6061-T6 Aluminum Alloy Research Articles

Mechanical Properties of 7075-T6 Aluminum Alloy in Electrically Assisted Forming

The coupling effects of electrical pulse, temperature, strain rate, and strain on the flow behavior and plasticity of 7075-T6 aluminum alloy were investigated and characterized. The isothermal tensile test and electrically assisted isothermal tensile test were performed at the same temperature, and the typical models were further embedded in ABAQUS for numerical simulation to illustrate the electroplastic effect. The results showed that electrical pulses reduced deformation resistance but greatly increased elongation. Compared with the traditional Johnson–Cook model, the proposed modified electroplasticity constitutive equations have a certain improvement in calibration accuracy for a highly nonlinear and thermoelectric coupling dynamic behavior. Moreover, combined with the electrically assisted three-point bending experiment, it was found that the springback angle decreases with the increase in current density. This is very close to the experimental result, further verifying the effectiveness of the thermoelectric coupling constitutive equation.

Modelling low-cycle fatigue behaviour of structural aluminium alloys

Abstract Recently, use of 6000 series aluminium alloys in braced frame structures has been increased due to their superior structural properties. Fracturing of braces as a result of low-cycle fatigue has a major impact on nonlinear behaviour of structures under earthquake loading. Therefore, modelling low-cycle fatigue life, i.e., number of reversals to failure, is important to understanding braced-frame structural performance. To date, there are no readily available methods for predicting the low-cycle fatigue behaviour of 6000 series aluminium alloys. This research study aims to provide structural engineers with a computationally efficient approach to assess aluminium alloy structures in the context of potential low cycle fatigue. For this purpose, 18 low-cycle high amplitude fatigue tests (up to ± 6% strain amplitude) were conducted to establish strain − life relationships for 6082-T6, 6063-T6 and 6060-T5 aluminium alloys. The obtained experimental results were then used to calibrate a low-cycle fatigue life model to capture the fracture behaviour of the studied materials. The comparison of experimental results and predicted fatigue behaviour shows the capability of the proposed model to predict to a high degree of precision the onset of fracture and the overall low-cycle fatigue behaviour of material.

Tribological properties study and prediction of QBe2 beryllium bronze and 7075-T6 aluminum alloys based on machine learning under mixed lubrication

Tribological properties of materials exhibit complex and non-linear correlation with working conditions under mixed lubrication. Selecting an appropriate data-driven method to predict tribological properties is important for accelerating material design and preparation. This paper investigates the tribological performance and wear mechanisms of QBe2 beryllium bronze and 7075-T6 aluminum alloy pairs under grease lubrication by using pin-on-disk friction and wear tests. The tribological performance under different conditions is further predicted using four machine learning algorithms: K-nearest Neighbors (KNN), Support Vector Machine (SVM), Artificial Neural Network (ANN), and Random Forest (RF). The experimental and machine learning results both show that reciprocating frequency has the most significant influence. The dominant wear mechanisms include ploughing and adhesive wear. Furthermore, among the four machine learning models, SVM model performs the best in predicting tribological properties of QBe2 beryllium bronze and 7075-T6 aluminum alloy under mixed lubrication.

Effect of Dynamic Corrosion and Degradation on Fatigue Life of an AA2024-T3 Aircraft Profile: Experimental, Statistical, and Numerical Analyses

The effect of parameters such as angle of attack, flow velocity, and electrolyte concentration (saline solution) on the extent of material degradation, as well as the morphology and depth of corrosion pits in an airfoil made of 2024-T3 aluminum alloy, was studied in detail. An orthogonal L9 design of experiments (Taguchi method) was applied to promote high pitting corrosion through the quality characteristic “the higher the better”. Potentiodynamic curves of the three experiments with low, medium, and high saline concentration were obtained through the CorrTest CS350 equipment. The above allowed the determination of the electrochemical corrosion parameters under static test conditions. The corroded airfoils were analyzed using light optical microscopy (LOM). In addition, the roughness measurements correlated with the extent of the degraded surface. A complete pit shape and depth characterization was obtained by applying mechanical ground, surface wear level monitoring (every 0.01 mm), and LOM observations. Pitting defects (depth and morphology) and mechanical strength reduction were considered by a finite element (FE) model to simulate the airfoil fatigue behavior. Numerical results helped to determine the contribution of pitting and the extent of degradation on sudden airfoil failure.

3-D microstructural effects on anisotropic behavior of fatigue crack initiation at constituent particles in an AA7075 T651 aluminum alloy using focused ion beam combined with EBSD, AFM and nano-indentation

3-D microstructural effects on anisotropic behavior of fatigue crack initiation at constituent particles in an AA7075 T651 aluminum alloy using focused ion beam combined with EBSD, AFM and nano-indentation

Assessment of surface treatment methods for strengthening the interfacial adhesion in CARALL fiber metal laminates

Metal and polymer interface bonding significantly influences the mechanical performance of fiber metal laminates (FMLs). Therefore, the effect of surface treatments (mechanical abrasion, nitric acid etching, P2 etching, sulfuric acid anodizing (SAA), and electric discharge machine (EDM) texturing) carried on aluminum 2024-T3 alloy sheets was evaluated considering surface morphology, surface topography, and surface roughness. Further, the influence of surface treatments on interfacial adhesion strength and failure mode between the aluminum alloy and carbon fiber prepreg was investigated. The surface treatments increased the surface roughness of the aluminum substrates. Surfaces treated using SAA, nitric acid, and P2 etchant showed improved wettability, while mechanically abraded and EDM textured substrates showcased hydrophobic behavior. The selected surface treatments significantly affected interfacial adhesion between the epoxy polymer and aluminum alloy. SAA and EDM texturing greatly enhanced the interfacial peel strength of FMLs. In the case of interfacial shear strength, EDM textured substrate showed superior performance, followed by SAA. Moreover, untreated and mechanically abraded specimens exhibited weaker bonding and adhesive failure at the aluminum-epoxy interface, whilst chemical treatments resulted in mixed model failure. EDM textured surface underwent cohesive failure, while a dominant mixed mode failure and fiber adhesion were observed in the SAA-treated specimen.

Stress Corrosion Behavior of MIG Welded Joints of 6082-T6 Aluminum Alloy at Different Temperatures

6082-T6 aluminum alloy is a commonly used aluminum alloy material in the field of rail transit because of its good molding properties, high mechanical properties, excellent corrosion resistance and weldability. In the high temperature and humid environment, the temperature change is bound to affect the stress corrosion resistance of the aluminum alloy and their welded joint. However, the influence mechanism of temperature on its stress corrosion resistance has not been explained in the existing research. In this paper, the mechanical properties and stress corrosion behaviors of melt-inert gas welded (MIG) 6082-T6 aluminum alloy welded joints were systematically studied under various temperatures condition. Results indicated the temperature scarcely affected stress corrosion cracking susceptibility index (PSCC) of base metal, while significantly affected the welded joint and higher temperature caused lower PSCC. After slow strain rate tensile test, a corrosion layer was formed, which was a typical brittle-toughness mixed failure, and the degree of brittleness increased with the increasing of temperature. Electrochemical analysis showed that corrosion resistance of the joint slightly decreased due to aluminum alloy accelerated dissolution caused by increasing of temperature. The proposed research will provide a theoretical basis for solving aluminum alloys used in rail transit, ship accessories and other industrial fields.

Propagation of a Fatigue Crack Through a Hole.

The stop-hole technique is a well-known strategy to extend the fatigue life of cracked components. The ability to estimate fatigue life after the hole is important for safety reasons. The objective here is to develop strategies for the accurate prediction of initiation and propagation life ahead of the stop-hole. Experimental work was developed in a Compact-Tension (CT) specimen made of 7050-T7451 aluminium alloy and with a 3 mm diameter hole. A total number of 625,000 load cycles were required to re-initiate the crack after the hole. Crack initiation life after the hole was estimated using the Theory of Critical Distances combined with the Smith-Watson-Topper parameter. A value of a0 = 31.83 µm was obtained for El Haddad parameter, which was used to define the critical distance. The predicted life was found to be only 4% lower than the experimental value. The fatigue crack growth (FCG) rate was calculated using a node release strategy, assuming that cyclic plastic deformation is the main damage mechanism and that cumulative plastic strain is the crack driving parameter. A good agreement was found between the numerical predictions of da/dN and the experimental results. The main result, however, is the proposed methodology, which allows predicting the initiation and propagation lives in notched components.

The Influence of Velocity and Pressure on Residual Stresses During The Backward and Forward Extrusion of AA6061 T6 Aluminium Alloy

The extrusion process is considered a cost-effective manufacturing method compared to alternative production techniques, offering excellent mechanical properties and high product quality. Combined extrusion further enhances efficiency by minimizing the need for additional processing steps, thereby saving time and reducing production costs. The die geometry and friction factors play a critical role in determining the success and quality of this process. In this study, AA 6061 T6 aluminium alloy was selected as the billet material to investigate a combined backward–forward extrusion process and to examine the influence of process parameters, such as velocity and pressure, on the residual stresses formed in the extruded products. Two punch types were utilized: a hexagonal punch for the backward extrusion direction and a square punch for the forward extrusion direction. For each punch type, three different cross-sectional areas (140, 130, 115 mm2) and three different forming velocities (0.25, 0.5, 1 mm/s) were tested to assess the effect of forming pressure on residual stresses. The experiments were conducted using a heat-treated H13 steel die with a hydraulic press under lubricated conditions. The findings indicate that increasing the cross-sectional area of the punch, which corresponds to a reduction in pressing pressure, results in higher residual stresses at a constant velocity. The highest residual stresses were observed in the hexagonal region (1315 MPa), corresponding to the backward extrusion process. Intermediate stress levels (

STUDY OF FORMABILITY IMPROVEMENT USING DIFFERENT ANNEALING CYCLES IN INCREMENTAL SHEET FORMING OF AA6061 T6

The formability of AA6061 T6 aluminium alloy is essential due to its high strength and low ductility, posing challenges in forming processes like Incremental Sheet Forming (ISF). Annealing mitigates internal stresses, reduces material hardness, and enhances ductility, thus improving formability. This study investigates the impact of annealing cycles on the formability, microstructure, and micro-hardness of AA6061 T6 sheets during ISF. Various annealing durations (1-15 hours) were tested, followed by ISF experiments. Results demonstrate a significant formability increase with longer annealing, with nearly 40% higher fracture forming height. Micro-hardness decreases with a longer annealing duration (almost 30%), indicating material softening. Microstructural analysis reveals grain growth and recrystallisation, facilitating plastic deformation and enhancing formability. These findings provide insights into the role of annealing in improving formability and mechanical properties in ISF processes, aiding in identifying optimal annealing duration for enhanced performance.

A Modified Multiaxial Fatigue Model and Its Application for the Fatigue Life Prediction of Aircraft Hydraulic Pipes.

The fatigue failure of a structure may occur under a multiaxial vibration environment; it is necessary to establish a better multiaxial fatigue life prediction model to predict the fatigue life of the structure. This study proposes a new model (MWYT) by introducing the maximum absolute shear stress into the WYT model. The feasibility of the MWYT model is verified by using the multiaxial fatigue experimental data of 304 stainless steel, Q235B steel, 7075-T651 aluminum alloy and S355J0 steel. Further, finite element vibration simulations are performed on a typical parallel hydraulic pipe structure, and the vibration simulation results of the pipe structure are verified through the vibration experiment. Finally, the MWYT model is used to predict the fatigue lives of the pipe structure under random excitation and pulsation excitation, respectively, and the fatigue life of the pipe structure under the combined loading from random excitation and pulsation excitation is predicted based on Miner's rule. By comparing with the design life of the aircraft, the predicted life of the pipe structure meets the service requirements for it.

Preparation and Corrosion Resistance of Superhydrophobic Composite Coatings on Shot-Peened AA 7075-T6 Aluminum Alloy

In order to further improve the corrosion resistance of 7075-T6 aluminum alloy after shot peening, corrosion-resistant superhydrophobic coatings (EP-HDTMS@SiO2) containing epoxy resin (EP), cetyltrimethoxysilane (HDTMS), and nano-silica (SiO2) were prepared by a simple spraying method on the surface of shot-peened AA 7075-T6 aluminum alloy. The effects of different EP/SiO2 mass ratios on the micro-morphology, surface wettability, and corrosion resistance of the superhydrophobic composite coatings were analyzed. Due to the combination of microstructure and the modification of low surface energy organics, the contact angle of EP-HDTMS@SiO2 coatings reached the superhydrophobic level (152.6°). The electrochemical tests showed that the corrosion current densities (Icorr) of the EP-HDTMS@SiO2 composite coatings were both significantly lower than those of the EP-HDTMS coatings and matrix aluminum alloys. The addition of SiO2 nanoparticles could improve the hydrophobicity and corrosion resistance of epoxy-based composite coatings. Due to the increase in surface roughness and epoxy resin, the shot-peened AA 7075-T6 alloy coating had high adhesion after the peel test. The prepared coatings also showed excellent corrosion resistance in the neutral salt spray test. This study provides a simple method for preparing stable superhydrophobic coatings on metal surfaces, which is expected to expand the application of 7075 aluminum alloy in harsh environments.

The Effect of Formal Specifications and Working Conditions on the Resistance and Vibration of the NACA 4415 Aircraft Wing Model

Due to their role in airplane performance, wings receive much attention considering their strength enhancement and vibration reduction. Many parameters have been considered and various materials have been used to achieve these objectives. The current work studies numerically the effect of the number of ribs and the angle of attack, on strength, response, and natural frequency at various speed values, using the ANSYS 2021 R1 solver. The adopting material is the AA 7075 T6 aluminum alloy with 71.7 GPa modulus of elasticity, 503 MPa tensile yield strength, 2810 kg/m3 density, and 0.33 Poisson’s ratio. Results show that when the velocity is increased by 30%, a corresponding elevation of 11% can be seen in vibrational distortion. Regarding the angle of attack, it was noted that doubling its value leads to a 28% reduction in vibration-induced deformation. This phenomenon occurs as a result of the alteration in the pressure distribution on the wing caused by the change in the angle of attack.

Research on Properties of Friction Stir Welding Butt Joint of 6061-T6 Aluminum Alloy Sheet

Abstract The friction stir welding (FSW) butt joint of 2mm 6061-T6 aluminum alloy was tested. The effects of welding speed and lower shoulder pressure on the microstructure and mechanical properties of the joint were analyzed, and the possible problems in the welding process of thin plate were analyzed in depth. The results show that the yield strength of the welded joint of 6061-T6 aluminum alloy increases with the increase of welding speed, and the mechanical properties of the joint are not sensitive to the change of the pressure under the shoulder. The core area of the welded joint is the weakest area due to the softening of the welded joint and the insufficient amount of plastic metal transfer.

Research on the process parameters and welded joint quality of resistance spot welding of aluminum composite for car bodies

Abstract The test uses a resistance welding machine to implement resistance spot welding of 6061-T6 aluminum alloy thin plate for automobile body and obtains the welding process parameters of resistance spot welding through the test. Using an orthogonal test scheme and extreme difference analysis method to test and further optimize the resistance welding process parameters, after lap resistance spot welding of a 6061-T6 aluminum alloy thin plate with a thickness of 2 mm, we analyze the welding appearance and complete the tensile test. The test results show that when the welding current is 60 KA, the welding pressure is 0.63 MPa, the thickness of the plate is 2.00 mm, the spot weld joints obtained from the specimen have no obvious defects, better molding, good welding quality and appearance, and its tensile shear value is 5.583 KN at maximum.

XRD and EBSD evaluation on deposition behavior and microstructure characteristic of HVOF sprayed 304SS coating on aluminum substrate

304 stainless steel (304SS) coating was deposited on 6061-T6 aluminum alloy substrate using High Velocity Oxygen Fuel Spraying (HVOF) for the purpose of heavy-load coatings on lightweight structural designing. The deposition behavior, phase composition and microstructure of such a 304SS coating were studied by means of SEM, EDS, XRD and EBSD to reveal the deposition mechanism and microstructure evolution. The bonding strength and microhardness of the coating were consequently characterized. Results revealed that the deposition morphology of sprayed 304SS particles on the surface of aluminum alloy substrate mainly exhibits embedded and adhered character, with interlayer adhered type. The HVOF sprayed 304SS coating consisted of austenite, ferrite and martensite phases, martensitic transformation occurred in the thermal spraying process, and was characterized by a fine grain and dominated by high angle grain boundaries (HAGB), because of the phase distribution, grain size, stress, and grain boundary type were directly associated with the molten state of sprayed particles in the coating as EBSD analyzed. The HVOF sprayed 304SS coating presented high bond strength above 52.6 MPa, and microhardness (345.4 HV0.1), was about 1.6 times higher than the original 304SS feedstock powders and 3.6 times to the substrate, that was of a combination factors of grain refinement and martensitic strengthening in the coating.

Mechanical Properties and Microstructure of 7075T6 Aluminum Alloy – DC01 Low Carbon Steel Rod Joints by Magnetic Pulse Welding

Mechanical Properties and Microstructure of 7075T6 Aluminum Alloy – DC01 Low Carbon Steel Rod Joints by Magnetic Pulse Welding

A Novel Tensile Fracture Location of Friction Plug Welding (FPW) Joints.

The fracture position of a friction plug welding (FPW) joint is typically located at or near the thermo-mechanically affected zone (TMAZ). Here, we found that microcracks in all FPW specimens initiate at the deformed plug center (DPC) zone and then propagate through the plug center along 45° shear surfaces, because the lowest hardness occurs at the DPC zone rather than the TMAZ or other zones, and the DPC zone presents a tilt fiber-like microstructure. Such a tilt microstructure stimulates formations and deformations of microvoids and propagation of microcracks along 45° shear surfaces. The ultimate tensile strength (237.7 MPa) and yield strength (220.8 MPa) of the FPW joint reach 78.8% and 85.7% of the base metal, respectively. These results indicate that 6061-T6 aluminum alloy can be effectively joined by the FPW technique.

High Strain Rate Deformation of Heat-Treated AA2519 Alloy.

This study examined the effects of heat treatment on the microstructure and dynamic deformation characteristics of AA2519 aluminum alloy in T4, T6, and T8 tempers under high strain rates of 1000-4000 s-1. A Split Hopkinson pressure bar (SHPB) was utilized to characterize the mechanical response, and microstructural analysis was performed to examine the material's microstructure. The findings indicated varied deformation across all three temper conditions. The dynamic behavior of each temper is influenced by its strength properties, which are determined by the aging type and the subsequent transformation of strengthening precipitates, along with the initial microstructure. At a strain rate of 1500 s-1, AA2519-T6 demonstrated a peak dynamic yield strength of 509 MPa and a flow stress of 667 MPa. These values are comparable to those recorded for AA2519-T8 at a strain rate of 3500 s-1. AA2519-T4 exhibited the lowest strength and flow stress characteristics. The T6 temper demonstrated initial stress collapse, dynamic strain aging, and an increased tendency for shear band formation and fracture within the defined strain rate range. The strain rates all showed similar trends in terms of strain hardening rate. The damage evolution of the alloy primarily involved the nucleation, shearing, and cracking of dispersoid particles.

Flow Behavior and Dynamic Recrystallization Mechanism of 7050-T7451 Aluminum Alloy during Hot Deformation

Flow Behavior and Dynamic Recrystallization Mechanism of 7050-T7451 Aluminum Alloy during Hot Deformation