Metal Deformation Processes Research Articles

Effect of Anions on Deformation of Gallium-Based Liquid Metal in Solution.

In this study, deformation behaviors of gallium-based liquid metals in acidified cupric sulfate or cupric chloride solutions with varying concentrations of chloride anion or sulfate anion were investigated to explore their potential applications in soft machines and electronics. Gallium-based liquid metals are known for their unique deformability, making them promising materials for various fields. Previous research has shown that deformation of the liquid metal can be achieved in the presence of acidified cupric or ferric salts. However, the specific influence of different anions on the deformation process remains unclear. Our findings indicate that the deformation rate of the liquid metal increases with higher concentrations of chloride ions and decreases with higher concentrations of sulfate ions in the solution. UV-vis absorbance spectra of the solutions were analyzed to identify the formation of hydrated cupric cations. It was observed that increasing the concentration of Cl- ions promotes the formation of cupric-chloro complexes, thereby reducing the concentration of hydrated cupric ions in the solution. Furthermore, the addition of sulfate ions to the solution enhances the ionic strength of the medium, leading to the dissociation of cupric-chloro complexes. Additionally, sulfate ions can form insoluble layers with gallium ions, which impede the deformation of the liquid metal. The deformation rate of the liquid metal was found to be inversely correlated with the concentration of cupric ions in the solution. These results provide valuable insights into the deformable behavior of gallium-based liquid metals and their potential applications in liquid metal-based soft robots. This study highlights the importance of understanding the role of different anions in the deformation process of liquid metals, shedding light on the design and optimization of soft machines and electronics utilizing these materials.

Thermodynamically consistent model of dislocation-mediated plasticity

ABSTRACT We present a thermodynamically consistent damage theory of deformation where the damage mechanism is determined by the presence of dislocations and their motion is the origin of plasticity. The damage parameter is proportional to the square root of the dislocation density of a network. For the evolution of damage, a gradient-flow equation, which describes the relaxation process of plastic deformation, is derived. Analysis shows that the dislocation-mediated plasticity is an activated process with upper and lower yield points, as opposed to a barrierless plasticity with a single yield point, which may be realised by other mechanisms of deformation. Dislocation nucleation is not a limiting factor of the dislocation-mediated plasticity because the free energy barrier for the nucleation is rather low. Application of the theory to the description of uniaxial deformation revealed many features of the experimentally observed deformation processes of metals, e.g. three stages of strain hardening with various characteristics dependent on the material and rate of loading. Applications of the theory to processes of dynamic loading of materials, which simultaneously undergo phase transformations, can bring deeper understanding of the material behaviour.

Optimization of Surface Roughness of Brass by Burnishing

Abstract—Cylindrical components are important inseveral industrial applications. The surface quality plays a role in part performance. Non-ferrous surfaces are difficultto-finishduetoseveralissuesencounteredingrindingthatis optimum for ferrous metals. Burnishing process, as a metaldeformation process, is believed to be more suitable since iteliminates sticking, wheel dulling and overheating. Themain objective of this work is to optimize the burnishingprocess that can be used to finish the surface of machinedparts. To achieve this, burnishing tool was designed andconstructed in such a way that it can be simply mounted orfixed onto the tool holder of the CNC lathe machine.Experiments are made according to the response surfacemethodology (RSM), in order to improve the reliability ofresults and to reduce the size of the experimental planwithout loss of accuracy. In this work, four burnishingparameters, namely, burnishing speed, feed, depth ofpenetration and number of passes were selected in order tostudy their effects on the surface roughness. Mathematicalmodels, which depend basically on the utilized experimentaldesign, have been developed. Variance of analysis wasconducted to determine the prominent parameters and theadequacy of the models. The results showed that goodsurface roughness can be obtained with minimum cost bytransferring the CNC lathe machine from machine tool tosuper-finishing machine using the proposed burnishing tool.From an initial average roughness of about Ra (4-5 µm), thespecimen could be finished to average roughness of 0.09 µm.

Application of Cryogenic Technologies in Deformation Processing of Metals

Application of Cryogenic Technologies in Deformation Processing of Metals

Surface stretch forming process based on collaborative control of sheet metal deformation and die contact state

In this study, we propose a novel method of surface stretch forming, named the Surface Stretch Forming based on Collaborative Control of Sheet Metal Deformation and Die Contact State (SF-CCDC). By controlling the motion paths of the discrete clamps, the contact process with the die, and the deformation process of the sheet metal can be changed. The processes of conventional stretch forming (SF-C) and SF-CCDC were numerically simulated. The results show that in SF-CCDC, the shearing effect of the die edge on the sheet metal can be reduced through the collaborative control of sheet metal deformation and contact with the die. Compared to SF-C, the maximum thinning rate is reduced by 50%, and the risk of stretch cracking is lower in SF-CCDC. Furthermore, both the center and edge areas of the sheet make contact with the die simultaneously, ensuring adequate deformation constraints and preventing wrinkling defects. Experiments were conducted to demonstrate the reliability and adaptability of the SF-CCDC method for forming double-curved surfaces.

Plastic deformations of ceria nanocubes under compression: An atomistic simulations study

The mechanical properties and elementary deformation processes of ceria nanoparticles are investigated under uniaxial compression using quasi-static atomistic simulations and a fixed charge empirical potential. Results show a strong size-dependence of both the stress response and the plastic deformation phenomena that are characterized by amorphization and recrystallization processes that initiate from the surfaces in smaller-size samples, while the propagation of {111} nanotwins is observed in larger nanoparticles. In particular, we point out that the recrystallized phase is made of reoriented fluorite that behaves as a structural seed for the nucleation of 16<112>{111} partial dislocations at the origin of the nanotwins. Similarities with plastic deformation processes of FCC metals at the nanoscale are outlined and discussed.

Energy Storage and Dissipation in Consecutive Tensile Load-Unload Cycles of Gum Metal.

Multifunctional β-titanium alloy Gum Metal, characterized by a relatively low elastic modulus, superelastic-like behavior and high strength, was subjected to cyclic tensile loadings. The characteristics of macroscopic scale energy storage and dissipation in the consecutive loading-unloading cycles were studied. Various kinds of energy components related to the alloy deformation process were determined experimentally and analyzed using thermodynamic relations. The values of the entire work needed to deform the alloy Wext, the work used for recoverable deformation Wrec consisting of the elastic deformation energy Wel , the superelastic-like energy Wpt , and the energy of thermoelastic effect Eth , were derived from the Gum Metal stress and temperature vs. strain curves. The irrecoverable mechanical energy Wir expended on plastic deformation, the dissipation energy Q, and finally the stored energy Es were estimated. The stored energy represents a change in the internal energy of the deformed material and is an essential measure of cold-worked state. The Es value turned out to be not large for the Gum Metal, which confirms the alloy low hardening property. The energy components determined for each of the 24 loading cycles enabled us to analyze various stages of the Gum Metal deformation process, including necking and damage.

High strain rate deformation of conductive materials with use of pulse magnetic fields

The study of metal deformation processes under extreme impacts is relevant due to the need to predict the behavior of materials in operational and critical modes using various deformation models. In this case, the key factor is to expand the range of experimentally determined/achievable parameters for their verification. The high energy density of the magnetic field and a reliable and simple technique for monitoring its parameters make it possible to use the magnetic pulse method of generating controlled pressure pulses of microsecond duration with an amplitude of ∼1 GPa. A classification of methods for high strain rate deformation of conductive materials by magnetic-pulse loading is carried out and features of magnetic-mechanical. An analysis of the experimental results showed the applicability of the magnetic-pulse method for studying plastic deformation processes with strain rates up to 104 1/s and more and the possibility to formulate requirements for the magnetic system and pulse current sources.

Теоретическое моделирование процессов деформации металлов на литейно-ковочном модуле новой модификации

Рассматривается задача об определении полей температуры и параметров напряженно-деформированного состояния в металле при обработке в литейно-ковочном модуле. Принцип работы данного устройства совмещает в себе кристаллизацию расплава металла и последующее деформирование в заданный профиль за счет обеспечения подвижности стенок кристаллизатора. Построена математическая модель деформирования материала с учетом трения и теплоотвода на поверхностях контакта с оснасткой. Материал полагается термовязкопластичным, со свойствами, зависящими от температуры. Описан разностный численный метод решения задачи. В вычислительных экспериментах получены поля температуры, скоростей перемещений, напряжений и деформаций для производства полосы из алюминиевого сплава. The problem of determining the temperature fields and parameters of the stress-strain state in metal during processing in a casting and forging module is considered. The principle of operation of this device combines the crystallization of the metal melt and subsequent deformation into a given profile by ensuring the mobility of the walls of the mold. A mathematical model of material deformation is constructed taking into account friction and heat dissipation on the contact surfaces with the tooling. The material is supposed to be thermo-visco-plastic, with temperature-dependent properties. A difference numerical method for solving the problem is described. In computational experiments, fields of temperature, displacement velocities, stresses and deformations were obtained for the production of a strip of aluminum alloy AD0.

Eddy current measurement in hollow conducting tube in electromagnetic forming process

Electromagnetic forming (EMF) is a high strain rate metal deformation process that utilizes Lorentz force to expand or compress the conducting tube. Stored electrostatic energy of capacitor bank is discharged through solenoid coil which surrounds the conducting tube. Capacitor bank and solenoid coil form a series R-L-C circuit during current discharge through the coil and hence, the coil current is damped sinusoidal. Coil current produces time varying magnetic field which induces eddy current in conducting tube. Interaction of eddy current in the tube and magnetic field in air gap between tube and coil causes Lorentz force to expand or compress the conducting tube. The eddy current is a vital parameter in electromagnetic forming study and its measurement is almost unfeasible owing to very few mm gap between coil and conducting tube. Here we establish a novel method to determine the eddy current in a cylindrical tube, using a superposition theorem, when a damped sinusoidal current is passed through a finite solenoid coil. The present study uses a Al-Mg alloy tube to demonstrate this method of eddy current determination.

A duality‐based coupling of Cosserat crystal plasticity and phase field theories for modeling grain refinement

AbstractHigh‐rate deformation processes of metals entail intense grain refinement and special attention needs to be paid to capture the evolution of microstructure. In this article, a new formulation for coupling Cosserat crystal plasticity and phase field is developed. A common approach is to penalize kinematic incompatibility between lattice orientation and displacement‐based elastic rotation. However, this can lead to significant solution sensitivity to the penalty parameter, resulting in low accuracy and convergence rates. To address these issues, a duality‐based formulation is developed which directly imposes the rotational kinematic compatibility. A weak inf‐sup‐based skew‐symmetric stress projection is introduced to suppress instabilities present in the dual formulation. An additional least squares stabilization is introduced to suppress the spurious lattice rotation with a suitable parameter range derived analytically and validated numerically. The required high‐order continuity is attained by the reproducing kernel approximation. It is observed that equal order displacement‐rotation‐phase field approximations are stable, which allows efficient employment of the same set of shape functions for all independent variables. The proposed formulation is shown to yield superior accuracy and convergence with marginal parameter sensitivity compared to the penalty‐based approach and successfully captures the dominant rotational recrystallization mechanism including block dislocation structures and grain boundary migration.

Establishment and Analysis of Simulation Model for Single-pass 20 Steel Spinning

With the continuous advancement of computer technology, finite element simulation has been gradually applied to the analysis of plastic deformation of metals. If a strong spinning simulation model of 20 steel cylindrical parts can be established to effectively simulate the stress, strain and surface quality of the metal deformation process, it can provide a scientific basis for the setting of spinning process parameters, thus reducing the number of spinning process experiments to determine spinning process parameters.

The usage prospects investigation of the software environments for simulation modeling at the development and optimization of the machine-building production

The investigation results of the applied simulation modeling programs market from the point of view of the usage possibility and expediency at the development or optimization of technological processes on domestic machinebuilding enterprises are presented. The analysis of the technological processes features in machine-building, and in particular aircraft construction, at domestic enterprises is carried out. The production features of the metalconsuming products and semi-finished products from the point of view these processes simulation expediency are considered. The expediency of carrying out simulation modeling of machine-building production, which provides adequate analysis results at minimal costs in comparison with other modeling methods are shown. The main criteria for choosing of specific simulation software are given. Keywords mechanical engineering technologies; metal-intensive production; aircraft construction; deformation processing of metals and alloys; foundry; equipment productivity; optimal stocks of semi-finished products; insurance stocks; simulation modeling; visualiz

Влияние прокатки и кручения под высоким давлением в камере Бриджмена на количественные характеристики полос сдвига в аморфном сплаве на основе Zr

Amorphous alloys based on metal components demonstrate a unique ability to realize plastic deformation under the influence of external mechanical stresses. Influenced by substantial degrees of plastic deformation in alloys, one can observe shear bands (SB) in the form of rough lines on the polished surface of the sample. The concept of shear band formation in amorphous metallic glasses varies greatly from plastic deformation processes in crystalline metals and alloys. Unlike crystalline metals, amorphous metallic glasses can exist in a spectrum of structural states with accompanying mechanical, thermodynamic, and physical properties of materials. The formation and evolution of shear bands control the fluidity and plasticity of almost all metallic glasses at room temperature, and in many cases, the formation of dominant shear bands rapidly leads to failure. The literature does not contain any rigorous quantitative description of SB main parameters, which could adequately describe in the analytical form the process of plastic deformation of amorphous alloys, similar to the dislocation and disclination theories of plastic deformation of crystals. An open question remains how the transition from macroscopic deformation to severe plastic deformations of amorphous alloys affects the key SB characteristics. In this work, using the method of optical profilometry, the author studied in detail the quantitative characteristics of the steps formed by shear bands on the surface of deformed samples of the massive amorphous alloy Zr60Ti2Nb2Cu18.5Ni7.5Al10 after high-pressure torsion (HPT) and after rolling. The study identified that the design of shear bands depends on the deformation method and showed that the magnitude of deformation had the controlling effect on the shear bands thickness (the height of the steps). The transition from deformation by rolling (e=0.4) to plastic deformation during HPT (e=2.6) leads to the threefold increase in the power of shear bands and the average distance between them.

Electromagnetic forming of aluminum alloy sheet metal utilizing a low-frequency discharge: A new method for attractive forming

In existing electromagnetic sheet metal forming processes, the sheet metal is typically deformed away from the coil under repulsive Lorentz forces. This deformation mode makes it difficult to apply the forming technology to dent repair without disassembly of the automobile body and aircraft fuselage. To solve this problem, a new electromagnetic attractive forming process with a low-frequency discharge current was developed in this work. Different from previous attractive forming methods, only a single coil and a single power supply are required that is low cost and easy to implement. Both numerical and experimental studies have demonstrated that an AA1060-H24 aluminum alloy sheet with a thickness of 1 mm can be effectively attracted towards the coil with a maximum deformation of more than 8 mm after a single discharge. More importantly, the mechanism of the attractive forming process has been clarified in detail through the analysis of the Lorentz force characteristics and deformation process of sheet metal. It has been pointed out that the current waveform after the first peak plays a vital role in improving the attractive force and the attractive forming process, which can be optimized by introducing a crowbar circuit. Meanwhile, it is found that the deformed shape of sheet metal caused by a repulsive force helps to facilitate the subsequent reverse deformation under an attractive force. This is also an important reason why an obvious attractive forming can be achieved, although the attractive force is much smaller than the repulsive force during the forming process. The obtained results have the significance for fundamental understanding of electromagnetic forming process, and further applications can be expected using the developed forming method.

Computer Simulation of the Metal Deformation Process in an Equal Channel Step Matrix with Additional Backpressure

Theoretical studies of the process of round cross-section billets pressing in equal-channel step matrices of various designs by modeling are carried out. It was found that the backpressure created by the narrowing of the matrix channels has a favorable effect on the stress-strain state of the metal, which in turn allows for better processing of the structure of the deformable metal. It is also found that when using an equal-channel step matrix with narrowing channels, the deformation force increases, which cannot be attributed to the positive sides of these matrix designs. It was found that the most optimal results were obtained when using an equal-channel step matrix with a narrowing of the intermediate channel.

Use of the Correlation between Grain Size and Crystallographic Orientation in Crystal Plasticity Simulations: Application to AISI 420 Stainless Steel

Crystal plasticity models attempt to reproduce the complex deformation processes of polycrystalline metals based on a virtual representation of the real microstructure. When choosing this representation, a compromise must be made between level of detail at the local level and statistical significance of the aggregate properties, also taking into account the computational cost of each solution. In this work, the correlation between crystallographic orientation and grain size is considered in the definition of virtual microstructures for the simulation of the mechanical behavior of AISI 420 stainless steel (consisting of a ferrite matrix with large carbide precipitates), in order to improve the accuracy of the solution without increasing model complexity or computation time. Both full-field (DAMASK) and mean-field models (Visco Plastic Self Consistent (VPSC)) are used together in combination with experimental results to study the validity of the assumptions done in each of the models.

Modeling and simulation of dynamic recrystallization behavior for Q890 steel plate based on plane strain compression tests

AbstractIn view that the traditional dynamic recrystallization (DRX) model cannot effectively predict the DRX process in the hot deformation process of sheet metal, DRX behavior modeling and simulation of q890 steel plate based on the plane strain compression test are designed. The plane strain thermal simulation tests were performed at 1,223–1,373 K and the strain rates of 1–50−1 on Gleeble-3500 thermal–mechanical simulator. The flow stress curves were well smoothed. The stress–strain data were investigated for the analysis of the dynamic recrystallization in the process of thermal deformation. The activation energy of DRX was calculated as Q = 394.53 kJ/mol by the simulation data. The equation of peak strain was developed with the flow stress data by the Zener–Hollomon parameter. The DRX transformation fraction of Q890 steel was studied, and the DRX kinetics equation was developed by the Avrami equation. The experimental data are in good agreement with the calculated values, which proves the reliability of the DRX model and can be widely used in real life.

Comparative modeling of the disregistry and Peierls stress for dissociated edge and screw dislocations in Al

Many elementary deformation processes in metals involve the motion of dislocations. The planes of glide and specific processes dislocations prefer depend heavily on their atomic core structures. Atomistic simulations are desirable for dislocation modeling but their application to even sub-micron scale problems is in general computationally costly. Accordingly, continuum-based approaches, such as the phase-field microelasticity, phase-field dislocation dynamics (PFDD), generalized Peierls–Nabarro (GPN) models, and the concurrent atomistic–continuum (CAC) method, have attracted increasing attention in the field of dislocation modeling because they well represent both short-range cores interactions and long-range stress fields of dislocations. To better understand their similarities and differences, it is useful to compare these methods in the context of benchmark simulations and predictions. In this paper, we apply the CAC method and different PFDD variants – one of them is equivalent to a GPN model – to simulate an extended (i.e., dissociated) dislocation in Al with initially pure edge or pure screw character in terms of the disregistry. CAC and discrete forms of PFDD are also employed to calculate the Peierls stress. By conducting comprehensive convergence studies, we quantify the dependence of these measures on time/grid resolution and simulation cell size. Several important but often overlooked differences between PFDD/GPN variants are clarified. Our work sheds light on the advantages and limitations of each method, as well as the path towards enabling them to effectively model complex dislocation processes at larger length scales.

Parametric optimization of the generation of the porous layer for lubrication in tube drawing process

For severe metal deformation processes such as metal drawing operations, the use of porous lubricant carrier layer on metal surfaces has been proposed in recent literature for better lubricant retention and effectiveness under extreme conditions. The porous layer may be generated by different methods and the method chosen in this study involves electroplating a thin layer of an alloy of tin and zinc on the parent metal and subsequent selective etching of zinc. The aim of this study is to optimize parameters for specific application of the new technique in steel tube drawing operation using Taguchi's experimental design procedures. Experiments are designed based on three controllable factors namely electric current density, process time and Sn-Zn composition by weight in electrolyte at three levels. L9 orthogonal array is used for this study. The regression models have been constructed for drawing force and surface roughness along with verification of the model fit using (R2) values and analysis of variance (ANOVA). The optimal values for parameters have been identified using signal to noise (S/N) ratio. All the calculations are obtained by using Minitab software. The optimal levels for: current density (I) is 1 A/cm2; for plating time (T) is 12 min and; Sn:Zn composition is 1:6. This study may pave the way for industrial adoption of the new technique of using porous layer in tube drawing operations to bring out the associated benefits of doing away with the conventional lubrication systems that have proven environmental hazards.