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The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 &deg, C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%&mdash, Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement.

Fil: Maciel, Gisele. Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Agropecuaria Balcarce; Argentina. Fil: Maciel, Gisele. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnológico de los Alimentos; Argentina. Maciel, G. (2020). Expeller de soja: acondicionamiento de materia prima, eficiencia de extracción, composición, calidad y almacenabilidad del producto extrusado. (Tesis de doctorado). Universidad Nacional de Quilmes, Bernal, Argentina. El expeller de soja es uno de los principales subproductos obtenidos de la extracción de aceite por extrusado-prensado (E-P) del poroto. Su calidad es muy variable y se carece de una norma que sirva de referencia para su comercialización. Se sabe que el proceso de E-P y la calidad de la materia prima son las principales fuentes de variación en la calidad del expeller. El expeller se utiliza como ingrediente en la formulación de raciones para animales y por lo tanto su composición puede afectar los rendimientos productivos (ej. ganancia de peso, producción de leche, etc.). Además, es conocido su creciente uso en la industria de alimentos para consumo humano a través de la producción de proteínas texturizadas y micronizadas. Por estos motivos es indispensable comprender el efecto de los procesos previos de acondicionamiento sobre la eficiencia de extracción de aceite y las propiedades funcionales de las proteínas, como así también conocer las condiciones de almacenamiento seguro del subproducto con el fin de conservar su calidad. En el capítulo I se caracterizó la composición y calidad del poroto de soja y del expeller producido en las principales zonas productoras de soja en Argentina. Para ello se recolectaron pares de muestras de poroto y expeller de soja en once plantas de E-P y se analizaron en laboratorio. Los resultados permitieron caracterizar física, química y microbiológicamente el expeller de soja, destacándose que se encontró una importante variabilidad tanto en la materia prima como en el producto extrusado. Se establecieron relaciones entre parámetros de composición del poroto de soja y parámetros de calidad del expeller. Una de las principales conclusiones prácticas de este capítulo es que la eficiencia de extracción de aceite, y por lo tanto la composición del expeller de soja, se vieron claramente afectadas particularmente por el contenido de humedad del poroto de soja. En el capítulo II se estudió el efecto de la humedad del grano acondicionado en la eficiencia de extracción de aceite por E-P. Para ello se realizó un ensayo a escala real en una planta de E-P. Se utilizaron lotes diferentes de poroto de soja a los que se les realizó un tratamiento de secado con aire a 115 °C hasta alcanzar diferentes humedades (9, 11 y 13% b.h.). Posteriormente se realizó el tratamiento de E-P con la finalidad de evaluar la humedad que permite alcanzar los mayores niveles de eficiencia de extracción de aceite. Otros lotes de soja fueron secados a temperaturas del aire de 80 y 115 °C hasta alcanzar una humedad de 9% (b.h.). En todos los tratamientos se midió la temperatura alcanzada por el grano de soja y la variabilidad en la humedad de granos individuales. La composición del poroto obtenido y del expeller resultante y la eficiencia de extracción de aceite por E-P fueron evaluadas. Se pudo confirmar que la eficiencia de extracción de aceite se favorece a medida que disminuye la humedad del poroto de soja (de 13 a 9% b.h.). Sin embargo, no se encontraron diferencias significativas en la eficiencia de extracción de aceite cuando se evaluó el efecto de la temperatura del aire de secado. En el capítulo III se abordó la temática del almacenamiento del expeller de soja. En primer lugar se determinaron las isotermas de sorción de agua del expeller de soja. Para esto, se evaluó el efecto del contenido de aceite residual en las curvas de humedad de equilibrio, se ajustó el modelo de Halsey Modificado utilizado para oleaginosas y se propuso un nuevo modelo (Halsey Mejorado), que incorpora al modelo base el contenido de aceite con su correspondiente parámetro. Este modelo tiene la versatilidad de predecir el contenido de humedad de equilibrio del expeller (y la humedad de almacenamiento segura) en función de contenido de aceite residual, aspecto sumamente importante dado la gran variabilidad observada en este parámetro composicional. Seguidamente se evaluó la almacenabilidad del producto a través de la determinación de su tasa de respiración para diferentes condiciones de temperatura y humedad. En función de los resultados se pudieron establecer las condiciones de almacenamiento seguro del expeller y predecir las pérdidas de materia seca en el tiempo. Por otra parte se evaluó el efecto del almacenamiento hermético y convencional a diferentes condiciones de humedad (6, 9 y 12% b.h.) con y sin agregado de gomas. El ensayo se realizó en bolsas plásticas confeccionadas con silo bolsa con una capacidad de 2,5 kilos de expeller. En todos los casos se realizaron muestreos a los tiempos t0, t1, t2, t3 y t4, correspondientes a la muestra control y luego de 28, 56, 112 y 189 días de almacenamiento, luego de los cuales se evaluaron diversos parámetros de calidad. Los resultados indicaron que a 6 y 9% (b.h.) de humedad el expeller se pudo almacenar por 189 días sin cambio en ninguno de los parámetros de calidad evaluados. Mientras que el almacenamiento a 12% (b.h.) de humedad resultó en un incremento de la acidez y en altos recuentos de unidades formadoras de colonias de hongos xerófilos, que se vio reflejado en altos niveles de dióxido de carbono medidos. El sistema de almacenamiento hermético permitió retardar el desarrollo de hongos y el deterioro del aceite residual (acidez) a la humedad de almacenamiento más alta (12% b.h.). El agregado de gomas “per se” no tuvo consecuencias sobre los indicadores de calidad del expeller. En el capítulo IV se realizó una caracterización de los cambios estructurales y el estado de desnaturalización de las proteínas de las muestras de poroto y expeller de soja provenientes de las plantas de E-P evaluadas en el capítulo I. Esta caracterización se realizó mediante calorimetría diferencial de barrido modulada y espectroscopía infrarroja por transformada de Fourier. Por otro lado, se abordó el acondicionamiento de la materia prima y su efecto en aspectos de calidad funcional de las proteínas presentes en el expeller de soja. Para ello se realizó un experimento a escala de laboratorio donde un lote de poroto de soja se sometió a tratamientos de secado con una temperatura del aire de secado de 25°C (control), 40, 55, 70 y 90 °C hasta alcanzar una humedad final de 10,5% (b.h.). En la muestra inicial y en las obtenidas de todos los tratamientos de secado se analizó composición y el índice de dispersabilidad de la proteína (PDI). Posteriormente se realizó un experimento a escala real en una planta de E-P donde se realizaron tratamientos con una temperatura del aire de secado de 80 y 115 °C a diferentes lotes de poroto de soja y se evaluó el efecto del secado sobre la composición y funcionalidad de la proteína de soja. Los resultados del ensayo de laboratorio indicaron que la solubilidad/dispersabilidad y por lo tanto la funcionalidad de las proteínas se vio afectada a partir del tratamiento térmico realizado a 70 °C, siendo el de 90 °C el que mayor efecto presentó. Los tratamientos de secado realizados a escala real no presentaron un importante efecto en el PDI del poroto, mientras que el posterior proceso de E-P presentó un efecto significativo en dicho parámetro. Esta reducción en la funcionalidad proteica fue mayor en las muestras tratadas a 115 °C que podría indicar un posible efecto “sensibilizador” sobre la proteína de soja.

The aim of this study is to consolidate the Al-Ni powders using the equal channel angular pressing method in order to achieve improved structural and mechanical properties. Thus, both alloying ability at low temperature, as a result of consolidations of ultrafine grained alloy by equal channel angular pressing method, and the average grain size and grain boundary angle have been studied and the effect of Nickel has been investigated. Severe plastic deformation and consolidation process with 15 passes of equal channel angular pressing, having route C, have been carried out at 200°C using pure aluminum and aluminum with 10 wt.% of nickel. Electron backscatter diffraction was used to obtain scanning electron microscopy images and to determine the average grain size and average grain boundary angle. Density measurements of samples have been carried out using the Archimedes principle and the microhardness distributions have been obtained using the HV 0.5 method. © 2018 Polish Academy of Sciences Institute of Physics. All rights reserved.

WOS: 000435838600015, The effects of grain refinement and phase composition on superplasticity and damping capacity of eutectic Zn-5Al and eutectoid Zn-22Al alloys were investigated. For grain refinement, equal-channel angular pressing (ECAP) was applied to these alloys. ECAP completely eliminated the as-cast lamellar microstructures of both alloys and resulted in ultrafine-grained structures along with room temperature superplasticity. Furthermore, these microstructural changes with ECAP increased the damping capacity of both alloys in the dynamic hysteresis region, where damping arises from viscous sliding of phase/grain boundaries. Dynamic recrystallization at the surface and thermally activated viscous motion of grain/phase boundaries at the subsurface of the samples of both alloys were proposed as the damping mechanisms in the region where the alloys showed combined aspects of static/dynamic hysteresis damping behavior. Although the grain size is larger in Zn-5Al compared to Zn-22Al, it showed higher damping capacity due to the different sliding characteristics of its phase boundaries., Scientific Research Projects of Karadeniz Technical University, Turkey [10501]; World Academy of Sciences (TWAS) under the Visiting Researchers Program of the TWAS-UNESCO Associateship Scheme [3240290077], This research was partially supported by Scientific Research Projects of Karadeniz Technical University, Turkey, under Grant no: 10501. Dr. G. Purcek was also supported by The World Academy of Sciences (TWAS) under the Visiting Researchers Program of the TWAS-UNESCO Associateship Scheme (Ref. 3240290077).

To improve the efficiency of the joints formation, a new method of pressing in the longitudinal direction is proposed. This paper presents a predictive model for the pressing force depending on the state of the wood and the parameters of the pressed mortise. The most significant factors are the width of the mortise and the moisture content of the wood. Interestingly, the depth of the mortise formation is a less significant factor, which means that the pressing technology will allow to form a long glue line and accordingly high joint strength due to sufficient profile length. In the test range of factors, the best results in terms of energy costs are shown by a minimum mortise width of 4 mm. Further research should be devoted to the study of the formation of small width mortises (4 mm or less) and the investigation of their quality.

This work deals mechanical and tribological properties of pure copper, reinforced by various weight percentages of tin, before and after the application of equal channel angular pressing. It is found that the hardness, yield, and ultimate shear strengths are considerably improved through ECAP due to grain refinement. The effect of ECAP process on mechanical properties of dilute copper alloys is more significant than that of the pure condition. Also, the strengthening behavior is slightly intensified by increasing the amount of tin content in pure copper. Additionally, work-hardening potential of CP–Cu is restricted due to the ECAP process and also, through the production of dilute copper alloys. The results showed that the effect of ECAP on friction coefficient reduction is more sizeable than making the dilute alloys. Furthermore, the reduction of electrical conductivity in the deformed materials relies on the lattice distortion increase of copper due to the addition of Sn to Cu and the increment of dislocations density. Finally, ECAP procedure and alloying together, terminate to the better wear response of the materials. © 2019 Elsevier Ltd

To overcome some possible deficiencies of pure copper, dilute alloying and employment of equal channel angular pressing seem the cost-effective solutions. In this work, dilute copper alloys with the tin amount of 0.18, 0.3, and 0.5 wt.% were obtained with continuous casting and subsequently, they were subjected to ECAP process up to four passes. It was shown that integrated treatment by dilute alloying and ECAP lead to 182% improvement of the corrosion resistance as compared to the as-received condition due to the grain refinement. Meanwhile, the alloying impact on current density is decreased with the ECAP process which may result from the changes at the distribution of Sn atoms in Cu. The difference in measured corrosion current density of unprocessed and ECAPed samples for the alloys Cu-0.3%Sn and Cu-0.5%Sn are 15% and 2%, respectively. The corrosion improvement by means of current density reduction due to the alloying before the ECAP process is about 45% while this value after the ECAP diminishes to 35%. Microstructure analysis showed that four passes of ECAP process cause the average grain size of the pure copper to less than 700 nm and the Cu-0.5%Sn to about 550 nm. Also, the HAGBs fraction of the ECAPed pure Cu is 74%, while the corresponding magnitude for the Cu-0.5%Sn is 78%. © 2019 Politechnika Wrocławska

The current paper presents a collection of numerical, mathematical, and statistical techniques to predict strain behavior and required pressing force of 7075 aluminum alloy within the different parameters of equal-channel angular pressing (ECAP). Accordingly, response surface methodology was utilized to estimate the contribution percentage of the processing parameters (i.e., die channel angle, outer corner angle, coefficient of friction, and punch rate) on effective plastic strain, standard deviation of effective strain, and required pressing force of the deformed sample; then, regression modeling relationships were presented for each of the three outputs. Also, a suitable coincidence was found between the predicted regression model, numerical approach, theoretical technique, and experimental work. It is found that the achieved results could be used as a successful guideline for evaluation of the ECAP process. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.

The Zn-22 wt.%Al was processed using five different selected routes including thermal, thermo-mechanical and severe plastic deformation (SPD) techniques in order to produce ultrafine grained (UFG) microstructure for achieving room temperature (RT) and high strain rate (HSR) superplasticity, and to compare the same set of the results. After all routes, the microstructural evolutions and RT uniaxial tensile tests at different strain rates ranging from 1 × 10-3 to 1 × 100 s-1 were investigated. The smallest grain size was achieved to be 300 nm after the thermo-mechanical process including conventional hot and cold rolling steps. However, the lamellar microstructure of the alloy was not completely eliminated during that process. On the other hand, equal-channel angular pressing (ECAP) as one of the SPD techniques decreased the grain size down to 400 nm with a lamellar-free microstructure. The maximum elongation value was achieved to be 330% with the sample tested at 1 × 10-3 s-1 after a thermo-mechanical process including conventional hot and cold rolling, and an aging stage between these rolling steps. It was found that lamellar-free microstructure causes higher superplastic elongation even if it has higher grain size compared to the sample having partially lamellar structure. © 2015 Elsevier B.V.

An experiment on high-speed deformation of aluminum alloy A3003 by dynamic channel angular pressing is described. During dynamic pressing, the material is exposed to two deformation modes. They are compression-tension due to the interaction of shock and rarefaction waves when the sample hits the bottom of the first channel, and a simple shear localized at the joint of the channels. The features of structure formation under the action of each deformation mode are determined. It was found that a high dislocation density and the presence of localized deformation zones caused by shock-wave loading, have a significant influence on the formation of the structure upon dynamic channel-angular pressing. The mechanisms of hardening and the contribution of dislocation and grain-boundary components to the overall hardening of the alloy are determined. © Published under licence by IOP Publishing Ltd. LLC TESCAN

Two Zn-Al alloys, eutectoid Zn-22Al and dilute Zn-0.3Al, were processed through equal-channel angular pressing (ECAP). The ECAP-processed alloys were subjected to long-term natural aging at room temperature for 120 days in order to investigate the effect of long-term natural aging on high-temperature superplasticity and the deformation behavior of these alloys. The grain size of the Zn-22Al alloy increased from 200 nm after ECAP to 400 nm after the natural aging process. The Zn-0.3Al alloy with a grain size of 1.3 µm after ECAP demonstrated a reasonably stable microstructure with the grain size of ~ 1.7 µm after long-term natural aging. The naturally aged ultrafine-grained (UFG) Zn-22Al alloy showed an excellent superplastic elongation of about 1800% at 200 °C. Grain boundary sliding was determined as the dominant deformation mechanism in this alloy. On the contrary, a considerably low elongation to failure of 230% was recorded in the naturally aged fine-grained (FG) Zn-0.3Al alloy at 150 °C, and dislocation creep was evaluated as the main deformation mechanism for this alloy. Detailed microstructural analyses showed that the FG Zn-0.3Al alloy was exposed to grain boundary corrosion during the natural aging process due to the presence of Al precipitates at grain boundaries whereas such formation was not observed in the UFG Zn-22% Al alloy. Grain boundary sliding was hindered by grain boundary corrosion and the cavity nucleation at the corroded grain boundaries caused a premature failure leading to such a low elongation in the Zn-0.3Al alloy. © 2018 Elsevier B.V.

13th International Conference on Superplasticity in Advanced Materials, ICSAM 2018 Three Zn-Al alloys, namely Zn-22Al, Zn-5Al and Zn-0.3Al, were subjected to equal-channel angular pressing (ECAP), and the effect of ECAP on their microstructure and room temperature (RT) superplastic behavior were investigated in detail referring to previous studies reported by the authors of the current study. ECAP remarkably refined the microstructures of three alloys as compared to their pre-processed conditions. While the lowest grain size was achieved in Zn-22Al alloy as 200 nm, the grain sizes of Zn-5Al and Zn-0.3Al alloys were ~540 nm and 2 µm, respectively, after ECAP. After the formation of fine/ultrafine-grained (F/UFG) microstructures, all Zn-Al alloys exhibited superplastic behavior at RT and high strain rates. The maximum superplastic elongations were 400%, 520% and 1000% for Zn-22Al, Zn-5Al and Zn-0.3Al alloys, respectively. It is interesting to point out that the highest RT superplastic elongation was obtained in Zn-0.3Al alloy with the largest grain size, while Zn-22Al alloy having the lowest grain size showed the minimum superplastic elongation. This paradox was attributed to the different phase compositions of these alloys. The formation of Al-rich ?/? phase boundaries, where grain boundary sliding is minimum comparing to Zn-rich ?/? and ?/? phase boundaries of Zn-Al alloys, is the lowest level in Zn-0.3Al alloy among all the alloys. Therefore, it can be concluded that if it is desired to achieve high superplastic elongation in Zn-Al alloys at RT, keeping Al content at a possibly minimum level seems to be the most suitable way. © 2018 Trans Tech Publications, Switzerland

Quasi-single phase (dilute) Zn-0.3Al alloy was subjected to severe plastic deformation via equal-channel angular extrusion/pressing (ECAE/P), and the effects of ECAP on its room temperature (RT) and high strain rate (HSR) superplasticity and deformation mechanism were investigated. Multi-pass ECAP may refine the coarse-grained microstructure into the fine grained (FG) one. The grain size of Zn-matrix phase decreased down to 2.0m after ECAP. Many spherical Al-rich precipitates decomposed and homogeneously distributed inside the matrix phase. They are ultrafine grained (UFG) ?-particles with the grain sizes ranging from 50nm to ~200nm. This special microstructure having FG and UFG micro-constituents brought about an improvement in RT superplasticity even at HSRs. While multi-pass ECAP decreased flow stress of the alloy, its elongation to failure increased substantially depending on the initial strain rates. The maximum elongation was 1000% at a low strain rate of 10-4s-1, and 350% elongation was achieved at a high strain rate of 10-2s-1. Grain boundary sliding (GBS) was found to be the main deformation mechanism in region-II as the optimum superplastic region. © 2015 Elsevier B.V..

WOS: 000400454500023, The effect of grain size on the damping capacity of a dilute Zn-0.3Al alloy was investigated. It was found that there was a critical strain value (ae1 x 10(-4)) below and above which damping of Zn-0.3Al showed dynamic and static/dynamic hysteresis behavior, respectively. In the dynamic hysteresis region, damping resulted from viscous sliding of phase/grain boundaries, and decreasing grain size increased the damping capacity. While the quenched sample with 100 to 250 A mu m grain size showed very limited damping capacity with a loss factor tan delta of less than 0.007, decreasing grain size down to 2 A mu m by equal channel angular pressing (ECAP) increased tan delta to 0.100 in this region. Dynamic recrystallization due to microplasticity at the sample surface was proposed as the damping mechanism for the first time in the region where the alloy showed the combined aspects of dynamic and static hysteresis damping. In this region, tan delta increased with increasing strain amplitude, and ECAPed sample showed a tan delta value of 0.256 at a strain amplitude of 2 x 10(-3), the highest recorded so far in the damping capacity-related studies on ZA alloys, Scientific Research Projects of Karadeniz Technical University, Turkey [10501]; World Academy of Sciences (TWAS) under the Visiting Researchers Program of TWAS-UNESCO Associateship Scheme, This research was supported by Scientific Research Projects of Karadeniz Technical University, Turkey, under Grant No: 10501. Dr. G. Purcek was also supported by The World Academy of Sciences (TWAS) under the Visiting Researchers Program of TWAS-UNESCO Associateship Scheme.

Properties of Cu-Cr-Zr alloy with ultrafine-grained (UFG) structure produced by equal-channel angular pressing (ECAP) via different routes have been investigated. Special attention was paid to the optimization of multi-functional structural, thermal, electrical and mechanical properties of the alloy by aging of UFG one. Multi-pass ECAP via different routes gives rise to the formation of a deformation-induced submicrocrystalline structure with the grain (subgrain) sizes in the range of 200-300. nm depending on applied routes which leads to high hardness and strength in the Cu-Cr-Zr alloy with reduced ductility. Amongst the applied routes, route-Bc was found to be the best processing path for achieving the lowest grain size, the highest hardness and strength. Aging of 8Bc-processed UFG samples increases the hardness and strength of Cu-Cr-Zr alloy while retaining an electrical conductivity comparable to that of aged coarse-grained (CG) one. A satisfactory electrical conductivity of 71%IACS without considerable loss of peak hardness was achieved after aging of 8Bc-processed UFG alloy at 425. °C for 240. min. The precipitation strengthened UFG alloy remains its stable behavior at elevated temperatures up to 450. °C. © 2015 Elsevier B.V.

Aluminium metal matrix composites were processed by stir casting technique with commercially pure aluminium as the matrix material and 5, 10 vol.% of SiC (30 ?m) particulates as the reinforcement. Al-SiCp composites were subjected to severe plastic deformation through equal channel angular pressing (ECAP). As cast Al-SiCp composites shows uniform distribution of particles and there is no change in the particle distribution after ECAP. It was found that ECAP refines the grain size of matrix material. In Al-5 vol.% SiCp composite grain size was reduced to 8 ?m from 45 ?m after two ECAP passes whereas in Al-10 vol.% SiCp composite grain size was refined to 16 ?m from 45 ?m after first ECAP pass. Hardness and compression test were conducted at room temperature to evaluate the mechanical properties of the composites. Both the composites exhibit improvement in mechanical properties after ECAP. � 2009 Elsevier Ltd. All rights reserved.

Equal channel angular pressing (ECAP) is currently being widely investigated because of its potential to produce ultra-fine grained microstructures in metals and alloys. A sound knowledge of the plastic deformation and strain distribution is necessary for understanding the relationships between strain inhomogeneity and geometry of die. Considerable research has been reported on finite element analysis of this process, assuming 2D plane strain condition. The 2D models are not suitable due to the component geometry, especially for workpiece with cylindrical cross-section. In the present work 3D simulation of ECAP process was carried out, using ABAQUS/Standard software, for different channel angles for a strain hardening aluminium alloy (AA6101). Strain inhomogeneity is presented and discussed for all cases. Pattern of variation of strain along some selected radial lines in steady-state zone is presented. � 2008 Elsevier B.V. All rights reserved.

cited By 0; International audience; Low cost composite ceramics based on zircon-mullite-zirconia-alumina phases were prepared by reaction sintering of boehmite (AlOOH) and zircon (ZrSiO4) powders. Boehmite to zircon weight ratios of the starting powders were varied (10 to 90 wt. %). The green compacts were made by uniaxial pressing at 7 MPa followed by cold isostatic pressing at 250 MPa. A reactive sintering in air of these compacts was made at different temperatures between 1400 and 1600°C during 2 hours. A quantitative evaluation of the present phases was based on XRD. Dilatometric tests on the reaction-sintered composites were carried out in order to study the zirconia phase's transformations and their thermal expansion coefficient (α). In addition, the effects of both boehmite/zircon ratios and sintering conditions on the mechanical properties (Hardness Hv, Elastic modulus E and fracture toughness KIC) of the obtained composites were characterized by Vickers indentation. © Copyright 2015, The Australian Ceramic Society.

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 titanium was selected for the study. Tubular specimens were extruded to three passes using two processing routes through an ECAP die with an angle of 150 degrees between the two intersecting channels. Sand was used as a mandrel during the pressing. Analysis of force-stroke diagram was carried out, work from registered force-stroke diagram was calculated and compared with theoretical calculations. The mechanical properties and the microstructure were also investigated. To determine the influence of surface area to volume ratio of the specimens (referred to as the shape difficulty factor, SDF), data obtained in the current study on ECAP of tubular CP-Titanium was compared with data available in the literature on Hooker extrusion and conventional solid extrusion of CP-Titanium. Improvement in mechanical properties was observed in both the Routes. The grain size was reduced from similar to 18 mu m to similar to 12 mu m. 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. (c) 2005 Elsevier B.V. All rights reserved.

Equal-channel angular pressing (ECAP) is a prominent technique that imposes severe plastic deformation into materials to enhance their mechanical properties. In this research, experimental and numerical approaches were utilized to investigate the mechanical properties, strain behavior, and damage prediction of ECAPed 7025 aluminum alloy in various conditions, such as die channel angle, outer corner angle, and friction coefficient. Experimental results indicate that, after the first pass, the yield strength, ultimate tensile strength, and hardness magnitude are improved by approximately 95%, 28%, and 48.5%, respectively, compared with the annealed state, mainly due to grain refinement during the deformation. Finite element analysis shows that the influence of die channel angle is more important than that of outer corner angle or friction coefficient on both the strain behavior and the damage prediction. Also, surface cracks are the main cause of damage during the ECAP process for every die channel angle except for 90°; however, the cracks initiated from the neighborhood of the central regions are the possible cause of damage in the ECAPed sample with the die channel angle of 90°. © 2014, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Equal Channel Angular Pressing (ECAP) is currently being widely investigated because of its potential to produce ultrafine grained microstructures in metals and alloys. A sound knowledge of the plastic deformation and strain distribution is necessary for understanding the relationships between strain inhomogeneity and die geometry. Considerable research has been reported on finite element analysis of this process, assuming threedimensional plane strain condition. However, the two-dimensional models are not suitable due to the geometry of the dies, especially in cylindrical ones. In the present work, three-dimensional simulation of ECAP process was carried out for six outer corner radii (sharp to 10 mm in steps of 2 mm), with channel angle 105¶Çü▒, for strain hardening aluminium alloy (AA 6101) using ABAQUS/Standard software. Strain inhomogeneity is presented and discussed for all cases. Pattern of strain variation along selected radial lines in the body of the workpiece is presented. It is found from the results that the outer corner has a significant influence on the strain distribution in the body of work-piece. Based on inhomogeneity and average strain criteria, there is an optimum outer corner radius., {"references":["V. M. Segal, \"Material Processing by simple shear\", Mater. Sci. Eng. A\n197 (1995) 157-164.","V. M. Segal, \"Equal channel angular extrusion: from macromechanics to\nstructure formation\", Mater. Sci. Eng. A 271 (1999) 322-333.","Y. Iwahashi, J. Wang, Z. Horita, M. Nemoto, T. G. Langdon, \"Principles\nof equal channel angular pressing of ultra-fine grained materials\",\nScripta Mater. 35 (2) (1996) 143.","Yi-Lang, Shyong Lee, \"Finite element analysis of strain conditions after\nequal channel angular extrusion\", J. Mater. Tech. 140 (2003) 583-587.","S. Li, M. A. M. Bourke, I. J. Beyerlein, D. J. Alexander, B. Clausen,\n\"Finite element analysis of the plastic deformation zone and working\nload in equal channel angular extrusion\", J. Mater. Eng. A 382 (2004)\n217-236.","Hl-Heon Son, Jeong-Ho Lee, Yong-Taek Im, \"Finite element\ninvestigation of equal channel angular extrusion with back pressure\", J.\nMater. Process. Technol. 171 (2006) 480-487.","C. J. Luis-Perez, R. Luri-Irigoyen, D. Gaston-Ochao, \"Finite element\nmodeling of an Al-Mn alloy by equal channel angular extrusion\", J.\nMater. Process. Tech. 153-154 (2004) 846-852.","Raghavan Srinivasan, \"Computer simulation of the equal channel\nangular extrusion (ECAE) process\", Scripta Mater. 44 (2001) 91-96.","H. S. Kim, \"Finite element analysis of equal channel angular pressing\nusing a round corner die\", Mater. Sci. Eng. A 315 (2001) 122-128.\n[10] A. V. Nagasekhar and Yip Tick-Hon, \"Optimal tool angles for equal\nchannel angular extrusion of strain hardening materials by finite element\nanalysis\", Comp. Mater. Sci. 30(3-4) (2004) 489-495\n[11] H. S. Kim, M. H. Seo and S. I. Hong, \"Finite element analysis of equal\nchannel angular pressing of strain rate sensitive metals\", J. Mater.\nProcess. Tech. 130-131 (2002) 497-503\n[12] A. V. Nagasekhar, Y. Tick-Hon, S. Li and H. P. Seow, \"Effect of acute\ntool-angles on equal channel angular extrusion/pressing\", Mater. Sci.\nEng. A 410-411 (2005) 269-272.\n[13] Fuqian Yang, Aditi Saran, K. Okazaki, \"Finite element simulation of\nequal channel angular extrusion\", J. Mater. Process. Tech. 166 (2005)\n71-78.\n[14] S. C. Yoon, P. Quang, S. I. Hong, H. S. Kim, \"Die design for\nhomogeneous plastic deformation during equal channel angular\npressing\", J. Mater. Process. Tech. 187-188 (2007) 46-50\n[15] C. W. Su, L. Lu and M. O. Lai, \"3D finite element analysis on strain\nuniformity during ECAP process\", Mater. Sci. Tech. 23-6 (2007) 27-\n735.\n[16] Hong Jiang, Zhiguo Fan, Chaoying Xie, \"3D finite element simulation\nof deformation behavior of CP-Ti and working load during multi-pass\nequal channel angular extrusion\", Mater. Sci. Eng. A (2007).\n[17] Tao Suo, Yulong Li, Qiong Deng, \"Yuanyong Liu, Optimal pressing\nroute for continued equal channel angular pressing by finite element\nanalysis\", Mater. Sci. Eng. A 466 (2007) 166-171.\n[18] J. K. Kim, W. J. Kim, \"Analysis of deformation behavior in 3D during\nequal channel angular extrusion\", J. Mater. Process. Tech. 176 (2006)\n260-267.\n[19] ABAQUS User-s Manual, Version 6.5.1, Hibbitt, Karisson & Sorensen\n2006.\n[20] C. Xu, K. Xia and T. G. Langdon, \"The role of back pressure in the\nprocessing of pure aluminum by equal-channel angular pressing\", Acta\nMater., 55 (2007) 2351-2360\n[21] D. Nagarajan, \"Processing of an aluminium alloy by ECAE prior to cold\nextrusion\", M.S. Thesis, Indian Institute of Technology Madras, India,\n2005, 47.\n[22] Patil Basavaraj V. Uday Chakkingal, T.S. Prasanna Kumar, \"Study of\nchannel angle influence on material flow and strain inhomogeneity in\nequal channel angular pressing using 3D finite element simulation\", Jl.\nof Mater. Process. Tech. 209 (2009) 89-95."]}

Equal Channel Angular Pressing (ECAP) process is an important process for producing ultrafine-grained microstructures in bulk metals and alloys. In the present work, aluminum alloy AA 6063 samples were subjected to ECAP for up to three passes using an ECAP die with a die angle of 105�. The strain imparted to the specimen after three passes was approximately 2.64. Compression testing of the ECAP specimens was carried out to determine the subsequent flow behavior. Two types of compression test specimen orientations, one parallel to the axis of pressed sample and the other at 45� to the axis of the pressed sample, were used for the study. The strain path change (SPC) parameter was used to quantify the strain path change involved in straining by ECAP followed by straining by uniaxial compression. Higher flow strength values were observed in compression in specimens machined at 45� to the axis of the ECAP specimens. Flow softening and anisotropic behavior have been studied with respect to the number of passes and processing routes. � 2008 Springer Science+Business Media, LLC.