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AA5083 bars processed by four pass ambient Equal Channel Angular Pressing were subjected to intersection annealing, where time and temperature were varied after each pass. The microstructures, texturing and compressive characteristics of the samples were meticulously examined. Due to the high annealing temperatures, both ultimate tensile strength and compressive stresses decreased with increasing grain size. However, intersection annealing at room temperature resulted in the best compressive yield strength. The deformation behavior of AA5083 billets was investigated using finite element analysis. Electron back scatter diffraction was employed to examine the texture of the Equal Channel Angular Pressed billet crystals. Extensive research was conducted on the tensile properties and Vickers microhardness. The finite element simulations revealed that the 900 die exhibited a significantly more uniform dispersion of plastic strain compared to the 1200 die. The renewal of additional slip mechanisms during the four Pass process was attributed to the grain refining that occurred after the 1-Pass and 2-Pass stages. Equal Channel Angular Pressing successfully produced a homogeneously ultra-fine grained microstructure. The increase in strength was attributed to grain refining and dislocation strengthening. Molecular dynamics simulations were employed to study the ECAPed approach of AA5083 providing insights into the deformation behavior and polycrystal formation.

The Copper-Nickel alloy, C70600, was subjected to severe plastic deformation by the equal channel angular pressing (ECAP) technique. The material was pressed at room temperature along route BC for eight passes. Microstructural analysis and mechanical characterization of the material were done for each of the ECAP pass samples. The initial homogenized material having equiaxial grains of average grain size 75 µm was reduced to 20 µm after eight ECAP passes. Electron backscatter diffraction data presented an increase in low angle grain boundaries with an increase in the number of ECAP passes. Initially, the ultimate tensile strength and the hardness increased by 56% and 94% respectively. After the fifth ECAP pass, a drastic reduction in ultimate tensile strength and ductility was witnessed. Hardness value remained constant after the fifth ECAP pass. Fractography analysis indicate the ductile mode of fracture with reduced dimple size at higher ECAP passes. [ABSTRACT FROM AUTHOR]

The production of nanostructure materials or ultrafine grain (UFG) has been noticed by most of research society due to high strength, wear resistance, formability and high plastic strain rate. These features result from microstructure materials (100-300 nm) and unique defect (grain boundary-dislocation) make these material ideal for medical implant and structured components of aerospace and energy systems. The ways of producing UFG for these advanced engineering projects have not been considered yet. Due to the fact that nanostructured materials can show a good mechanical strength, researchers are using different ways to change pure copper into nanostructure one. One of these methods is applying process in equal channel angular pressing (ECAP), which coarse grain copper changed to nanostructure one. In this study, machinability of UFG as well as coarse grain (CG) copper is really considered in turning. To evaluate the machinability, cutting force, tool wear, chip morphology and surface roughness have been studied. Experimental results confirmed that UFG copper can be machined more efficiently than CG copper. In other words, the amount of BUE is reduced during turning ECAP copper due to the hardening of the pure sample. In comparison to CG copper, cutting force and surface roughness for UFG copper were less. As a result, machining performance can be improved partly by cold-work applying ECAP process. [ABSTRACT FROM AUTHOR]

Severe Plastic Deformation (SPD) techniques have been used by researchers for last three decades in order to obtain Ultra-Fine Grained (UFG) materials. Equal Channel Angular Pressing (ECAP) is preferred more than other SPD techniques thanks to its high performance and practicability. Hexa Equal Channel Angular Pressing (Hexa-ECAP) – modified ECAP technique which enables to apply ECAP routes for cylindrical samples properly – was preferred in this study. Within the objective of this study, the effects of coefficient and ram velocity on the mean effective strain and strain inhomogeneity of Hexa-ECAP processed Al7075 aluminium alloy were investigated. Also, the effects of ram velocity and friction coefficient on hardness homogeneity were investigated benefitting from the similarity between the hardness distribution and the strain distribution.

When it comes to using bio-metals, the chemical and biocompatibility properties of titanium led to its widespread use in biomedical implants. However, pure titanium possesses lower mechanical properties than Ti alloys containing cytotoxic elements. Severe plastic deformation (SPD) techniques were able to cause a significant strength increase, corrosion behavior improvement, and the release of the alloying elements. In this study, the ECAP process was performed on commercially pure titanium with a square cross-section at two and four passes, which resulted in a finer grain size and a more uniform microstructure. In order to improve cell behaviors, etch treatment was performed to produce nano-rough and nano-texture surfaces for all Ti samples. The effect of surface etching on corrosion, surface roughness, and cell behaviors on ECAP and untreated samples was also investigated. Optical/Field Emission Scanning Electron Microscopy, Atomic Force Microscopy, and X-Ray Diffraction were used to study the microstructural characterizations of samples. In addition, the impact of grain structure on the contact angle, electrochemical corrosion behavior, osteoblast response, and cell viability was investigated. The titanium that was ECAPed four times provided finer grains (200 nm) than the unprocessed sample (25 µm). The potentiodynamic polarization test revealed that corrosion resistance of ECAPed samples was enhanced, which was associated with grain refinement, affecting the passive film formation. Corrosion resistance and wettability experienced an apparent increase after each ECAP pass. In conclusion, improvement of grain size and surface roughness was due to the simultaneous effect of ECAP and etching treatment that led to the osteoblast response and cellular activity of samples. [ABSTRACT FROM AUTHOR]

Equal Channel Angular Pressing (ECAP) is one of the most effective techniques for the formation of ultra-fine grained bulk material. The material is passed through the channel in the specially designed die in the ECAP process. The die design parameters like corner angle, channel angle and other parameters play an important role in the formation of ultra-fine grains. The die with optimum design parameters, with channel angle 90° and corner angle 20°, was designed and fabricated in the laboratory and commercial Aluminium AA6063 was used as sample material to investigate the mechanical behaviour/properties before and after the ECAP process. In the present work, the mechanical behaviour of commercially pure Aluminium processed by ECAP die with an optimum die design parameter is studied and examined. The path adopted was BC and pressing was done from 0 to 3 numbers of times. The results revealed that the grain size reduced from 530 to 220 nm and tensile strength increases from 275.8 to 368.4 MPa after three numbers of ECAP passes. [ABSTRACT FROM AUTHOR]

Different types of SPD techniques are applicable and have been studied by various researchers. All of them have several advantages and disadvantages. Equal Channel Angular Pressing (ECAP) is one of the most popular SPD techniques and is still being developed. The aim of this paper is to improve the efficiency of ECAP process by putting forward a novel design (Twisted Variable Channel Angular Pressing (TV-CAP)) and also to achieve higher mechanical properties when compared to conventional ECAP processes. For this purpose, a new TV-CAP die was designed by combining three different methods: ECAP, Twist Extrusion, and Direct Extrusion. The new design was able to integrate the advantages of each method to the workpiece material. In this context, the design parameters of the TV-CAP die were first identified by finite element analysis (FEA) in Deform-3D. The TV-CAP die was produced according to the determined parameters and AA5083 alloy was pressed with this novel die. Hardness and tensile tests were carried out to compare mechanical properties. In addition, Optical Microscope, SEM, TEM images were taken, and XRD and EBSD analyses were carried out to examine the changes in grain structure. As a result of this experimental study, an increase of 197.3% was observed in the hardness value and an increase of 144.7% was achieved in the tensile strength value by using the novel TV-CAP die. These results also agreed with the effective strain values obtained from the FEA. [ABSTRACT FROM AUTHOR]

This work aims to study the microstructural development of lead-containing aluminum alloy in the process of intense plastic deformation. The evolution of the AA2030 alloy obtained by the ECAP and long-term natural aging (within 45 months) has been analyzed using electron microscopes. The average grain size of the ECAP treated samples is 420 and 380 nm along the routes Bc and C, respectively. Long-term natural aging contributes to transforming grain boundaries without changing their size. The results have shown that the structure, phase distribution, and stoichiometric composition of the inclusions differ significantly during annealing, equal-channel angular pressing, and long-term natural aging. The strain route affects the dissolution kinetics and evolution of inclusions. A mechanism for refining the grains is proposed that is associated with high dislocation density, dislocation cells, grain and subgrain boundaries, as well as the evolution of inclusions in the ECAP AA2030 alloys. [ABSTRACT FROM AUTHOR]

Equal channel angular pressing (ECAP), expansion equal channel angular pressing (Exp.-ECAP), and hybrid equal channel angular pressing (HECAP) or (Hybrid ECAP) processes were applied to pure copper specimens within this study. After the application of ECAP, the die used in the application of the Exp.-ECAP process was optimized considering the strain inhomogeneity in the specimen and the maximum load that occurred during the process. Finite element method (FEM), artificial neural network (ANN), and genetic algorithm (GA) were utilized together for the optimization process. The optimized die equally minimizes the pressing load and the strain inhomogeneity that occurred in the specimen. Using the optimized die, Exp.-ECAP and HECAP processes were applied to pure copper. The Exp.-ECAP process was previously applied only for aluminum alloys and magnesium alloys. With the application of the Exp.-ECAP process to pure copper, this gap in the literature was removed. In addition, with the application of the HECAP process, the effects of the Exp.-ECAP passes applied after ECAP were also examined which was not done earlier. The specimens, on which ECAP, Exp.-ECAP, and HECAP processes were applied, were subjected to microstructure analysis and mechanical tests, and the effects of these processes were examined. The results obtained showed that the Exp.-ECAP process gave better results in grain refinement and mechanical properties. The Exp.-ECAP passes applied after the ECAP process within the scope of the HECAP process provided a more homogeneous distribution for the microstructure and the hardness. [ABSTRACT FROM AUTHOR]

Severe Plastic Deformation (SPD) techniques have been used by researchers for last three decades in order to obtain Ultra-Fine Grained (UFG) materials. Equal Channel Angular Pressing (ECAP) is preferred more than other SPD techniques thanks to its high performance and practicability. Hexa Equal Channel Angular Pressing (Hexa-ECAP) - modified ECAP technique which enables to apply ECAP routes for cylindrical samples properly - was preferred in this study. Within the objective of this study, the effects of coefficient and ram velocity on the mean effective strain and strain inhomogeneity of Hexa-ECAP processed Al7075 aluminium alloy were investigated. Also, the effects of ram velocity and friction coefficient on hardness homogeneity were investigated benefitting from the similarity between the hardness distribution and the strain distribution. [ABSTRACT FROM AUTHOR]

Diego Pedreira de Oliveira,1,* Tatiane Venturott Toniato,2 Ritchelli Ricci,2 Fernanda Roberta Marciano,3 Egor Prokofiev,4 Ruslan Z Valiev,4,5 Anderson Oliveira Lobo,6,* Alberto Moreira Jorge Júnior1,7,* 1Department of Materials Engineering, Federal University of São Carlos, São Carlos 13565-905, São Paulo, Brazil; 2Institute of Research and Development, University of Vale do Paraíba, São Paulo 12244-000, Brazil; 3Scientifical and Technological Institute, Brasil University, São Paulo 08230-030, Brazil; 4Saint Petersburg State University, Saint Petersburg 199034, Russia; 5Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000, Russia; 6LIMAV - Interdisciplinary Laboratory for Advanced Materials, Department of Materials Engineering, UFPI - Federal University of Piauí, Teresina 64049-550, Piauí, Brazil; 7University of Grenoble Alpes, CNRS, Grenoble INP-LEPMI, and SIMAP Labs, Grenoble 38000, France *These authors contributed equally to this work Background: Nanophase surface properties of titanium alloys must be obtained for a suitable biological performance, particularly to facilitate cell adhesion and bone tissue formation. Obtaining a bulk nanostructured material using severe plastic deformation is an ideal processing route to improve the mechanical performance of titanium alloys. By decreasing the grain size of a metallic material, a superior strength improvement can be obtained, while surface modification of a nanostructured surface can produce an attractive topography able to induce biological responses in osteoblastic cells. Methods: Aiming to achieve such an excellent synergetic performance, a processing route, which included equal channel angular pressing (ECAP), hot and cold extrusion, and heat treatments, was used to produce a nanometric and ultrafine-grained (UFG) microstructure in the Ti-6Al-7Nb alloy (around of 200 nm). Additionally, UFG samples were surface-modified with acid etching (UFG-A) to produce a uniform micron and submicron porosity on the surface. Subsequently, alkaline treatment (UFG-AA) produced a sponge-like nanotopographic substrate able to modulate cellular interactions. Results: After several kinds of biological tests for both treatment conditions (UFG-A and UFG-AA), the main results have shown that there was no cytotoxicity, expressed alkaline phosphatase activity and total protein amounts without statistical differences compared to control. However, the UFG-AA samples presented an attractive effect on the cell membranes, and cell adhesions were preferentially induced as compared with UFG-A. Both conditions demonstrated cell projections, but for UFG-AA, cells were more widely dispersed, and more quantities of filopodia formation could be observed. Conclusion: Herein, the reasons for such behaviors are discussed, and further results are presented in addition to those mentioned above. Keywords: SPD, ECAP, UFG Ti–6Al–7Nb alloy, implants, surface treatment, biological response

A growing interest in wrought magnesium alloys has been noticed recently, mainly due to development of various SPD (severe plastic deformation) methods that enable significant refinement of the microstructure and – as a result – improvement of various functional properties of products. However, forming as-cast magnesium alloys with the increased aluminum content at room temperature is almost impossible. Therefore, application of heat treatment before forming or forming at elevated temperature is recommended for these alloys. The paper presents the influence of selected heat treatment conditions on the microstructure and the mechanical properties of the as-cast AZ91 alloy. Deformation behaviour of the as-cast AZ61 alloy at elevated temperatures was analysed as well. The microstructure analysis was performed by means of both light microscopy and SEM. The latter one was used also for fracture analysis. Moreover, the effect of chemical composition modification by lithium addition on the microstructure of the AZ31-based alloy is presented. The test results can be helpful in preparation of the magnesium-aluminum alloys for further processing by means of SPD methods.

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The present study was initiated to investigate the influence of an ECAP die on the microstructure evolution and properties of commercial Al-Mg aluminum alloy in as-cast state. To characterize microstructural features an optical microscope was used. The properties of the as processed and initial state material were evaluated based on the hardness measurements. It was found that the applied ECAP die has the meaningful influence on the microstructure as well as the properties of the material.

In the present study, the wear behaviour of two aluminium alloys (AA-5754 and AA-5083) is analysed where these have been previously processed by severe plastic deformation (SPD) with equal channel angular pressing (ECAP). In order to achieve the objectives of this study, several disks made of these alloys are manufactured by isothermal forging from different initial states. The microstructures of the initial materials analysed in this study have different accumulated deformation levels. In order to compare the properties of the nanostructured materials with those which have not been ECAP-processed, several disks with a height of 6 mm and a diameter of 35 mm are manufactured from both aluminium alloys (that is, AA-5754 and AA-5083) isothermally forged at temperatures of 150 and 200 °C, respectively. These thus-manufactured disks are tested under a load of 0.6 kN, which is equivalent to a stress mean value of 18 MPa, and at a rotational speed of 200 rpm. In order to determine the wear values, the disks are weighed at the beginning, at 10,000 revolutions, at 50,000 revolutions and at 100,000 revolutions, and then the volume-loss values are calculated. This study was carried out using specific equipment, which may be considered to have a block-on-ring configuration, developed for testing in-service wear behaviour of mechanical components. From this, the wear coefficients for the two materials at different initial states are obtained. In addition, a comparison is made between the behaviour of the previously ECAP-processed aluminium alloys and those that are non-ECAP-processed. A methodology is proposed to determine wear coefficients for the aluminium alloys under consideration, which may be used to predict the wear behaviour. It is demonstrated that AA-5754 and AA-5083 aluminium alloys improve wear behaviour after the ECAP process compared to that obtained in non-ECAP-processed materials.

Analysis of the results of the microstructure and the mechanical properties change in AA1050 aluminum alloy of technical purity processed using ECAP (Equal Channel Angular Pressing) and KoBo deformation methods are presented in the paper.. ECAP process was performed according to Bc scheme in the range from 1 up to 10 passes. Changes of microstructure were analyzed using scanning electrone microscope equipped with electron backscattered diffraction (EBSD) system. Microstructure and fraction of high-angle grain boundaries in KoBo processed samples were similar to those observed in ECAP processed samples after four passes. The most significant microstructure refinement was observed in ECAP processed sample submitted to 10 passes. In ECAP method the systematic increase of mechanical properties was observed along with increase of deformation degree.

Today, many researchers focus on proposing severe plastic deformation (SPD) methods due to the superior mechanical and physical properties of achieved ultra-fine grain material. In all SPD methods a large strain is implied without any substantial dimensional change of work piece to generate UFG and even nanograin (NG) materials. Equal Channel Angular Pressing (ECAP) is one of the most successful techniques for industrial applications. Using a long and thin rod is limited in ECAP process .In the present study, a combined process composed of ECAP and Extrusion processes is used on Titanium grade 2. Titanium is extensively used in aviation and other industries because of its high strength to weight value. Using the combined process leads to production of long length and thin nanostructured rod. The main goal of this process is evaluation of the temperature in Extrusion process on nanostructures Titanium rods. At first, Titanium rods were processed for 4 passes by ECAP process at 400°C and then they were processed by Extrusion process at 5 different temperatures including 300, 350, 400, 450 and 500°C. The result showed that the best mechanical properties achieved for the specimen were extruded at 300°C. Strength and hardness were severely improved. Also, the microstructure was very homogenous and refined. The mechanical properties of titanium grade 2 after combined process were equivalent to titanium grade 5 which is used in medical applications and is expensive. [ABSTRACT FROM AUTHOR]

The tensile strength of metals and alloys can be considerably increased by severe plastic deformation, a consequence of the extreme grain refinement thus achieved. In the present work the deformation was performed by Equal Channel Angular Pressing and the material was an Al-4% Cu alloy. Characterization included tensile tests, and microstructural observation by optical and transmission electron microscopy. After four passes, the yield strength showed an increase of 310% over the undeformed alloy, a figure reduced to 160% by a 250 °C / 1 hour post - deformation anneal. Additionally, the alloy displayed a very low work hardening capacity, especially after the annealing heat treatment. After four deformation passes the grain size of the annealed specimens was estimated to be close to 500 nm. The tensile behaviour and the absence of work hardening were discussed in terms of the fine microstructure.

Equal Channel Angular Pressing (ECAP) is a very interesting method for modifying the microstructure in producing materials with ultrafine grain in sub-micrometer or nanometre range. Experiments demonstrate that these ultrafine structures may exhibit, by comparison with large - grained polycrystals, major differences in some fundamental properties. A nanostructured AA 3004 alloy was used to investigate the evolution of microhardness and microstructure on the cross-sectional plane X, after processing by ECAP at room temperature for up to six passes. The measurements show the average microhardness increases significantly after two passes with additional increases in subsequent passes. Microhardness values increase by more than two times after 6 passes. There is a reduction in grain size from of ~ 50μm in the initial condition to ~ 12 μm after 6 passes. The results also show that the microstructure and the microhardness evolve with increasing strain so that, after a total of 6 passes, the structure is almost homogenous throughout the cross-sectional plane of the billet.

Severe plastic deformation via equal-channel angular pressing was shown to induce characteristic ultra-fast diffusion paths in Ni (Divinski et al., 2011). The effect of heat treatment on these paths, which were found to be represented by deformation-modified general high-angle grain boundaries (GBs), is investigated by accurate radiotracer self-diffusion measurements applying the 63 Ni isotope. Redistribution of free volume and segregation of residual impurities caused by the heat treatment triggers relaxation of the diffusion paths. A correlation between the GB diffusion kinetics, internal friction, microstructure evolution and microhardness changes is established and analyzed in detail. A phenomenological model of diffusion enhancement in deformation-modified GBs is proposed. [ABSTRACT FROM AUTHOR]

This present research work deals with the design by finite element method (FEM) of the dies required for the isothermal forging of a Francis turbine blade taking into account that the starting material has been previously nanostructured through severe plastic deformation by equal channel angular extrusion. This nanostructured material possesses improved mechanical properties and hardness, better forgeability, and, under specific conditions, a superplastic behavior. Once this material is obtained, its flow rule has been determined through compression tests at different temperature values along with its subsequent fitting with artificial neural networks. Later on, these rules will be employed in the FEM simulations included in this present study. Furthermore, the results of the processing of these materials are shown comparing the properties of the mechanical components after their isothermal forging at different temperature values both with predeformed and non-predeformed material. This work is at the cutting-edge of technology because there are only a few technical papers about forging applications of nanostructured material. [ABSTRACT FROM PUBLISHER]

This paper aims to study bulk severe plastic deformation processes capable to produce ultrafine grain and also nanostructured 3D materials, interesting for processing in current industry. Samples of copper alloy were solution treated and then were subjected to repetitive Equal Channel Angular Pressing at room temperature in 1 to 8 passes, using route C. Severely deformed specimens were studied after each deformation pass. Their microstructural evolution and mechanical properties were investigated. Optical microscopy progression is evaluated on each separate ECAP pass. It is well known that although copper is a deficient resource it is used to the same extent as aluminum, a rich resource on the earth’s crust. This research signs up in the category of new technologies for obtaining bulk metallic nanostructures that allow more judicious use of copper alloys by the substantial improvement of properties of use.

The goal of this document is to promote a sequence of bulk-deformation processes able to produce ultrafine grain and also nanostructured wires with adequate length to be interesting for processing in metallurgical industry. Samples of aluminum Al 1100alloy (98.41 % Al) were subjected to repetitive Equal Channel Angular Pressing at room temperature in 1 to 4 passes. Severe deformed specimens were cold classical plastic deformed in wires. Microstructural evolution and mechanical properties were investigated. Optical microscopy progression is evaluated through a sequential interrupted process on each separate ECAP pass. The XRD studies reveal the influence of SPD on grain refinement of samples. A simply and new technology for obtaining intermediary products UFG and nanocristalline wires was developed.

Abstract: Samples of electrolytic tough pitch (ETP) copper were subjected to equal-channel angular pressing (ECAP) for up to 16 passes at room temperature following route Bc. The microstructural evolution was followed by Oriented Image Microscopy (OIM) and Differential Scanning Calorimetry (DSC) was used to estimate the activation energy and the recrystallization temperature after each ECAP pass. Also, mechanical properties after each pass were evaluated by tensile tests. Finally, electrical properties were analyzed. Results show that the stored energy increases on increasing ECAP deformation, while the recrystallization temperature decreases significantly. From a mechanical point of view a stable state is attained after 4 passes. Similarly, electrical conductivity slightly decreases down to a saturation state. [Copyright &y& Elsevier]

The present work, deals with grain refinement of medium carbon steel AISI 1045 (0.45% C), having different initial ferrite-pearlite microstructure resulted from thermal and thermomechanical treatment (TM). The purpose of TM steel processing was to refine ferrite and modify pearlite lamellae structure. The final grain refinement of steel structure was then accomplished during warm Equal Channel Angular Pressing (ECAP) at 400°C. Employment of this processing route, in dependence of the applied effective strain ϵef, resulted in extensive deformation of ferrite grains and cementite lamellae fragmentation. When applying higher shear stress ( ϵef = 4) the mixed structure of subgrains and ultrafine grains was formed within ferrite phase, regardless the initial steel structure morphology. In pearlite grains, modification of cementite lamellae due to shearing, bending, twisting, and breaking was found efficient as straining increased. Processes of dynamic polygonization and recrystallization in deformed structure also contributed to submicrocrystalline grains formation in deformed structure. Comparing results the course of lamellae cementite spheroidization was then more efficient in prior TM treated steel. The tensile deformation results confirmed the strength increase, however deformation behavior and strain hardening generally for different initial structural conditions of steel, showed diversity. [ABSTRACT FROM AUTHOR]

This paper aims to study bulk severe plastic deformation processes capable to produce ultrafine grain and also nanostructured 3D materials, interesting for processing in current industry. Samples of copper alloy were solution treated and then were subjected to repetitive Equal Channel Angular Pressing at room temperature in 1 to 8 passes, using route C. Severely deformed specimens were studied after each deformation pass. Their microstructural evolution and mechanical properties were investigated. Optical microscopy progression is evaluated on each separate ECAP pass. It is well known that although copper is a deficient resource it is used to the same extent as aluminum, a rich resource on the earth's crust. This research signs up in the category of new technologies for obtaining bulk metallic nanostructures that allow more judicious use of copper alloys by the substantial improvement of properties of use. [ABSTRACT FROM AUTHOR]

The equal channel angular pressing (ECAP) process is a promising technique for imparting a large plastic deformation to materials without a resultant decrease in cross-sectional area. In the present study, the suitability of this technique for the processing of tubular specimens has been investigated. Commercially pure aluminum was selected for the study. Tubular specimens were extruded to three passes using four processing routes through an ECAP die with an angle of 150° between the two intersecting channels. Sand was used as a mandrel during the pressing. Analysis of force–stroke diagram was carried out. The mechanical properties were also investigated. Improvement in mechanical properties was observed in all the routes. These investigations demonstrate that ECAP is a promising technique for improving properties of tubular materials while ensuring retention of shape (with the possibility of imparting further deformation to the specimen using the same die) and with low pressing pressures. [ABSTRACT FROM AUTHOR]

The goal of this document is to promote a sequence of bulk-deformation processes able to produce ultrafine grain and also nanostructured wires with adequate length to be interesting for processing in metallurgical industry. Samples of aluminum Al 1100alloy (98.41% Al) were subjected to repetitive Equal Channel Angular Pressing at room temperature in 1 to 4 passes. Severe deformed specimens were cold classical plastic deformed in wires. Microstructural evolution and mechanical properties were investigated. Optical microscopy progression is evaluated through a sequential interrupted process on each separate ECAP pass. The XRD studies reveal the influence of SPD on grain refinement of samples. A simply and new technology for obtaining intermediary products UFG and nanocristalline wires was developed. [ABSTRACT FROM AUTHOR]

Equal channel angular extrusion or pressing (ECAP) is a process used to impart severe plastic deformations (SPD) ( ε << 1) to materials with the aim of improving their mechanical properties by reducing the grain size. In this study, an analytical modeling of the ECAP processing force required, taking circular cross-section for ECAP dies into consideration, is developed where non-strain hardening materials are processed. To obtain the equation that relates the geometry and required force, the upper bound method was used after taking an appropriate and admissible field into consideration. In addition, a comparison between analytical methods and experimental results was made. In order to perform the experimental tests, an F-1050-AA (F means as fabricated) was selected and processed at room temperature. This alloy has a yield stress of 70 MPa and an insignificant strain hardening. The experimental results obtained agree closely with those provided by the analytical formulation. With this study, it is possible to have an analytical approach to the required force for performing the ECAP process. This could help scientists and practical engineers involved in SPD processes such as ECAP, to optimize ECAP dies and the process itself thanks to the knowledge of the analytical expressions of the required force. [ABSTRACT FROM AUTHOR]

Abstract: A complete understanding of how grain refinement, grain size, and processing affect the corrosion resistance of different alloys has not yet been fully developed. Determining a definitive ‘grain size–corrosion resistance’ relationship, if one exists, is inherently complex as the processing needed to achieve grain refinement also imparts other changes to the microstructure (such as texture, internal stress, and impurity segregation). This work evaluates how variation in grain size and processing impact the corrosion resistance of high purity aluminium. Aluminium samples with a range of grain sizes, from ∼100μm to ∼2000μm, were produced using different processing routes, including cold rolling, cryo rolling, equal channel angular pressing, and surface mechanical attrition treatment. Evaluation of all the samples studied revealed a tendency for corrosion rate to decrease as grain size decreases. This suggests that a Hall–Petch type relationship may exist for corrosion rate and grain size. This phenomenon, discussed in the context of grain refinement and processing, reveals several interesting and fundamental relationships. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure and mechanical properties of pure gold were examined after different number of equal channel angular pressing passes. The hardness and 0.2% proof stress from the compression tests were observed to increase only up to the fourth pass whereas the compressive strength at 40% strain kept increasing gradually with increasing the number of passes. Microstructure with low angle grain boundaries and shear bands were observed until the eighth pass and equiaxed grains with high angle grain boundaries were observed only after the twelfth pass. [Copyright &y& Elsevier]

An established dislocation density related, one-internal variable model was used, with some modifications, as a basis for modeling the mechanical response of aluminum alloy AA6111. In addition to conventional rolling, equal channel angular pressing (ECAP) was used to produce a wide range of grain sizes, down to the submicrometer scale. The samples were heat treated before and after both processes to optimize tensile ductility. Implementation of the model to uniaxial tensile response of the conventionally rolled and the ECAP processed materials confirmed its good predictive capability. The model was further used to formulate simple relations between true uniform strain and the constitutive parameters that allow reliable prediction of the uniform elongation. [ABSTRACT FROM AUTHOR]

Equal channel angular pressing is an innovative process for obtaining severe plastic deformations in materials. In this work an optimised design of the channel die is presented which improves deformations obtained in materials using standard dies. [Copyright &y& Elsevier]

The quantitative concentration of alloying elements in low-alloyed copper alloys is an important factor in forming electrical and mechanical characteristics. It is known that severe plastic deformation is accompanied by both a substantial refinement of the structure and changes in the kinetics of phase transformations during the deformation and the post-deformation thermal treatment. This paper presents the results of a comparative analysis of the Cu–0.2Cr and Cu–1.1Cr alloys subjected to equal-channel angular pressing at room temperature. The analysis was performed for the grain structure, solid solution, and second-phase particles using transmission electron microscopy, scanning electron microscopy, X-ray crystal analysis, and the small-angle diffraction method. It was found that the level of structure refinement and mechanical characteristics after equal-channel angular pressing was almost the same for both studied alloys. Post-deformation aging of the Cu–0.2Cr alloy leads to the development of polygonization and re-crystallization within it. The aging of the Cu–1.1Cr alloy shows a better thermal stability than that of the Cu–0.2Cr alloy. In the Cu–1.1Cr alloy, after aging, in comparison with Cu–0.2Cr, a denser-packed ensemble of fine particles with an average size of 54 ± 2 nm is formed. In this case, the average size of fragments is 270 ± 15 nm and the ultimate tensile strength reaches 485 MPa. [ABSTRACT FROM AUTHOR]

This work considers the development and the application of combined severe plastic deformation (SPD) techniques to produce contact wire with an enhanced complex of physical, mechanical, and service properties used for high-speed railway lines. This type of processing can be used as an alternative to most conventional production methods, including rolling and drawing. The proposed technique is based on the combination of radial swaging and equal-channel angular pressing, bundled with the wire-forming process. Laboratory contact wire samples with an enhanced complex of physical, mechanical, and service properties were produced during physical experiments. The composition of processed alloy samples meets modern requirements for contact wires for high-speed railways. Ultimate tensile strength of 560 ± 20 MPa, electrical conductivity of 76 ± 2% IACS, and relative tensile elongation of 20 ± 2% are achieved through the formation of a band structure. Fragments of 300 ± 20 nm were formed inside strips with the precipitation of secondary phase particles of 20–100 nm along the fragment boundaries, mainly during the aging process. [ABSTRACT FROM AUTHOR]