6061-T6 Aluminum Research Articles

Penetration performance and failure of long rods impacting aluminum targets

A numerical study concerning the deep penetration of long steel rods into 6061-T6511 aluminum targets at high impact velocities is presented. The range of impact velocities where these rods lose their penetration capability due to their nose deformation, or impact inclination, is explored. The numerical simulations follow several complex phenomena such as the onset of rod deformation and erosion, encountered in the tests with spherical and ogive nosed rods. It turns out that penetration depth decrease of spherical nosed rods at high impact velocities, is due to their nose deformation, while ogive nosed rods are more sensitive to impact inclination. At very high impact velocities both types of rods experience significant mass erosion, and their penetration process can be described by conventional hydrodynamic penetration model for eroding rods. The numerical simulations in this work are shown to follow test results for spherical and ogive nosed rods, impacting an aluminum alloy target at a large range of impact velocities. We show that these agreements can be achieved with relatively simple constitutive relations for the steel rods and the aluminum target.

Simulation and Experimental Investigation of Multi-Step Shot Peening for Surface Crack Repair in Aluminum Alloys

This study explores the impact of shot peening residual compressive stress on repairing surface cracks in the 7075-T651 aluminum alloy. Two models were developed for crack repair via shot peening and fatigue test finite element modeling. A multi-step numerical simulation introduced shot peening-induced residual stress into the fatigue test model, and subsequent simulations analyzed the crack repair mechanism. The research results indicate that increasing pressure and projectile size improve repair effectiveness, but higher pressure causes material damage, and larger projectiles decrease fatigue life. Crack repair effectiveness decreased with higher loading levels, more significantly at higher loads. Experimental and simulation results matched well, validating the simulation model for shot peen repair processes and offering optimization possibilities.

Semi-automatic miniature specimen testing method to characterize the plasticity and fracture properties of metals

Miniature-testing is essential to characterize the plastic response of materials for which the extraction of conventional full-size specimens is impossible. Examples are weld regions with high property gradients or electronic circuit components. Here, we present the design of a novel testing system for miniature specimens. After inserting the specimens with wedge-shaped shoulders, the system carries out the clamping, initial geometry scanning, and mechanical testing with digital image correlation in an automated manner. The automation prevents the accidental damaging of the miniature specimens during manual handling and adds to the robustness of the overall procedure. It is shown that the experiments with miniature specimens extracted from DP600 steel and aluminum 7075-T6 are highly reproduceable. More importantly, they lead to the same plasticity and fracture properties as experiments on conventional ten-times larger full-size specimens. A correction procedure accounting for the surface roughness, white layer and heat affect zone induced through wire EDM is provided. In addition to developing and validating the new experimental technique, it is applied to characterize a 22MnB4 rod material and stainless steel 316 L foil.

Effect of process parameters on friction stir welding of aluminium alloy AA6082–T6 with an interlayer using response surface methodology

In the present study, the effects of variation of process parameters on the mechanical properties of friction stir welded A6082–T6 aluminium alloy joints with Zinc (Zn) interlayer are experimentally investigated. Four process parameters, viz. rotational speed, welding speed, interlayer thickness and tool pin diameter are selected to fabricate the Friction Stir Welding (FSW) joints. After filling the Zn particles into the gap maintained between the plates, FSW is performed using different process parameters. Thereafter, tensile and impact strength tests are performed to evaluate the performance of the joints. It is analyzed that the tensile and impact strength of the joints vary from 121 to 197 MPa and 6 to 17 J, respectively. Subsequently, mathematical models are developed using Response Surface Methodology (RSM) to predict the effect of FSW process parameters on the tensile and impact strength of joints. Analysis of Variance (ANOVA) is used to check the level and degree of direct effect of process variables on the tensile and impact strength of the joints. It is observed from the results that tool rotational speed is the most influential process parameter, which enhances the mechanical properties of FSW joints, whereas an increase in welding speed reduces the mechanical properties of the joints.

Study on multi-field composite strengthening, surface integrity, and microstructural evolution mechanism of 7075-T6 aluminum alloy

Multi-energy field composite reinforcement technology has become a critical technique for improving the service life of key components in aviation engines. This paper aims to investigate the strengthening mechanism of high-speed cutting and solid particle-entrained waterjet peening (HSC-WJP) composite reinforcement on 7075-T6 aluminum alloy. Samples subjected to single solid particle-entrained waterjet peening (WJP) reinforcement were selected as the control group. The surface quality and microstructure evolution of 7075-T6 aluminum alloy after composite reinforcement were examined using SEM, EDS, XRD, TEM, and HRTEM techniques. The research results indicate that, under the same jet parameters, HSC-WJP composite reinforcement is superior to single WJP reinforcement in terms of surface roughness, except when the jet pressure is below 25 MPa and the track spacing is 0.53. The surfaces of the 7075-T6 aluminum alloy workpieces after reinforcement are mainly characterized by the presence of pits and micro-pores. Surface roughness shows a positive correlation with jet pressure and nozzle traverse speed. After HSC-WJP composite reinforcement, the surface roughness decreases by 0.132 μm compared to single WJP reinforcement, and the size of surface pits is reduced by 4–20 μm. Surface roughness decreases first, then increases, and then decreases again with increasing target distance, while it increases first and then decreases with increasing path spacing. A significant precipitation-free zone (PFZ) is present in the 7075-T6 aluminum alloy after reinforcement, and its width is positively correlated with the nozzle traverse speed. When the nozzle traverse speed is 120 mm/min, the average size of the PFZ at grain boundaries after single WJP reinforcement is 12–20 nm, while it decreases by approximately 3 nm after HSC-WJP composite reinforcement. The main precipitate phase in the reinforced aluminum matrix is η′ phase, and under the same jet parameters, the HSC-WJP grain size is smaller, approximately 25–34 nm, and exhibits significant dislocation walls and dislocation tangles, with a higher dislocation density compared to single WJP reinforcement.

Experimental study on eccentric compressive behaviors of 6061-T6 aluminum tubular long columns filled with concrete

In this paper, eccentric compressive experiments of 12 circular and 6 square concrete-filled 6061-T6 aluminum tubular (CFAT) long columns were carried out. The influence of the section form, thickness of aluminum tube, slenderness ratio, and eccentricity on the flexural performance of CFAT long columns was investigated. The results showed that all the specimens exhibited flexural-dominated failure. The variation of eccentricity had little impact on the overall failure mode of the aluminum tube, while it dramatically influenced the failure mode of the internal concrete. The internal concrete failed in concrete crushing for all the square columns, while it remained intact for the circular columns. This indicates that circular tubes provide a better constraint effect on the internal concrete, there by increasing the ultimate strain of concrete under compression. It was also found that the increase of eccentricity leads to the weakening of the confinement afforded to the internal concrete, while the increase of slenderness ratio has no obvious effect on the restraining effect. Finally, the applicability of current design provisions for concrete-filled steel tubular (CFST) long columns to CFAT long columns was evaluated, and design suggestions were proposed.

Effect of pin geometry, rotational speed, and dwell time of tool in dissimilar joints of low-carbon galvanized steel and aluminum 6061-T6 by friction stir spot welding

In this study, aluminum 6061-T6 plates were joined with low-carbon galvanized steel using friction stir spot welding. Three conical pins with varying lengths (short, medium, and long) were utilized, along with different dwell times and rotation speeds of the tool. The objective of this research was to compare the simultaneous effects of several important process parameters on mechanical and welding properties. The results indicate that the use of short conical pins significantly increased the microhardness in the upper aluminum plate. Conversely, increasing the pin length led to higher microhardness in the lower steel plate. Tensile shear loading was greater for short pins compared to medium pins, attributed to the influence of the tool shoulder. However, with increasing pin length, failure loading reached its highest value due to the dispersion of particles in the weld. The failure mode for short pins exhibited a mixed pattern, which transitioned to a ductile shape in all conditions as pin length increased. Overall, the most influential parameter was the tool penetration depth, which positively affected the obtained properties. The rotational speed of the tool was the second most significant parameter, followed by the dwell time.

High-Temperature Tensile Mechanical Properties and Microstructure of Rolled 6082-T6 Aluminum Alloy Sheets.

The tensile properties of rolled 6082-T6 aluminum alloy were tested at a high temperature, and the influences of tensile temperature on its flow stress and anisotropy were studied. The microstructure evolution was characterized using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was concluded that the tensile strength of the studied alloy decreases with increasing temperature. In higher-temperature deformation, the dislocation density decreases alongside the coarsening of precipitates, leading to a decrease in deformation resistance, and increase in the number of dimples and deepening of their sizes, exhibiting good plasticity. The alloy displays anisotropic mechanical properties at 200 °C due to the elongated grains and the orientation of the α-phase. The anisotropy becomes weaker with increasing temperature. There is no evident anisotropy at 400 °C, as the slip systems are activated more easily and the grains begin to recrystallize.

Nickel electroplating of 6061-T6 aluminum alloy using anodizing process as the pretreatment

Typically, aluminum and its alloys fail to be coated by the electroplating process due to the existence of an inherent oxide layer on the surface which reduces the adhesion between the coatings and the substrate. In this regard, suitable surface preparation is required before the electroplating process. In this study, the anodizing process is chosen as the surface pretreatment. For this purpose, the soft anodizing process was done in a 0.3 M oxalic acid electrolyte at 25 °C and 90 V for different duration. AAO dissolving process was performed to increase the diameter of the pores. Finally, electroplating of nickel was performed in a Watts bath at 40 °C, pH of 3, and different current densities. Three variable of anodizing and dissolving durations and electroplating current density were optimized by a response surface methodology to form a continuous layer of electroplated nickel on the surface. FE-SEM surface morphology, SEM cross-sectional observations, surface XRD characteristics and Daimler-Benz adhesion test were performed to characterize and evaluate the coatings. The optimization of the three variables led to a sequence process of a 9 min anodizing treatment, followed by a 100 min dissolving stage, then electroplating under a current density of 20 mA/cm2. The formation mechanism of the electroplated layer is thoroughly discussed.

Experimental study on TIG full welding and single pass welding quality of 6061-T6 aluminum alloy sheet

6061-T6 aluminum alloy plate (3 × 150 × 300 mm3) was welded by tungsten inert gas (TIG) welding. The welding process methods are single-pass welding process and full welding process respectively. The effects of different welding processes on the performance of TIG welding 6061-T6 aluminum alloy were compared and studied. The effects of microstructure and precipitation on the microhardness and tensile strength were analyzed by optical microscope, scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) characterization, electron backscattering diffraction (EBSD) characterization, microhardness and tensile test. The microstructure of the weld zone is mainly composed of aluminum solid solution (α-Al) dendritic structure and Al–Si eutectic structure. Through EBSD characterization analysis, the average grain size of the weld zone of the full welding process and the single-pass welding process is about 45 μm and 55 μm, and the grain size of the heat-affected zone and the weld zone of the two welded joints does not change significantly. The hardness curves of the two welded joints have the same distribution trend, which is roughly 'W' type distribution. In the tensile test, the tensile strength of the single pass welding process is lower than that of the full welding process, and the fracture of the tensile parts is dimple structure, which is ductile fracture. Through analysis and comparative study, the full welding process is better than the single-pass welding process when welding 6061-T6 aluminum alloy sheet.

The effect of friction spot stir welding in double rivet lap joint installation of aluminum 2024-T3 on the strength of shear tests

The process of joining materials is very necessary to facilitate the manufacture of industrial products. Among these connections are rivets, bolts, nails, glue, and welding which is mostly done on metal materials. The aircraft skin is usually connected with rivets through a drilling process. Joining metal materials, especially aluminum, uses many welding techniques. The welding method currently being developed is Friction Stir Welding (FSW). FSW developed the Friction Stir Spot Welding (FSSW) process in joining metals, especially in this study using 2024-T3 aluminum. The purpose of combining the rivet method with FSSW is to see the material’s mechanical characteristics when applied to aluminum material. The FSSW method uses a 2500 RPM engine speed milling machine using a blunt tool holder with a pin dimension of 2.5 mm. It is carried out using a pneumatic drill using a drill bit with a dimension of 2.5 mm. Aluminum 2024-T3 has of 200×20×2 mm dimensions, a hole spacing of 15 mm with double rivet lap joint installation. The results showed that the FSSW variation had a higher tensile shear strength of 2.8% than the drilling variation. However, the hardness value in the drilling variation is 56.3% higher than the FSSW variation in the Heat Affected Zone (HAZ). Microstructural observations also indicate differences in the HAZ region, where the FSSW is reduced in size and longer. This is due to the heat treatment process due to friction between the pin tool and the aluminum, thus changing the structure.

The effect of friction spot stir welding in installing rivet double cover lap joints on 7075–T6 aluminum plate on shear strength

FSSW is a variation of FSW developed in metal processes. The principle of FSSW is rotating an object that is wear-resistant and then rubbed with a plate joint. The use of FSSW can be utilized in the installation of rivets such as in the drilling process, so this process needs to be investigated. This is because the heat caused by rotation will change the mechanical properties of the material so further research is needed. In this study, a connection performance comparison was made between the FSSW method and the drill. The plate used is aluminum 7075-T6 with a lap joint connection type. To find out each performance, a shear test, hardness test, and metallographic test were carried out. From the results of the shear strength test, it can be concluded that the FSSW variation is the best with an average shear strength value of 755,190 MPa, while the drill variation has an average shear strength value of 470,227 MPa. The average value for drill variations in the HAZ area was 185.06 while for the FSSW variation, it only reached 147.75. The macro test results proved that the cause of the shear strength in the FSSW was greater than that of the drill, this was caused by the difference in the size of the rivet diameter due to the use of a bad rivet gun. Meanwhile, based on the results of micro photos, the size of the structure in the HAZ area will be relatively longer than the RAW section, this is caused by friction between the tool and the workpiece

Microstructure and mechanical properties of 7075-T6 aluminum alloy plates by welding with weld reinforcement rolling

The welding with weld reinforcement rolling (WR) process was proposed to improve the deteriorated mechanical properties of traditional arc welded (TW) joints of the 7075-T6 aluminum alloy. In this novel process, the welding process and joint strengthening process were performed simultaneously. A comprehensive investigation of the microstructure evolution during the WR process was conducted. Ultimate tensile strength and elongation determined from tensile testing of the joints were 427.4 MPa, 5.5 % for WR joint and 301.3 MPa, 3.4 % for TW joint. The microhardness of the fusion zone (FZ) and heat-affected zone 1 (HAZ1, the dissolution zone) in the WR joint exceeded that of the TW joint. These results suggest that the application of rolling force not only affected the FZ but also simultaneously strengthened the HAZ1 through deformation while having a comparatively less effect on the heat-affected zone 2 (HAZ2, the over-ageing zone). Quantitative assessments of the effects of different strengthening mechanisms on the strength were conducted, and dislocation strengthening was found to be the predominant factor in increasing the strength of the WR joint. Deformation within both the FZ and HAZ1 during the WR process was mainly due to dislocation slip, while sub-grain rotation was also observed.

Effect of strain rate on the deformation of 6061-T6 aluminum alloy at cryogenic temperature

This study investigates the tensile behavior and strain rate sensitivity (SRS) of a commercial Al6061-T6 Al alloy at various temperatures (i.e., 20, −50, and −150 °C). Uniaxial tensile tests were performed at the quasi-static strain rates of 10−2, 10–3, and 10−4 s−1. A significant improvement in mechanical properties was found at the cryogenic temperature (CT), due to the enhanced work-hardening behavior during CT deformation. The SRS exponent changed from a slightly positive value at RT to a negative one as the temperature is lowered. The dislocation density was evaluated for the samples strained to 5 and 8% at 20 °C and −150 °C using X-ray diffraction to probe the strengthening mechanisms during RT and CT deformation. The dislocation density was higher for the strain rate of 10−2 s−1 at RT and 10−4 s−1 for CT. In addition, electron back scatter diffraction (EBSD) based kernel average misorientation (KAM) and coincidence site lattice (CSL) boundary distribution analysis were conducted on the initial and 8% strain-interrupted samples at both temperatures to explain the effect of temperature and strain rate on work hardening behavior. Transmission electron microscopy (TEM) was applied to investigate the dislocation structures under different strain rate and temperatures. The cryogenically deformed sample exhibited a distinctive dislocation tangling phenomenon in proximity of the grain boundary, In contrast, the room temperature deformed sample demonstrated dislocation penetration occurring at the grain boundary. The character of SRS and improved work-hardening behavior can be attributed to changing dislocation kinetics with decreasing stacking fault energy (SFE) at cryogenic temperature.

On the design and structural study of a rear swing arm for an electric bike

As electric bikes continue to grow in popularity, it is important to ensure that they are equipped with well-designed components. One such component is the rear swing arm (RSA). This study deals with the design and structural analysis of an RSA used for electric bikes. This RSA is composed of two swing arms (one on each side of the bikes), a yoke, a suspension block, and bolts or screws. First, an analytical approach was developed to calculate the initial values for the width and shape of the swing arm. Next, experimental data were used to analyze the response of the RSA and determine the final profile for the swing arms and yoke structure. Finally, the finite element approach was implemented to assess the stress, displacement, and fatigue responses of the RSA when subjected to realistic excitations and conditions. The initial results depicted the following characteristics for the RSA: C-channel profile, 43 mm height, and 2 mm wall thickness. These results implied that the maximum shear force would occur in a region representing approximately 15.5% of the total length of the RSA. Further analysis and calculations showed that this region would decrease to approximately 2.85% of the total length of the RSA. For the final design, the mechanical performance of the RSA was observed to remain acceptable despite the relatively high Von Mises stress values around these singularities. This study assumed the use of 7075 T651 aluminum alloy as the primary material for the RSA.

On the laser surface pre-treatment to enhance the surface texture, wettability and adhesion bonding strength of aluminium 7075-T6 laminates

ABSTRACT In this study, a laser surface pre-treatment strategy was applied to aluminium 7075-T6 alloy, in which the laser power, speed and frequency were varied to determine the best modified surface property in terms of surface wettability. Surface texture, topography, roughness, contact angle and adhesive bonding strength of the treated surface were measured and characterised. Results showed that the laser-treated surface at a laser power of 30 W, speed of 1.2 m/s and frequency of 8 kHz provided the highest surface wettability by showing the lowest contact angle of 17°, which was attributed to the deeper surface cavities and higher surface roughness. The laser treatment increased the adhesion strength up to 8.5 MPa which was 45% higher than that of the untreated surface (of 5.9 MPa). Its adhesion strength nearly matched with that of the oxalic acid treatment. The laser-treated failed specimen shows predominantly adhesion–cohesion failure mode with a strong interfacial bonding. FTIR spectra confirmed the presence of required functional chemical groups of the adhesive after curing, demonstrating a strong bonding force and affinity between the adhesive and the modified surface. The findings clearly indicate that the laser surface pre-treatment would be a viable surface modification strategy without environmental and health hazard to provide adequate strength in the adhesively bonded joints.

Research on the surface corrosion behavior of 7075-T6 aluminum alloy during high-speed machining and particle inclusion water jet composite reinforcement

7075 aluminum alloy is widely used in the aerospace field, and its use process is subjected to serious corrosion environment. This study aims to explore the influence mechanism of high-speed machining and shot peening water jet composite surface reinforcement on the corrosion behavior of 7075-T6 aluminum alloy. The 7075-T6 aluminum alloy was subjected to shot peening water jet (WJP) and high-speed machining combined with shot peening water jet (HSC-WJP) composite surface reinforcement treatments. The results showed that at a jet pressure of 20 MPa, a jet target distance of 7.5 mm, a nozzle moving speed of 660 mm/min, and a track spacing of 0.33 mm, the self-corrosion potential and polarization resistance were the highest, and the self-corrosion current density was the lowest, with the largest capacitance arc radius. Compared to the WJP treatment, the HSC-WJP-20MPa shifted the self-corrosion potential towards the positive direction by 0.01 V, increased the polarization resistance by 724 Ω cm2, and reduced the self-corrosion current by 7.9 %. The HSC-WJP-7.5 mm reduced the self-corrosion current density by 50.02 % and increased the polarization resistance by 24.9 %. The HSC-WJP-660 mm/min decreased the self-corrosion current density by 52.1 % and increased the polarization resistance by 44.5 %.The samples subjected to HSC-WJP composite reinforcement had fewer and smaller corrosion product sizes.

Corrosion damage repair of 7075-T6 aluminum alloy by ultrasonic nanocrystal surface modification

This study explored the corrosion resistance of 7075-T6 aluminum alloy by immersing it in a 3.5% NaCl solution to induce corrosion damage, and subsequently repairing the sample surface using ultrasonic nanocrystal surface modification (UNSM). UNSM was found to effectively repair the defects on the surface of the pre-corroded sample and improve its stress corrosion crack (SCC) resistance. The improvement in corrosion resistance and SCC resistance of sample was mainly due to the compressive residual stress and grain refinement caused by UNSM, which not only improved the pitting resistance but also effectively inhibited the initiation and extension of stress corrosion cracks.

Laser ablation impulse dependence on beam Spatial-Profile

In many previous studies, laser ablation impulse was evaluated using fluence, which is obtained by dividing the beam energy by the beam projection area on the target. This method does not consider the difference in the spatial profile of the beam energy. However, in certain applications, the effect of the profile should be evaluated for a more precise estimation of the impulse. In this study, the dependence of the ablation impulse of a nanosecond pulse laser on the beam profile was investigated. Pure aluminum, extra-super duralumin, and oxygen-free copper were used as the ablation target materials. The ablation impulse, laser energy, and beam profile were simultaneously observed. A dependence of the impulse on the beam profile was observed for all the target materials. A novel equation containing two tuning parameters that connect the profile and impulse was derived using a simple physical model. By fitting these parameters, the parameters with which the impulse could be predicted from the beam profile with sub-μN·s precision was obtained for all the target materials. This work not only establishes a method for predicting the ablation impulse from a given profile, but also proposes parameters that are independent of the profile’s effect. These parameters can be used to quantitatively evaluate impulse generation.

Effects of workpiece size on bending angle in laser forming of al 6061-T6 sheet

In the laser forming process, the effect of workpiece size, including variations in width and length, plays a crucial role in determining product quality. To better understand the deformation behavior and obtain the desired bending angle with varying workpiece sizes, the size effect on laser forming of Al 6061-T6 aluminium alloy has been investigated. Due to the fact that Al 6061-T6 alloy sheets have more deformability and high strength properties, they have been studied in this paper. A three-dimensional numerical model that considers temperature-dependent properties of the material, and convection-radiation heat losses is constructed to investigate the sheet deformation. The numerical model is verified by performing experimental tests under the considered operating conditions. The suggested model is found to be in reasonable agreement with the experimental findings, and it is shown to have a maximum error less than 8 % when predicting the bend angle. Computed results through the numerical model show that the bending response is increased with the increase in workpiece width; however, it is marginally affected with workpiece length. Based on simulation results, the edge effect is also explored in relation to workpiece size. Edge effect increases as sheet width increases; whilst it decreases as sheet length increases. This investigation will be helpful in laser-based forming industries for obtaining desired bending of Al 6061-T6 sheets.