Deformation Behavior Of Aluminum Alloy Research Articles

The deformation behavior of aluminum alloy in a novel severe plastic deformation process known as combined SSE-FE process

In this study, a novel method for severe plastic deformation (SPD) was introduced, entitled as Combined SSE-FE (CSSE-FE). The process was investigated experimentally and numerically on AA1050 alloy. After this process, due to the unique design of the die channel, the sample significantly fills the die outlet channel. Also, the CSSE-FE process can produce large strains without repeating the cycle. Therefore, this parameter was increased by around 53.16 % in comparison to simple shear extrusion (SSE) process after the first pass. Also, microhardness was increased by about 87.93 % in comparison to annealed sample.

Modified Arrhenius constitutive model and simulation verification of 2A12-T4 aluminum alloy during hot compression

An accurate constitutive model is imperative to describe the deformation behavior of aluminum alloy in numerical simulation of thermal plastic forming process. In this study, isothermal uniaxial compressions of 2A12-T4 aluminum alloy were conducted by Gleeble-3500 thermal-mechanical simulator under the temperature of 300–450 °C and strain rate of 0.01–10 s−1. Three different Arrhenius constitutive models, including strain compensation (SC), genetic algorithm (GA) and K-function modification (KM), were established basing on the double correction of the true stress–strain curve by considering the effect of temperature variation and interfacial friction. The prediction accuracy of three models were assessed by the correlation coefficient (R), average absolute relative error (AARE) and the logarithm of the mean square error (ln (MSE)). The results show that the newly KM constitutive model considering the coupling effect of temperature and strain rate showed excellent agreement with the experimental data and best prediction capability with lowest error. Hot processing map based on the Murty-Rao criterion shows that high temperature and low strain rate is suitable for stable forming. In order to verify the reliability of the proposed model in numerical simulation, the established KM Arrhenius constitutive equation is secondarily developed in DEFORM 3D software and used in the hot compression process under the stable forming conditions obtained from hot processing map. The simulated force–displacement curves and maximum load values under forming conditions were well match with the experiment trends, which proved the reliability of the KM constitutive equation in the finite element numerical simulation.

A dislocation density-based model considering dynamic strain aging for annealed and water-quenched aluminum alloys under low-temperature conditions

Low-temperature forming is a novel manufacturing method for aluminum alloy components. To better understand the flow characteristics and deformation behavior of aluminum alloys at low temperatures, uniaxial tensile tests were conducted with an initial strain rate range of 2.5 × 10−4–1 × 10−2 s−1 and a temperature range of 77–298 K for annealed (O) and water-quenched (WQ) 2060 Al–Cu–Li alloys. The results showed that the two tempered alloys exhibited excellent work hardening at lower temperatures, resulting in improved ductility, especially in the WQ-tempered alloy. Dynamic strain aging (DSA) caused by interactions between solute atoms and moving dislocations occurred at higher temperatures and lower strain rates, which resulted in serrated flow. Because moving dislocations were additionally pinned by solute clusters, the flow stress increased. The stress increase and negative strain rate caused by DSA could not be captured using the typical dislocation density-based K-M model. Thus, a modified K-M model that considered DSA was proposed to describe the tensile behavior of the studied alloys, and the stress-strain values predicted by the proposed model agreed well with the experimental ones.

A micromechanics-based damage constitutive model considering microstructure for aluminum alloys

Aluminum alloys undergoing deformation exhibit complex multi-type-void damage evolution driven by microscale heterogeneous deformation; in return, the accumulated damage evolution would affect the microscale heterogeneous deformation. Meanwhile, the above interaction depends significantly on the microstructure characteristics and determines the macroscale flow and ductile fracture behaviors. These make it difficult to model the deformation response and ductile fracture of aluminum alloys with various microstructures. Aiming at this issue, a micromechanics-based damage constitutive model considering the mutual effects between microstructure, micro/macro-scale deformation, and damage and fracture was developed in this study for deformation of aluminum alloys under tension-dominated loading conditions. During the modeling, the damage was characterized in terms of the evolutions of coexisting multi-type voids. The multiple-type voids were modeled separately as functions of the local micro-strain/stress of their respective phases and microstructure characteristics according to the micromechanical mechanisms. Furthermore, a self-consistent method was employed to calculate the heterogeneous micro-strain/stress of phases and the overall macroscale flow behavior of the multiphase aggregate. In particular, the constitutive behavior of each phase in the self-consistent method was modeled by coupling the softening effect of void evolution and microstructure characteristics, thus the interaction between microscale heterogeneous deformation and damage evolution was captured. The model parameters were determined by matching the calculated and experimental evolutions of the multi-type voids measured via in-situ synchrotron radiation X-ray computed tomography and load-displacement curves during deformation. Applied to the 2219 aluminum alloy, this model accurately predicts the flow stress, damage evolution and fracture behavior under various microstructures and those of tailor-welded blanks with a gradient microstructure. Furthermore, the model clarifies the mutual effects between the microstructure, damage evolution and deformation behavior of aluminum alloys. The developed model can also be generalized to other multiphase metals containing a distribution of hard-brittle particles. And it is thus believed to be with a well general prediction for the deformation response and ductile fracture of this kind of multiphase metals with various microstructures or gradient microstructures, and further facilitates the understanding of their complex damage evolution and flow behavior.

Dislocation density based modelling of electrically assisted deformation process by finite element approach

Application of electric current, while deforming the material is known to aid the deformation process due to electroplastic effect. The experimentally observed behaviour during the application of electric current is generally correlated to the combined effect of Joule heating and localized electron–dislocation interaction. As the governing mechanism of electroplasicity lacks consensus, constitutive modelling of the said behaviour is challenging and scarce. The mathematical models reported in the literature often found to describe the electrically assisted deformation behaviour by only considering Joule’s heating effect. A fully coupled thermal–metallurgical model is required to underpin the mechanism of electrically assisted deformation process. In this work, we are presenting a novel strategy to predict the electrical assisted deformation process by developing a fully coupled thermal and dislocation density based constitutive model. This modelling approach is implemented in a commercial finite element software using subroutines. The implemented model is evaluated to predict the electrical assisted deformation behaviour of aluminium alloys subjected to both continuous and pulsed current. The implemented model is able to successfully simulate the electrical assisted deformation process.

Research on compression deformation behavior of aging AA6082 aluminum alloy based on strain compensation constitutive equation and PSO-BP network model

It is important to model the flow behavior of an aged aluminum alloy AA6082 as an extrusion material before design and optimize of the forming process. In this study, the isothermal compression tests were carried out on Gleeble-3800 thermal simulator in the temperature range of 423−773 K and the deformation condition of 0.01–1.0 s−1 to study the cold temperature and hot deformation behavior of aluminum alloy AA6082. Considering the experimental error, the discussion based on friction and temperature correction is carried out. According to the modified data, based on the traditional Arrhenius constitutive model, a method combining the strain compensation Arrhenius model and PSO-BP neural network was proposed to describe the flow behavior of aluminum alloy AA6082. The prediction ability and stability of the model are evaluated by using the linear correlation coefficient(r), the average relative errors (AARE), the Root mean square errors(RMSE) and the relative errors (RE) in statistical analysis. The results show that the 3-10-8-1 double hidden layer neural network model based on PSO-BP has higher effect in predicting the flow characteristics of aging aluminum alloy AA6082 than that of Arrhenius model based on strain compensation. The linear correlation coefficient, mean relative error and root mean square error are 0.9996 %, 2.001 % and 1.665 MPa respectively.

Multiaxial deformation behavior of aluminum alloy 6061 subjected to fire damage

Aluminum alloy AA6061 is of interest to the US Navy for ship structure applications due to its light weight, ease of manufacturing, corrosion resistance and strength. However, response to complex loading subsequent to fire damage presents a concern for practical applications. The purpose of this study is to evaluate the effect of fire damage on the microstructure and material response of AA6061 with applied tensile, torsional, and combined loading. Fire exposure was simulated in a controlled environment and testing under multi-axial loading conditions was carried out on virgin and fire damaged samples to evaluate mechanical response. Because of the non-circular sample cross-section, a three-dimensional digital image correlation technique was used to capture the evolution of local strains over the gage length of a deforming specimen subjected to tensile and/or torsional loading. Additionally, microstructure was investigated by electron backscatter diffraction at target cross-section locations subsequent to fire exposure and/or mechanical testing. Results indicate a 60–70% strength reduction with fire exposure. Fire exposed samples achieved higher maximum tensile load during combined loading compared to pure tensile loading. Microstructure was relieved by fire exposure while mechanical loading reveals strain-induced grain refinement. With sample geometry leading to stress concentrations, a deviation from yield values predicted by conventional yield criteria was observed; multi-axial stress-strain data can be of help in assessing the state of aluminum alloy structures after fire exposure.

Analysis of the Stamping Speed for Sheet Metal Forming of Aluminum Alloy 5052-H112

Deep drawing is the most advanced sheet metal forming technique. In today’s demanding environment is the global environment and energy saving, the process has been supposed to play a vital role in light-weight component industry. Light-weight, high strength, low density and extreme corrosion aspects must be almost guaranteed in a deep drawn product. However, due to those requirements, thinning and wrinkling and other defects will be increased also. Numerous elements such as blank-holder pressure, punch force, speed of punch, blank shape, thickness variation, surface-to-surface friction coefficient, material characteristic,…influenced to the success of methods as well as the quality of the products. In addition, worldwide manufacturers keep getting the most goods done in less time. Indeed, the increasing of productivity should be also dealt because it proportionally relates to the stamping speed. This paper investigates the influence of punch velocity on deformation behavior of aluminum alloy 5052–H112. Finite Element Method was used to perform Nakajima test at several of punch velocities of specimen widths and monitor fluctuations in magnitude of von Mises stress, the major strain and minor strain. Forming Limit Curve (FLC) was obtained at different velocities and almost uniform. Stretching and sliding across the top of the punch resulted in thinning of sheet metal. Beside this, the action of punch stroke resulted in the production of more von Mises concentrated stress and the largest specimen in widths had shown the peak value of von Mises stress compared with the other specimens at all different velocities. Furthermore, the ratio of the major strain to the minor strain is influenced by the mass of material at the contact area and keeps consistent over the variation in velocities of punch. This will pave the way for future studies of the optimization of the stamping speed in deep drawing.

Evaluation for High Temperature Deformation Behavior of Aluminum Alloy by Digital Image Correlation Method

Evaluation for High Temperature Deformation Behavior of Aluminum Alloy by Digital Image Correlation Method

Influence of Punch Velocity on Deformation Behavior in Deep Drawing of Aluminum Alloy

Deep drawing is one of the important sheet-forming processes. Several process parameters are responsible for producing defect-free products of deep drawing. Out of those parameters, blank holder force is one of the widely studied process parameters, which significantly influence deep drawing. In the present study, the effect of velocity of the punch on deformation behavior of aluminum alloys is investigated. FEM simulation is conducted using commercially available software ABAQUS. It is found through FEM simulation that effective stress increases by nearly 56% with an increment in punch velocity from 150 to 350 mm/s. Besides this, equivalent plastic strain increases by five times on increment in punch velocity from 150 to 350 mm/s. von Mises stress and equivalent plastic strain found to be maximum at flange radii region (die corner) at all velocities of punch. Wrinkling is found to be absent during deformation (loading step) at all punch velocities. Wrinkling is obtained in deep drawn cups after unloading of the punch at all punch velocities except the lowest velocity of 150 mm/s. The phenomenon of wrinkling was found to be pronounced with increment in velocity of the punch after unloading of the punch. For prevention of wrinkling tendency during deep drawing, the velocity of punch should be less than 200 mm/s. Besides this, punch force, effective stress, and equivalent plastic strain found to increase nonlinearly due to increment in punch stroke. It is gathered through FEM simulation that wrinkling phenomenon increases with increment in punch velocity due to unloading of the punch during deep drawing.

Numerical and experimental investigation of fully-coupled and uncoupled finite element model for electromagnetic forming of Aluminium Alloy Al 3014

Electromagnetic forming is a high-velocity forming process in which repulsive forces between conducting coil and workpiece are generated by mutual inductance, thus, creating opposite magnetic fields and Lorentz forces on conducting bodies. In such processes, the formability can be enhanced owing to the high-speed deformation of the material. This paper presents a fully-coupled numerical model and experimental study of the deformation behaviour of aluminium alloy (AL3014) using closed die magnetic pulse forming. The current density, magnetic flux density and Lorentz force of 1mm thick sheet were estimated numerically. The effect of deforming sheet on magnetic flux and induction was considered. As a result of which the percentage error in sheet deformation reduced from 10% for the existing uncoupled model to 5% for the fully coupled proposed model.

Finite element modeling of Conform-HPTE process for a continuous severe plastic deformation path

A novel continuous severe plastic deformation (SPD) approach was proposed by combining continuous extrusion forming (Conform) with high pressure torsion extrusion (HPTE), which is called Conform-HPTE process. Finite element method (FEM) simulations were employed to investigate the severe plastic deformation behavior of aluminum alloys under various processing conditions. The results showed that the novel Conform-HPTE process effectively accumulated large plastic strain after a single deformation pass. During the Conform-HPTE process, the Conform machine not only provided driving power for the whole equipment, but also introduced shear deformation and heating in the specimen for subsequent HPTE process. The subsequent HPTE process further introduced severe plastic deformation in the specimen. And the severe gradient shear deformation condition could lead to the formation of refined and gradient microstructure. Therefore, the novel Conform-HPTE process could be a promising industrial SPD technique to continuously produce advanced engineering materials with the advantages of energy and cost saving and high process efficiency.

Deformation behaviour during deep drawing operation under simple loading path: A simulation study

Deep drawing is a significant metal forming process which is used in sheet metal forming operations. By this process complex shapes can be manufactured with significant accuracy. In this study, the prediction of deformation behaviour of aluminium alloy during an axi-symmetric cup drawing operation is studied numerically. For this purpose, 3D Finite Element (FE) simulation of a simple cup drawing process has been conducted using ABAQUS software. The simulation is done by considering the isotropic hardening and von Mises stress criteria. As the deep drawing process commences, the variation of generated von Misses stresses and plastic equivalent strain are observed at different stages of deformation and the change in strain energy generation of aluminium alloy sheet have been analyzed.

Finite Element Simulation of Deformation Behaviour of Aluminium Alloy Processed by Cyclic Constrained Groove Pressing

Finite Element Simulation of Deformation Behaviour of Aluminium Alloy Processed by Cyclic Constrained Groove Pressing

Role of Vanadium Addition on Hot Deformation Behavior of Aluminum Alloy 5083

The effect of V addition on the hot deformation behavior of AA5083 was investigated. Single axial compression tests were conducted on the cast and homogenized samples with strain rates ranging from 0.01 to 10 s−1 and deformation temperatures ranging from 300 to 450 °C. The results showed that the contents of V (0–0.10, in wt.%) do not change the grain size of alloy 5083 significantly in the as cast and homogenized conditions, but the formation of fine Al3V particles in the alloy with an addition of 0.05 wt.% V can increase the flow stress, and its activation energy is 10.0% higher than that of V-free alloy 5083. The processing maps show that the appropriate process domain for alloy 5083 with 0.05 wt.% V changes at different true strains. The mechanism for deformation softening is discussed as well.

Constitutive Equation and Processing Maps of Al-7Si-0.3 Mg Hybrid Composites: a Novel Approach to Reduce Cost of Material by Using Agro-Industrial Wastes

The waste materials are not only found abundantly but also a threat to the environment. However, it can be used as a good additive for composite materials which turns industrial-waste into industrial-wealth. The hypothesis of present study is the utilization of the waste materials not only reduces the production cost but also beneficial for the environment. Aluminium with waste particles (agro and industrial) is prepared by using double stir-casting process. The hot deformation behaviour of aluminium alloy and aluminium hybrid composites was studied over deformation temperature range of 300–500 °C and strain rate of 0.1–10 s−1. The processing maps were developed for addition of different weight fractions (0, 7.5, 10 and 12.5%) of waste particles with A356 alloy to identify the safe and unsafe domains during hot processing. The A356/10%RHA-10%Fly ash hybrid composite achieved higher efficiency and high activation energy compare to base alloy and other hybrid composites.

Modeling high temperature deformation characteristics of AA7020 aluminum alloy using substructure-based constitutive equations and mesh-free approximation method

This research was aimed to assess the potential of a radial basis function (RBF) approximation method against the dislocation substructure-based constitutive model in predicting high-temperature deformation behavior of the AA7020 aluminum alloy. Hot compression tests were performed over a range of strain rate of 0.1–100 s−1 and a range of temperature of 350–500 °C up to a strain of 0.6. The hot deformation behavior of the alloy was first described by a substructure kinetic-based constitutive equation, with the effects of strain, strain rate and temperature together with dynamic recovery parameters taken into consideration. A RBF approximation method was then developed to model the flow behavior of the material. The RBF model, as a kind of novel mesh-free function estimation approach, was trained and tested with the obtained datasets from the hot compression tests. The performance of the developed analytical and neural computational models was evaluated using statistical criteria. The results showed that the RBF model was more proficient and accurate in predicting the hot deformation behavior of this aluminum alloy than the substructure-based constitutive model.

Eddy current induced dynamic deformation behaviors of aluminum alloy during EMF: Modeling and quantitative characterization

Unveiling the quantitative influence of the induced eddy current in electromagnetic forming (EMF) is of great significance to realize the precision control of the forming process. To this end, a semi-phenomenological model for predicting the current-carrying dynamic deformation behaviors of aluminum alloy is established by introducing a rate-dependent electroplasticity (EP) model and an elastic thermal expansion model into the high-strain-rate constitutive model. In the modeling process, the electroplastic energy density (EPED), which is a function of prestrain and current density, is defined as the dominant factor of EP-induced stress drop and its threshold value is determined. Moreover, a rate-dependent factor is formulated to consider the effect of wide-range strain rate variation on EP-induced stress drop. Applied to uniaxial-stress EMF process, the present model exhibits preferable prediction accuracy by comparing the predicted results of analytical calculation with experimental ones. The present model captures the characteristic stress responses of EMFed samples, i.e. monotonic strain hardening followed by long-range flow softening. It is found that the peak stress and EP softening ratio both increase with EPED, which can be attributed to the combined influences of increased current density, electric resistivity and acceleration on the competition between strain rate hardening and EP induced softening.

Tensile Deformation Behaviors of Aluminum Alloy 2219 at High Temperatures from 415°C to 515°C

This study is carried out to provide detailed hot deformation information on aluminum alloy AA2219-O. The uniaxial tensile tests are carried out to study the hot deformation behaviors. The test temperature ranges from 415°C to 515°C, and the strain rates are 0.001s-1 and 0.01s-1. Additionally, the analysis of the strain rate sensitivity coefficient indicates that the AA2219-O exhibits the trend of superplasticity at temperatures above 475°C.

Investigation of direct extrusion channel effects on twist extrusion using experimental and finite element analysis

Twist extrusion (TE) is a relatively new severe plastic deformation technique in which radial deformation is heterogeneously distributed in the sample. In this research, in order to achieve favorable properties, a direct extrusion (DE) channel was embedded after the twist zone at the bottom of the TE die. The plastic deformation behavior of aluminum alloy 6063 (AA6063) was investigated in the TE process, with and without the DE channel. AA6063 successfully underwent TE under the conditions designed using the finite element analysis. According to the simulation results, a very heterogeneous distribution of the equivalent plastic strain (PEEQ) was observed in TE, while the TE+DE simulation exhibited more homogeneous PEEQ in the central and lateral regions. Microstructural evolution analysis using scanning electron microscope and Vickers microhardness evaluations showed that utilizing the DE channel increased the hardness and provided a more homogenous microstructure. Moreover, tensile testing results indicated an increase in strength and enhanced mechanical properties of the TE+DE processed AA6063.