BUSCADOR RECOLECTA

Over these last few years, there has been a growing interest in developing mechanical components from submicrometric materials due to the significant improvement that these materials present compared to their original state. This present research work deals with the study of the mechanical properties of a connecting rod isothermally forged from different starting materials. These materials are as follows: annealed aluminum alloy (AA) 5754, the same alloy previously deformed through equal channel angular pressing (ECAP) and a third case where the previously ECAP-processed material is subjected to a recovery heat treatment. A comparison is made between finite volume (FV) simulations and experimental tests with respect to hardness, plastic strain and forging force. Furthermore, the improvement in the mechanical properties of the connecting rod forged from predeformed material is evaluated in comparison to the connecting rod forged with annealed material. The microstructure of both cases is also compared at the end of the manufacturing process., The authors acknowledge the support given by the Ministerio de Ciencia e Innovación (Spain) (Research Project: DPI2013-41954-P.

Ultrafine grained materials have a great deal of both scientific and technological interest because they allow outstanding properties
to be obtained. An improvement in the mechanical strength and in the ductility and a better fatigue behaviour are properties to
be expected with these materials. However, in spite of the great number of scientific publications that deals with the mechanical
property improvement, the number of practical applications of these materials is scant. In this present research work, equal channel
angular pressing (ECAP) is used as a severe plastic deformation process (SPD) to obtain billets which are subsequently isothermally
forged to obtain a connecting rod with submicrometric grain size. The optimization of the design process is shown as well as the
die design. The objective variables to be fulfilled are the correct filling of the die and the required force to obtain the part. Moreover,
a comparison is also included between the mechanical properties thus obtained and those obtained with traditional methods.
Moreover, optical and SEM micrographs are also included in this research work., The authors of this present research work acknowledge the support given by the Ministry of Science and Innovation from Spain (now Ministry of Economy and Competitiveness), through both the Research Project DPI2010-18941 and the Research Project DPI2013-41954-P.

The most important difficulties when the behaviour of a part that is subjected to external mechanical forces is simulated deal with the determination of both the material thermo-mechanical properties and its boundary conditions. The accuracy of the results obtained from the simulation is directly related to the knowledge of the flow stress curve. Therefore, the determination of a material flow rule which is valid for both a wide temperature range and different initial deformation conditions in the starting material presents a great deal of interest when simulation results close to the experimental values are required to be obtained. In this present study, a novel flow stress curve is proposed that is able to accurately predict the behaviour of both materials with no previous accumulated strain and materials that have been previously subjected to severe plastic deformation processes. Moreover, it is possible to use it both for hot and cold working. The results are analysed in a wide test temperature range, which varies from room temperature to 300 °C, and from material previously processed by angular channel extrusion or with no previous strain accumulated. It is shown that the flow rule proposed is effective to model the material behaviour in a wide temperature range and it makes it possible to take the recrystallization phenomena that appear in previously deformed materials into account. In addition, the results obtained are compared with those predicted by other flow rules that exist in the prior literature. Furthermore, the study is complemented with finite element simulations and with a comparison between simulation and experimental results., The authors acknowledge the support given by the Spanish Ministry of Economy and
Competitiveness under the research project DPI2013-41954-P.

This present research work deals with the development of ultrafine grained cams obtained from previously ECAP (Equal Channel Angular Pressing)-processed material and manufactured by isothermal forging. The design and the manufacturing of the dies required for the isothermal forging of the cams are shown. Optimization techniques based on the combination of design of experiments, finite element and finite volume simulations are employed to develop the dies. A comparison is made between the mechanical properties obtained with the cams manufactured from material with no previous deformation and with those from previously SPD (Severe Plastic Deformation)-processed material. In addition, a comparative study between the experimental results and those obtained from the simulations is carried out. It has been demonstrated that it is possible to obtain ultrafine grained cams with an increase of 10.3% in the microhardness mean value as compared to that obtained from material with no previous deformation., The authors of this present research work acknowledge the support given by the Spanish
Ministry of Economy and Competitiveness through the Research Project DPI2013-41954-P.

Trabajo presentado a The Manufacturing Engineering Society International Conference, MESIC 2015 (Barcelona), In the present study, the design of the dies required for the isothermal forging of a cam is analysed by finite volume method.
Specifically, cams are of great importance in automotive industry, where a lower weight and an improvement in the lubrication or
in the materials to be in contact lead to a significant reduction in the fuel cost.
The flow stress curves of one Al-Mg alloy were firstly determined by using compression tests. Once these flow stress curves
were obtained, FV simulation was employed. In the forging process, the optimum die configuration has been selected. To this
end, several aspects have been taken into account such as the force required for the forging, the correct die filling, the introduced
plastic strain and the damage imparted to the billet., The authors acknowledge the support given by the Spanish former Ministry of Economy and Competitiveness
under the research project DPI2013-41954-P.

Severe plastic deformation (SPD) processes have attracted a great deal of both scientific and technological interest over the last few years as a consequence of the improvements that are possible to obtain in the microstructure and mechanical properties of the materials manufactured through the use of these kind of processes. However, the practical applications of such materials to obtain mechanical components are significantly fewer. As a direct consequence, the same thing has been observed in the development of studies that show the in-service behaviour of the mechanical components developed in this way. Since one of the industrial objectives of these SPD processes is to obtain functional parts, it is necessary to carry out studies to fill this gap. Therefore, in this study, an analysis of the wear that cams undergo when manufactured from an AA5083 aluminium-magnesium alloy is carried out. The cams were isothermally-forged from materials with and without previous SPD processing by equal channel angular pressing (ECAP). Subsequently, the wear behaviour of these cams was analysed by using specific equipment, which may have been considered to have a block-on-ring configuration, developed for testing in-service wear behaviour of mechanical parts. From this comparative wear study with cams, it is shown that previously-processed materials by ECAP have a better wear performance. Moreover, finite element modelling (FEM) simulations were also included to predict wear in the cams processed in this way. A good agreement between FEM and experimental results was obtained. It is this aspect of performing the wear tests on functional and real mechanical components, and not on laboratory samples, which makes this present research work novel., This research was funded by the Spanish Ministry of Science and Innovation (former Spanish Ministry of Economy and Competitiveness) through the Research Project DPI2013-41954-P.

En la presente tesis doctoral se aborda el diseño de un componente mecánico con estructura submicrométrica, obtenido a partir de material previamente procesado mediante Deformación Plástica Severa (SPD) por Extrusión en Canal Angular Constante (ECAP). Esta tesis doctoral se ha desarrollado en el marco de las actividades llevadas a cabo en el Proyecto Nacional de Investigación (DPI 2013-41954-P). Para la realización de esta tesis doctoral, se va a emplear una nueva ley de fluencia y una metodología para obtener el daño crítico, que permita caracterizar el comportamiento de la AA5083, en el proceso de forja del componente mecánico. Mediante simulaciones por volúmenes finitos y por elementos finitos se va a diseñar un conjunto de matrices, para la fabricación del componente mecánico por forja isotérmica. Por último, se va a estudiar el daño por desgaste en funcionamiento del componente mecánico. Primeramente, se obtendrá mediante ensayos de fatiga la carga adecuada, para que el fallo en el componente se produzca por desgaste y no por fatiga. Y seguidamente se analizará su comportamiento en servicio. Los resultados obtenidos en esta tesis doctoral mostraron que el material con grano submicrométrico tiene por un lado, mejores propiedades mecánicas y por el otro, un mejor comportamiento en servicio., This present doctoral thesis deals with the design of a mechanical
component with submicrometric structure obtained from a material previously
processed by Severe Plastic Deformation (SPD), in this case, Equal Channel
Angular Pressing (ECAP). This doctoral thesis has been developed under the
framework of the activities carried out in the National Research Project DPI
2013-41954-P. In order to carry out this present doctoral thesis, a new flow rule
along with a new methodology so as to obtain critical damage are to be
employed, where this will allow the behaviour of AA5083 in the forging process
of the mechanical component to be characterized. Through both finite volume
and finite element simulations, a set of dies will be designed in order to
manufacture the mechanical component by isothermal forging. Finally, the
damage due to wear will be studied during the life of the mechanical
component. First, the adequate load will be obtained by fatigue tests so that the
failure in the component takes place due to wear and not due to fatigue.
Subsequently, life behaviour will be analysed. The results obtained in this
present doctoral thesis will show that the material with submicrometric grain
size has, on the one hand, better mechanical properties and, on the other hand,
a better life behaviour., Ministerio de Ciencia e Innovación, Proyecto Nacional de Investigación DPI2013-41954-P, Programa Oficial de Doctorado en Ingeniería de Materiales y Fabricación (RD 1393/2007), Materialen eta Fabrikazioaren Ingeniaritzako Doktoretza Programa Ofiziala (ED 1393/2007)

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., This research was funded by the Spanish Ministry of Science and Innovation (former Spanish Ministry of Economy and Competitiveness) through the Research Project DPI2013‐41954‐P.

Trabajo presentado a The Manufacturing Engineering Society International Conference, MESIC 2015 (Barcelona), This present research work deals with the analysis of the design of different specimen geometries so that by finite volume
simulations, the appearance of cracks may be predicted in the case of forging processes. To this end, each of the geometries
selected are studied by means of compression tests between plane shape dies in the same conditions (T = 25 ºC). On the one
hand, a value for the critical damage value is obtained by applying the Cockroft-Latham’s criterion and on the other hand, a
damage distribution along all the specimen volume with the aim of defining a specimen which shows the most likely place for the
crack to appear. This crack location may be also determined through visual inspection with the aim of being able to evaluate this
experimentally in the near future., The authors acknowledge the support given by the Spanish former Ministry of Economy and Competitiveness
under the research project DPI2013-41954-P.

Assessing the damage produced in plastic deformation processes permits the optimum manner to shape a material
that could avoid any cracks from appearing. In this present research work, the absolute critical damage in the
following aluminium alloys: AA5754, AA5083 and AA3103 is to be determined. In order to do this, compression
tests between plane-shape dies will be performed for the abovementioned alloys at a temperature range which
varies from 25 °C to 300 °C and using Cockroft–Latham's prediction model. Furthermore, the results obtained by
finite volume simulations will be compared with those obtained by experimental tests with isothermal upsetting.
Given that in these last few years there has been a growing interest in obtaining mechanical components from
submicrometric and/or nanometric structure materials which have been previously-processed by severe plastic
deformation (SPD), this present research work deals with the determination of absolute critical damage for the
abovementioned alloys once they have been ECAP (Equal Channel Angular Pressing) processed. This is considered
to be of interest since it could allow the prediction of optimal processing conditions in advance., The authors of this present research work acknowledge the support given by the Spanish Ministry of Economy and Competitiveness through the Research Project DPI2013-41954-P.

Over the last few years there has been an increasing interest in the study and development
of processes that make it possible to obtain ultra-fine grained materials. Although there exists
a large number of published works related to the improvement of the mechanical properties in
these materials, there are only a few studies that analyse their in-service behaviour (fatigue and
wear). In order to bridge the gap, in this present work, the fatigue and wear results obtained for
connecting rods manufactured by using two different aluminium alloys (AA5754 and AA5083)
previously deformed by severe plastic deformation (SPD), using Equal Channel Angular Pressing
(ECAP), in order to obtain the ultrafine grain size in the processed materials are shown. For both
aluminium alloys, two initial states were studied: annealed and ECAPed. The connecting rods were
manufactured from the previously processed materials by using isothermal forging. Fatigue and wear
experiments were carried out in order to characterize the in-service behaviour of the components.
A comparative study of the results was made for both initial states of the materials. Furthermore,
Finite Element Modelling (FEM) simulations were used in order to compare experimental results
with those obtained from simulations. In addition, dimensional wear coefficients were found for
each of the aluminium alloys and initial deformation states. This research work aims to progress the
knowledge of the behaviour of components manufactured from ultrafine grain materials., The authors of this present research work acknowledge the support given by the Spanish
Ministry of Economy, Industry and Competitiveness (former Spanish Ministry of Economy and Competitiveness)
through the Research Project DPI2013-41954-P.

In this research work, a study on the mechanical properties of isothermal forging for connecting rods is
made from previously ECAP (Equal Channel Angular Pressing)-processed AA1050 and AA5083 aluminium
alloys. This severe plastic deformation (SPD) process is used in order to achieve a starting material with
a submicrometric structure, thus improving the mechanical properties of the part. In this study, the
design and the experimentation process is shown, where this involves the design stage by finite element
simulations, the experimental tests and the use of metallographic techniques for the required properties
to be analysed. Itis observed thatthere is an improvementin the mechanical properties when the starting
material is ECAP-processed before carrying out the isothermal forging. This improvement consists in an
increase of 20% in the hardness of the final connecting rod which also possesses a microstructure grain
size of 500 nm. To come to these conclusions,the results obtained with the connecting rods manufactured
by isothermal forging from previously ECAP-processed material are compared with those conventionally
manufactured. Therefore,the feasibility and the advantages ofthe industrialmanufacturing ofmechanical
components by isothermal forging from ECAP-processed material are demonstrated here as mechanical
properties are achieved, as well as a better flow of the material and at a lower forging temperature. In
the existing bibliography, there are no research works dealing with the manufacturing of connecting
rods from ultra-fine grained material and that is the reason why this present study is considered to be of
scientific and technological interest, and therefore, it may be considered to be at the frontline of current
knowledge., The authors of this present research work acknowledge the support given by the Ministry of Economy and Competitiveness from Spain, through the Research Projects DPI2010-18941 and DPI2013-41954-P.