Aluminum-magnesium Alloy Research Articles

Spectral quadrature for the first principles study of crystal defects: Application to magnesium

We present an accurate and efficient finite-difference formulation and parallel implementation of Kohn-Sham Density (Operator) Functional Theory (DFT) for non periodic systems embedded in a bulk environment. Specifically, employing non-local pseudopotentials, local reformulation of electrostatics, and truncation of the spatial Kohn-Sham Hamiltonian, and the Linear Scaling Spectral Quadrature method to solve for the pointwise electronic fields in real-space and the non-local component of the atomic force, we develop a parallel finite difference framework suitable for distributed memory computing architectures to simulate non-periodic systems embedded in a bulk environment. Choosing examples from magnesium-aluminum alloys, we first demonstrate the convergence of energies and forces with respect to spectral quadrature polynomial order, and the width of the spatially truncated Hamiltonian. Next, we demonstrate the parallel scaling of our framework, and show that the computation time and memory scale linearly with respect to the number of atoms. Next, we use the developed framework to simulate isolated point defects and their interactions in magnesium-aluminum alloys. Our findings conclude that the binding energies of divacancies, Al solute-vacancy and two Al solute atoms are anisotropic and are dependent on cell size. Furthermore, the binding is favorable in all three cases.

Modeling of casting technology of large-sized ingots from deformable aluminum alloys

An industrial technology for semi-continuous casting of large-sized ingots from wrought aluminum alloy 1580 has been developed through the use of complex modeling, including computer modeling and physical modeling. The ProCAST and ANSYS software packages equipped with the FLUENT module were used for computer modeling. The physical modeling was carried out on a laboratory semi-continuous casting unit (SCCU), which represents a tenfold reduced physical model of an industrial casting unit for the vertical semi-continuous casting of ingots from aluminum alloys. An aluminum-magnesium alloy with the addition of 0.05% (wt.) of scandium was used as the object of modeling. The results of computer modeling were tested at the SCCU, and then computer modeling was carried out for casting a large ingot. According to the modes obtained in the simulation, an ingot with a section of 1310 × 560 mm was cast under industrial conditions, which had a good surface quality with the absence of casting defects. In the microstructure of an industrial ingot and an ingot cast on the SCCU, there were no primary intermetallic compounds Al3(Sc, Zr), which makes it possible to strengthen the alloy upon annealing. To check the manufacturability during rolling, billets with a size of 40 × 120 × 170 mm were cut from these ingots, which were hot-rolled to a thickness of 5 mm, and then cold rolled to a thickness of 1 mm. The rolling results revealed good workability of the alloy, which was reflected in the high quality of the surface and the absence of cracks at the edges of the rolled stock. The mechanical properties of sheets obtained from both ingots were at the same level, which proves the reliability of casting modes for ingots obtained by complex modeling and the validity of their use for industrial conditions of the semi-continuous casting of large ingots from aluminum alloys.

Elucidation of the joining and interface mechanism of lightweight difficult-to-weld materials joined by explosive impact force

Explosive welding can be used to join materials using controlled explosions, creating materials with desirable properties. Assistant Professor Mami Mihara-Narita, Department of Physical Science and Engineering, Nagoya Institute of Technology (NIT), Japan, is exploring the potential of joining technology by explosive welding for the multi-materialism of lightweight materials such as magnesium alloy and aluminium alloy and evaluating their characteristics for practical use. She hopes that her work will contribute to the weight reduction of transportation materials, as well as benefiting transportation equipment and clean energy materials. Mihara-Narita is collaborating closely with Professor Yoshimi Watanabe and Associate Professor Hisashi Sato from NIT, and Dr Yasumasa Chino and Dr Hisashi Mori from the National Institute of Advanced Industrial Science and Technology (AIST and UACJ corporation) in this work. The team is also performing characteristic analysis of explosive welded materials, using a transmission electron microscope to observe interfacial microstructure. The researchers are also evaluating joint strength by shear test, measuring hardness and micro deformation by nanoindentation method and measuring residual stress by X-ray diffraction and neutron diffraction method. In addition they are investigating fatigue strength in order to ensure materials are suitable for use in transportation equipment. Fatigue strength will continue to be a key focus for the researchers moving forward, and they will also be performing data analysis of their data on explosive welding conditions, metallographic structure and various properties of explosive welding clad material.

Al-Mn Intermetallics in High Pressure Die Cast AZ91 and Direct Chill Cast AZ80

Manganese-bearing intermetallic compounds (IMCs) are important for ensuring adequate corrosion performance of magnesium-aluminium alloys and can be deleterious to mechanical performance if they are large and/or form clusters. Here, we explore the formation of Al-Mn IMCs in Mg-9Al-0.7Zn-0.2Mn produced by two industrial casting processes, high-pressure die casting (HPDC) and direct chill (DC) casting. As Al8Mn5 starts forming above the α-Mg liquidus temperature in this alloy, we consider its formation during melt handling as well as during casting and heat treatment. In HPDC, we focus on sludge formation in the holding pot, partial solidification of IMCs in the shot chamber, and Al-Mn IMC solidification in the die cavity. In DC casting, we focus on interactions between Al-Mn IMCs and oxide films in the launder system, Al-Mn IMC solidification in the billet, and the partial transformation of Al8Mn5 into Al11Mn4 during solution heat treatment. The results show that minimising pre-solidification in the shot sleeve of HPDC and controlling pouring and filtration in DC casting are important for ensuring small Al-Mn intermetallic particles in these casting processes.

Regularities of Friction Stir Processing Hardening of Aluminum Alloy Products Made by Wire-Feed Electron Beam Additive Manufacturing

Friction stir processing of additive workpieces in the sample growth direction (the vertical direction) and the layer deposition direction (the horizontal one) was carried out. The hardening regularities of aluminum-silicon alloy A04130 and aluminum-magnesium alloy AA5056 manufactured by electron beam additive technology were studied. For each material, 1 to 4 subsequent tool passes were performed in both cases. It was found that the formation of the stir zone macro-structure does not significantly change with the processing direction relative to the layer deposition direction in additive manufacturing. The average grain size in the stir zone after the fourth pass for AA5056 alloy in the horizontal direction was 2.5 ± 0.8 μm, for the vertical one, 1.6 ± 0.5 μm. While for the alloy A04130, the grain size was 2.6 ± 1.0 μm and 1.8 ± 0.7 for the horizontal and vertical directions, respectively. The fine-grained metal of the stir zone for each alloy in different directions had higher microhardness values than the base metal. The tensile strength of the processed metal was significantly higher than that of the additively manufactured material of the corresponding alloy. The number of tool passes along the processing line is different for the two selected alloys. The second, third and fourth passes have the most significant effect on the mechanical properties of the aluminum-magnesium alloy.

Dynamics of deformation bands initiated by impact of an indenter on the surface of aluminum-magnesium alloy

The dynamics of macrolocalized deformation bands generated by the impact of a Vickers indenter on the surface of an AlMg6 aluminum-magnesium alloy deformed under creep conditions was studied by high-speed video recording and acoustic emission methods. It has been established that these bands are the trigger for the development of a macroscopic jump in plastic deformation on the creep curve. It is shown that in alloys exhibiting the Portevin-Le Chatelier effect it is necessary to take into account the initiation and propagation of deformation macrobands during surface erosion damage and to estimate the volume and morphology of the plastic zone during impact microindentation of a deformable alloy. Keywords: intermittent deformation, deformation band, impact, indenter, aluminum-magnesium alloy.

Modeling of AMg6 alloy recrystallization in the forged layer during the overlay welding of a material in the process of hybrid additive manufacturing

The regularities of static recrystallization during the welding of metal layer over the face of a prismatic specimen pretreated by plastic deformation are studied. This problem is of interest in selecting the rational parameters for the process of hybrid additive manufacturing of light and high-strength linear elements of segmented structures made of aluminum-magnesium alloys via layer-by-layer forging with a pneumatic hammer. For this purpose, the two independent problems of the one-sided forging of a prismatic specimen and temperature evolution during the plasma-arc welding of a layer over the same specimen are solved numerically. The fields of accumulated deformations and the history of temperature changes in the specimen are used to calculate the volume fraction of statically recrystallized material in the work-hardened layer under the influence of a thermal cycle temperature. The forging calculation was performed based on the LS-DYNA® package, the thermal problem was solved in Comsol Multiphysics®, and the fraction of recrystallized material was calculated by making use of the Wolfram Mathematica system. In the numerical model, the impact of the pneumatic hammer was estimated by means of a strain-gauged steel target, and then was verified by evaluating the distortions of the cross-section of the forged bar made of AMg6 alloy measured in the experiment. The thermal effect was calculated taking into account the PI controller, which automatically controls the overlaying process in the hybrid additive manufacturing plant. The volume fraction of a statically recrystallized material was calculated using Avrami's law and data on the dependence of the time of 50% transformation of the material on the accumulated deformation and the temperature taken from the literature on aluminum-magnesium alloy 5083, which is similar to AMg6. The model predicts a high sensitivity of the fraction of recrystallized material to previous plastic deformation and to the maximum temperature in the thermal cycle of overlay welding, and therefore a more localized boundary layer of recrystallized material compared to the boundary layer in plastic deformation. The results of calculation demonstrate the effectiveness of layer-by-layer pressure shaping strategies for providing deep-layer plastic deformation. In terms of the degree of recrystallization, the use of rational modes of overlay welding and forging can ensure the synthesis of products with high strength and ductility characteristics in hybrid additive manufacturing processes.

Nonlinear dynamics of an individual Portevin--Le Chatelier deformation bands

Based on high-speed studies of the dynamics of Portevin--Le Chatelier ambryo bands with a temporal resolution of up to 20 μs and a spatial resolution of up to 10 μm/px, their classification is proposed, which includes four types of bands depending on the nature of interaction with other bands and the sample surface (using the example of a polycrystalline aluminum-magnesium alloy). It has been found that all types of ambryo bands demonstrate nonlinear dynamics with a sharp acceleration of the band tip and the growth rate of its volume at the final stage before reaching the sample surface. A phenomenological model of the nonlinear growth of the ambryo band is proposed, which explains the exponential self-acceleration stage observed experimentally. The sharp absorption of acoustic noise at the stage of accelerated band growth is discussed. Keywords: nonlinear dynamics, Portevin--Le Chatelier effect, deformation ambryo bands, acoustic emission, dislocation mobility, aluminum-magnesium alloy.

ATLAS 5251

Abstract Atlas 5251 is a wrought, non-heat-treatable, aluminum-magnesium alloy (5xxx series). Alloy 5251, registered in 1972, is essentially the same as the old N4 alloy and is produced primarily in Europe for a variety of common alloy applications. It offers properties similar to those of alloy 5052 for the same temper. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: Al-484. Producer or source: Atlas Steels.

Warm Deep Drawing by Friction Heating Punch

Warm processing was performed by frictional heat generation between different materials installed inside the punch. Forming with press machine is a technology for processing materials by applying heat and force, and is an important technology for industrial machines such as automobiles and electronic devices. For light metals such as aluminum alloys and magnesium alloys, it may be difficult to form depending on the type of alloy in cold deep drawing. As a method of improving formability, warm working is performed in which the metal die heated and deep drawing is performed. However, warm working requires many control devices such as heating and cooling for the mold. Using a prototype punch with a built-in friction heat generation jig, friction heat was generated by combining several types of steel materials. The changes in the exothermic temperature were mainly investigated in the combination of different materials. The test materials were carbon steel, tool steel, and stainless steel. The heat generation temperature generated by friction was measured by a thermocouple installed inside the heat generation jig. The friction surface of the jig after frictional heat generation was observed by a microscope. In frictional heating, the temperature of the processed area reached more than 350 °C in a few minutes. The proposed method was able to heat the punch. After frictional heating, the load of deep drawing of pure aluminum sheet decreased. It was found that there is a possibility of improving workability by warm deep drawing.

Joining of light materials with highly corrosion-resistant metal by shot lining

Magnesium and aluminum alloys are widely used in various industries owing to several attractive properties such as low density, high strength to weight ratio and reusability. However, magnesium alloys and high-strength aluminum alloys have undesirable properties including poor corrosion resistance and wear resistance. Therefore, surface modification is necessary to improve such properties of those alloys. In the present study, the high-corrosion resistance foil was joined to the surface of alloys using shot peening. The base materials were a commercially available magnesium alloy and aluminum alloy, and the high-corrosion resistance foils were pure aluminum, pure titanium, pure copper, pure nickel, pure iron and austenite stainless steel. The thickness of foils range from 0.02 to 0.06 mm. Shot peening was performed with a centrifuge equipment. The shots had an average diameter of 1.0 mm and were made of cast steel. The peening velocity was 60 m/s, and the peening time was 10 s. The processing temperature was 300 and 350 ℃ to facilitate plastic deformation. No voids and cracks were observed at the bonding interface. In bending test, the metal foil did not peel off even when the substrate was broken, and the metal foil was tightly bonded.

Research status and prospect of dissimilar light alloy welding technology

Magnesium alloys, aluminum alloys and titanium alloys are currently widely used light alloy materials with good prospects. The welding of Mg/Al/Ti dissimilar light alloys has a wide range of application requirements in aerospace, automobile manufacturing, electronic information and other fields, and is a hot topic of current research. This article summarizes the welding research results of Mg/Al/Ti dissimilar light alloys in recent years, outlines the current research status of welding technology of Mg/Al/Ti dissimilar light alloys, analyzes the common problems and solutions in welding, and proposes further Carry out the research of Mg/Al/Ti welding technology and basic theory, look forward to the effective ways to improve the welding performance of Mg/Al/Ti dissimilar light alloys and future research directions, and promote the promotion of Mg/Al/Ti dissimilar light alloy joints The practicality of it is of great significance.

Sulfosalicylic/oxalic acid anodizing process of 5854 aluminum-magnesium alloy: Influence of sealing time and corrosion tendency

In this paper, anodizing process of 5854 aluminum-magnesium alloy (5854Al-Mg) in oxalic acid (OXA) was investigated in the absence and presence of 5-sulfosalicylic acid (SSA). Electrochemical and surface morphological techniques were used to study the corrosion resistance and film characterizations. Furthermore, the influence of sealing time on corrosion rate was addressed. It was observed that the corrosion current density decreased with the addition of SSA and increasing with sealing time. Maximum coating efficiency was 90.72% in the presence of 0.09 M SSA at 50 min of sealing period. The open circuit potential (OCP) was shifted to a more positive direction indicating the formation of passive film. While, the values of polarization resistance (Rp) of aluminum alloy were higher in the presence of SSA. Scanning electron microscopy (SEM) showed that the addition of SSA improved the surface properties. The anodizing of 5854 Al alloy in the presence of SSA resulted in the formation of anodic films of higher hardness, less roughness, and high film thickness as compared with OXA alone. Reaction kinetics models were proposed. The best fitting was obtained with zero-order reaction kinetics. Half-life time was increased from 9.05 to 123.3 min in case of OXA/SSA anodizing process. In addition, four mathematical equations were suggested to represent the corrosion current density as a function of time. Power model was the most significant one as compared with linear, second order, and exponential models.

Нелинейная динамика индивидуальных полос деформации Портевена--Ле Шателье

Based on high-speed studies of the dynamics of Portevin-Le Chatelier ambryo bands with a temporal resolution of up to 20 and a spatial resolution of up to 10 , their classification is proposed, which includes four types of bands depending on the nature of interaction with other bands and the sample surface (using the example of a polycrystalline aluminum-magnesium alloy) . It has been found that all types of ambryo bands demonstrate nonlinear dynamics with a sharp acceleration of the band tip and the growth rate of its volume at the final stage before reaching the sample surface. A phenomenological model of the nonlinear growth of the ambryo band is proposed, which explains the exponential self-acceleration stage observed experimentally. The sharp absorption of acoustic noise at the stage of accelerated band growth is discussed.

Динамика деформационных полос, инициированных ударом индентора о поверхность алюминий-магниевого сплава

The dynamics of macrolocalized deformation bands generated by the impact of a Vickers indenter on the surface of an AlMg6 aluminum-magnesium alloy deformed under creep conditions was studied by high-speed video recording and acoustic emission methods. It has been established that these bands are the trigger for the development of a macroscopic jump in plastic deformation on the creep curve. It is shown that in alloys exhibiting the Portevin-Le Chatelier effect, it is necessary to take into account the initiation and propagation of deformation macrobands during surface erosion damage and to estimate the volume and morphology of the plastic zone during impact microindentation of a deformable alloy.

МОДЕЛИРОВАНИЕ РАСПРЕДЕЛЕНИЯ ОСТАТОЧНОЙ ПОРИСТОСТИ МЕТАЛЛИЧЕСКОГО ИЗДЕЛИЯ ПРИ АДДИТИВНОМ ПРОИЗВОДСТВЕ С ПОСЛОЙНОЙ ПРОКОВКОЙ

Porosity, which occurs in products made of aluminum-magnesium alloys synthesized by wire-arc surfacing, significantly worsens the characteristics of fatigue strength. The developed technology of hybrid additive manufacturing with layer-by-layer forging of each deposited layer of material is able to minimize the porosity of the product. To select the rational parameters of the technological process, the evolution of the porosity distribution over the cross-section of a linear element after its single forging with a pneumatic hammer is investigated. A numerical model of the process is constructed in the LS-DYNA® package, where the Gurson–Tvergaard–Needleman relations are taken as constitutive equations of plastic deformation of the material and porosity evolution. To determine the parameters of the Johnson–Cook hardening law, tests of the AMg6 alloy were performed in a wide range of strain rates. The impact of the pneumatic hammer in the numerical model was calibrated using an accelerometric and strain-gauged steel target, as well as by distortions of the cross-section of a forged bar made of AMg6 alloy. Calculations according to the model are compared with experimental data, for which two linear segments were made by additive manufacturing with and without layer-by-layer forging, from the cross-sections of which the slots processed for pore visualization were prepared. With this method of pressure treatment, the decrease in porosity in the boundary layer of the workpiece mainly depends on the accumulated plastic deformations and does weakly sensitive the appearance of a stressed state. The model allows you to predict the size of the area under the hammer head depending on the processing mode, within which the porosity is eliminated by forging. The use of such modes will ensure the manufacturing of products without residual porosity in the processes of additive manufacturing by surfacing with layer-by-layer forging.

A comparative investigation on weld metal properties of similar and dissimilar TIG welded joints on Al-Mg alloys

Similar and dissimilar welding of aluminum-magnesium alloy plates 5083 and 5010 was performed based on their marine application due to the excellent corrosion resistance, ability to retain strength post welding, and improved strength when operated at sub-zero temperature. TIG welding was employed for joining the plates using ER 5356 as the filler alloy due to its excellent corrosion resistance to saltwater and high concentration of Al-Mg matrix which enhances the intermetallic bond thereby increasing its strength. Two sets of welding, one consisting of dissimilar weld with 5010 and 5083 and the second with similar weld between two 5083 plates were considered for the research. Mechanical tests like Tensile, Bend, Hardness, and corrosion with microstructural analysis were performed on all the weld samples and it was observed that samples of similar welds had marginally higher tensile values than the samples of dissimilar welds. The microstructure analysis displayed that the weld and HAZ regions of dissimilar welds were dense and isolated while the HAZ of similar welds had minor amounts of Cu which inhibits grain growth thereby effecting the strength.

Numerical investigation on crack analysis of H13 fixed die and structural analysis of moving die with two different materials

Die casting is forcing molten metal into a mould with high pressure. Die casting has two dies namely moving die and fixed die where the moving one will move over the fixed die. Die casting is majorly used for high-volume production. This paper focused on the physical phenomenon of die casting for two dies (moving die and fixed die) using two different alloy materials with variable material chemical compositions. The numerical analysis is carried out for the die casting process to determine the crack formation zone by temperature distribution and structural analysis by stress-strain relationship. The numerical analysis is carried out for both the dies. The fixed die is analyzed with an H13 tool steel material with two moving die materials as aluminum alloy (A356) and magnesium alloy (AZ91D). Both the dies (fixed and moving) were designed by using design software and meshing is carried out followed by analysis using the analysis software. The physical parameter for the dies is applied that is temperature distribution is carried out by applying a temperature of 850 °C and 650 °C over the fixed die for aluminum and magnesium alloy, respectively. Structural analysis is carried out for the moving die with a load of 1,000 N for both aluminum and magnesium alloys with 1000 number of iterations. The results from the numerical analysis are derived and analyzed for both temperature distribution and structural analysis. The crack formation zone is found out by means of temperature gradient and the stress-strain relationship is found out by means of structural analysis. From the results, it was concluded that the crack zone is obtained at 1.22E-10 °C/mm and 6.856E-14 °C/mm of thermal gradient and structural analysis in terms of maximum stress of 446.94 MPa and 448.52 MPa for aluminum and magnesium alloys, respectively.

The role of robotics in additive manufacturing: review of the AM processes and introduction of an intelligent system

PurposeAdditive manufacturing (AM) is a rapidly evolving manufacturing process, which refers to a set of technologies that add materials layer-by-layer to create functional components. AM technologies have received an enormous attention from both academia and industry, and they are being successfully used in various applications, such as rapid prototyping, tooling, direct manufacturing and repair, among others. AM does not necessarily imply building parts, as it also refers to innovation in materials, system and part designs, novel combination of properties and interplay between systems and materials. The most exciting features of AM are related to the development of radically new systems and materials that can be used in advanced products with the aim of reducing costs, manufacturing difficulties, weight, waste and energy consumption. It is essential to develop an advanced production system that assists the user through the process, from the computer-aided design model to functional components. The challenges faced in the research and development and operational phase of producing those parts include requiring the capacity to simulate and observe the building process and, more importantly, being able to introduce the production changes in a real-time fashion. This paper aims to review the role of robotics in various AM technologies to underline its importance, followed by an introduction of a novel and intelligent system for directed energy deposition (DED) technology.Design/methodology/approachAM presents intrinsic advantages when compared to the conventional processes. Nevertheless, its industrial integration remains as a challenge due to equipment and process complexities. DED technologies are among the most sophisticated concepts that have the potential of transforming the current material processing practices.FindingsThe objective of this paper is identifying the fundamental features of an intelligent DED platform, capable of handling the science and operational aspects of the advanced AM applications. Consequently, we introduce and discuss a novel robotic AM system, designed for processing metals and alloys such as aluminium alloys, high-strength steels, stainless steels, titanium alloys, magnesium alloys, nickel-based superalloys and other metallic alloys for various applications. A few demonstrators are presented and briefly discussed, to present the usefulness of the introduced system and underlying concept. The main design objective of the presented intelligent robotic AM system is to implement a design-and-produce strategy. This means that the system should allow the user to focus on the knowledge-based tasks, e.g. the tasks of designing the part, material selection, simulating the deposition process and anticipating the metallurgical properties of the final part, as the rest would be handled automatically.Research limitations/implicationsThis paper reviews a few AM technologies, where robotics is a central part of the process, such as vat photopolymerization, material jetting, binder jetting, material extrusion, powder bed fusion, DED and sheet lamination. This paper aims to influence the development of robot-based AM systems for industrial applications such as part production, automotive, medical, aerospace and defence sectors.Originality/valueThe presented intelligent system is an original development that is designed and built by the co-authors J. Norberto Pires, Amin S. Azar and Trayana Tankova.

Закономерности течения материала по контуру инструмента и стабильность механических свойств материала зоны перемешивания при СТП образцов сплава АМг5 больших толщин

Introduction. Friction stir welding and processing are almost identical processes of severe plastic deformation at elevated temperatures. These technologies differ mainly in the purpose of its use: the formation of a hardened surface layer or producing a welded joint. However, it is known that both during welding and during processing of heavy gauge workpieces temperature gradients occur. As a result, the conditions of adhesive interaction, material plastic flow, and the formation of the stir zone change as compared to thin-sheet workpieces with fundamentally different heat dissipation rates. In this connection, the purpose of the work is to determine the regularities of the structure formation and stability of the mechanical properties in different directions in the material of 35-mm-thick aluminum-magnesium alloy samples produced by friction stir welding/processing. Research Methodology. The technique and modes of friction stir welding and processing of AA5056 alloy workpieces with a thickness of 35 mm are described. Data on the equipment used for mechanical tests and structural research are given. Results and discussion. The data obtained show the excess mechanical properties of the processing zone material over the base metal ones in all studied directions. Material structure heterogeneities after friction stir welding/processing of heavy gauge workpieces have no determining effect on the stir zone properties. At the same time, there is no clear correlation between the tensile strength values and the load application direction, nor is there any significant difference in mechanical properties depending on the location of the samples inside the stir zone. The average ultimate tensile strength values in the vertical, transverse, and longitudinal directions are 302, 295 and 303 MPa, respectively, with the yield strength values of 155, 153 and 152 MPa, and the relative elongation of 27.2, 27.5, 28.7 %.