Aluminum Alloy Sheets Research Articles

Research on the 2A11 Aluminum Alloy Sheet Cyclic Tension–Compression Test and Its Application in a Mixed Hardening Model

The increasing application of aluminum alloy, in combination with the growth in the complexity of components, provides new challenges for the numerical modeling of sheet materials. The material elastic–plasticity constitutive model is the most important factor affecting the accuracy of finite element simulation. The mixed hardening constitutive model can more accurately represent the real hardening characteristics of the material plastic deformation process, and the accuracy of the material property-related parameters in the constitutive model directly affects the accuracy of finite element simulation. Based on the Hill48 anisotropic yield criterion, combined with the Voce isotropic hardening model and the Armstrong–Frederic nonlinear kinematic hardening model, a mixed hardening constitutive model that considers material anisotropy and the Bauschinger effect was established. Analysis of the tension–compression experiment on the sheet using finite element method. Using the finite element model, the optimum geometry of the tension–compression experiment sample was determined. The cyclic deformation stress–strain curve of the 2A11 aluminum alloy sheet was obtained by a cyclic tensile–compression test, and the material characteristic parameters in the mixed hardening model were accurately determined. The reliability and accuracy of the established constitutive model of anisotropic mixed hardening materials were verified by the finite element simulation and by testing the cyclic tensile–compression problem, the springback problem, and the sheet in bending, unloading, and reverse bending problems. The tensile–compression experiment is an effective method to directly and accurately obtain the characteristic parameters of constitutive model materials.

Theoretical and Numerical Investigation of the Limit Strain of a 5754-O Aluminum Alloy Sheet Considering the Influence of the Hardening Law

Theoretical and Numerical Investigation of the Limit Strain of a 5754-O Aluminum Alloy Sheet Considering the Influence of the Hardening Law

Mechanical performance and failure behavior of screw-bonded joints of aluminum sheets and cross-laminated birch veneer plates

Integrating wood-based lightweight components into advanced multi-material car bodies requires capable and reliable technologies for joining or bonding of dissimilar materials. Therefore, the present experimental study investigates hybrid lap joints of 1.5 mm-thick sheets of EN AW-6016-T4 aluminum alloy and 9 mm- or 13 mm-thick plates of cross-laminated 1 mm-thick birch veneers. Two self-cutting screws and single-component polyurethane-based adhesive were used for each joint. The mechanical performance and the fracture behavior were tested under both quasi-static and cyclic shear-tensile loadings. At each load condition fracture of the joint occurred, but neither fracture of the aluminum alloy sheet nor fracture of the veneer plate were observed. Debonding of the aluminum alloy sheet from the birch veneer plate was identified as critical failure mechanism. The adhesive provided the main contribution to both the static strength and the fatigue performance of the joints. However, the energy absorption of the joint was mainly determined by the pull-out resistance of the screws, which was dependent on the thickness of the veneer plate. To optimize the strength-to-weight ratio of the joint and to exploit the load-bearing potential of the materials, the focus should be placed on the improvement of the bonding conditions or on the adaptation of the sheet/plate thicknesses.

Effect of Diamond Burnishing on the Properties of FSW Joints of EN AW-2024 Aluminum Alloys

The article presents the results of an analysis of the surface roughness parameters, microhardness, and the stresses of the surface layer ofFSW butt joints subjected to the burnishing process with a diamond tip. This can be useful in selecting the optimal parameters of the burnishing process, ensuring the best properties of the surface layer of the FSW joint. Burnishing force and feed rate influence were analyzed according to the two-factor three-level full factorial statistical completed plan PS/DC 32. The tested material was 2024-T3 aluminum alloy sheets with a thickness of 2 mm. The results show that burnishing significantly reduced the surface roughness from Sa = 6.46 μm to Sa in the range of 0.33 μm–1.7 μm. This treatment provides high compressive residual stresses σx from −86 to −130 MPa and σy from −158 to −242 MPa. Microhardness increased from 84.19% to 174.53% compared to butt joints. Based on the obtained results, multi-criteria optimization was carried out. This optimization allows us to obtain a compromise solution ensuring compressive stresses in the surface layer (σx=−123 MPa and σy=−202 MPa) and microhardness HV=362.56 mm/mm2 with the roughness of the weld surface Sa = 0.28 µm, Sku = 3.93 and Spc = 35.88 1/mm.

Effect of Si content on earing behavior in deep drawing of 3104 aluminum alloy sheets

Effect of Si content on earing behavior in deep drawing of 3104 aluminum alloy sheets

Significance of underwater friction stir welding on the weld integrity of thin sheets of aluminum (AA1050-O) and brass (CuZn34) joints

Classical friction stir welding (C-FSW), because of its solid-state joining nature, offers several benefits over traditional fusion welding for joining dissimilar materials. C-FSW conducted in open air, are affected by several weld flaws and thick Intermetallic Compounds (IMCs) that reduce the weld joint quality. In this study, FSW of thin sheets of aluminum alloy (AA1050-O) and brass (CuZn34) in lap joint configuration was performed in air and underwater. The main objective of this study was to investigate the feasibility of underwater-FSW (UW-FSW) for obtaining aluminum and brass (Al-Brass) joints at different values of shoulder plunge depth (SPD) and tool rotational speed (N). To determine the effect of welding temperature at different values of SPD and N on the formation of weld joints, K-type thermocouples were used. Underwater welding reduced the welding temperature and thermal cycle time. The optical images of C-FSW joints revealed the presence of kissing bonds, wavy patterns, cracks, tunnels, and void defects. In UW-FSW, the faster cooling rate significantly reduced these weld flaws. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used for the microstructural characterization. EBSD and TEM results show fine microstructure and precipitates in UW-FSW specimens. The X-ray diffraction results demonstrated that the weld joint interface primarily consisted of Al-Cu & Cu-Zn IMCs in the form of Al4Cu9, Al2Cu, AlCu3, AlCu4, CuZn5, and Cu5Zn8. The amount of IMCs was less in the joints produced by UW-FSW. The obtained results were used to understand the variation in the weld strength of C-FSW and UW-FSW joints at different values of SPD and N. To further evaluate the interface of the Al-Brass weld joint, energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) were employed. EDS confirmed the presence of brass fragments in the stirred zone of aluminum substrate. TEM and SEM images illustrated fine precipitates and formation of thin IMC layers in UW-FSW. The tensile test result shows that the UW-FSW remarkably improved the joint strength. The percentage increase in the joint tensile strength for UW-FSW was found 42%, 30% and 50% higher than C-FSW for lower, medium and high heat input welding conditions. The lower heat input in UW-FSW significantly suppressed the formation of weld flaws and IMCs, which collectively improved the tensile strength of the weld joint.

Cryogenic friction behavior of aluminum alloys sheets under dry contact condition

Friction is one of the most important boundary conditions in aluminum alloys cryogenic deep drawing. The friction coefficient of AA5052 sheets under dry contact condition was measured at room temperature (RT) to − 190 °C. The friction behavior of aluminum alloys sheets during cryogenic deep drawing process was revealed by analyzing the macro and micro friction morphologies of sheets and tools surfaces. The results showed that the mean friction coefficient first increased and then decreased with decreasing temperature. Adhesive friction and plowing friction showed opposite trends with decreasing temperature at friction stable phase. The adhesive friction first decreased and then increased, while the plowing friction first increased and then decreased. In addition, the cryogenic temperature inhibited the adhesion tendency of aluminum alloys.

Die Surface Design Method for Smoothing Shock Line in Sheet Metal Forming

Replacing the material of automobile body panels from steel sheets to aluminum alloy sheets is an approach to reducing the automobile weight. In the press forming of panel parts with aluminum alloy sheets, it is necessary to smooth stepped linear marks of about 5 μm to 50 μm generated during press forming to satisfy the surface quality of the panel parts. These linear marks are called shock lines, which are generated when the blank sheet slides on the die corner radius during press forming. In this research, the protrusion shape of forming dies that enables us to smooth a shock line is investigated using a 1.2-mm-thick 6000 series aluminum alloy sheet. The shock line is smoothed by applying a trapezoidal surface pressure to the blank sheet near the shock line at the bottom dead center. We propose a method of using finite element analysis to calculate the protrusion shape from the amount of elastic displacement of the dies that occurs when the target surface pressure is applied to the dies surface. The protruding shape calculated by the proposed method has been applied to the forming dies for the door inner panel of the 6000 series aluminum alloy sheet. As a result, in our experiments, the shock line has been smoothed by using these forming dies.

Tehnologije spajanja limova od čelika i legura aluminija - pregled stanja

Multi-material design was developed as a modern design concept for lightweight structures (Lightweight design - LW) which aims to integrate different types of materials into one structure. The main problem when joining sheets made of different, i.e. dissimilar materials, primarily steel and aluminum alloys, are the different mechanical, physical and chemical properties of the materials being joined. Through this paper, the state of the art will be analyzed when it comes to modern technologies for joining steel and aluminum alloys sheets. The term "modern joining technique" refers to all innovative joining technologies that have been developed or have seen significant application in the last few years.

Performance analysis of similar and dissimilar self-piercing riveted joints in aluminum alloys

In this work, similar (2A12) and dissimilar (6061) aluminum alloy sheets are validly joined using self-piercing rivet process. A quasi-static experiment is proposed to investigate the mechanical behaviors, failures mode, and mechanism of the different joints. Moreover, a method based on deep learning algorithm is anticipated to detect the appearance defects of the SPR welded joints. The results indicated that 2A12 joints of similar sheets contained the advantageous static strength and 6061 similar sheet joints had superior anti-vibration performance conducts. The joints with 6061-2A12 sheets introduced the most decent and comprehensive mechanical properties. The main failure mode of 2A12 similar sheet joints was substrate fracture. The performance of the substrate affects the failure mode of the joint and the plasticity of the substrate is better. When the time comes, the failure mode is mostly pull-off failure. Poor plasticity of the substrate can easily lead to substrate breakage. The reason for joint pull-off and button fall-off failure is that there is large plastic deformation in the lower plate of the joint and the mechanical internal locking structure is damaged. 2A12 substrate breakage belongs to a composite fracture that combines intergranular fracture and microvoid aggregation type fracture. The area of the 6061 substrate near the edge of the sample is shear fracture and the area near the center of the sample thickness is dominated by microvoid aggregation type normal fracture. The effectiveness of the method was verified by conducting a series of experiments and the detection accuracy of the method can reach about 90%. The detection speed was as high as 50 frames per second (FPS), which can effectively solve the problem that the rivet quality was difficult to monitor.

Mechanical performance of hybrid joints of aluminum sheets and laminated beech veneer plates: an experimental prestudy

Wood-based materials offer a high potential for the lightweight design of modern car bodies. Therefore, this prestudy investigates the static strength of screw-bonded lap joints of 1 mm-thick sheets of EN AW-6016-T4 aluminum alloy and 4.5 mm-thick plates consisting of three 1.5 mm-thick cross-laminated beech veneers. Plates with cover veneers oriented longitudinal (L) or transverse (T) to the uniaxial loading direction and with veneer stacking orders designated as L/T/L and T/L/T were used. Two self-cutting screws and polyurethane-based adhesive were used for hybrid joining. The stacking order and thus the fiber orientation of the cover veneers influenced the fracture behavior, which became evident in the force-displacement curve monitored during uniaxial shear-tensile testing of the joints. Veneer plates with the L/T/L stacking order withstood higher maximum tensile force but pro-vided lower pull-out resistance of the screws than plates with the T/L/T stacking order. However, regardless of the stacking order of the veneers the adhesive layer between the aluminum alloy sheet and the veneer plate mainly determined the maximum tensile force and thus the static strength of the joints, whereas the screws contributed only little.

Process-induced damage and its effect on strength of composite - aluminum alloy joint by FDS technique

Flow drilling screw (FDS) is a novel joining technique that enables high-speed joining of dissimilar metals with one-shot process of hole machining, female thread forming and fastening from one side. The damage after FDS process and its effect on joint strength and fracture behaviour near the screw by load-bearing tests for FDS joints between aluminum alloy and carbon fibre reinforced thermoplastics (CFRTP) are evaluated. Cross-sectional observation after joining process reveals that delamination in CFRTP is clearly suppressed and matrix resin is filled in the screw thread compared to the case with CFRP using thermosetting resin. In the joint strength test with shear loading and the cross-shaped tensile tests where the screw is pulled out in its axial direction, only the fibre micro-buckling is observed until fracture. These experimental results recommend that CFRTP laminates should be applied as composite side since this technique utilizes frictional heat by the screw that can contribute to plastic flow or deformation of the thermoplastic resin with high fracture toughness. It is also clarified that damage growth is further suppressed by using CFRTP/Al hybrid laminates where aluminum alloy sheets are inserted between CFRTP plies, which leads to improve the joint strength.

Analysis of Tribological Performance of New Stamping Die Composite Inserts Using Strip Drawing Test

This article assesses the tribological performance of new composite tool sets for stamping dies. Four sets of composite countersamples were tested. These consisted of polyurethane resin with mineral filler (base variant) and modified with aluminium powder (10wt%) and roving fabric (5wt%). Strip samples for the strip drawing tests were cut from AMS5599 (Inconel 625) corrosion-resistant nickel alloy, AMS5510 (321) corrosion and heat-resistant steel and AMS6061-T4 heat treatable aluminium alloy sheet metals. The influence of the type of sample material on the coefficient of friction (COF) was observed. The smallest values of the COF over the entire range of clamping force values used on AMS5599 and AMS5510 sheets were observed during tests with countersamples made of the base variant of composite. When testing the AMS6061-T4 aluminium alloy sheet, the countersamples modified with roving fabric provided the lowest value of COF, which stabilised at a value of about 0.197 as pressure was increased.

Research on wrinkling in rubber forming of the convex flange with 2A12 aluminum alloy sheet

Research on wrinkling in rubber forming of the convex flange with 2A12 aluminum alloy sheet

Square Cup Forming of Locally Solution-Treated Aluminum Alloy Sheets by Hydromechanical Forming Method

Square Cup Forming of Locally Solution-Treated Aluminum Alloy Sheets by Hydromechanical Forming Method

Fracture Analysis of Sheet Aluminum Alloy AA2024-T3 Through a Complex-Loading Cross-Die Test

Lightweight materials such as aluminum alloys are, nowadays, well recognized as one of the most popular choices in the aerospace industry owing to their fantastic strength-to-weight ratio. Their fabricability is, nevertheless, doubtful down to their low elongation, especially in the present day where geometrical complexity is hugely demanded. Truly understanding fracture behaviors of such sheet metal would benefit all involved parties. To achieve that challenging goal, proper fracture-analysis models and implementation methods are definitely crucial. This work proposes the recent Lou–Huh fracture criterion to describe the rupture behavior of sheet aluminum alloy AA2024-T3. To build such a damage mechanics model, a string of Nakajima stretching and notched tensile tests must be performed to acquire critical strain data, precisely measured using the 2D-DIC principle. The data are used to calibrate the model. A fracture locus (FL), defining an extensive AA2024-T3 fracture threshold, is then established out of the fine-tuned model. The FL is directly coupled into an ABAQUS/Explicit FE process simulation model via the Fortran-based subroutine VUMAT. This leading-edge implementation can supposedly emulate realistic damage evolution by monitoring and actively removing the elements whose degree of injury has reached a certain limit. At the end, the complete integrative FE model is empirically validated through an industrial X-shaped specimen, deformed under nonlinear strain paths. Fracture locations, shapes and development on the FE-simulated specimen are observed and contrasted with those on the experimental one. It is obviously shown that the results from both approaches agree remarkably well in all aspects. When compared with the famous fracture forming limit curve (FFLC), the Lou–Huh FL combined with the element-removal VUMAT implementation clearly outperforms. In summary, the proposed model and the implementation procedure are practically outstanding fracture evaluators of AA2024-T3, wonderfully predicting and vividly laying bare crack appearance and growth.

Inhomogeneous flow stresses in FSW jointed aluminum alloy sheets inversely identified by FE-VFM

Inhomogeneous plastic flow stresses are identified for the friction stir welded aluminum alloy 6061-T6 sheets using a new finite element-based virtual fields method (FE-VFM). The FE-VFM is an enhanced virtual fields method developed based on the formulations in a common FE scheme. In the present study, the following novel numerical schemes are newly adopted in the FE-VFM: (1) a two-step identification process, (2) partitioning of the whole domain of interest with an interpolation of the constitutive parameter within each subdomain, and (3) the normal distribution type virtual fields. The non-uniform stress method (nUSM) is also considered for comparison. Before applying the developed method to a real experiment, the FE-VFM is verified via numerical feasibility tests using ideal deformation data of the FE simulations conducted with the artificially generated target welding materials. The feasibility tests show that the proposed FE-VFM can calculate the inhomogeneous flow stresses of the welded aluminum sheets with reliable accuracy. In the experimental applications, plastic properties measured by FE-VFM and nUSM are compared in terms of the distributions of yield stress, uniform elongation, and ultimate tensile tests. Also, identified inhomogeneous flow stresses are validated by simulating the two tensile tests loaded parallel and perpendicular to the weld line. The validation reveals that the proposed FE-VFM can give more accurate measurements over the nUSM owing to its ability to capture the mechanical properties in the narrow thermo-mechanically affected zone (TMAZ).

Effects of temperature on friction and degradation of dry film lubricants during sliding against aluminum alloy sheets

Hotmelts are nowadays widely used as dry film lubricants (DFL) in aluminum sheet forming. However, their chemical composition and the degradation of functional additives during the forming process are rarely reported. The present work investigates the chemical composition of three hotmelts deposited on aluminum alloy sheets with electrical discharge-textured (EDT) and mill-finished (MF) surfaces using mass spectrometry (MS), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The surface topographies and the tribological conditions were investigated at temperatures between room temperature and 100 °C using single-pass sliding experiments. The results show considerable change of the tribological conditions due to reduction of friction modifiers and antiwear additives during sliding particularly at 100 °C.

Impact of the Initial Phase Composition of Alloys on the Effects Manifested by Yield Sites That Occur on Sheet Aluminum Alloys Subjected to Impact-Oscillatory Loading

The impact of the initial phase composition of alloys was evaluated, in particular, the content of Cu, Mn, and Mg in aluminum alloys D16ChATW, 2024-T351 and aluminum alloy T, which in its physical and mechanical characteristics is close to alloy 6013. The impact was evaluated on the effects manifested by yield sites that occur on aluminum alloys that were subject to the dynamic non-equilibrium processes (DNPs) at the expense of impact-oscillatory loading of different intensities under conditions of static tensioning, The one-time DNP, to which the investigated aluminum alloys were subjected at the pre-set levels of elastic strain followed by static tensioning, was found to cause yield sites formation. This is due to self-organization of the alloy structure, which contributes to alloy plasticization. The initial phase alloys composition impact on the yield sites, which occurs when impulse energy of a different intensity is applied to the alloys, was analyzed. The specimens from the aluminum alloys undergoing DNPs of the same level were compared. This made it possible to conclude that alloys D16ChATW and 2024-T351, which have a higher content of Cu, Mn, and Mg, have longer yield sites upon subsequent static tensioning. On the basis of the experimental results, in particular, physical studies, the authors derived a physical and mathematical model of the yield sites that appear after DNPs.

Deformation response research on aluminum sheets with different central pre-cracked defects under quasi-static hydraulic pressure loading

The crack behavior and bending deformation of pre-cracked sheet are coupled under the pressure loading. Two theoretical methods (SCMLD and PTELD) were used to compare and verify the bulge test data of intact aluminum alloy sheets, and the applicability of the two methods in equilibrium bulge test were discussed. ABAQUS extended finite element method (XFEM) and the parameters of fracture energy based on experiments were used to simulate the bulging deformation and failure behavior of pre-cracked sheet, the results agreed with the experimental test data well. What is more, the slope of h−p curve reflects the equivalent bending stiffness, which is affected by the crack shape length rather but not the crack shape.