Alloy AA Research Articles

High-Velocity Impact Response of Directly Recycled Aluminium Alloy AA6061 Plates

High-Velocity Impact Response of Directly Recycled Aluminium Alloy AA6061 Plates

Enhancement of Mechanical Properties and Microstructure of Aluminium alloy AA2024 By adding TiO2 Nanoparticles

Modern engineering applications, especially in the automotive and aerospace industries, require essential and appealing properties such as lightweight with high strength and resistance. The key objective of the present study is to investigate the effect of TiO2 nanoparticles on the microstructure, impact strength, hardness and wear resistance of the stir cast aluminum alloy AA2024, An aluminium alloy was reinforced with different mass fractions (0 %, 2.5 %, 5 %, 7.5 %) of titanium dioxide nanoparticles by stir casting followed by solution annealing at 500°C for 3 h, quenching in water and aging at 175°C for 3 h. Results showed that regular morphology and fine grain size of primary AA2024 particles are achieved after the addition of 2.5 wt.% TiO2 compared to the sample without the addition of nanoparticles composite. In addition, it was found that adding nanoparticles increased energy absorption, and this effect is improved by increasing impact strength by adding nanoparticles, the impact strength increased from 5 j/m2 to 7 j/m2 at 5%. At the same time, the increase of nanoparticles effect decreases the mass losses (increase in wear resistance). With a weight fraction of 5 wt.% TiO2, the alloy exhibits the highest value of hardness.

Effect of Nano Particle Size on Mechanical and Fatigue Behavior of TiO2 Particular—Reinforced Aluminum Alloy Composites

Aluminum alloys are among the most widely used materials in the parts and vehicle sectors due to their high strength-to-weight ratio and qualities such as higher corrosion and wear resistance, as well as minimal thermal growth when compared to other metals. This research involved matrix alloy AA7075 aluminum reinforced with constant 7 wt. % TiO2 (with different particle sizes 30, 70, and 100 nm). The goal of this study is to improve the mechanical (impact strength and young modulus) and fatigue properties of AA7075 alloy-based metal matrix composites, and fatigue. AA7075 composites with a constant weight percentage of 7wt.% of TiO2 and variable particle size have been successfully synthesized by the stir casting route. Microstructural examinations revealed that nanocomposites with (30nm) particle size have better distribution and less porosity compared to the other particles size. The nanocomposite having 30 nm particle size was found to have maximum improvement UTS and YS in comparison with the other nanocomposites, 20.45%, and 12.87% respectively, and minimum elongation. An increase in particle size and fatigue results indicates the decreasing trend of fatigue life and strength. The higher endurance fatigue limit was recorded to be (23.875 MPa) for (30 nm) nanocomposite.

Coupling Taguchi experimental designs with deep adaptive learning enhanced AI process models for experimental cost savings in manufacturing process development

The Aluminum alloy AA7075 workpiece material is observed under dry finishing turning operation. This work is an investigation reporting promising potential of deep adaptive learning enhanced artificial intelligence process models for L18 (6133) Taguchi orthogonal array experiments and major cost saving potential in machining process optimization. Six different tool inserts are used as categorical parameter along with three continuous operational parameters i.e., depth of cut, feed rate and cutting speed to study the effect of these parameters on workpiece surface roughness and tool life. The data obtained from special L18 (6133) orthogonal array experimental design in dry finishing turning process is used to train AI models. Multi-layer perceptron based artificial neural networks (MLP-ANNs), support vector machines (SVMs) and decision trees are compared for better understanding ability of low resolution experimental design. The AI models can be used with low resolution experimental design to obtain causal relationships between input and output variables. The best performing operational input ranges are identified for output parameters. AI-response surfaces indicate different tool life behavior for alloy based coated tool inserts and non-alloy based coated tool inserts. The AI-Taguchi hybrid modelling and optimization technique helped in achieving 26% of experimental savings (obtaining causal relation with 26% less number of experiments) compared to conventional Taguchi design combined with two screened factors three levels full factorial experimentation.

Nanoparticle-enabled additive manufacturing of high strength 6061 aluminum alloy via Laser Powder Bed Fusion

Wrought aluminum alloy AA6061 is widely used in automotive, aerospace, and other industries due to its good properties, including high strength, excellent corrosion resistance, and good weldability. However, when using Laser Powder Bed Fusion (LPBF) for AA6061, hot cracking becomes a serious problem. In this work, AA6061 powder with internally dispersed nanoparticles has been adopted in a LPBF process. Through optimization of printing parameters, components with minimal porosity (less than 0.5 %) have been successfully produced without cracks. Additionally, by employing a chessboard printing strategy to create finely detailed cellular and grain structures, we have achieved significantly enhanced mechanical properties in its as-printed state for AA6061. These components exhibit an impressive yield strength (YS) of 233 MPa and ultimate tensile strength (UTS) of 310 MPa while maintaining a ductility of approximately 10 %. This performance surpasses that of commercial AA6061 and other Al-Si alloys, establishing it as a high-strength material suitable for various applications.

Three-dimensional simulation of finite element ultrasonic welding of aluminum alloy AA-6061

Three-dimensional simulation of finite element ultrasonic welding of aluminum alloy AA-6061

Investigation of Weldability in Friction Stir Welding of Aluminum Alloys AA5754 and AA2024

Investigation of Weldability in Friction Stir Welding of Aluminum Alloys AA5754 and AA2024

Optimising the quality of several welds in a metal-inert gas arc joining of AA6082 and AA7075 using the grey-based Taguchi technique

In recent times, welding procedures have become increasingly crucial for fabrication and manufacturing businesses. Gas metal arc welding, also known as metal inert gas (MIG) welding, has attracted much attention because of its versatility. Its benefits include low capital needs, high deposition rates, high productivity, and simplicity in adjusting to automation. It has drawn much interest because of its versatility in welding metallic materials and ease of automation. This work's objective is to maximise the multi-performance properties of the aluminium alloys AA6082 and AA7075's MIG-welded butt junction by using a hybrid grey-based Taguchi technique. During MIG welding, With the L9 Taguchi orthogonal array, the welding speed, gas flow rate, and current were optimised. Weld joint integrity has been evaluated using the fusion zone's Vickers microhardness, per cent elongation, tensile strength, and yield strength. The ideal welding current for the MIG process is 140 A, the perfect welding speed is 10 mm/min, and the excellent gas flow rate is 18 lit/min. The material showed 159.68 MPa of tensile strength, 112.79 MPa of yield strength, 16.79% of percentage elongation, and 70.95 HV of hardness under optimal conditions. With a 63.99% contribution to the process, welding speed greatly affected the weldments' overall performance. The confirmatory test confirmed the optimisation procedure also demonstrated that optimising numerous welded joint performance factors may be achieved effectively with the grey-based Taguchi approach.

Effect of underwater friction stir welding parameters on AA5754 alloy joints: experimental studies

The water as a welding environment may generate serious technological and metallurgical problems but in certain cases, the physicochemical properties of water can be used effectively, e.g., to impart the specific properties of welded materials. The purpose of the work was verification of effectiveness of the water cooling of aluminium alloy AA5754 for various sets of technological parameters of underwater friction stir welding (UFSW). For the joints performed with the range of parameters of rotational speed: 475–925 rpm and welding speed: 47.5–95 mm/min, the following examinations were carried out: visual tests, radiographic tests, static tensile test, fractography (SEM, scanning electron microscope) analysis, and surface texture analysis performed with 3D measurement system. All of the joints were characterized with some amount of flash. Besides, depending on the values of selected parameters, the defects arising from inadequate stirring were found—tunnel defects and melting. The best appearance of the joint was obtained for the set of parameters of 925 rpm and 47.5 mm/min. The samples of the same joint were found to be of the highest mechanical properties—ultimate tensile strength (UTS) of 194 MPa and elongation (A) of 9.2%. The results were confirmed by the fractography analysis, which in this case indicated the ductile fracture mode. Dynamic plastic behaviour strongly depends on the process parameter values, which was reflected in the results of surface texture analysis. The parameter selection resulted in significant changes in the roughness results (from 8 to 14.2 µm depending on the sample) as well as the flow ring distance of the weld (from 20 to 50 µm depending on the sample).

Realization of Friction Stir Welding of Aluminum Alloy AA5754 Using a Ceramic Tool

When engaging in the friction stir welding of aluminum/aluminum joints, the conventional use of tools made of hard metal and steel involves a complex and costly production process. These tools experience wear over welding distances and require frequent replacement to ensure the consistency of the welded seams. The exploration of silicon nitrite as a tool material emerges as a promising alternative in this scenario. The heightened hardness of non-oxide ceramics anticipates a diminished wear rate compared to traditional welding materials, translating into an extended operational lifespan. Nevertheless, the adoption of ceramics introduces challenges initially perceived as detrimental to friction stir welding. The inherent brittleness of silicon nitrite makes it susceptible to breakage under specific loads, and thermal stresses within the component can lead to failure. To mitigate these vulnerabilities, a ceramic material with high thermal shock resistance and a low proportion of sintering additives was used. Employing these accurately designed tools friction stir welding (FSW) was performed on sheets of AA5754, followed by a comprehensive examination of their microstructural and mechanical properties. It was demonstrated that a joint efficiency of 88% can be achieved, and that an increase in hardness within the stir zone occurred as a consequence of grain refinement. Furthermore, the Portevin–Le Chatelier effect, which is characteristic of this alloy, was influenced by the FSW process.

Evaluation the effect of multi-pass friction stir processing on the wear, mechanical properties, and microstructure of the AA1050/ZrO2 surface nanocomposite

This work presents surface nanocomposites of aluminum alloy AA1050, reinforced with zirconium oxide (ZrO2) nanoparticles developed through multipass friction stir processing (FSP). This article attempts to study the effects of the number of passes on the wear rate, microhardness profile, tensile properties, and macrostructure of surface nanocomposites. The results demonstrate that an improved distribution of ZrO2 nanoparticles is obtained following each FSP pass, and that the number of passes increases with a decrease in stir zone (SZ) grain size. Consequently, it was found that applying FSP passes continuously enhances the materials' microhardness and tensile characteristics. In the microstructure development of the stir zone during the ZrO2 nanoparticle FSP, dynamic recrystallization (DRX) was an essential mechanism. The main reason for this is that surface nanocomposites with homogenous ZrO2 particle dispersion and no discernible particle clustering in the stir zone were shown by microstructural studies conducted through FSP, which significantly reduced the matrix grain size. The AA1050 base metal (BM) has an ultimate tensile strength, yield strength, and hardness of 59.2 MPa, 24 MPa, and 30.1 respectively. The nanocomposite generated by 5 FSP passes exhibits improved yield stress (55 MPa), tensile strength (94.5 MPa), and microhardness (86.5 HV), but its tensile ductility decreased from 34% to 23.8% when compared to the base metal. Tensile strength that is higher is the outcome of fine dimples' ability to pin the dislocation movement during tensile loading. According to fractographic studies, the ductile–brittle mode replaced the dimple-shaped ductile fracture mode.

Exploratory data analysis & EDS analysis on tool chip adhesion under dry and nano minimum quantity lubrication machining environment

Adhesion, abrasion, plowing and transverse displacement are the major causes of origin of friction. During dry machining of ductile materials, chips are fused with the rake face of the cutting tool and contribute to the formation of the built up edge. Built up edge protects the rake face of the tool from wear, but makes the machined surface rough. To improve the tribological properties and to decrease the tool-chip adhesion, cutting fluids are used. Cutting fluids are added to the machining zone to minimise cutting temperature and friction, but they result in environmental and health degradation. Surface texturing of tools is a potential way to modify the tribological properties of mating surfaces in order to increase the tribological qualities and decrease the tool-chip adhesion. The performance of surface textured tools depends upon orientation, dimple depth, width and pattern. Under lubrication regime, microholes in surface textured tools acts both as lubrication reservoir and traps wear debris to reduce abrasive wear. Nano Minimum Quantity Lubrication (nano-MQL) is an advanced lubrication technique used in machining processes, specifically designed to minimize the use of lubricants while maintaining effective lubrication. This method involves delivering an extremely small amount of high-performance lubricant directly to the cutting zone. The MoS2 lubricant with sunflower oil is typically in the form of nanodroplets, which are much smaller than conventional minimum quantity lubrication (MQL) droplets. The Exploratory Data Analysis (EDA) methodology enables the identification of patterns, trends, and outliers within the collected data, offering insights into the complex interplay of factors affecting the machining of Aluminium Alloy AA2024. At a spindle speed of 3500 rpm the feed force decreases by 37% under dry environment when compared with nano-MQL environment. Under dry environment average surface roughness reduces by 27% when compared with nano-MQL environment.

A study of dynamic recovery and recrystallisation mechanisms in aluminium alloy AA7050 at different thermomechanical processing conditions

The effects of hot deformation strain rates and temperatures on aluminium alloys' dynamic recovery and recrystallisation mechanisms have been widely discussed in the literature. However, their influence remains controversial due to a need for comprehensive and detailed thermomechanical testing and characterisation data across a wide range of hot deformation conditions. In this study, hot compression tests of AA7050 were conducted at strain rates of 0.0005–5 s−1 and temperatures of 380–460 °C. The geometrically necessary dislocation (GND), low-angle grain boundary (LAGB) and high-angle grain boundary (HAGB) were acquired by the latest high angular resolution, high-speed EBSD detector (OI Symmetry 2), and their underlying mechanisms were analysed in relation to Zener-Hollomon parameter (Z). It was found that within the tested range of the hot compression condition (ln (Z) between 20.23 and 29.45), continuous dynamic recrystallisation (CDRX) predominates at lower ln (Z) values with its activity being initially increased and then decreased as ln (Z) rises, while discontinuous dynamic recrystallisation (DDRX) becomes dominant at higher ln (Z) levels. This transition of the dominant mechanism is intriguingly reflected in the evolution of HAGB length, which increases, then decreases and finally increases again. The LAGB length shows a relatively linear relationship with ln (Z), and the average GND density exhibits a near-linear correlation until reaching a plateau. Based on the obtained results, the transformation of the dominant microstructural evolution mechanisms with increasing ln (Z) was clarified: from grain growth, to recovery, to CDRX, and then to DDRX, along with the quantitative trend of HAGB length per unit area. This transformation mechanism is believed to encompass the full range of material processing window, providing a basis for justifying the previous controversial proposition in literature and a guide for defining and fabricating microstructures in manufacturing applications.

Modeling of bonding pressure based on the plastic deformation mechanism of interfacial voids closure in solid-state diffusion bonding

The model of the diffusion bonding pressure was established using the analysis calculation method and further verified by the finite element analysis (FEA) and the experiments. The normalized temperature was defined as the ratio of temperature and the melting point of the base materials. And the normalized bonding pressure was defined as the ratio of the applied bonding pressure and the yield strength at the bonding temperature. The contribution of the plastic deformation to the void closure expressed a linear relationship with the normalized bonding pressure, of which the slope was 3. The relationship was appropriate in TiAl6V4, pure copper C11000, aluminium alloy AA6061, stainless steel SUS 304, and Ni-based alloy Inconel 617 using analysis calculation. The diffusion bonding pressure design range can be summarized as σn = 0.05–0.577. Subsequently, the analytic computational model was verified by FEA. The results showed that the maximum stress was concentrated in the position of the void neck. And the linear relationship between the normalized bonding pressure and the bonded ratio was also tenable. There was a stable static error existed between FEA and the analytic computational analysis. Furthermore, the experimental verification showed the verification and accuracy of the analytic computational analysis results.

Dynamic recrystallisation: A quantitative study on grain boundary characteristics and dependence on temperature and strain rate in an aluminium alloy

Dynamic recrystallisation (DRX) usually occurs during hot forming of metallic materials, significantly impacting the mechanical properties of the final parts. Although DRX has been studied for decades, the types of DRX that occurs in high stacking fault energy (SFE) materials like aluminium alloys are still controversial, and their dependence on both temperature and strain rate is surprisingly missing. To fill these gaps, in the present study, uniaxial compression tests on an aluminium alloy AA6061 were carried out at different temperatures from 250 to 475 °C and strain rates from 0.01 to 1 s-1. The grain orientation and misorientation before and after the hot deformation were quantitively characterised using high-resolution Electron Backscatter Diffraction (EBSD) with a misorientation resolution of 0.05°, enabling high-angle grain boundaries (HAGBs), low-angle grain boundaries (LAGBs) and geometrically necessary dislocations (GNDs) to be accurately quantified and correlated against temperature and strain rate. Results reveal that both continuous dynamic recrystallisation (CDRX) and geometric dynamic recrystallisation (GDRX) occurred concurrently, resulting in the formation of discontinuous HAGBs and fine equiaxed grains, respectively. The misorientation angle distributions of the discontinuous HAGBs exhibit an opposite trend compared to those of the fine grains’ HAGBs. Both temperature and strain rate significantly affect the density of HAGBs formed by DRX, but have little effect on their misorientation angle distributions. This study sheds light on the fundamental understanding of DRX and provides comprehensive experimental data for future modelling of DRX processes in high SFE materials.

Mechanical and tribological behaviours of friction stir welding using various strengthening techniques

The present study investigates the research conducted on friction stir welding of aluminium alloys AA6061. The experiments were conducted under optimal parametric settings, and the specimens were subsequently subjected to post-processing techniques such as heat treatment and shot peening. The enhancement of weldment strength is contingent upon secondary processing, eliminating internal stress and improving surface qualities. Subsequently, the weldment will undergo mechanical testing and tribometer testing. The conventional testing protocol was implemented to assess the hardness, yield, and tensile strength. The wear and friction test examined the effects of various process factors. The load conditions were set at 10, 30, 50, and 70 N, while the sliding distance was set at 700 m and 1400 m. The experiments were carried out in dry sliding conditions at room temperature and the resulting data were recorded as average values. The welded AA6061 samples exhibited superior hardness and ultimate tensile strength, with the highest average values observed after heat treatment and subsequent shot peening. Attributed to the strengthening effect and achieving an ultra-fine grain size. The results of this inquiry indicate that the yield strength and ultimate tensile strength of the welded sample were significantly increased by heat treatment and shot peening. In particular, when compared to the as-welded AA6061 aluminium alloy sample, the sample's yield and ultimate tensile strength were 39.49 % and 38.7 % greater, respectively. The tribometer test revealed that a rise in load and sliding distance results in an increase in wear rate and a drop in the coefficient of friction. Under a load of 70 N and a sliding distance of 1400 m. s, the heat-treated and shot-peened AA6061 specimen showed a 27.3 % lower wear rate and a 29.6 % lower coefficient of friction compared to the as-welded AA6061 specimen.

Comparative electrochemical and thermodynamic study of cold-rolled steel, Al alloy AA5754, and Zn corrosion in fluoride and chloride solutions

This study investigates the effects of fluoride and chloride ions on the corrosion of cold-rolled steel, aluminium alloy AA5754, and zinc, using ammonium bicarbonate as a buffer at pH 4 and compares electrochemical findings with thermodynamic calculations of E-pH diagrams. The distinct electrochemical behaviours of fluoride and chloride ions were confirmed, with fluoride-induced corrosion leading to the significant complex formation on cold-rolled steel and AA5754, the latter leading to a narrowing of the Al passive region. However, a comprehensive analysis of all ionic species in the solution (F−, Cl−, NH4+ and HCO3−) and their complex equilibria reveals that zinc's corrosion is primarily influenced by the overall ionic strength of the solution and further complexation with the buffering agent at higher pH levels, should these conditions occur during corrosion. In addition, this analysis also highlights the subtle differences in the stabilization effects of open circuit potential on cold-rolled steel and AA5754. The results underscore the importance of considering the overall solution equilibrium in thermodynamic analyses and provide a foundation for further research on the role of F- and Cl- ions in zirconium conversion coatings.

Correlated 4D-STEM and EDS for the classification of fine Beta-precipitates in aluminum alloy AA 6063-T6

Tuning the properties of aluminum alloys AA 6063-T6 involves artificial aging to induce precipitate formation, particularly β’’ and β’ phases. Previous characterization challenges due to their similar appearance are addressed here by correlating 4D scanning transmission electron microscopy (4DSTEM) and energy-dispersive spectroscopy (EDS) mapping. This approach allows us to analyze the structure and composition of precipitates individually, overcoming limitations of conventional imaging and structural analysis techniques when the precipitates appear simultaneously, as is often the case. We present detailed characterizations of needle-shaped Beta precipitates, revealing distinct diffraction patterns (DPs) and compositional differences. The method's applicability extends beyond aluminum alloys, offering a promising strategy for complex composite material characterization with multimodal scanning transmission electron microscopy (STEM) techniques.

Numerical Study on the Effect of Geometrical Changes on the Deformation Behaviour of Recycled Aluminium Alloy AA6061 undergoing High Velocity Impact using Hyperworks-Radioss

Numerical analysis is important to predict material behaviour without require an experimental implementation. This manuscript focuses on a numerical prediction establishment of a direct recycled aluminium alloys AA6061 undergoing Taylor Cylinder Impact test using Johnson-Cook model in HyperWorks Radioss. The numerical setup was first validated against the experimental data at the velocity range of 179 to 212 m/s. Good agreement between simulation and experimental data was obtained within the range that exhibits a mushrooming shape fracture mode. A parametric study was then conducted to study the deformation behaviour of the selected recycled aluminum alloys within the validated range at various geometrical settings. The analysis was made by focusing on the post-impact configuration of the projectile at different impact velocities in terms of residual length, deformed diameter, and the final length-to-diameter ratio. It was found that a broader projectile experienced a less significant reduction in its final length (Lf/Lo goes from 0.87 to 0.9 for projectile diameter 9mm to 34mm) and a smaller increase in the deformed diameter compared to a thinner projectile (Df/Do goes from 1.18 to 1.12 for projectile diameter 9mm to 34mm). It was found that a thinner projectile experienced more diameter expansion than length reduction post impact. In addition, a longer projectile experienced more residual length reduction (Lf/Lo goes from 0.92 to 0.87 for projectile length 2mm to 14mm) and more radial deformation compared to the one with a smaller initial length (Df/Do goes from 1.06 to 1.18 for projectile length 2mm to 14mm). All projectiles showed more significant changes on the deformed diameter compared to the changes in residual length post-impact. The results helped the understanding of a critical aspect of the deformation behaviour of recycled aluminum alloy AA6061 more effectively compared to experimental work implementation.

Characteristics analysis and monitoring of friction stir welded dissimilar AA5083/AA6061-T6 using acoustic emission technique

The joining of aluminum alloys using fusion welding often leads to issues such as hot tears, porosity, distortion, and solidifying cracks. To address these challenges, solid-state welding processes like Friction Stir Welding (FSW) are preferable. This study investigates the FSW of dissimilar aluminum alloys AA 5083 and AA 6061-T6, employing Acoustic Emission (AE) techniques for real-time monitoring. FSW was conducted under conditions with no defects, pinhole defects, and piping defects. The resulting joints were evaluated for their mechanical properties and metallurgical characteristics. Microstructural analysis was performed using an optical microscope, revealing that the defect-free condition achieved the highest tensile strength of 256 MPa and superior hardness of 93 HV at the stir zone. Tensile failure commonly manifested within the heat-affected zone (HAZ) of AA 6061-T6, primarily due to grain enlargement and the impact of Mg2Si precipitates. Examination of the fractured regions via scanning electron microscopy revealed ductile-mode fractures featuring elongated dimples and microvoids. AE parameters such as hits, amplitude RMS, and energy were analyzed, demonstrating that defect-free welds had consistent AE signal patterns, while significant variations were observed in pinhole and piping defect conditions due to larger defect areas. The findings suggest that AE monitoring is effective in detecting and analyzing welding defects, providing valuable insights into the FSW process for dissimilar aluminum alloys.