Aluminum Alloy Plates Research Articles

A study on temperature field and process of FSW thick 2219 aluminum alloy plate

A study on temperature field and process of FSW thick 2219 aluminum alloy plate

Analysis of microstructure and wear resistance of friction stir welded joints of 7075-T6 aluminum alloy

The 10 mm thick 7075-T6 aluminum alloy plate is welded by friction stir welding with the inclination of the main shaft of 0.5°. There is no obvious thinning on the weld surface, and the welded joint is well formed. The microstructure of the joint as a whole is "funnel" shaped, and there are multi gradient flat "onion rings". The grains in the weld nugget zone are equiaxed and the grains are significantly refined, and the grains in the heat-mechanical affected zone appear mixed crystal phenomenon and have obvious deformation. During the welding process, the hardness of the welded joint is reduced due to high temperature annealing. When the spindle speed is 500 rpm and the welding speed is 120 mm/min, the maximum surface hardness of the welded joint is 178.77HV. Compared with the base metal after annealing, the hardness of the weld nugget area is increased by about 25% due to the grain refinement strengthening and the precipitation of the reinforcing phase. The wear resistance of welded joints is inversely proportional to the hardness. When the spindle speed is 300 rpm and the feed speed is 120 mm/min, the wear resistance is the best. The friction type is mainly adhesive wear, supplemented by particle wear and fatigue wear.

Effect of Lode angle and projectile diameter on the ballistic resistance of 6061-T651 aluminum alloy plates struck by hemispherical nosed projectile

Aluminum alloy has been gradually applied to the field of armor protection because of its excellent material properties. The research on its ballistic resistance has important theoretical and engineering application value. In order to study the ballistic resistance of 6061-T651 aluminum alloy plate, the impact tests of 6061-T651 aluminum alloy plate against hemispherical nosed projectile with a diameter of 12.66 mm were carried out with a light gas gun system and the ballistic limit velocity and failure mode of the target plate were obtained. Subsequently, the numerical simulations corresponding to the tests were carried out by using the Lode dependent and independent fracture criteria, and the effect mechanism of the Lode angle on the numerical simulation results were analyzed. Finally, the effect of projectile diameter on the ballistic resistance of the target plate was analyzed by the expansion of numerical simulation. The research results show that the numerical simulation will be quite different from the test results if the effect of the Lode angle on the material fracture strain is not considered. As the diameter of the projectile increases, the armor-piercing efficiency of the hemispherical nosed projectile is improved since the energy dissipation mechanism of the target plate gradually changes from ductile hole enlargement to shear plugging.

The microstructure and mechanical properties of aluminum/steel welded joint by FSLW

Friction stir lap welding experiments between 6061 aluminum alloy and DP590 dual-phase steel plates were carried out. The effects of welding parameters and the addition of Cu foil interlayers with 0–0.3 mm thickness on the microstructures and mechanical properties of the lap joints were investigated. The shear strength of the joint reached the maximum value of 5337 N and showed a mixed ductile-brittle fracture mode when the welding speed, the rotating speed, and the thickness of the Cu foil intermediate layer were set to 80 mm/min, 900 rpm, and 0.1 mm, respectively. The plastic Al2Cu and AlCu intermetallic compounds formed through Al and Cu reaction at the aluminium alloy/steel interface play a beneficial role in the Cu-added joint strength.

Impact resistance of single-cell and multi-cell sandwich aluminum plates filled with aluminum foam

The aim of this paper is to investigate the impact resistance and energy dissipation capacity of a new type of multi-cell sandwich aluminum alloy plate filled with aluminum foam, in comparison to the single-cell structure. To achieve this goal, 30 sandwich aluminum alloy plates were tested using a drop hammer test machine, varying impact velocity, wall thickness, and the number of internal diaphragms. The results were analyzed and finite element analysis was conducted to explore the energy dissipation mechanisms and the effect of aluminum foam on multi-cell plates. The findings revealed three failure modes and three stages of the impact force time history curve. Multi-cell plate exhibited showed much better specific energy absorption compared with the single-cell plate. Taking an example displacement of 22.5 mm, which differentiates the specific energy absorption the most between the two types of structures, the multi-cell plate exhibited an average increase of 332% in specific energy absorption compared to the single-cell plate. The numerical simulations were consistent with experimental results and highlighted the contribution of different components to energy dissipation in both structures.

Reducing Interface Defects and Porosity of Adhesive Bonded Aluminum Alloy Joints via Ultrasonic Vibration.

The surface microstructure formed by physical or chemical modification is essential for the desired joint strength. However, defects in the bonding interface and adhesive can be found. Such defects decrease shear strength and durability. In this study, ultrasonic vibration was applied to liquid adhesive on the sandblasted aluminum alloy plates. With ultrasonic treatment, the joints obtained the compact bonding interfaces and lower porosity of the adhesive layer. The treatment improved the shear strength by 9.1%. After two weeks of hydrothermal aging, the shear strength of joints only sandblasted decreased drastically by 48.9%, while it was 14% for the joints with ultrasonic vibration. The cavitation effect in the adhesive was detected by the aluminum foil erosion method. The result showed that a great number of micro-jets generated by the cavitation effect have intensive impact on the bonding interface which provide the adhesive with powerful force to fill the micro-grooves. Another finding in this work is that bubbles were gathered in the adhesive away from the vibration area. This mechanism was successfully used to reduce the porosity of the adhesive layer of joints.

Experimental measurement of moisture distribution in the adhesive layer using near‐infrared spectroscopy

AbstractAdhesive joints are degraded when exposed to moist conditions, making it essential to assess the permeation distance of absorbed moisture. However, monitoring the water penetration in the adhesive layer is challenging because the adhesive layer is sandwiched between the adherends. To overcome this difficulty, we proposed a new monitoring system using fiber‐type near‐infrared spectroscopy (NIRS), and the moisture distribution at the joint was successfully observed by introducing quartz glass as one side of the substrate. First, the change in the absorbance spectra owing to water absorption by an epoxy adhesive was investigated by immersing epoxy‐coated aluminum alloy plates in temperature‐controlled water. It was found that the water content can be evaluated by monitoring the change in the peak intensity appearing around 1900–1950 nm. Next, water penetration into the adhesive layer sandwiched between the quartz glass and aluminum alloy was investigated by scanning the surface. The water permeation distance was found to change with temperature. Under the 23°C immersion condition, approximately 2.5 mm of water penetration was observed after 8 weeks. Because the simulation results using Fick's law of diffusion showed similar trends, it was experimentally confirmed that Fickian diffusion dominates the water distribution in the adhesive layer.

Investigation of microstructure of fretting wear behavior in 6061-T6 aluminum alloy

PurposeThe purpose of this study is to investigate the microstructure of fretting wear behavior in 6061-T6 aluminum alloy. The fretting wear of blind riveted lap joints of 6061-T6 aluminum alloy plates, which are widely used in aircraft construction, was investigated. Fretting damages were investigated between the contact surface of the plates and between the plate and the rivet contact surface.Design/methodology/approachExperiments were carried out using a computer controlled Instron testing machine with 200 kN static and 100 kN dynamic load capacity. Max package computer program was used for the control of the experiments. Fretting scars, width of wear scars, microstructure was investigated by metallographic techniques and scanning electron microscopy.FindingsIt was found that fretting damages were occurred between the plates contacting surface and between the plate and rivet contact surface. As load and cycles increased, fretting scars increased. Fretting wear initially begins with metal-to-metal contact. Then, the formed metallic wear particles are hardened by oxidation. These hard particles spread between surfaces, causing three-body fretting wear. Fretting wear surface width increases with increasing load and number of cycles.Originality/valueThe useful life of many tribological joints is limited by wear or deterioration of the fretting components due to fretting by oscillating relative displacements of the friction surfaces. Such displacements are caused by vibrations, reciprocating motion, periodic bending or twisting of the mating component, etc. Fretting also tangibly reduces the surface layer quality and produces increased surface roughness, micropits, subsurface microphone.

Weld Defect Detection of a CMT Arc-Welded Aluminum Alloy Sheet Based on Arc Sound Signal Processing

The cold metal transfer (CMT) process is widely used in thin plate welding because of its characteristics of low heat input and stable arc. In actual production, a larger weld gap, misalignment, or other problems due to assembly error lead to serious welding defects, such as burn-through and a lack of fusion. The arc sound contains a wealth of information related to the quality of the weld. This work analyzes the mechanism of CMT arc sound generation, as well as the correlation between the time–frequency spectrum of the arc sound signal and welding quality. This paper studies the extraction of the multi-channel time–frequency spectrum of an arc sound and inputs it to a custom convolutional neural network for the CMT welding defect identification of thin aluminum alloy plates. The experimental result shows that the average accuracy of the proposed model is 91.49% in the defect identification of a CMT arc-welded aluminum alloy sheet, which is higher than that of the single-channel time–frequency convolutional neural network and other traditional classification models.

Theoretical Analysis of Flexural Time-Varying Properties of Aluminum Alloy-Reinforced RC Beam under Atmospheric Environment

This paper aims to reveal the degradation of the flexural load capacity of reinforced concrete (RC) beams reinforced with aluminum alloy (AA) under atmospheric conditions. For the same, first, time-varying models of the flexural load capacity of RC beams were developed before and after reinforcement with AA and steel plate based on the time-varying properties of the materials. Subsequently, upon collecting existing test data, the reliability of the models was verified. Finally, the parameters of AA-reinforced and steel plate-reinforced RC beams were analyzed to investigate the influence of factors such as concrete cover depth, cross-sectional area of reinforcing material, and cooperative working coefficient of reinforcing material and concrete (demonstrate the ability of reinforcement material and concrete to work together) on the remaining service life, rust initiation time, and cracking time. The results show that under atmospheric environment, the flexural time-varying degradation model for RC beam can be divided into three stages: pre-rusting, rusting-pre-cracking, and post-cracking, with differences in the dominant factors at each stage. In terms of long-term performance, AA reinforcement is significantly more efficient than steel plate reinforcement. This study provides some theoretical basis for the design of AA reinforcement in the atmospheric environment.

The Residual Stress Relief and Deformation Control of Al Alloy Thin-Walled Antenna Components by Ultrasonic Regulation

The residual stress fields of the initial billet and subsequent machining in the material bring great challenges to the precision machining and geometrical stability of aluminum alloy thin-walled components. To ensure that a certain type of large-sized aluminum alloy thin-walled antenna has a small flatness deformation during forming, this paper firstly employed the ultrasonic critical refraction longitudinal wave (LCR wave) detection method to measure the different depth ranges’ residual stress distribution of 5A06/6061/7075 aluminum alloy plate, both as blanks and after multiple milling. Additionally, the effects of inherent residual stress (IRS) and machining-induced residual stress (MIRS) on the subsequent milling deformation were analyzed. After that, combined with the self-developed ultrasonic stress relief (USR) system, the deformation control effect of a thin-walled plate after eliminating residual stress in each stage was tested. The results show that the ultrasonic stress relief treatment can quickly and efficiently eliminate the IRS and MIRS with small flatness deformation. By introducing the URS treatment in the blank, rough machining, and semi-finishing stages, the components before each subsequent machining are in a low-stress state, and the component deformation can be gradually controlled so that the final thin-walled antenna has a smaller flatness.

The Hypervelocity Impact Behavior and Energy Absorption Evaluation of Fabric

In this work, the mechanical behavior and energy absorption characteristics of flexible fabric under hypervelocity impact (HVI) were investigated. Basalt fabric, ultra-high molecular weight polyethylene (UHMWPE) fabric, and aluminum alloy (Al) plate were chosen to be the sample materials for their excellent mechanical properties and applicative prospect in spacecraft shielding. HVI experiments had been conducted with the help of a two-stage light-gas gun facility, wherein Al projectile with 3.97 mm diameter was launched at velocities in the range 4.1~4.3 km/s. Impact conditions and areal density were kept constant for all targets. The microstructural damage morphology of fiber post-impact was characterized using a scanning electron microscope (SEM). Analysis results show that a brittle fracture occurred for Basalt fiber during HVI. On the contrary, the ductile fractures with large-scale plastic deformation and apparent thermal softening/melting of the material had happened on the UHMWPE fiber when subjected to a projectile impact. According to the HVI shielding performance and microstructural damage analysis results, it can be inferred that ductile fractures and thermal softening/melting of the material were the prevailing energy absorption behaviors of UHMWPE fabric, which leads to absorbing more impact energy than Basalt fabric and eventually, contributes the superior shielding performance.

Deep Transfer Learning Approach for Localization of Damage Area in Composite Laminates Using Acoustic Emission Signal

Intelligent composite structures with self-aware functions are preferable for future aircrafts. The real-time location of damaged areas of composites is a key step. In this study, deep transfer learning was used to achieve the real-time location of damaged areas. The sensor network obtained acoustic emission signals from different damaged areas of the aluminum alloy plate. The acoustic emission time-domain signal is transformed into the input image by continuous wavelet transform. The convolutional neural network-based model automatically localized the damaged area by extracting features from the input image. A small amount of composite acoustic emission data was used to fine-tune some network parameters of the basic model through transfer learning. This enabled the model to classify the damaged area of composites. The accuracy of the transfer learning model trained with 900 samples is 96.38%, which is comparable to the accuracy of the model trained directly with 1800 samples; the training time of the former is only 17.68% of that of the latter. The proposed method can be easily adapted to new composite structures using transfer learning and a small dataset, providing a new idea for structural health monitoring.

Experiment/simulation correlation-based methodology for metallic ballistic protection solutions

A methodology is developed based on the coupling of a finite element code with an optimisation module for the design of land vehicle armouring composed of lightweight aluminium alloy and high strength steel plate. Following an experiment/simulation correlation, a numerical model has been built and calibrated considering monolithic plates and then verified considering a bi-metal protection against tungsten carbide projectile mimicking the core of a 7.62×51 AP8 ammunition. In addition, a method is proposed to obtain the vres−vi curve for the full 7.62×51 AP8 bullet from the vres−vi curve obtained from the core only.

Interfacial microstructure and strength of magnetic pulse welded A5052 aluminum alloy/SPCC steel lap joint

A5052 aluminum alloy and SPCC steel plates were welded using magnetic pulse welding, and interfacial microstructure and strength of the lap joint were examined. The A5052 aluminum alloy and the SPCC steel plates were used for a flyer plate and a parent plate, respectively. Charging energy stored in capacitor and gap between the A5052 aluminum alloy and the SPCC steel plates were changed. Microstructure was examined by using an optical microscope, a scanning electron microscope and a scanning transmission electron microscope. Tensile-shear test was used for evaluating the strength of the joint. The magnetic pulse welding of A5052 aluminum alloy and SPCC steel was achieved at the charging energy above 6.0 kJ and at the gap between the plates above 1.0 mm. The range of charging energy in which the strong welding is accomplished was different at each gap and the range increased with decreasing the gap. The lap joint was not fractured at the welding interface by the tensile-shear test whereas the fracture occurred at a part of the aluminum base metal. The welding interface exhibited characteristic wavy morphology. An intermediate layer was produced along the wavy interface. Scanning transmission electron microscope observation revealed that the intermediate layer is composed of fine Al-Mg grains and dispersed dendritic Al-Fe intermetallic compound particles.

Numerical Simulation of Temperature Fields during Laser Welding-Brazing of Al/Ti Plates.

The formation of dissimilar weld joints, including Al/Ti joints, is an area of research supported by the need for weight reduction and corrosion resistance in automotive, aircraft, aeronautic, and other industries. Depending on the cooling rates and chemical composition, rapid solidification of Al/Ti alloys during laser welding can lead to the development of different metastable phases and the formation of brittle intermetallic compounds (IMCs). The effort to successfully join aluminum to titanium alloys is associated with demands to minimize the thickness of brittle IMC zones by selecting appropriate welding parameters or applying suitable filler materials. The paper is focused on the numerical simulation of the laser welding-brazing of 2.0 mm thick titanium Grade 2 and EN AW5083 aluminum alloy plates using 5087 aluminum filler wire. The developed simulation model was used to study the impact of laser welding-brazing parameters (laser power, welding speed, and laser beam offset) on the transient temperature fields and weld-pool characteristics. The results of numerical simulations were compared with temperatures measured during the laser welding-brazing of Al/Ti plates using a TruDisk 4002 disk laser, and macrostructural and microstructural analyses, and weld tensile strength measurements, were conducted. The ultimate tensile strength (UTS) of welded-brazed joints increases with an increase in the laser beam offset to the Al side and with an increase in welding speed. The highest UTS values at the level of 220 MPa and 245 MPa were measured for joints produced at a laser power of 1.8 kW along with a welding speed of 30 mm·s-1 and a laser beam offset of 300 μm and 460 μm, respectively. When increasing the laser power to 2 kW, the UTS decreased. The results exhibited that the tensile strength of Al/Ti welded-brazed joints was dependent, regardless of the welding parameters, on the amount of melted Ti Grade 2, which, during rapid solidification, determines the thickness and morphology of the IMC layer. A simple formula was proposed to predict the tensile strength of welded-brazed joints using the computed cross-sectional Ti weld metal area.

Energy Transfer Efficiency Based Nonlinear Ultrasonic Testing Technique for Debonding Defects of Aluminum Alloy Foam Sandwich Panels

In order to improve the accuracy of detection results of debonding defects of aluminum alloy thin plate, the nonlinear ultrasonic technology is used to detect the simulated defect samples, aiming at problems such as near surface blind region caused by the interaction of incident wave, reflected wave and even second harmonic wave in a short time due to the small thickness of thin plates. An integral method based on energy transfer efficiency is proposed to calculate the nonlinear ultrasonic coefficient to characterize the debonding defects of thin plates. A series of simulated debonding defects of different sizes were made using aluminum alloy plates with four thicknesses of 1 mm, 2 mm, 3 mm and 10 mm. By comparing the traditional nonlinear coefficient with the integral nonlinear coefficient proposed in this paper, it is verified that both methods can quantitatively characterize the size of debonding defects. The nonlinear ultrasonic testing technology based on energy transfer efficiency has higher testing accuracy for thin plates.

Microstructure and mechanical properties of A7N01-T4 aluminum alloy metal inert gas welded joints filled with self-designed 7A48 aluminum alloy wire

7××× aluminum alloy is a metal with a high tendency to weld cracks. In the welding process, 7××× aluminum alloy wire was seldom used but low strength matching 4××× and 5××× aluminum alloy wire was used for joining, which had poor mechanical properties of welded joints. In this paper, a self-designed low copper 7A48 wire containing scandium was used as filler material for metal inert gas (MIG) welding of 4 mm thick A7N01-T4 aluminum alloy plates. The results show that the A7N01-T4 MIG welded joints were obtained with good seam formation and no crack formation. The equiaxed dendrites in the weld zone were found. The precipitated phases were primarily Mg-rich and Zn-rich, forming a typical 7××× aluminum alloy structure. In the fusion zone, fine equiaxial crystals were found, with a width of about 100 μm. In the heat-affected zone, grains growth occurred and the precipitated phase was dissolved or aggregated. The hardness of the WZ reached 81.7% of that of the base material and the softening of the WZ was not significant. The average tensile strength and elongation of the specimens were 364.9 MPa and 17.5%, respectively. The tensile fracture occurred in WZ and the fracture was dominated by microporous aggregation shear fractures with localized cleavage fractures occurring.

Influence of Material Removal Strategy on Machining Deformation of Aluminum Plates with Asymmetric Residual Stresses

In this paper, the effects of material removal strategies and initial stress states on the machining deformation of aluminum alloy plates were investigated through a combination of finite element simulation and experiments. We developed different machining strategies described by Tm+Bn, which removal m mm materials form top and n mm materials from the bottom of the plate. The results demonstrate that the maximum deformation of structural components with the T10+B0 machining strategy could reach 1.94 mm, whereas with the T3+B7 machining strategy was only 0.065 mm, decreasing by more than 95%. The asymmetric initial stress state had a significant impact on the machining deformation of the thick plate. The machined deformation of thick plates increased with the increase in the initial stress state. The concavity of the thick plates changed with the T3+B7 machining strategy due to the asymmetry of the stress level. The deformation of frame parts was smaller when the frame opening was facing the high-stress level surface during machining than when it was facing the low-stress level. Moreover, the modeling results for the stress state and machining deformation were accurate and in good accordance with the experimental findings.

Deep cryogenic treatment of AA7050: tensile response and corrosion susceptibility

Cryogenic treatments represent an innovative technology developed with the aim of improving the performance of metallic alloys. The beneficial effects on steels are well documented in the literature, whereas their influence on other materials, such as aluminum alloys, is still not completely clarified. Even if the scientific literature reports conflicting data and conclusions, the industrial applications of such treatments are constantly growing. In the present experimental work, the mechanical and corrosion properties of a high-performance 7050 aluminum alloy plate were studied after cryogenic treatment at − 196 °C in liquid nitrogen. Tensile tests were performed on heat-treated samples, and intergranular corrosion tests were carried out on prismatic samples, according to ASTM G110-92 standard. The specimens were exposed to the corrosive environment and the effect of intergranular corrosion was measured by quantitative analysis using light-optical microscopy (LOM). Whereas trifling variation was observed in the mechanical resistance and plastic behavior, the corrosion tests showed a benefic effect of the cryogenic treatment. The microstructure was investigated by FEG-SEM analysis, revealing a different distribution of precipitates near the grain boundaries, which was able to reduce the electrochemical potential difference among these regions and the center-grain.