Aluminum Alloy Components Research Articles

Porosity suppression and mechanical property improvement of wire-arc directed energy deposited TiCp/Al-Cu alloys joint by oscillating pulsed wave laser beam welding

Hybrid manufacturing technology combining wire-arc directed energy deposition (WA-DED) and laser beam welding (LBW) presents a promising avenue for efficiently manufacturing large-size aluminum alloy components. The high tendency of porosity defects, particle decomposition, and fusion zone softening are outstanding challenges in the LBW welding of additively manufactured particle-reinforced aluminum alloys. Herein, a WA-DED-processed Al-6.3Cu alloy embedded with 0.6 wt% TiC particles was employed as weldment. Four different laser beam modes, including continuous wave (CW), pulsed wave (PW), oscillating continuous wave (OCW), and oscillating pulsed wave (OPW), were used to join TiCp/Al-6.3Cu alloy. The effects of different laser modes on the porosity defects, microstructure evolution, and mechanical properties of WA-DED particle-containing aluminum alloy joints were studied comparatively. Multi-scale characterization results showed that the enhanced molten pool flow via laser beam modulation effectively suppressed porosity defects and facilitated the uniform particle distribution. The OPW mode provides an optimal effect on porosity inhibition and weld microstructure refinement compared to the pulsed or oscillating modulation modes. The heat-treated LBW joint via OPW mode achieved excellent comprehensive mechanical properties, whose elongation and ultimate tensile strength reached 9.5% and 449 MPa, respectively. This enhanced performance can be attributed to the decreased porosity, refined weld microstructure, and high-density nano-precipitation. This study provides fundamental guidance for the welding of high-strength Al-Cu alloy fabricated by additive manufacturing.

Enhancing mechanical properties and defects elimination in 2024 aluminum alloy through interlayer friction stir processing in wire arc additive manufacturing

In this study, a hybrid wire arc additive manufacturing (WAAM) and interlayer friction stir processing (IFSP) approach was utilized to enhance the quality of 2024 aluminum alloy components. The defects characteristic, microstructure evolution, and mechanical properties of the fabricated components and after T6 heat treatment were analyzed systematically. Our analysis reveals that IFSP can break and dissolve the eutectic phases, significantly reduce porosity defects and refine the grain size of the as-deposited materials, thus improving the overall mechanical properties. Notably, compared to the WAAM as-deposited component, the yield strength (YS) and ultimate tensile strength (UTS) in the top-layer stir zone (SZ) of IFSP component increased from 154 ± 3 to 267 ± 2 MPa, and from 258 ± 12 to 360 ± 3 MPa, respectively. However, in the middle-layer SZ, S-phase precipitation and coarsening induced by thermal cycling during additive manufacturing slightly reduced the tensile properties. Post-T6 heat treatment led to uniformly distributed properties in the IFSP component along both horizontal and vertical directions, with the YS, UTS, and elongation (EL) averaging 353 ± 9 MPa, 470 ± 4 MPa, and 10.5 ± 1.6%, closely matching those of wrought counterparts. The significant improvements in mechanical properties are primarily attributed to the elimination of porosity and precipitation of fine needle-like S-phase. This research not only demonstrates the potential of IFSP in enhancing the mechanical properties of WAAM-fabricated 2024 aluminum alloy but also offers a promising technique for producing high-quality components suitable for high-performance aerospace applications.

Semi-Analytical Solution Model for Bending Deformation of T-Shaped Aviation Aluminium Alloy Components under Residual Stress

Structures composed of aviation aluminium alloys, characterized by their limited rigidity and thin-walled configurations, frequently exhibit deformation after processing. This paper presents an investigation into T-shaped components fabricated from pre-stretched 7075-T7451 aviation aluminium alloy sheets, examining the effects of residual stress and the geometrical parameters of T-shaped components on their deformational behavior. A semi-analytical model, developed to elucidate the bending deformation of T-shaped components subjected to residual stress, was validated through finite element analysis and empirical cutting experiments. The experimental results revealed that the bending deformation deflection of the T-shaped specimen was 0.920 mm, deviating by a mere 0.011 mm from the prediction provided by the semi-analytical model, resulting in an inconsequential error margin of 1.2%. This concordance underscores the precision and accuracy of the semi-analytical model specifically designed for T-shaped components. Moreover, the model’s simplicity and ease of application make it an effective tool for predicting the bending deformation of thin-walled T-shaped components under a range of residual stresses and dimensional variations, thereby demonstrating its significant utility in engineering applications.

Tailoring properties of directed energy deposited Al-Mg alloy by balancing laser shock peening and heat treatment

Wire arc-directed energy deposition (WADED) has shown great advantages and potential in fabricating large-scale aluminum (Al) alloy components. However, WADED Al alloys typically exhibit low strength and reliability due to pore defects and lack of work hardening or precipitation strengthening. This study utilized a combination of laser shock peening (LSP) and annealing to regulate the microstructure of WADED Al-Mg4.5Mn alloy and enhance mechanical properties. The effects of LSP and annealing on phase composition, pore distribution, and microstructures at multiple scales were systematically investigated to reveal the mechanical property improving mechanism. The results demonstrated that LSP-induced plastic deformation formed a defect-free zone by closing near-surface pore defects. LSP created the hardened layer with gradient mechanical properties by inducing gradient changes in grain size, the number of low-angle grain boundaries (LAGBs), and dislocation density along the depth direction. The annealing process promoted grain coarsening and reduced excessive dislocations and LAGBs, weakening the work hardening effect caused by LSP. Furthermore, the high-density dislocations and high stored energy generated by LSP accelerated the recrystallization, facilitating growth of near-surface grains. The defect-free zone, dislocation strengthening, and LAGBs strengthening were responsible for the increase in strength, while the synergistic deformation between hardened layers and soft core facilitated maintaining excellent elongation. The strength and elongation of WADED Al alloy can be synergistically improved by balancing the effects of LSP and heat treatment.

Microstructure evolution and mechanical properties of Al–Cu–Mn–Cd alloy fabricated by CMT-wire arc additive manufacturing

The high-performance additive manufacturing of relatively small aluminum alloy components has been widely proven successful. However, wire arc additive manufacturing (WAAM) has always been challenging in achieving uniform microstructure and high mechanical properties when manufacturing large-sized parts. Therefore, this study used cold metal transition wire arc additive manufacturing (CMT-WAAM) to prepare Al-5.49Cu-0.4Mn-0.29Cd (ACMC) alloy to obtain a uniform microstructure and improve its mechanical properties. The results show that the as-deposited (AD) samples have an obvious layered deposited structure. The grains in the microstructure are all equiaxed crystals and a large amount of copper-rich eutectic phase precipitates at the grain boundaries. After heat treatment, the vast majority of the eutectic phase dissolves, and θ'phase, with a size of 100–200 nm, uniformly precipitates in the α-Al matrix. The ultimate tensile strength (UTS) and yield strength (YS) of the heat-treated (HT) specimen can reach 483.7 MPa and 412.3 MPa, respectively. There is no significant difference in the mechanical properties between the transverse and longitudinal directions of thin-walled samples. Based on experimental results and theoretical analysis, the strengthening mechanism and fracture mechanism of CMT-WAAM aluminum alloy were revealed. This work provides a theoretical basis for the microstructure optimization and mechanical performance improvement of ACMC alloy, which is of great significance for the high-performance preparation of large-sized components in the aerospace field.

Micro-adhesive wear and microhardness behavior of friction stir welded 2524-T3 aluminium alloy

Friction Stir Welding (FSW) emerges as a compelling solid-state welding technique for aluminium alloy components used as aircfrat materials. Despite being a solid-state process and mitigating numerous solidification challenges, it retains its thermomechanical nature, affecting the material's microstructure and, consequently, its mechanical properties. This concise communication sought to assess the impact of the FSW process on the micro-adhesive wear and microhardness properties of the 2524-T3 alloy. The results showed that the FSW process was executed successfully on 2524-T3 aluminium alloy plates as well as the great influence of intermetallic particles on hardness and micro-adhesive wear.

Molding performances of ZL205A aluminum alloy fabricated by wire arc additive manufacturing based on gray correlation theory

Evaluation indicators such as aspect ratio, dilution rate, microhardness, wear resistance and electrochemical corrosion resistance are crucial to assess the quality of arc additive manufacturing of aluminum alloys. This paper investigated the impact of the process parameters of the Cold Metal Transfer (CMT) arc additive manufacturing on molding performances of single pass-single layer samples. A three-factor, three-level orthogonal table was devised incorporating welding speed, wire feed speed, and dry extension as the three principal process parameters. Combined with the gray correlation theory, the Shape-Performance Coefficient (SPC) was established to provide a comprehensive evaluation of the molding performances of the samples. The results indicated that the priority sequence of the three process parameters on molding performances was wire feed speed, welding speed, and dry extension. The ideal process parameters are: a welding speed of 9 mm/s, a wire feed speed of 4 m/min, and a dry extension of 10 mm. If the wire feed speed is too high and the welding speed is too low, the aspect ratio and dilution rate of the sample will increase, resulting in larger grain size and more porosity defects. This has the consequence of decreased wear resistance and corrosion resistance for the sample. Compared to the ZL205A cast aluminum alloy (CastZL205A), the most exceptional additive manufacturing sample exhibits a ten-fold reduction in the average grain size and a 144.88% increase in electrochemical corrosion resistance. The findings presented in this paper establish data support for thin-walled parts arc additive manufacturing with ZL205A aluminum alloy and provide a theoretical foundation for the repair of critical aluminum alloy components.

Fracture Behaviour of Aluminium Alloys under Coastal Environmental Conditions: A Review

Aluminium alloys have been integral to numerous engineering applications due to their favourable strength, weight, and corrosion resistance combination. However, the performance of these alloys in coastal environments is a critical concern, as the interplay between fracture toughness and fatigue crack growth rate under such conditions remains relatively unexplored. This comprehensive review addresses this research gap by analysing the intricate relationship between fatigue crack propagation, fracture toughness, and challenging coastal environmental conditions. In view of the increasing utilisation of aluminium alloys in coastal infrastructure and maritime industries, understanding their behaviour under the joint influences of cyclic loading and corrosive coastal atmospheres is imperative. The primary objective of this review is to synthesise the existing knowledge on the subject, identify research gaps, and propose directions for future investigations. The methodology involves an in-depth examination of peer-reviewed literature and experimental studies. The mechanisms driving fatigue crack initiation and propagation in aluminium alloys exposed to saltwater, humidity, and temperature variations are elucidated. Additionally, this review critically evaluates the impact of coastal conditions on fracture toughness, shedding light on the vulnerability of aluminium alloys to sudden fractures in such environments. The variability of fatigue crack growth rates and fracture toughness values across different aluminium alloy compositions and environmental exposures was discussed. Corrosion–fatigue interactions emerge as a key contributor to accelerated crack propagation, underscoring the need for comprehensive mitigation strategies. This review paper highlights the pressing need to understand the behaviour of aluminium alloys under coastal conditions comprehensively. By revealing the existing research gaps and presenting an integrated overview of the intricate mechanisms at play, this study aims to guide further research and engineering efforts towards enhancing the durability and safety of aluminium alloy components in coastal environments.

Effects of a hybrid post-treatment on microstructure and mechanical properties of cold sprayed AA7050 deposits

Cold spray additive manufacturing (CSAM) technology is a promising and efficient method for preparing high-strength aluminum alloy components. In this work, AA7050 deposits were prepared by high-pressure cold spraying, and a hybrid post-treatment (i.e., annealing + hot compression + solid solution and aging) was proposed to improve the mechanical properties of the deposits. The results of the study indicated that the annealing alone was insufficient to eliminate all defects within the AA7050 deposits. After annealing, the porosity of the material decreased from 2.34% to 1.62%. The subsequent hot compression and aging treatment promoted the precipitation of strengthening phases and homogenized the microstructure, reducing the porosity of the AA7050 deposits to 0.18%. As a result, the mechanical properties of the materials further improved. The ultimate tensile strength of the CSAMed AA7050 after aging treatment reached 557.7 MPa, which was 337.4% and 149.3% higher than that of the as-sprayed and annealed materials, respectively. Furthermore, fracture surfaces analysis indicated that the fracture mechanism of the specimens changed from brittle to ductile mode after the hybrid post-treatment.

Effect of deposition strategies on microstructures, defects and mechanical properties of 5356 aluminum alloy by wire arc additive manufacturing

Effect of deposition strategies on microstructures, defects and mechanical properties of 5356 aluminum alloy by wire arc additive manufacturing

The role of peening processes as a pre‐treatment to anodizing on fatigue behavior of aircraft aluminum alloy

AbstractIn this work, the possibility of employing shot peening and laser peening as pre‐treatments to a tartaric–sulfuric anodizing process on the fatigue behavior of 7050‐T7451 aluminum alloy components was investigated. The surface modifications and stress fields induced by the combination of the peening and anodizing processes were evaluated by scanning electron microscopy and residual stress assessment methodologies based on diffraction techniques, respectively. It was found that the anodizing process alone results in a significant reduction in fatigue life compared to the as‐machined condition especially in the high‐cycle fatigue (HCF) region of the S–N diagrams due to the presence of defects within the anodic layer that act as stress concentrators facilitating the initiation of fatigue cracks. The application of both shot and laser peening treatments is demonstrated to offset the negative effects induced by anodizing, offering greater safety margins useful for the design of critical aeronautical structures.

The effect of heat treatment on the microstructure and mechanical properties of multilayer AA6061 alloy fabricated by additive friction stir deposition

Multilayer AA6061 aluminum alloy components were successfully fabricated by the additive friction stir deposition (AFSD). The effect of heat treatment on the microstructure and mechanical behavior of the aluminum alloy components was studied. Due to dynamic recrystallization, AFSD AA6061 sample presented a 93.2% average reduction in grain size as compared to base material (BM) (∼ 39.13 µm). Abnormal grain growth was observed in the AFSD-HT sample, and the average grain size of AFSD-HT sample was 592 µm. There was an occurrence of texture formation in the AFSD and AFSD-HT samples, mainly due to severe shear deformation during AFSD process. The maximum texture density of AFSD-HT sample was increased to 17.84. In the BM sample, apart from the β" strengthening phases, hard-brittle intermetallic compounds of Al5FeSi aggregated along the boundaries of the coarser grains. Due to the high temperature generated during the process of AFSD, the β" strengthening phases dissolved into the matrix, and significantly reduced the strength and hardness. After heat treatment, the AFSD AA6016 alloy recovered 18% of its strength at a loss of 2.8% ductility. High density β" strengthening phases precipitated, resulting in increased strength and hardness.

On revealing hidden entrainment damage during in situ tensile testing of cast aluminum alloy components

Tensile tests have been conducted on die-cast coupons of an Al-Si-Cu alloy, which have been found to contain no pores via X-ray inspection. Due to the digital image correlation used during tensile testing, either single or multiple strain concentrations have been detected and subsequently characterized. In all cases, oxide films have been found on fracture surfaces at the site of the strain concentrations. The analysis of a crack away from the fracture surface has also shown it to be an oxide bifilm. These results pour doubt on the effectiveness of quality assurance practices employed in industry.

Experimental and numerical studies of impact loading on single-layer reticulated shells with aluminium alloy gusset joints

Aluminium alloy materials have found extensive application in large-span space grid structures. While research on the mechanical properties of aluminium alloy materials and components is generally well-established, there remains an incomplete understanding of the overall structure. Therefore, further investigation into the overall performance of aluminium alloy reticulated shells is crucial to promote their use in spatial structures, guiding structural design and addressing practical engineering challenges. This study focuses on the design of a single-layer aluminium alloy reticulated shell with a 2 m span, which was subjected to an impact test to examine its dynamic response and failure mode. By comparing and analysing stress, acceleration, and displacement time-history curves obtained from these different test conditions, the dynamic response behavior of the reticulated shell was determined. To simulate the impact on reticulated shells, explicit dynamic analysis was conducted using non-linear finite element software LS-DYNA. Based on the deformation characteristics and failure phenomena observed during the impact test, three distinct failure modes were defined for the single-layer reticulated shell. Through parameter analysis using the validated finite element model, it was determined that increasing the thickness (tp) of the aluminium alloy gusset plate or reducing the radius (R) of the gusset plate effectively enhances the overall stiffness and impact resistance of the single-layer reticulated shell. Overall, this research contributes to a deeper understanding of the performance of aluminium alloy reticulated shells under impact loads. The findings provide valuable insights for guiding structural design and addressing practical engineering problems in the field of spatial structures.

Mechanical properties prediction of high-strength aluminium alloy components formed under the PHF process

Pre-strengthening hot/warm forming (PHF) technology can effectively shorten the microstructure evolution process of aluminium alloy deformation and heat treatment, and has a broad application prospect. In this paper, the process parameters in PHF are abstracted into sequence data, which is used as the input of long short-term memory neural network (LSTM) model to predict mechanical properties of aluminium alloy components after PHF process. Besides, the prediction models based on Random Forest (RF), Support Vector Regression (SVR) and Back Propagation Neural Network (BPNN) are established and compared with LSTM model. In addition, a Few-Shot Learning method based on the constitutive model is proposed to predict the properties of aluminium alloys.

Study on stability of H-type section aluminum alloy perforated members under axial compression and eccentric compression around weak axis

Aluminum alloy components have the advantages of light weight, high strength, favorable machinability, and good acid corrosion resistance, which can greatly reduce maintenance costs and easy to make the structures with beautiful appearance. Based on the shortcomings of existing research fields, the stability of H-type section 6082-T6 aluminum alloy perforated members under axial compression and eccentric compression around weak axis is studied by combining experimental and numerical simulation methods in this paper. The test results of aluminum alloy members under axial compression and aluminum alloy members under eccentric compression around weak axis with different web opening numbers, opening diameters, slenderness ratios and eccentric distances are analyzed. The verified finite element model is used to carry out the extensive parameter analysis focusing on the key variables. Based on the test and numerical simulation results of the stability bearing capacity of 134 members, the design methods for H-type section aluminum alloy perforated members under axial compression and eccentric compression are proposed and evaluated by reference to the existing specification.

The effect of heat treatment on the microstructure and electrochemical corrosion behavior of multilayer AA6061 alloy fabricated by additive friction stir deposition

Multilayer AA6061 aluminum alloy components were successfully fabricated by additive friction stir deposition (AFSD). The effect of heat treatment on the microstructure and electrochemical corrosion behavior of the AA6061-T6 aluminum alloy components was studied. The average grain size in AFSD samples was 2.67 μm, where 89.7 % of grains were smaller than 5 μm. Abnormal grain growth was observed in the heat-treated AFSD (AFSD-HT) sample, and the average grain size of AFSD-HT sample was 592 μm. In the base material (BM) sample, apart from the β″ strengthening phases, hard-brittle Al5FeSi intermetallic compounds (IMCs) aggregated along the boundaries of the coarser grains. Due to the high temperature generated during the process of AFSD, β″ phases dissolved into the matrix. After heat treatment, a larger amount of fine needle-like β″ phases were re-precipitated in the AFSD-HT sample. Al5FeSi IMCs accelerated the corrosion of the Al matrix. Fine β″ phases significantly inhibited the corrosion expansion to Al matrix and improved the corrosion resistance of AA6061 alloys.

Cold-wire assisted arc direct-energy deposition of VC-strengthening 5A06 aluminum alloy: Microstructures and mechanical properties

In this study, vanadium carbide (VC) was initially introduced into the molten pool using the cold wire method to refine the deposit grains and enhance the mechanical properties of arc direct energy deposition (ADED) aluminum alloy. Next, the grain structure's evolutionary behaviors and the second phase in the VC-strengthening ER5A06 aluminum alloy deposits were investigated, and the grain refinement mechanism was determined. The findings demonstrated that the cubic Al10V phase was produced after introducing VC, and the grain structure in the middle stable region of the building wall was transformed from coarse columnar grains (with an average size of 42.3 μm) into equiaxed fine grains (with an average size of 16.4 μm). Both Al10V and VC were coherent to α-Al in terms of orientation: (020)α-Al//(444)Al10V, [101―]α-Al//[112―]Al10V, and (111)α-Al//(111)VC and [011]α-Al//[011]VC. Their interatomic and interplanar spacing misfits were lower than 5 %, facilitating the heterogeneous nucleation of α-Al during molten pool solidification. Moreover, under multiple thermal cycles of ADED, the pinning effect of VC and Al10V effectively restricted the grain growth, thus enabling the building wall to steadily maintain a uniform, equiaxed, and fine-grained structure. Due to grain refinement and homogenization, the horizontal and vertical ultimate tensile strengths of the straight wall were improved by 16.8 % and 50.2 % (351.6 and 348.1 MPa), respectively, thereby eliminating the mechanical anisotropy. This work can provide a theoretical foundation and a novel method for the fine microstructure regulation and reinforcement of ADED aluminum alloy components.

Research Progress of Aluminum Alloy Welding/Plastic Deformation Composite Forming Technology in Achieving High-Strength Joints.

Fusion welding causes joint deterioration when joining aluminum alloys, which limits the use of aluminum alloy components in high-end equipment. This paper focuses on an overview of how to achieve high-strength aluminum alloy welded joints using welding/plastic deformation composite forming technology. The current technology is summarized into two categories: plastic deformation welding and plastic deformation strengthening. Plastic deformation welding includes friction stir welding, friction welding, diffusion welding, superplastic solid-state welding, explosive welding, and electromagnetic pulse welding. Plastic deformation strengthening refers to the application of plastic deformation to the weld seam or heat-affected zone, or even the whole joint, after welding or during welding, including physical surface modification and large-scale plastic deformation technology. Important processing parameters of plastic deformation welding and their effects on weld quality are discussed, and the microstructure is described. The effect of plastic deformation strengthening technology on the microstructure and performance evolution, including the hardness, tensile strength, fatigue property, residual stress, and hot cracking of aluminum alloy welded joints, and its evolution mechanism are systematically analyzed. Finally, this paper discusses the future development of plastic deformation strengthening technology and anticipates growing interest in this research area.

Corrosion and stress corrosion cracking characteristics of 4043 aluminium alloy fabricated through directed energy deposition process

Additive manufacturing (AM) has emerged as a crucial element of Industry 4.0. In the pursuit of fabricating lightweight components, AM of aluminium alloys has become the centre of focus in recent years. This study investigates aluminium alloy (ER4043) components fabricated by arc-based directed energy deposition (DED-arc) for their corrosion and stress corrosion cracking (SCC) behaviour in 0.6 M NaCl solution at room temperature. Electrochemical characteristics in 0.6 M NaCl solution were investigated using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests. Electrochemical results revealed that the DED samples fabricated using a tungsten inert gas (TIG) welder as the energy source demonstrated better resistance against corrosion when compared to those developed through cold metal transfer (CMT) based DED. The prolonged exposure of samples in 0.6 M NaCl facilitated the growth of a stable passive oxide film leading to enhanced corrosion resistance. Slow strain rate tests (SSRT) conducted in air and 0.6 M NaCl solution showed that DED samples are susceptible to SCC. The fractography of the fractured SSRT samples indicated the mode of failure to be intergranular.