artificial neural network based fatigue life assessment of riveted joints in AA2024 aluminum alloy plates and optimization of riveted joints parameters

The objective of this paper is to provide the fatigue life of riveted joints in AA2024 aluminum alloy plates and optimization of riveted joints parameters. At first, the fatigue life of the riveted joints in AA2024 aluminum alloy plates is obtained by experimental tests. Then, an artificial neural network is applied to estimate the fatigue life of riveted lap joints based on the number of lateral and longitudinal holes, punch pressure, gap between the edge of hole and rivet, rivet shank diameter, and rivet shank length. Also, meta heuristic optimization algorithm is applied to calculate the riveting process parameters. Finally, sensitivity analysis is used to obtain the influence of parameters affecting the riveting process on the fatigue life.

A Novel Method to Measure Equi-Biaxial Residual Stress by Nanoindentation

BackgroundThe accurate measurement of residual stresses (RS) is crucial for predicting the performance of mechanical components, as RS can significantly impact fatigue life, fracture, corrosion, and wear resistance. Different experimental methods were developed to measure RS, including non-destructive techniques. Among these methods, instrumented nanoindentation has emerged as a promising approach to assess equi- or non-equi-biaxial RS states. This technique analyzes variations in the mechanical response of indentation on a stressed or stress-free component to estimate residual stresses. Previous studies proposed different approaches to establish a relationship between RS and indentation parameters, such as contact area, peak load, mean contact pressure, indentation work, etc. However, the correlation between RS and peak load variation, commonly assumed to be linear, showed limitations, particularly when dealing with compressive RS.ObjectiveThe aim of this work is to develop a hybrid procedure, based on finite element (FEM) simulations and experimental analyses, to measure the equi-biaxial residual stresses. In particular, it is based on the analysis of the nanoindentation peak load variation generated by the presence of residual stresses on a component.MethodsTo overcome the limitations of the linear assumption, nanoindentation experiments were combined with finite element analyses (FEA). FEA simulations were used to estimate the correlation between RS and peak load variation, providing a better understanding of the non-linear relationship. A proper experimental setup, consisting in a stress generating jig, was designed and manufactured to perform nanoindentations on a sample, made by aluminium alloy AA 7050 T451, subjected to external mechanical stress with the aim to validate the FEA model. FEA and the digital image correlation (DIC) technique were also used to verify that the induced stress field was the expected one.ResultsObtained results revealed that the proposed method is a valid way to measure residual stresses. In fact, it offers an improved correlation between RS and peak load variation. In addition, by integrating nanoindentation experiments and FEA, a more accurate assessment of RS can be also achieved.ConclusionsThis research contributes to the development of a consistent methodology for RS measurement using instrumented nanoindentation.

Investigation of welding quality and internal elongation problem in aluminum extrusion

AA6082 aluminum alloys are particularly useful in heavy industry and machinery manufacturing given their mechanical properties, but when extruding complex profiles used in these sectors, one of the main problems is the welding problem. In order to prevent the welding defects by suitable die design, two different porthole extrusion die set were designed and manufactured using different design techniques in this study. Extrusion trials were conducted for each die. The analysis examined how die design affects profile exit temperature, stress and strain distribution, and billet interface. It also aimed to characterize the effect of die design on welding quality through tensile tests, hardness tests, and microstructural observations. The results show that tapering the mandrel and die plate parts at an angle causes compression of the material flow and reduces the volume of the weld chamber and helps to direct material to the critical regions. This design approach offers a solution for the welding problem of complicated profiles.

Optimization of friction stir spot welding parameters for joining dissimilar AZ31B magnesium alloy and AA6061 aluminium alloy using response surface methodology

Optimization of friction stir spot welding parameters for joining dissimilar AZ31B magnesium alloy and AA6061 aluminium alloy using response surface methodology

Effect of Laser Welding Parameters with Different Fillers on Solidification Cracking and Mechanical Properties of AA7075

AA7075 is considered a ‘non-weldable’ alloy using fusion welding methods. In this study, laser welding is applied in pulse mode to weld 2 mm thick AA7075 aluminum alloy plates using different fillers. The aim is to identify the influence of welding parameters and fillers on solidification cracking susceptibility during laser welding using the circular patch test (CPT). X-ray radiography was used to detect and measure cracks in the CPT samples. Furthermore, the effects of the laser welding process and chemical composition of fillers on the accumulated crack length (CCL), microstructure, and mechanical properties were investigated. Moreover, the mechanical behavior and local deformation of the fusion zone (FZ) were investigated using micro-flat tensile tests with digital image correlation. The mechanical properties of the FZ were correlated with the CCL as well as with the microstructure of the FZ, which was investigated experimentally. The results show that the chemical composition of fillers and welding speed affect the CCL of solidification cracks. Changes in the microstructure were observed within the fusion zone, and the structure became uniform and finer with the formation of Mg2Si and magnesium-rich, copper, and zinc (η-phase) particles.

Influence of synthesizing parameters on surface qualities of aluminium alloy AA5083/ CNT/MoS2 nanocomposite in powder metallurgy technique

Aluminium alloys are indispensable in all manufacturing industries, particularly mechanical engineering. The objective of this study is to enhance the mechanical, wear, and corrosion properties of aluminium alloy AA5083 by incorporating nanoparticles as reinforcements, thereby creating hybrid aluminium nanocomposites. The base material utilised in this study was AA5083, with the reinforcement nanoparticles selected as Carbon nanotubes (CNTs) and Molybdenum disulfide (MoS2) at concentrations of 5 % and 3 % respectively. Nanocomposites were fabricated using the Powder Metallurgy (PM) technique, employing specific contrasting parameters including Ball mill speed (280, 320, 360, and 400 rpm), Mixing time (20, 30, 40, and 50 min), Compaction pressure (300, 350, 400, and 450 MPa), and Sintering time (2, 3, 4, and 5 h). The operating parameters of powder metallurgy were assessed using the Design of Experiments (DOE) L16 Orthogonal Array, and their corresponding outcomes were analyzed. The results revealed that there is a significant correlation between the mixing time and microhardness of the nanocomposites. The wear and corrosion reduction rates had a significant impact on the sintering time parameter. The present study determined that the highest recorded microhardness value was 136 VHN, while the lowest observed rates of wear and corrosion were 0.192 mm3/m and 0.00081 mm/year, respectively. Scanning electron microscopy (SEM) images clearly depicted the presence of various structural defects, such as pits, cracks, delamination, voids, and cusps, in the wear and corrosion samples that exhibited reduced strength.

Mitigation effects of over-aging (T73) induced intergranular corrosion on stress corrosion cracking of AA7075 aluminum alloy and behaviors of η phase grain boundary precipitates during the intergranular corrosion formation

The stress corrosion cracking (SCC) behaviors of over-aged and peak-aged AA7075 aluminum alloys in a 5 wt% NaCl solution were compared. Even though the over-aging process induced intergranular corrosion (IGC), it decreased the SCC susceptibility of the material. Grain boundaries (GBs) with misorientation angles less than 30° and the grain matrix were considered factors that reduced the IGC propagation rate, thereby preventing the development of SCC in the over-aged material. η phase grain boundary precipitates (GBPs) underwent de-alloying, forming Cu-enriched particles during the IGC formation. However, the cathodic properties of these particles are not the key factors determining whether the IGC will occur or not.

Numerical investigation of the surface recrystallization during the extrusion of a AA6082 aluminum alloy under different process conditions

Numerical investigation of the surface recrystallization during the extrusion of a AA6082 aluminum alloy under different process conditions

Effect of Tool Travel Rate on Microstructure Evolution and Mechanical Properties of Dissimilar Friction Stir Welded Joints of AA7075 and AA6061 Aluminium Alloys

Effect of Tool Travel Rate on Microstructure Evolution and Mechanical Properties of Dissimilar Friction Stir Welded Joints of AA7075 and AA6061 Aluminium Alloys

Moisture-induced defects produced by direct laser joining of AA7075 aluminum and PEEK

The present investigation aims to determine how polymer moisture and volatile compounds influence the mechanical behavior of hybrid metal-polymer joints made by Laser-Assisted Joining. Experimental laser joining tests were performed on AA7075 aluminum alloy and Polyetheretherketone (PEEK). Some polymer samples were pre-treated through drying to remove the moisture stored in the PEEK before joining. Laser spot joints were produced with dried and as-received samples at different heating times. Different characterization techniques were adopted to determine the influence of moisture on the performance of the joints. Single lap shear tests were performed to assess the mechanical behavior of the joints. Fracture surface analysis was carried out through Optical Microscopy to determine the influence of the moisture content on the mechanical behavior. The results indicated a significant influence of moisture on the mechanical behavior of the joints. This led to the formation and coalescence of voids at the metal-polymer interface that affected the mechanical behavior of the joints. Dried samples were characterized by higher shear force (up to 33 %) and higher toughness (up to 130 %) compared to as-received samples.

Effect of Process Variables on Interface Friction Characteristics in Strip Drawing of AA 5182 Alloy and Its Formability in Warm Deep Drawing

Warm forming is widely used to enhance the formability of aluminum alloy sheets. In warm deep drawing, the process variables significantly affect frictional characteristics at the tool–blank interface. It has been a conventional approach to use a constant value of friction coefficients in the finite element (FE) simulations. However, this can occasionally result in suboptimal accuracy of the predictions. In the present work, strip drawing tests were carried out on AA5182 aluminum alloy sheets to investigate the effect of important process variables, namely, temperature, contact pressure, and drawing speed, on the friction coefficient in the warm forming temperature range (100–250 °C) under lubricated condition. The results obtained from the strip drawing tests were used for defining the friction conditions in the simulation of warm deep drawing of cylindrical cups incorporating the variation of the friction coefficient with contact pressure and speed at different temperatures. The Barlat89 yield criterion was used to define the effect of anisotropy in the material. The Voce hardening law and Cowper–Symonds model were used to incorporate the effect of strain hardening and strain rate, respectively, in the simulation. Drawability and peak force were compared with the predictions when a constant friction coefficient was assumed. Warm deep drawing experiments were conducted to validate the predicted drawability and load–displacement curves. It is clearly observed that the accuracy of prediction of the limiting drawing ratio and peak load through simulations is improved by incorporating the effect of pressure and speed on friction coefficient as it captures the local variations of friction during warm deep drawing precisely, rather than assuming a constant average friction coefficient at all the tool–blank contact areas.

Phase-field simulation of the dendrite growth in aluminum alloy AA5754 during alternating current electromagnetic stirring laser beam welding

Electromagnetic stirring is known to promote material flow, reduce porosity, uniform elements distribution, and refine grain in laser beam welding (LBW), which enhances the applicability of LBW in various industries. In this study, a phase-field model of dendrite growth in AA5754 Al alloy electromagnetic stirring laser beam welding was established. The model considered the thermal electromagnetic Lorentz force resulting from the interaction between the electric field generated by the Seebeck effect and the magnetic field, as well as the temperature gradient and solidification rate of the solidification interface obtained from the computational fluid dynamics electromagnetic stirring LBW model. The variation rules of dendrite growth with different magnetic parameters and effects are analyzed. Comprehensively, the magnetic field promotes the solidification rate, thus promoting interfacial instability and a large magnetic flux density leads to a faster interface instability. The solidification rate as well as the temperature gradient affect the growth rate, and the accelerated growth caused by the solidification rate with a high frequency and a large magnetic flux density effectively inhibits the slow growth caused by the temperature gradient. The thermal electromagnetic Lorentz force is the main factor for the branch increment at low frequencies, while both thermal electromagnetic Lorentz force and temperature gradient increase the number of branches at high frequencies. The calculated average branch numbers considering various factors in the stable stage under different magnetic parameters were consistent with the results of the scanning electron microscope tests.

LCF behaviour of high strength aluminium alloys AA 6110A and AA 6086

The proposed research presents the comprehensive investigation of the Low Cycle Fatigue (LCF) behaviour of two high-strength aluminium alloys of series AA 6xxx: the conventional alloy AA 6110A and the newly developed alloy AA 6086. Both alloys were characterised in the as-cast condition after homogenisation, extrusion, and T6 heat treatment.The quasi-static strength and hardness of the aluminium alloy AA 6086 were found to be significantly higher if compared to the AA 6110A alloys, while the ductility was a little bit smaller. The LCF tests showed that the AA 6086 alloy is more suitable for the high-cycle fatigue regime. On the other hand, the engineering advantage of the AA 6110A alloy is only for low-cycle fatigue applications if less than 100 loading cycles are expected in the service life of the analysed structure. The fatigue cracks formed predominantly on the α-AlMnSi intermetallic particles in both alloys, and, during LCF tests, exhibited small crack propagation. The area of the fatigue crack growth was much smaller than the area of the forced fracture. At smaller amplitude strains the fatigue striations were present at the fracture surface, while, at higher amplitude strains, they were not present. The obtained experimental results represent a good basis for engineering design applications of the analysed alloys AA 6086 and AA 6110A.

Experimental Research on Wolfram Inert Gas AA1050 Aluminum Alloy Tailor Welded Blanks Processed by Single Point Incremental Forming Process.

The present paper aims to study the behavior of tailor welded blanks subjected to a single point incremental forming (SPIF) process from an experimental point of view. This process was chosen to deform truncated cone shapes of AA1050 aluminum alloy with different thicknesses. A uniaxial tensile test was performed to determine the mechanical characteristics of the alloy. Initial experimental tests implicated the use of variable wall angle parts which were processed on unwelded sheet blanks for determination of the behavior of the material and the forming forces. Afterwards, the wolfram inert gas (WIG) welding technique was used for joining two sheet blanks with different thicknesses either through one pass on one side, or by one pass on both sides. The conclusion of this paper indicates that one-sided welded blanks cannot be deformed successfully without fracture. In case of two-sided welded blanks, the results showed that the desired depth of 25 mm can be reached successfully. In case of the SPIF process, if welded blanks must be deformed, then the suitable method is to weld the blanks on both sides.

Prediction of formability and effects of process parameters on the adhesively bonded composite metallic sheets

The study investigates the deep drawing process for bimetallic sheets formed by bonding dissimilar metals (AA1100 aluminium alloy and C36000 brass) with epoxy-based adhesive. Experimental exploration of process parameters, including blank diameter, stacking sequence, lubrication, and strain rate, was conducted to analyse their impact on load–displacement behaviour and thickness strain distribution. Additionally, the study assessed fracture susceptibility, material flow characteristics (tearing and wrinkling), and the requisite drawing force for the bonded specimens. Results indicate enhanced formability and mechanical properties in bonded sheets compared to individual metal sheets, demonstrating the potential advantages of this approach. The bonded sheets demonstrated improved formability and mechanical properties compared to individual metals. Notably, the maximum drawing force for the bonded sheet (170 mm diameter) significantly increased to 24.2 kN, surpassing individual sheets by 69.85% for AA1100 and 40.54% for C36000. The analysis identified a vulnerable region (12–15 mm from the centre) under maximum risk of failure and consistent deformation patterns in samples with varying diameters and lubrication, providing valuable insights into the behaviour of bonded bimetallic sheets in deep drawing.

The Effect of Soaking Time on Mechanical Properties of Roll-Bonded AA3003 and AA4045 Used for Heat Exchangers

Due to the rising need for energy saving, high-performing automotive heat exchangers, demand has significantly grown in recent years. As a result, effective fin-tube heat exchangers are becoming more popular. These tubes are typically made by rolling flat strips of AA3003 aluminum alloys that have either one or both sides coated with AA4xxx alloys. The AA3003 type of alloy is typically used as the core, which is then covered in either AA4045 or AA4343, which melts during the brazing process to adhere the fins to the tubes. To maintain the optimal size and distribution of manganese (Mn)-containing precipitates, preheating parameters are carefully controlled. Then, longer soaking times or higher soaking temperatures result in larger precipitates, which cause the final product to exhibit poor mechanical properties. Therefore, it is crucial to optimize the different manufacturing steps, such as homogenization, soaking time, and brazing in order to achieve a high quality product. Studies on the impact of homogenization temperature and time on the microstructure of AA3xxx aluminum alloys have been conducted. However, there has been little research on the impact of soaking (reheating) time on AA3003 cladded alloys. Hence, the effects of isothermal soaking time on the microstructure and mechanical properties of AA3003 cladded with AA4045 alloy were investigated in this work. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the microstructure and identify intermetallic phases. The final microstructure in terms of grain structure at various homogenization times was characterized by electron backscattered diffraction (EBSD). After the hot-rolling and cold-rolling of the as-received material, large particles of intermetallic (mainly in the form of Chinese script morphology consisting of Fe-Mn-Si) were broken into smaller particles with an increased Fe, Mn, and Si content, indicating the formation of an α-Al(Fe,Mn)Si phase. The α-Al(Mn,Fe)Si was found to be a dominant dispersoid precipitate in the modified AA3003 core. Coarsening of the Al(Mn,Fe)Si dispersoids at 505 °C was only observed at a 45 h homogenization time. The hardness trend with homogenization time was found to be similar to that after homogenization, cold working, and annealing, with exception of an increase in hardness in the latter possibly due to strain hardening (from cold-rolling).

Fatigue Analysis of Welded Joints Using a Thin-Walled Al/Fe Explosive Welded Transition Joints.

The study presents an analysis of S355J2+N steel and AA5083 aluminum alloy welded structural joints using explosion welded transition joints of reduced thickness. The transition joint thickness reduction significantly hinders the welding of the joints due to the risk of damage to the Al/steel interface as a result of the high temperatures during welding. In the previous article, the strength of the transition joint was analyzed but ship structures, apart from static loads, are subjected to many different cyclical loads. Welded structural joints are analyzed to determine the welding influence on the fatigue life and fracture type of the transition joints. The results of the fatigue tests show that the fatigue damage in the specimens occurs in the aluminum welded joint, and not in the explosively welded joint. The damage obtained was characteristic of cruciform welded joint specimens and both types of root and toe damage occurred. Based on the obtained results, fatigue curves for the joint were determined and compared to the fatigue curves for the AA5083 base material. The experimental fatigue curve was also compared with the design curve for welded aluminum structures from Eurocode. The conducted analysis showed the possibility of using Al/steel explosion welded transition joints of reduced thickness to transfer cyclical loads.

Miniaturized S-shaped flexible magnetic pulse welding coil design for engineering applications

Magnetic pulse welding (MPW) as a new solid-phase welding technology in the manufacturing field has vast application prospects. However, the application of MPW in engineering is severely limited by the large working area required for existing coils resulting in poor flexibility of the process. In this paper, a highly flexible, miniaturized S-shaped stereoscopic coil was proposed to reduce the working area required for the MPW process. The required working area was reduced to 32 × 30 mm. Numerical simulations were performed to determine the most suitable coil cross-section size. In addition, the feasibility of the coils was verified by welding AA5052 aluminum alloy and 316 L stainless steel through the new stereoscopic coils. Quasi-static tensile testing, laser microscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) were used to characterize the mechanical properties of the joints, weld interface morphology and element diffusion, respectively. It was revealed through simulation that the impact velocity of the new stereoscopic coil during MPW (342 m/s) was slightly higher than that of the conventional flat coil (327 m/s) at the same discharge energy. This indicated that the coil could achieve reliable welding. The AA5052-316 L joint welded by the new stereoscopic coil was demonstrated to be reliable by experiments. Furthermore, microscopic observation revealed that two effective bonding regions were formed at the interface. In addition, continuous interfacial waves and element diffusion were observed at the welding interface. Finally, the typical parts of AlFe double-cap beam structure were successfully welded by using a new stereoscopic coil. The coil is beneficial to broaden the application field of MPW.

The Effects of Titanium Dioxide (TiO2) Content on the Dry Sliding Behaviour of AA2024 Aluminium Composite

The low density, low expansion coefficient, and strong corrosion resistance at room temperature of Aluminium alloys have made them a popular choice for engineering applications. In this study, Aluminium AA2024 alloys are prepared with different weight contents of ceramic material, titanium oxide (TiO2) nanoparticles (0%, 2.5%, 5%, and 7.5% wt.) of a particle size of 30 nm using the metal stir casting method. The hardness property and wear resistance with the effect of heat treatment are investigated using a pin-on-disc wear device for both the base alloy and the reinforced alloys. The result shows the prosperity of 5wt.% of TiO2 to attain the optimum hardness and wear resistance. Using the optimum content of TiO2 and heat treatment, the hardness and wear resistance of 5wt.% TiO2-AA2024 nanocomposite has been significantly improved after heat treatment over the unreinforced Aluminium matrix. Statistically, the hardness and wear resistance are improved by 68% and 22%, respectively. This is due to an increased number of fine precipitates besides their uniformly distributed after heat treatment. Furthermore, casting AA2024 Aluminium alloy material mainly has S (Al2CuMg) and Al3TiCu phases. The appearance of a large number of S phases causes a significant improvement in the properties of the alloy.