Aluminum Alloy Research Articles

Shaking table test and simulation on seismic performance of aluminum alloy reticulated shell structures under elastic and elastic-plastic stage

This study aims to analysis the dynamic characteristics and seismic response behavior of aluminum alloy reticulated shell structures especially pay attention to the internal force changes in the elastic and elastic-plastic stages. A scaled test model of aluminum alloy single-layer spherical reticulated shell was designed and manufactured, and a shaking table test was carried out to obtain its dynamic characteristics and seismic response. The modal parameters of the reticulated shell structure, including frequency, modal shape and damping ratio, are obtained by white noise scanning frequency and frequency domain decomposition (FDD) technology. The response of the reticulated shell structure in the elastic stage and the elastic-plastic stage is discussed, including the node acceleration, displacement and strain response under different peak ground acceleration (PGA). The finite element method (FEM) is used for numerical simulation analysis. An effective numerical simulation method for analyzing the seismic performance of aluminum alloy single-layer reticulated shells is proposed. The internal force development and structural displacement of structures under strong earthquakes are studied. The test results show that under the action of horizontal ground motion, the vertical stiffness of the small rise-span ratio aluminum alloy reticulated shell is small, and the radial and ring members mainly bear the out-of-plane bending moment and axial force. In addition, the horizontal deformation of the reticulated shell structure and the in-plane rotation of the joints are the main reasons for the members to enter the plasticity, resulting in bending and torsional deformation of the members in the weak area. Axial pressure and bending moment control the force mechanism of the members, which is the cause of bending and torsional instability of the members.

Surface chemistry characterization of AA2014 aluminum alloy powder through triboelectric charging

Traditional characterization techniques for powders primarily focus on bulk properties, often neglecting the critical role of surface chemistry variations that influence the performance in applications such as additive manufacturing. The method presented in this work addresses this gap by utilizing triboelectric charging concept to gain a comprehensive understanding of powder surface state under varying environmental conditions. In particular, the study investigates the detection of surface chemistry variations of AA2014 powder caused by an exposure to various relative humidity (RH) levels through a change in triboelectric charging behavior. The surface variations are analyzed in parallel with X-ray photoelectron spectroscopy (XPS). The findings reveal a direct correlation between elevated RH and increased hydroxide species content at the surface of the powder. The triboelectric charging experiments demonstrated a significant RH-dependent variations of charge accumulation, with higher humidity levels leading to reduced static charge buildup on the powder particles. The charge accumulation behavior in the powder was fitted with the compressed exponential relaxation model. The results showed that each surface chemical species exhibits a distinct correlation between charging rate and charge accumulation, confirming the method's effectivity to detect subtle variations in surface chemistry. The variations in the exponent of the fitted model were shown to be characteristics to the surface scale of the powder particles.

Enhancement of the mechanical properties of semi-stationary bobbin tool friction stir welded joints in AA2219 through post-weld heat treatment

This research investigates the enhancement of AA2219 joints formed by semi-stationary bobbin tool friction stir welding (SSBT-FSW) through post-weld heat treatments. Although solid-state processes such as SSBT-FSW are able to produce superior welds without common defects seen in conventional fusion welding of aluminum alloys of the 2XXX series, the thermal cycle in SSBT-FSW can deteriorate mechanical properties by causing precipitate dissolution and over-aging. The research proposes using a heat treatment sequence to induce solubilization and re-recipitation of precipitates in a more favorable distribution, re-activating the precipitation-hardening. Since abnormal grain growth is very difficult to avoid during heat treatments of welded samples, the analysis focuses on the evolution of the microstructure during solution heat treatment and on the influence of grain size, texture, and precipitate distribution on grain growth. The origin and evolution of the grain growth during solution heat treatment have been observed. Hardness measurements and tensile tests show that post-weld heat treatments can effectively restore the mechanical properties of the joints to the levels of those of the base material. Understanding the relationships between microstructure, abnormal grain growth and mechanical behavior of the joints aids the optimization of the SSBT-FSW process for broader industrial application, especially in the aerospace industry, where high-performance aluminum welded structures are critical.

An enhanced Hosford–Coulomb fracture model for predicting ductile fracture under a wide range of stress states

In this study, an Enhanced Hosford–Coulomb (EHC) fracture model is proposed, which suits a wide range of stress states. The model is validated by quantitatively investigating the ductile fracture behaviors of Ti-6Al-3Nb-2Zr-1Mo titanium alloy through experiments and numerical simulations, and the fracture morphologies are characterized using scanning electron microscopy. The results show that the EHC model has higher accuracy in predicting ductile fracture strain for Ti-6Al-3Nb-2Zr-1Mo alloy compared to the original Hosford–Coulomb (HC) model. Finally, the accuracy and material applicability of the EHC model are further verified with X80 pipeline steel and AA2024-T351 aluminum alloy, demonstrating its advantages.

A novel approach to control thermal induced buckling during laser welding of battery housing through a unilateral N-2-1 fixturing principle

Battery housing (BH) in modern electric vehicles must meet demanding functional requirements. The design and geometry of the BH become intricate to prevent damage during collisions and to ensure absolute impermeability to gases and water during operation. Moreover, in the pursuit of a lightweight BH, manufacturers rely on high-strength 6xxx aluminium alloys, posing significant challenges for the welding processes. It is estimated that up to 30 m of weld length is required during the construction of battery housings including joining the lid and under-shield to the main structural frame and joining the ribs to the frame for standard vehicles. Due to the increasing use of thin sheets for lightweighting the structure, thermal-induced buckling may occur and generate critical dimensional unconformities going beyond design tolerances. This underpins the need to optimise fixturing design to control thermal-induced buckling.This paper goes beyond the state-of-the-art “N-2-1” approaches for fixturing thin and deformable parts and proposes the new principle of “unilateral N-2-1 fixturing”. The driving idea is adding unilateral restraints to the direction of thermal contraction, which ultimately causes buckling; and, keeping the direction where the thermal expansion occurs in a free state. The methodology is based on three main steps: (1) physics-based modelling of parts and fixtures using a thermo-mechanical FEA simulation; (2) calibration of the weld heat source using metallographic data; (3) validation using optical scanning technology. The methodology was demonstrated during the laser beam welding of a high-strength aluminium 6xxx thin deformable lid to a rigid high-strength 6xxx aluminium extrusion frame. Results indicated that the thermal induced buckling deformation was reduced from 15 mm, when using the state-of-the-art fixturing approach, to approximately 2 mm with the proposed methodology.

Research on online deformation monitoring of thin-walled parts driven by digital twin

Thin-walled parts are widely used in aerospace. Because thin-walled parts have thin walls, weak stiffness, and are easy to deform and other characteristics, it is easy to produce deformation in the processing, affecting the quality and accuracy of the workpiece processing. Therefore, accurate and efficient online real-time monitoring of the deformation of thin-walled parts has become a vital issue in process control. The visualization, real-time monitoring, and iterative optimization of digital twin technology can effectively solve the problem of online monitoring of thin-walled parts processing. Therefore, this paper proposes a digital twin driven deformation monitoring method for thin-walled parts, which realizes the effective monitoring of deformation during the processing of thin-walled parts. Firstly, the digital twin architecture for online deformation monitoring of thin-walled parts is established, and the critical technologies of the digital twin for online deformation monitoring of thin-walled parts are proposed. Secondly, the Support Vector Regression (SVR) finite element surrogate model is established to realize the rapid simulation of thin-walled parts cutting. At the same time, a One-Dimensional Convolutional Neural Network (1DCNN) combined with the Self-Attention Mechanism (SAM) deformation prediction model was established based on sensor data. The real-time monitoring and accurate prediction of the deformation of thin-walled components are realized through the parallel guidance of the deep learning and surrogate model. Finally, an experimental analysis was carried out by machining thin-walled plates of aluminum alloy 7075, and the fit of the monitoring models was above 95%, thus verifying the validity of the proposed method.

Achieving excellent strength and plasticity of aluminum alloy through refining and densifying precipitates

Achieving excellent strength and plasticity of aluminum alloy through refining and densifying precipitates

An aging processing design scheme derived from precipitation thermo-kinetic synergy of heat-treatable aluminum alloys

An aging processing design scheme derived from precipitation thermo-kinetic synergy of heat-treatable aluminum alloys

Analysis of grain structure, precipitation and hardness heterogeneities, supported by a thermal model, for an aluminium alloy 7075 deposited by solid-state multi-layer friction surfacing

Thermomechanical cycles during multi-layer friction surfacing (MLFS) cause microstructural and mechanical heterogeneities in the deposited high-strength Al alloy, 7075. The thermal profile and heat accumulation were investigated in this study using a multilayer numerical thermal model of the MLFS process; additionally, these variables were linked to experimentally observed microstructural heterogeneities. Compared with the feedstock, grain sizes decreased by 55–80%. The mean grain size at the bottom and top areas of a given layer was finer than that in the middle of the layer because of the enhanced recrystallisation, which resulted from the friction and shear deformation experienced by the deposited material. The differences in the thermal cycle and plastic strain rate of the bottom and top areas along the layers resulted in a gradual increase in the grain size at the bottom of each layer and a reduction in the grain size at the top of each layer. The grain growth and continuous dynamic recrystallisation mechanisms are governed by the temperature and strain rate, those mechanisms determine the intra- and inter- layer grain sizes. The accumulated heat, owing to subsequent experimental deposition, resulted in excessive growth of the precipitates in the bottom layers. The strengthening of the solid-solution and Guinier-Preston zones significantly increased the microhardness of the top layer. Post-deposition T6 heat treatments confirmed the restoration of a uniform distribution of microhardness.

Laser Directed Energy Deposition Additive Manufacturing of Al7075 alloy: Process Development, Microstructure, and Porosity

7xxx series aluminum alloys are priority materials adopted in aerospace because of their lightweight property and excellent mechanical performance. The combination of lightweight material and additive manufacturing techniques can significantly promote lightweight design in many industries. This study developed the optimal process for manufacturing Al7075 alloy by laser-aided directed energy deposition and revealed the material properties of the as-deposited Al7075 specimens. Firstly, single-track experiments were conducted by varying laser power, printing speed, and powder delivery rate in broad ranges. Results indicated that the printing speed and powder delivery rate impact the surface finish and shape of single-track beads considerably. Block specimens printed with the optimal parameters selected from the single-track experiments present crack-free quality and have a high relative density of up to 99.89%. Second phases with rich Cu, Mg, and Zn elements along the inter-dendritic regions and grain boundaries were observed from the microstructure inspection. The composition of zinc in the deposited samples is lower than usual, which leads to a relatively low microhardness.

Achieving microstructural homogeneity in the stir zone across thick AA6061 welds using self-reacting bobbin tool friction stir welding

This study focuses into strategizing the usage of self-reacting bobbin tool friction stir welding (SRBT-FSW) to obtain consistent microstructural homogeneity along the thickness of AA6061 aluminium alloy (AA) thick plates during welding. The SRBT-FSW technology, distinguished by its dual-shoulder design, represents a significant step forward in FSW by eliminating the requirement for a backing anvil and promoting balanced heat distribution. This study seeks to address the issues of maintaining uniform microstructural characteristics throughout the weld zone, which is crucial for the mechanical performance and durability of welded joints in structural applications. The experimental study entails the systematic welding of AA6061 plates of 6 mm thickness using a self-reacting bobbin tool under a fixed processing condition. Electron backscatter diffraction (EBSD) was used to characterize the grain structure and phase distribution over the weld. Mechanical parameters like as tensile strength and hardness were determined to establish correlations between microstructure and mechanical performance. The results demonstrated that SRBT-FSW significantly enhances microstructural homogeneity across the weld zone, leading to improved mechanical properties. In the Bottom Zone (BZ), a refined grain structure with an average grain size (AGS) of 3.53 µm and a random or weak texture was observed, contributing to enhanced hardness and mechanical performance, with an ultimate tensile strength (UTS) of 220 MPa. In contrast, the Top Zone (TZ) exhibited a coarser AGS of 4.33 µm with a pronounced {111} crystallographic texture, resulting in a slightly lower UTS of 205 MPa. The Middle Zone (MZ), influenced by the greater heat input from both the TZ and BZ, showed an intermediate AGS of 3.99 µm, predominantly oriented along the {101} plane, and achieved a UTS of 194 MPa, with a slight reduction in ductility. This study highlights the potential of self-reacting bobbin tool friction stir welding as a reliable method for making high-quality, homogeneous welds in thick aluminium plates and paving way for their wider application in the aerospace, automotive, and shipbuilding industries, where homogeneous microstructural qualities are of significant importance.

Laser powder bed fusion of high-strength crack-free Al7075 alloy with the in-situ formation of TiB2/Al3Ti-reinforced phases and nucleation agents

The existence of solidification cracks caused by columnar grains in precipitation-hardened aluminium alloys limit the applicability of Al7075 components manufactured via laser powder bed fusion (LPBF) additive manufacturing. A novel approach was developed to co-incorporate submicron-sized B and micron-grade Ti6Al4V to eliminate hot cracks and to effectively transform coarse columnar grains into fine equiaxed grains, thus improving the mechanical performance of LPBF-fabricated modified Al7075 material. The grain refinement was mainly attributable to the heterogeneous nucleation promoted by the combination of in-situ-formed L12-Al3Ti and TiB2 nano-sized phases. After an optimised T6 heat treatment, excellent comprehensive mechanical properties were achieved, with a tensile strength of 460 MPa and an elongation of 13 %. This research provides an efficient and cost-effective path for addressing crack-sensitive metallic materials used for LPBF additive manufacturing processes.

Corrigendum to “Comparative review and experimental validation of Tribological and Mechanical Properties of Zinc Aluminium Alloy (ZA27) and Aluminium Zinc Alloy (Al-25Zn)” [J. Alloy. Metall. Syst. 7 (2024) 100099

Corrigendum to “Comparative review and experimental validation of Tribological and Mechanical Properties of Zinc Aluminium Alloy (ZA27) and Aluminium Zinc Alloy (Al-25Zn)” [J. Alloy. Metall. Syst. 7 (2024) 100099

Effect of different heat treatment on thermal and electrical conductivity, and microhardness of Erbium-reinforced in-situ processed (ZrB2/Al2O3) 7085 AA nanocomposites for high temperature applications

High structurally stable 7085 aluminium alloy (7085 AA) is increasingly gaining more attention in industries such as automotive, electrical and high-temperature applications due to its demand for prolonged usage. The performance potential of conventional 7085 AA properties can be enhanced by reinforcing it with appropriate ceramic nanoparticles (AZ), namely, Aluminium oxide (Al2O3), Zirconium diboride (ZrB2), and rare earth metals, i.e. Erbium (Er), which makes it to be utilized for high-temperature industrial applications. Thus, the primary objective of the present study is to develop 7085 AA/AZ-Er composites having enhanced thermal, electrical and mechanical properties. The composites was synthesized through an In-situ process, followed by homogenization, solution treatment and artificial ageing (T6 and T74 heat treatment). The results obtained through T6 and T74 heat treatment were compared. The concentration of AZ was maintained at 1.0 wt.%, whereas Er was varied by 0.1. 0.3 and 0.5 wt.% in the 7085 AA/AZ composites. The superior properties of 7085 AA/AZ- Er composites achieved in this study are as follows: Thermal conductivity- 153.5 ± 0.7 W/m·K, Electrical conductivity- 21.99 ± 0.08 MS/m, and Hardness- 217.12 ± 3.2 Hv. The hardness and thermal conductivity of T6 heat-treated Er-based composites are found to be superior, while T74 heat-treated composites exhibited significant improvements in electrical conductivity. It is concluded that the appropriate addition of Er concentration plays a vital role in enhancing mechanical, electrical and thermal properties irrespective of the heat treatment process.

Characteristics of Particle-Wet Wall Impact Damage: Effects of Liquid Film Parameters

Particle impact damage significantly affects the safe and stable operation of energy and chemical process equipment. During particle transportation, a liquid film may form on the wall, influencing the damage mechanism caused by particle effect. This study investigates the effects of liquid film parameters, specifically viscosity and thickness, on wall damage. Hydroxypropyl Methylcellulose (HPMC) solution was applied as a liquid film, and the effect of the liquid film's viscosity and thickness was examined through impact damage experiments using a particle (45 steel) and a wall (1060 aluminum alloy) with the liquid film. Results indicate that the presence of a liquid film can inhibit wall damage. Increased liquid film viscosity and thickness reduce wall damage, but they affect the turning points of damage characteristic parameters differently concerning impact angle and velocity. Finally, the study establishes correlation between dry and wet impact by introducing the effect coefficient of liquid film. This reveals the alteration rules of the influence coefficient and proposes a wet impact damage model, providing a reference for the damage prediction in process equipment.

Dynamic optimization design of thin plate structure based on surrogate model

Abstract To enhance dynamic optimization efficiency in traditional thin plate structures, surrogate models are integrated for structural dynamic size optimization, reducing dependence on high-precision finite element simulations. This paper focuses on optimizing the aluminum alloy sheet as the subject of research. The parameters of the specimen are optimized through sensitivity analysis, based on the comparison between the free mode Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA) results. The modified specimen undergoes validation under a four-edge clamped boundary condition. Subsequently, random vibration analysis is conducted to determine the root mean square (RMS) value of the acceleration response. Employing surrogate model technology, four models are constructed using parametric modeling and experimental design methods. These models are then compared for their fitting effectiveness. The results indicate that the RBF model exhibits the highest accuracy in fitting each response, effectively replacing dynamic simulation. Finally, the RBF combined with the NSGA-II method, optimizes the specimen’s structural size, resulting in a 21.6% reduction in mass and an 18.60% decrease in acceleration response. These outcomes demonstrate satisfactory optimization results, ensuring accuracy while enhancing the dynamic characteristics of the specimen structure. This research offers valuable insights for related engineering applications.

Mechanical performance analysis method for ribbed H-section aluminum alloy members with initial curvature and torsion angle

In this study, an experimental investigation was conducted on the axial compression performance of ribbed H-section aluminum alloy members with initial curvature and torsion angle under varying boundary conditions, including one end hinged with the other rigidly connected, and both ends rigidly connected. Ultimate bearing capacity and failure modes were identified under real loads and subsequently compared with previous findings from our research group on members with hinged ends. To account for initial imperfections introduced during processing and transportation, 3D scanning technology was utilized to capture the precise geometrical dimensions, constructing an accurate numerical simulation model. The experimental results were corroborated with numerical simulations, leading to the proposal of an analytical method for members with initial curvature and torsion angle. Furthermore, extensive parametric analysis elucidated the impact of initial curvature, torsion angle, and slenderness ratio on the ultimate bearing capacity, culminating in the formulation of the stability factor and calculated length factor based on numerical outcomes. The study discovered significant variances in bearing capacity under different boundary conditions, with one-end hinged and one-section rigidly connected, and two-end rigidly connected conditions exhibiting 1.4 and 2.1 times the capacity of the hinged-at-both-ends scenario. Under different boundary conditions, the axial compression members were subjected to flexural-torsional buckling failure. Moreover, when the ultimate bearing capacity was reached, the lower flange of the member and the web near the lower flange appeared obvious buckling phenomenon. The numerical analysis aligned well with experimental data, validating the simulation method's reliability and revealing the stress distribution and evolution during member failure. These findings offer vital theoretical insights and technical support for engineering design and practical applications.

Additively-manufactured lattice-grid sandwich cylinders and elastoplastic multi-failure analyses

Aluminum alloy lattice-grid sandwich cylinders, comprising a symmetric pyramidal truss core and open grid face-sheets, are additively manufactured using the selective laser melting method. The compression behaviors of these sandwich cylinders are investigated. Failure is controlled by three competing mechanisms: global buckling, core shear instability and grid buckling, with the active failure mode determined by the cylinder geometry and the material yield stress. Failure criteria are defined in terms of the effective elastoplastic properties of the grid-skins and core, which agree well with the measured and simulated failure responses, and are applied to generate multi-failure maps with cylinder geometrical parameters as axes. The maps help with failure load prediction and design optimization. For these cylinders, grid buckling is proposed as the dominant failure mode.

Tribological Behavior of Hybrid Aluminum-TiB2 Metal Matrix Composites for Brake Rotor Applications

This research investigates the feasibility of hybrid aluminum metal matrix composites (MMC) incorporating TiB2 particles for brake rotor applications. The composites were produced by incorporating both in-situ, submicron-sized TiB2 particles and regular micron-sized TiB2 powders via stir and squeeze casting techniques into a A206 aluminum alloy matrix. Systematic adjustments in the fractions of in-situ and ex-situ TiB2 particles were conducted to evaluate their impact on wear behavior and mechanisms. Combination of both particle types allowed composites with up to 10 vol% of reinforcements. Composites with higher proportions of ex-situ particles demonstrated increased wear resistance compared to those solely composed of in-situ particles, control specimens without TiB2, and conventional cast iron counterparts. The lowest wear rate for the hybrid composites sliding against phenolic brake pads was 1.1 x 10-5 mm3/Nm, signifying a 3-fold reduction relative to cast iron sliding against the same pads. Wear analysis elucidated distinctive mechanisms within the hybrid composites, characterized by mild fragmented abrasive wear, adhesive wear, and plastic deformation, accompanied by the formation of an intermixed tribo-oxide layer.

Study on the Electron Beam Repair Welding of 5000 Aluminum Alloys

Electron beam welding (EBW) has been attracted due to its high energy density, high depth-to-width ratio, low thermal strain, compared with arc and laser welding. In addition, it ensures high quality weld joint in structural metals in a wide range of thickness from 0.025 mm to 300 mm. Therefore, EBW is widely used in industries such as automotive, aviation, nuclear power plant, etc. Although a lot of studies on EBW for several decades have been presented, EB based repair welding with supplement of filler metal has less reported. In this work, EB repair welding for 5083 aluminum alloys was investigated because the aluminum alloys are becoming more important as a lightweight material in mobility industries. Material characterization and mechanical properties of the repair-welded specimens were evaluated, compared with characteristics of base metal and bead welding without repair. The optimized experimental conditions showed tensile strength of 294 MPa, which is a similar to base metal. Our study indicates that EB repair welding can be considered for the candidate of repair welding of aluminum alloys.