Jesus Ruiz-Hervias

Jesus Ruiz-Hervias
Universidad Politécnica de Madrid | UPM · Departamento de Ciencia de los Materiales

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75
Publications
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697
Citations

Publications

Publications (75)
Article
The purpose of this paper is to investigate the relationship between hydride morphology, in particular the presence of radial hydrides (RHs), stress state and failure mechanisms associated with the ring compression test (RCT). Samples of ZIRLO® cladding were pre-hydrided and subjected to thermo-mechanical treatments to precipitate long radial hydri...
Chapter
Residual stresses can be induced by fabrication processes and service conditions that lead to non-uniform deformations. In the standard test method for residual stress analysis by x-ray diffraction (EN 15305), the validation is done by using reference specimens with known normal residual stress. However, the method also stablishes restrictions to t...
Poster
Full-text available
Industrial and manufacturing processes, as rolling, extrusion, forging, drawing, coating… modify material properties. Mechanical and fracture magnitudes of the final product are different than raw material. In situ material characterization is a challenge task to know the real material properties of a product in its final state in components which...
Article
During some operations previous to the dry storage, which involve high temperature and hoop stress on the cladding, a part of the hydride platelets may precipitate along the radial direction. As a consequence, cladding embrittlement may occur. In this paper, the experimental techniques developed for the authors to produce hydride reorientation in u...
Article
Full-text available
This paper presents an original procedure to determine the softening curve in concrete from a diametric Brazilian test and a three point bend test. An inverse procedure is proposed combining experimental results, numerical finite element computation and an iterative algorithm, called algorithm AMS-UPM, developed expressly for this research. The sta...
Article
Full-text available
Tensile stress-strain curve of metallic materials can be determined by the representative stress-strain curve from the spherical indentation. Tabor empirically determined the stress constraint factor (stress CF), ψ , and strain constraint factor (strain CF), β , but the choice of value for ψ and β is still under discussion. In this study, a new ins...
Article
In this work, the hoop fracture toughness of ZIRLO® fuel cladding is calculated as a function of three parameters: hydrogen concentration, temperature and displacement rate. To this end, pre-hydrided samples with nominal hydrogen concentrations of 0 (as-received), 150, 250, 500, 1200 and 2000 ppm were prepared. Hydrogen was precipitated as zirconiu...
Article
The geometry of the nuclear fuel cladding (thin-walled tube) makes it difficult to obtain its hoop mechanical properties. A new procedure is devised to obtain the constitutive equation of nuclear fuel cladding along the hoop direction from ring compression tests. The method combines experimental results, finite element simulations and an original i...
Article
It is well known that the presence of hydrides in nuclear fuel cladding may reduce its mechanical and fracture properties. This situation may be worsened as a consequence of the formation of hydride blisters. These blisters are zones with an extremely high hydrogen concentration and they are usually associated to the oxide spalling which may occur...
Article
A series of Al2O3/Y2O3-stabilized zirconia (Y-TZP) ceramic composites with different zirconia contents (5 and 40 vol% Y-TZP) and fabricated by different green processing techniques (a novel tape casting and conventional slip casting) were studied. The microstructure and mechanical properties of the composites were investigated systematically, by me...
Conference Paper
Full-text available
An original procedure to determine the softening curve in concrete has been proposed by the authors. This inverse method combines experimental results, finite element simulations and an iterative algorithm to adjust the experimental data. The end product of the process is a softening curve that allows us to very accurately reproduce the experimenta...
Article
In this study, an Inconel 625-Cr3C2 cermet coating was deposited on a steel alloy by laser cladding. The elastic and plastic mechanical properties of the cermet matrix were studied by the depth sensing indentation (DSI) in the micro scale. These results were compared with those obtained from an Inconel 600 bulk specimen. The values of Young's modul...
Article
Full-text available
Residual stress measurements were conducted by time-of-flight neutron diffraction and Rietveld analysis method in Al2O3/Y-TZP ceramic composites fabricated by different green processing techniques (a novel tape casting and conventional slip casting) and with different Y-TZP content (5 and 40vol.% Y-TZP). The results show that the residual stresses...
Conference Paper
The ring compression test applied to nuclear fuel cladding is relatively easy to perform but difficult to interpret. It can be representative of the loading state associated to a hypothetical spent fuel assembly drop accident. This is particularly important for spent fuel cladding subjected to drying operations previous to storage and transportatio...
Article
Full-text available
Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of residual stresses induced by machining in Inconel 718 under static loading at ro...
Article
Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loadi...
Article
Full-text available
Residual strain profiles were measured by neutron diffraction in alumina-aluminum titanate ceramic composites sintered at two different temperatures, namely 1450 and 1550°C. The results show that irrespective of the direction and the sintering temperature, the obtained profiles are almost flat, with very similar results for both temperatures. In ad...
Article
It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium pl...
Article
The main objective of the present investigation was to assess the constitutive behaviour of the graded structures produced by laser shock processing (LSP) on laser welded joints made between thin sheets of ferritic and austenitic stainless steel. First, the evolution of surface strain patterns during uniaxial loading of the as welded and LSP treate...
Article
Full-text available
In this work, autogenous laser welding was used to join thin plates of low carbon ferritic and austenitic stainless steel. Due to the differences in the thermo-physical properties of base metals, this kind of welds exhibit a complex microstructure, which frequently leads to an overall loss of joint quality. Four welded samples were prepared by usin...
Article
In this work, a new methodology is devised to obtain the fracture properties of nuclear fuel cladding in the hoop direction. The proposed method combines ring compression tests and a finite element method that includes a damage model based on cohesive crack theory, applied to unirradiated hydrogen-charged ZIRLOTM nuclear fuel cladding. Samples with...
Article
Full-text available
This paper addresses several peculiar properties of ferritic/austenitic welded joints (Black and White Joints-BWJ) of thin sheets, which are emerging nowadays due to cost saving and satisfactory service performance. Starting from 3D thermal field modelling approached by considering Goldak’s double ellipsoidal heat source, together with a contributi...
Article
In this paper, the experimental techniques employed to reproduce in the laboratory the distribution and morphology of the hydrides during the different steps of the nuclear fuel cycle are reported. A cathodic charging technique was employed to produce ZIRLO cladding samples with an homogeneous distribution of hydrides and concentrations of 150, 250...
Article
It is known that the mechanical properties of nuclear fuel cladding are affected by the presence of hydrides. A number of studies have been devoted to the measurement of the average mechanical properties of the zirconium matrix and the hydrides from a macroscopic point of view. In this paper, nanoindentation techniques were employed to determine th...
Article
The present investigation addresses the mechanical behavior and residual stress field of dissimilar joints produced by laser welding. Microstructure characterization and residual strain scanning, carried out by neutron diffraction, were used to assess the joints features. It was found that the heat source position influences the base metals dilutio...
Article
The paper presents some preliminary results of an ongoing research intended to qualify a highly resistant duplex stainless steel wire as prestressing steel and, gets on insight on the wires fracture micromechanism and residual stresses field. SEM fractographic analysis of the stainless steel wires indicates an anisotropic fracture behavior in tensi...
Article
The method reported in the literature to calculate the stress–strain curve of nuclear fuel cladding from ring tensile test is revisited in this paper and a new alternative is presented. In the former method, two universal curves are introduced under the assumption of small strain. In this paper it is shown that these curves are not universal, but m...
Article
Residual stresses developed during wire drawing influence the mechanical behavior and durability of steel wires used for prestressed concrete structures, particularly the shape of the stress–strain curve, stress relaxation losses, fatigue life, and environmental cracking susceptibility. The availability of general purpose finite element analysis to...
Article
The structural integrity of nuclear fuel cladding is affected by the precipitation of hydrides during operation, which may embrittle the cladding. The aim of this work is to obtain the mechanical and fracture properties of the cladding as a function of the hydrogen content and testing temperature. To this end, the embrittlement caused by circumfere...
Article
The paper addresses the fracture propagation and stress corrosion behaviour of laser hybrid welds achieved between low carbon steel and stainless steel thin sheets. The crack propagation within these overmatched in strength welds was investigated by crack tip opening displacement (CTOD) on CT specimens notched transverse to the weld. A Digital Imag...
Article
Full-text available
Residual strains were measured in the ferrite phase of pearlitic steel rods along the radial, axial and hoop directions. Two samples with different initial diameters were subjected to one drawing pass (using same drawing parameters) with 20% section reduction and measured in two different neutron diffraction instruments. The results show that the r...
Article
Cold-drawn steel rods and wires retain significant residual stresses as a consequence of the manufacturing process. These residual stresses are known to be detrimental for the mechanical properties of the wires and their durability in aggressive environments. Steel makers are aware of the problem and have developed post-drawing processes to try and...
Article
The effects of changes in the temperature and the stretching levels of the stress-relieving treatments of prestressing steel wires are discussed. Five industrial treatments, in the range of the commercial stabilizing of prestressing wires, are studied, combining three temperatures and three stretching force levels. After the treatments, mechanical...
Article
The paper addresses the influence of the structural heterogeneities on the overall mechanical performance of dissimilar joints made of carbon steel (CS) and stainless steel (SS). Optical microscopy and microhardness measurements were used to characterize the inhomogeneous welded joint. Microhardness determination provided an alternative and efficie...
Article
The investigation addresses the overall performance of black and white joints (BWJ) of low carbon steel (LCS) and stainless steel thin sheets achieved by laser hybrid welding. Assuming that the structural integrity is directly influenced by the processing temperature, a thermal simulation of BWJ of thin sheets was developed. Afterwards, the base me...
Chapter
Residual strain profiles were measured by synchrotron X-ray radiation in Al(2)O(3)/Y-stabilized ZrO(2) (YSZ) ceramic laminates. Different stacking sequences were employed, including alternating layers containing 5 and 40 vol.% YSZ. Residual strains were found to be fairly constant within each layer; although they change at the interface between lay...
Article
This work shows the effect of the initial residual stress state on the stress relaxation behavior of cold-drawn steel rods. The evolution of residual strains at several locations along the rod diameter was measured in-situ by neutron diffraction during a stress relaxation experiment. It was found that if residual stresses are significant, stress re...
Article
This paper presents the performances of an original longitudinal magnetization system, designed to assure the magnetic flux concentration on the tube wall. This magnetization system is made of several small peripheral solenoids disposed around each tube, parallel to the tube axis, and was used to investigate the interaction between the arc and the...
Article
The paper addresses the temperature field prediction of dissimilar joints of low carbon steel and stainless steel achieved by SMAW (MMAW) and TIG welding. Thermal field modelling is approached by considering the authors' contribution related to weld pool shape coefficients. Infrared thermography temperature measurements were used to validate the FE...
Article
The investigation addresses the mechanical performance and stress corrosion behaviour of dissimilar joints of low carbon steel and stainless steel thin sheets achieved by laser hybrid welding. The micro-hardness test was used as an alternative method to estimate the changes in mechanical properties of the different regions of the joint (elastic mod...
Article
Full-text available
The effect of hydrides on the mechanical behaviour of the zirconium-alloy cladding employed as nuclear fuel barrier was studied in this paper. Ring tensile tests were performed on samples with different hydrogen concentrations and a 3D finite element model was developed to simulate the test. Hydrides were introduced by cathodic charging with hydrog...
Article
The paper approaches the behaviour of AA6061-T4 cold rolled vs. as cast, both processed by Friction Stir technique. This was assessed by using microstructural analysis, HV microhardness tests and residual stresses measurements. The transversal compressive residual stresses found on the processed layer are obtained by using the "cold working" Fricti...
Conference Paper
The structural integrity of hydrogen charged zircaloy cladding was studied in this paper. Ring tensile tests were performed on samples with different hydrogen concentrations, and a 3D finite element model was developed to simulate the test. The results show that the mechanical properties in the hoop direction do not depend very strongly on the hydr...
Article
The mechanical properties and the durability of cold-drawn eutectoid wires (especially in aggressive environments) are influenced by the residual stresses generated during the drawing process. Steelmakers have devised procedures (thermomechanical treatments after drawing) attempting to relieve them in order to improve wire performance. In thiswork...
Article
Residual stress profiles were measured by neutron diffraction in AI(2)O(3)/Y-TZP ceramic composites containing 5 and 40 vol.% Y-TZP fabricated by conventional slip casting and by a novel tape casting route. Residual stresses in the zirconia are tensile and increase as its volume fraction decreases. For the alumina matrix, residual stress is compres...
Article
Full-text available
Cold-drawing is employed to fabricate wires and rods, which are mainly used as structural reinforcements in construction as well as in the tyre industry. As a consequence of processing, a residual stress profile is developed. In this paper, residual stress profiles are measured by neutron diffraction in cold-drawn pearlitic steel rods subjected to...
Article
The experimental and numerical difficulties, limitations of different techniques and interpretation of the measurements of residual stress distribution are examined to improve the performance of the cold drawn eutectoid steel wires. The residual stress profile was measured by neutron, synchrotron, and X-ray diffraction, and also numerical simulatio...
Article
En este artículo se resume el trabajo desarrollado por los autores durante estos últimos años para mejorar el comportamiento de las armaduras activas del hormigón pretensado mediante el control de sus tensiones residuales. En esta primera parte se examinan las técnicas de caracterización de dichas tensiones, sus dificultades y limitaciones, así com...
Article
En este artículo se resume el trabajo desarrollado por los autores durante estos últimos años para mejorar el comportamiento de las armaduras activas del hormigón pretensado mediante el control de sus tensiones residuales. En esta segunda parte se analiza la influencia que tienen las tensiones residuales en las tres propiedades mecánicas básicas pa...
Article
Full-text available
Currently, after appropriate heat treatments, the 6xxx aluminium alloys are used in a variety of applications including aircraft fuselage skins and automobile body panels and bumpers, instead of more expensive 2xxx or 7xxx alloys. The paper presents the results of the residual stress analysis in case of Friction Stir Processing - FSP of AA6061-T4 p...
Article
Residual stresses associated with cold-drawing influence the mechanical properties of steel wires. This paper summarizes the work carried out by the authors in attempting to improve the performance of such wires based on residual stress control. The possibilities of residual stress characterization were discussed in the first part, a paper presente...
Article
A good correlation was found between residual longitudinal stresses and times to rupture in the stress corrosion test proposed by the International Federation of Prestressing. Important differences in rupture times can be achieved in cold-drawn pearlitic wires by changing their profiles of residual stresses, specially at the wire surface. All these...
Article
Prestressing steel wires have excellent mechanical properties but there is a need to improve their durability in aggressive environments. In this work, the influence of residual stresses on the environmentally assisted cracking of these wires is studied. A good correlation has been found between residual stresses at the surface of the wires and the...
Article
Cold-drawing is employed to fabricate wires and rods, which are mainly used as structural reinforcements in construction as well as in the tyre industry. As a consequence of processing, a residual stress profile is developed. The wires are subjected to post-drawing thermo-mechanical treatments with the aim of improving their durability and stress r...
Article
The development of residual stresses in two Al2O3+5vol.% yttria-tetragonal zirconia polycrystal (Y-TZP) ceramic composites fabricated by conventional slip casting and by joining green cast tapes was investigated. Neutron diffraction profiles revealed compressive microstresses (−200MPa) in the Al2O3 matrix and tensile ones (2200MPa) in the Y-TZP par...
Article
Neutron strain scanning measurements on a eutectoid steel rod that has been subjected to standard industrial coiling and straightening operations are presented. Strains were determined non-destructively using two different diffractometers, one at a steady-state neutron source and the other at a pulsed spallation neutron source, with measurements ma...
Article
Residual stress profiles in the three principal directions in a cold-drawn pearlitic rod were calculated by a three-dimensional finite element simulation and measured by synchrotron X-ray diffraction. It has been shown that anisotropy of cold-drawn pearlite has to be considered for accurate simulations of residual stresses of steel wires.
Article
Residual stress profiles have been measured in the ferrite and cementite phases of a cold-drawn eutectoid steel rod by neutron and synchrotron X-ray diffraction in three orientations (axial, radial and hoop). Neutron diffraction was employed to measure the ferrite stresses, whereas synchrotron radiation was used for ferrite and cementite stresses....
Article
En esta tesis doctoral se investiga el comportamiento mecánico de una aleación al-zn-mg (aa 7017-t651) fabricada por laminación, cuando se encuentra sometida a fatiga en presencia de ambientes gaseosos con un contenido variable de humedad. Para llevar a cabo la investigación se ha diseñado una cámara de ensayos de ultra alto vacío, que permite cont...
Article
Resumen. La corrosión bajo tensión de las armaduras activas está generando problemas de durabilidad en las estructuras pretensadas construidas en la proximidad de ambientes agresivos. En este trabajo se pone de manifiesto la influencia que tienen las tensiones residuales producidas por el proceso de conformado (trefilado) en la fragilización por hi...
Article
Full-text available
RESUMEN El objetivo de la presente comunicación es presentar un nuevo procedimiento que permite determinar la curva tensión deformación plástica de un material a partir de un ensayo de compresión diametral. El método combina los resultados experimentales del ensayo de compresión diametral, cálculos numéricos por elementos finitos y un algoritmo ite...
Article
Full-text available
RESUMEN En este artículo se ha estudiado, mediante el ensayo de compresión diametral (RCT), el comportamiento mecánico y en rotura de vainas de combustible nuclear de ZIRLO TM hidruradas. El hidrógeno se introdujo en las muestras mediante carga catódica y se precipitó en forma de hidruros circunferenciales mediante un tratamiento térmico. Los ensay...
Article
The investigation addresses the overall performance of black and white joints (BWJ) of low carbon steel and stainless steel thin sheets achieved by laser hybrid welding. First, thermal field modelling is carried out by considering Goldak's double ellipsoidal heat source model, together with a contribution of the authors related to the shape coeffic...
Article
En la última década, la Comisión 9 de la fib, encargada de todo lo relativo a los materiales y sistemas de pretensado, ha dedicado una gran atención a la mejora de la durabilidad de las estructuras pretensadas. Uno de los aspectos que ha considerado de especial interés es el control del estado de tensiones residuales que presentan las armaduras act...

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