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Sample records for acero inoxidable aisi

  1. "CARACTERIZACIÓN Y PROPIEDADES MECANICAS DE LA SOLDADURA DE UN ACERO INOXIDABLE FERRIRICO AISI 430"

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    Moreno Rodríguez, Arturo

    2012-01-01

    En la presente trabajo se investiga la soldabilidad del acero inoxidable ferrítico AISI 430. Las propiedades mecánicas y la microestructura se relacionan con las variables operativas del proceso de soldadura, de ahí que jueguen un papel importante para lograr óptimas propiedades. Buscando la mejora de las propiedades mecánicas de las uniones soldadas, posteriormente, se les aplicó un tratamiento térmico post-soldadura. Las uniones se realizaron mediante el proceso de soldadu...

  2. Comportamiento electroquímico de un acero inoxidable AISI 430 implantado con cerio

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    Abreu, C. M.

    2002-10-01

    Full Text Available Chemical treatment in solutions containing cerium compounds has been widely used for prevention of localized corrosion in aluminium alloys (pitting corrosion as well as in stainless steels (crevice corrosion. Ionic implantation presents several advantages for stainless steels. The present paper is devoted to study the effect of cerium implantation on the properties of passive films formed on an AISI 430 stainless steel in alkaline medium. The electrochemical study is performed by cyclic voltammetry and EIS. The chemical characterisation of the oxides film developed is performed by XPS, and the morphological study corresponds to SEM examination. The results show that cerium implantation hinders magnetite formation as well as chromium oxidation processes.

    En los últimos años, se ha extendido el uso de disoluciones de sales de cerio como tratamiento para mejorar la resistencia localizada de las aleaciones de aluminio y para incrementar la resistencia a la corrosión en resquicio de diversos aceros inoxidables. En el caso de estos últimos, la adición de cerio mediante implantación iónica supone notables ventajas con respecto a otros tratamientos. En este artículo se investiga el efecto que ejerce la implantación de cerio sobre la película pasivante de un acero inoxidable ferrítico AISI 430. Para ello, se analiza el comportamiento electroquímico en medio básico mediante la utilización de voltametría cíclica y espectroscopia de impedancia electroquímica. La caracterización química de la película de óxidos formada se realiza mediante XPS, y el estudio morfológico mediante SEM. Los resultados muestran una importante inhibición en la formación de magnetita, así como una reducción en el proceso de oxidación que experimenta el cromo en el acero implantado con cerio.

  3. Evaluación del grado de sensibilización en el acero inoxidable AISI

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    González, O.

    2003-12-01

    Full Text Available Austenitic stainless steel, when heat-treated at 550-850 °C, became susceptible to intergranular corrosion in acids. This phenomenon, know as sensitization, it is result from the precipitation of chrome carbides in the grain boundary, making these areas less resistant to corrosion. Two different electrochemical reactivation tests are compared with a destructive test and related to the classification of its respective microstructures. It was established a quantitative methodology to evaluate the degree of sensitization in AISI 304 and also to compare the correspondence of the results with the data of the automatic and portable EPR device for non-destructive field measurement of the degree of sensitization. The used electrochemical techniques were the EPR (Electrochemical Potentiokinetic Reactivation or single loop test and the PRP (Pasivation Reactivation Potentiokinetic or double loop test. The destructive test used was boiling, 120 h ferric sulfate-50 % sulfuric acid, according to the standard practices ASTM A-262 practices B. The classifications of each structures were according to the standard practices ASTM A-262 practices B.

    El acero inoxidable austenítico, cuando se calienta en un rango de temperatura entre 550 y 850 °C es susceptible a corrosión intergranular en ácidos. Este fenómeno, conocido como sensibilización, es resultado de la precipitación de carburos de cromo en el límite de grano, haciendo esas áreas menos resistentes a la corrosión. Se comparan dos pruebas diferentes de reactivación electroquímica con una prueba destructiva, relacionándolas con su respectiva microestructura. Se estableció una metodología cuantitativa para evaluar el grado de sensibilización del acero AISI 304 y se comparó con los datos generados de una herramienta no destructiva de campo, automática y portátil, para medir el grado de sensibilización. Las técnicas electroquímicas usadas fueron: la EPR (Reactivación electroqu

  4. Tratamiento térmico del acero inoxidable ferrítico AISI 430L sinterizado en atmósfera de N2-H2

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    Ruiz-Prieto, J. M.

    2005-12-01

    Full Text Available In this Work the influence of sintering AISI 430L stainless steel in N2-H2 atmosphere on its properties and microstructure have been studied. The presence of nitrogen in the sintering atmosphere leads to complex nitrides formation the AISI 430L sintered steel microstructure. A subsequent heat treatment was applied to modify this microstructure in order to improve the mechanical properties and corrosion resistance of these ferritic stainless steels.Los aceros inoxidables ferríticos, son aceros que contienen esencialmente cromo (12-30 % junto con níquel y molibdeno en cantidades que, en general, no sobrepasan el 1 % y, en ocasiones, se les adicionan otros elementos como son el aluminio, silicio, titanio o niobio. En el presente trabajo de investigación se ha evaluado la influencia del nitrógeno presente en la atmósfera de sinterización sobre la microestructura y propiedades del acero inoxidable ferrítico AISI 430L. Además, se ha realizado un tratamiento térmico posterior de hipertemple y maduración con el objeto de incrementar las propiedades mecánicas y a corrosión de este acero inoxidable, mediante la modificación microestructural de los nitruros complejos de hierro y cromo precipitados durante la etapa de sinterización.

  5. Vida a la fatiga de juntas soldadas del acero inoxidable AISI 316L obtenidas mediante el proceso GMAW

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    Puchi-Cabrera, E. S.

    2007-06-01

    Full Text Available An investigation has been conducted in order to determine the effect of both the metallic transfer mode (pulsed arc or short circuit and the O2 content in the Ar/O2 gas mixture, of the gas-metal arc welding process (GMAW, on the fatigue life under uniaxial conditions of welded joints of 316L stainless steel. It has been concluded that the mixture of the protective gases employed in the process could have an important influence on the fatigue life of the welded joints of such steel in two different ways. Firstly, through the modification of the radius of curvature at the joint between the welding toe and the base metal and, secondly, through a more pronounced degree of oxidation of the alloying elements induced by a higher O2 content in the mixture. As far as the metallic transfer mode is concerned, it has been determined that the welded joints obtained under a pulsed arc mode show a greater fatigue life in comparison with the joints obtained under short circuit for both gas mixtures.

    Se ha llevado a cabo una investigación con la finalidad de determinar el efecto, tanto del modo de transferencia metálica (arco pulsado o cortocircuito como del contenido de O2 en la mezcla de gases protectores Ar/O2, del proceso de soldadura a tope mediante arco metálico con protección gaseosa (GMAW, sobre la vida a la fatiga en condiciones uniaxiales de juntas soldadas del acero inoxidable AISI 316L. Dicho trabajo ha permitido concluir que la composición de la mezcla de gases protectores del proceso GMAW pudiera tener una influencia importante en la vida a la fatiga de las juntas soldadas de dicho material, a través de dos formas distintas: primero, mediante la modificación del radio de curvatura entre la raíz del cordón de soldadura y el metal base y, en segundo lugar, a través del mayor grado de oxidación de los elementos de aleación. En cuanto al modo de transferencia metálica, se determinó que las juntas soldadas mediante arco pulsado

  6. Estudio de la influencia microbiológica en la corrosión de latones (UNS C68700, UNS C443 y acero inoxidable AISI 316;

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    Ohanian, Mauricio

    2014-06-01

    Full Text Available Microorganisms may play an important role in the corrosion process and generate conditions which affect the rate and/or the mechanism of deterioration. They become visible by the formation of biofilms: clusters of microorganisms and extracellular polymers. These biofilms affect not only the durability of the material, but also reduce the heat transfer. The present work studied the growth of aerobic and anaerobic heterotrophic microorganisms and sulfate reducing bacteria on aluminum brass (UNS C68700, admiralty brass (UNS C443 and stainless steel AISI 316 in exposure experiments held in the Bay of Montevideo (Uruguay. The influence of the biofilm growth on the corrosion behavior was studied by electrochemical techniques: polarization curves and Electrochemical Impedance Spectroscopy (EIS. The selection of the most suitable material for the exposure conditions is discussed and hypotheses of the corrosion mechanism are presented. Although stainless steel AISI 316 presented the lowest corrosion rate it showed localized deterioration.Los microorganismos influyen de manera significativa en el proceso corrosivo y generan condiciones que afectan la velocidad y/o el mecanismo de deterioro. Su presencia se manifiesta por la formación de bio-películas: conglomerados de bacterias y polímeros extracelulares. Dichas bio-películas afectan la durabilidad del material, la velocidad de flujo y la transferencia de calor. En el presente trabajo se evalúa el crecimiento de microorganismos heterótrofos aerobios, heterótrofos anaerobios y bacterias sulfato-reductoras sobre latón aluminio (UNS C68700, latón almirantazgo (UNS C443 y acero inoxidable AISI 316. Asimismo, se estudia la influencia del crecimiento de la bio-película sobre el comportamiento corrosivo mediante técnicas electroquímicas: curvas de polarización y espectroscopia de impedancia electroquímica. Las exposiciones se realizan en la Bahía de Montevideo, estuario del Río de la Plata

  7. Estudio de impedancia de la corrosión del acero inoxidable AISI 316L en las regiones pasiva y de picadura

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    Polo Sanz, José Luis

    1999-12-01

    Full Text Available Impedance measurements were performed on an AISI 316L stainless steel immersed in a 5% NaCl solution at room temperature. Some samples were polarized up to the passive and pitting regions, respectively. The Nyquist plots in the rest potential and in the passive region show high impedance with capacitive behaviour. The impedance diagram in the pitting region shows three loops: a capacitive loop at high frequencies, a loop with inductive effects at intermediate frequencies, and a second capacitive response at low frequencies. To validate the impedance data Kramers-Kronig relations were applied in the pitting región.

    Se estudia la corrosión del acero inoxidable AISI 316L en solución de NaCl al 5% y a temperatura ambiente, utilizándose probetas polarizadas hasta las regiones pasiva y de picadura. Se obtuvieron diagramas de impedancia en el potencial de corrosión y en esas dos regiones. Los diagramas de impedancia en el potencial de corrosión y en la región pasiva muestran comportamiento capacitivo. En la región de picadura los diagramas de impedancia presentan tres bucles capacitivos: un bucle capacitivo a altas frecuencias, un bucle con efectos inductivos a frecuencias intermedias y un segundo bucle capacitivo a bajas frecuencias. Se aplicaron las transformadas de Kramers-Kronig a los resultados de impedancia obtenidos en la región de picadura.

  8. CATALIZADOR ESTRUCTURADO DE Pt/Al2O3 SOBRE UNA ESPUMA DE ACERO INOXIDABLE (AISI 314 PARA LA OXIDACIÓN DE CO

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    Juan P. Bortolozzi

    2011-01-01

    Full Text Available Se obtuvo un catalizador estructurado por recubrimiento de Pt/Al2O3 sobre las paredes de una espuma de acero inoxidable AISI 314. Para estabilizar térmicamente e incrementar la rugosidad de la superficie de la espuma original se realizó un tratamiento a 900°C por 2 h. El soporte, Al2O3, y el metal activo, Pt, se incorporaron por inmersión. Las técnicas de caracterización aplicadas, XRD, LRS y SEM-EDX, permiten concluir que el tratamiento térmico previo indujo la formación de óxido de cromo y de las espinelas Mn1+xCr2-xO4-x y FeCr2O4 como fases principales en las paredes del sustrato. El espesor de la capa formada es cercano a 1 μm y los cristales producidos tienen forma octaédrica. El cubrimiento de alúmina presentó en general una apariencia homogénea, sin interacción con los óxidos formados durante el tratamiento. El Pt se distribuyó de manera uniforme, resultando un catalizador muy activo para la reacción test elegida: oxidación de monóxido de carbono.

  9. Decapado del acero inoxidable AISI 316L utilizando una mezcla ecológica de H2O2-H2SO4-HF

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    Gómez, P. P.

    2005-12-01

    Full Text Available This study reports the pickling of austenitic AISI 316L stainless steel (SS using a mixture of hydrogen peroxide (H2O2, sulphuric acid (H2SO4 and hydrofluoric acid (HF at pH 2.0. The stability of H2O2 was also studied using different concentrations of ferric ion from 0 to 40 g/l and temperature from 25 to 60 °C. The pickling rate at 50 °C in the presence and absence of 40 g/l ferric ion was 2.6 and 0.2 mg/dm2 day (mdd, respectively. p-Toluene sulphonic acid was used as stabilizer of H2O2.En la presente investigación se estudia el decapado del acero inoxidable AISI 316L utilizando una mezcla de agua oxigenada (H2O2 y los ácidos sulfúrico (H2SO4 y fluorhídrico (HF a pH 2,0. La estabilidad de la mezcla H2O2-H2SO4-HF se ha ensayado variando el contenido de iones férrico de O a 40 g/l y la temperatura de 25 a 60 °C. La velocidad de decapado a 50 °C ha sido de 2,6 y 0,2 mg/dm2 día (mdd, en ausencia y presencia de 40 g/l de iones férrico, respectivamente. Se ha utilizado el ácido p-toluen sulfónico como estabilizante del H2O2.

  10. Transformaciones Microestructurales en Soldaduras Disímiles de Acero Inoxidable Austenítico con Acero Inoxidable Ferrítico

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    Sara María Aguilar-Sierra; Claudia Patricia Serna-Giraldo; Ricardo Emilio Aristizábal-Sierra

    2015-01-01

    En este trabajo se estudian los fenómenos metalúrgicos que ocurren en la soldadura SMAW de un acero inoxidable ferrítico AISI 430 con un acero inoxidable austenítico AISI 316L. Para el estudio se utilizaron dos tipos de electrodos: austenítico AWS E309L y dúplex AWS E2209-16, ambos con un diámetro de 3,2 mm. Las uniones soldadas se realizaron con un solo pase y se variaron simultáneamente la corriente y la velocidad de soldadura; las condiciones fueron ...

  11. Recubrimientos de aluminio-silicio realizados por deposición química de vapor en lecho fluidizado sobre el acero inoxidable AISI 316

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    José Luddey Marulanda Arevalo

    2013-12-01

    Full Text Available Los recubrimientos de aluminio-silicio fueron depositados sobre el acero inoxidable AISI 316 mediante deposición química de vapor en lecho fluidizado (CVD-FBR, en el rango de temperaturas de 540 a 560 ºC, utilizando un lecho formado por 2,5 g de silicio y 7,5 g de aluminio en polvo, y 90 g de lecho inerte (Alúmina, el cual se hizo fluidizar con Ar. Como gases activadores se usó una mezcla de HCl/H2, en relaciones de 1/10 a 1/16. Además, se varió el tiempo de deposición de los recubrimientos de 45 minutos a 1.5 horas, con una relación en volumen de 50% de gases activos y 50% de gases neutros. Se realizó una simulación termodinámica con la ayuda del programa informático Thermocalc, para obtener información de la posible composición y cantidad de material depositado, para las condiciones seleccionadas. En los recubrimientos se encuentran FeAl2Si, Fe2Al5 y FeAl2. Los recubrimientos aluminio-silicio fueron tratados térmicamente, para mejorar sus propiedades mecánicas y su comportamiento frente a la oxidación, por la interdifusión de los elementos de aleación, ya que el tratamiento térmico hace que el aluminio difunda hacia el substrato, y el hierro difunda hacia la superficie del recubrimiento, logrando la transformación de los compuestos anteriores en FeAl, Al2FeSi, Cr3Si, AlCrFe y AlFeNi.

  12. Evaluación del comportamiento estructural y de resistencia a la corrosión de armaduras de acero inoxidable austenítico AISI 304 y dúplex AISI 2304 embebidas en morteros de cemento Pórtland

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    Medina, E.

    2012-12-01

    Full Text Available The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304 and duplex EN 1.4362 (AISI 2304 have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR, of reinforcements embedded in ordinary Portland cement (OPC mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure.

    Se ha evaluado el comportamiento mecánico y estructural de dos aceros inoxidables corrugados, el austenítico EN 1.4301 (AISI 304 y el dúplex EN 1.4362 (AISI 2304, y se han comparado con el tradicional acero al carbono B500SD. El estudio se ha realizado en tres niveles: a nivel de barra, de sección y de pieza. Las diferentes características mecánicas de los aceros inoxidables condicionan el comportamiento a nivel de sección y de pieza estructural. El estudio del comportamiento frente a la corrosión de los dos aceros inoxidables se ha realizado mediante mediciones electroquímicas monitorizando el potencial de corrosión y la resistencia de polarización de armaduras embebidas en probetas de mortero contaminado con diferentes concentraciones de cloruros durante un tiempo de exposición de un año. Ambos aceros inoxidables permanecen en estado pasivo en las probetas para todos los contenidos de cloruros.

  13. Structure and properties of the Stainless steel AISI 316 nitrided with microwave plasma; Estructura y propiedades del acero inoxidable AISI 316 nitrurado con plasmas de microondas

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    Becerril R, F

    1999-07-01

    In this work were presented the results obtained by nitridation on stainless steel AISI 316 using a plasma generated through a microwave discharge with an external magnetic field using several moistures hydrogen / nitrogen to form a plasma. The purpose of nitridation was to increase the surface hardness of stainless steel through a phase formation knew as {gamma}N which has been reported that produces such effect without affect the corrosion resistance proper of this material. (Author)

  14. Efecto de la modificación superficial de alambres delgados de acero inoxidable AISI 302 mediante plasma electrolítico sobre sus propiedades mecánicas

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    Gallegos, A.

    2012-12-01

    Full Text Available In this work different tests using electrolytic plasma (EP on thin wires of stainless steel AISI 302 in an inert solution were performed. Tensile tests were carried out in order to measure changes in the mechanical strength of the samples; moreover, both the morphological and microstructural changes also were evaluated. It was found that after 10 s of the application of EP, the samples surface was uniformly covered by nodules-like and craters similar to those found in the melting and cooling periods of EP. The results show a significant surface grain refinement, leading to crystalline arrangements with sizes less than 200 nm and also an increase in the samples tensile strength of at least 57 % respect to steel base.

    En este trabajo se realizaron ensayos de aplicación de plasma electrolítico (PE sobre alambres delgados de acero inoxidable AISI 302 en una solución inerte. Las probetas se sometieron a ensayos de tracción, con el fin de medir cambios en su resistencia mecánica; adicionalmente fueron evaluadas en sus cambios morfológicos y microestructurales. Se encontró que después de 10 s de aplicación de PE, la superficie de las probetas estaba uniformemente cubierta por nódulos y cráteres propios del ciclo de fusión y enfriamiento del PE; se evidenció un significativo afinamiento del grano superficial, llegando a ordenamientos cristalinos de tamaño menor a 200 nm y también se observó que la capa superficial afectada presentó un incremento de la resistencia a la tracción de al menos un 57 % respecto al acero base.

  15. Soldabilidad del acero inoxidable austenitico

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    Pedro Pablo Torres-Medina

    2002-01-01

    Full Text Available This work involves welding stainless steel AISI 321H applying technical specifications according to welding standards, know the properties and phenomena that occur in the base metal and select the appropriate input material to ensure good quality of the process.

  16. Análisis de soldabilidad de aceros inoxidables con aceros de medio y bajo carbono por SMAW

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    José Luddey Marulanda Arevalo

    2013-12-01

    Full Text Available Se presenta un estudio de la soldabilidad de aceros inoxidables austeníticos AISI 304 y AISI 316 con aceros de bajo y medio carbono AISI 1020 – AISI 1045, empleando como materiales de aporte los electrodos EutecTrode® 52 NG, 54 NG y 57 NG, mediante el proceso de arco eléctrico con electrodo revestido (SMAW. Para analizar la soldabilidad de estos electrodos cuando se realiza la unión de aceros inoxidables con aceros al carbono, se practicaron pruebas metalográficas y ensayos mecánicos de dureza, doblez y tracción, con el fin de observar el comportamiento tanto de la zona afectada térmicamente como del cordón de soldadura, a partir del cambio en las propiedades mecánicas y metalúrgicas en las diferentes regiones de las uniones soldadas. Durante el proceso de soldadura se siguió una especificación del procedimiento de soldadura (WPS, para que los resultados fueran repetibles, minimizando los problemas de agrietamiento en caliente, agrietamiento en frío, formación de fase sigma y precipitación de carburos.

  17. Estudio de propagación de grietas por fatiga en un acero inoxidable austenítico metaestable

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    Bouet, Nicolas

    2010-01-01

    Doble titulació Este proyecto evalúa el comportamiento de la propagación de grietas en un acero inoxidable austenítico metaestable, el AISI 301. Este acero puede transformar una parte de su microestructura en martensita bajo deformación aplicada. Las experiencias han sido llevadas a cabo en el Centro de Integridad Estructural y de Fiabilidad de materiales de la ETSEIB-UPC durante el primer semestre del curso escolar 2009 - 2010. Se estudia cuatro tipos de aceros AISI 301, ca...

  18. Relaciones cuantitativas entre los contenidos de azufre y de sulfuros en los aceros inoxidables tipo AISI 303: influencia de la composición química de los sulfuros

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    Botella, J.

    1999-06-01

    Full Text Available The work has been done with ten AISI 303 stainless steel rods which have similar chemical compositions, except for sulphur which varies between 0.25 and 0.36%. These steels are studied by Scanning Electron Microscopy (SEM and Energy Dispersive X-Ray Spectrometry (EDX. The sulphides are chemically microanalysed and the occupied volume determined by automatic image analysis. It can be inferred that the chemical composition of sulphides in AISI 303 steels is variable to some extent even though the steel chemistry is almost invariable. This could mean that solidification conditions and thermomechanical transformations are able to affect resulting in variations of sulphide compositions. Quantitative relations between sulphur and sulphide contents are established and the influence of sulphide chemical compositions on those relations is studied. The experimental results are compared with those obtained from theoretical calculations. A good approach is obtained when the difference between chemical compositions of real sulphides and the theoretical one, MnS, is taken into account.

    Se trabaja con una serie de diez redondos de aceros inoxidables tipo AISI 303 de composiciones químicas prácticamente iguales a excepción del azufre que varía entre 0,25 y 0,36%. Se examinan los aceros mediante Microscopía Electrónica de Barrido (MEB y Espectrometría de Dispersión de Energías de Rayos X (EDX acoplada al MEB, analizándose químicamente los sulfuros y determinando, mediante análisis automático de imágenes, los volúmenes ocupados por los sulfuros. Parece deducible que la composición química de los sulfuros en el AISI 303 puede ser discretamente variable aún siendo prácticamente invariable la composición química del acero. Ello podría significar que las condiciones de solidificación y las transformaciones termomecánicas pueden influir, dando como resultado variaciones en la composición química de los sulfuros. Se establecen

  19. Propagación de la transformación martensítica inducida por deformación en la velocidad de crecimiento de grietas por fatiga de aceros inoxidables austeníticos metaestables

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    Rodríguez Nogal, Javier

    2007-01-01

    En este proyecto se ha realizado una introducción a los aceros inoxidables, su uso, aplicación y breve historia de su origen. A continuación se ha estudiado en detalle la transformación martensítica inducida por deformación en los aceros inoxidables austeníticos metaestables, por ser este tipo de inoxidables los analizados en el proyecto. Se ha realizado la caracterización microestructural de un redondo de acero inoxidable austenítico metaestable calidad AISI 301, así como una ...

  20. Efecto de la adición de cobre y estaño en el comportamiento a la corrosión por picadura del acero inoxidable AISI 304

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    Pardo, A.

    2004-10-01

    Full Text Available The influence of copper and tin addition on the pitting corrosion resistance of AISI 304 stainless steel in 3.5 % NaCl at 20 °C has been studied using potenciodinamic and cyclic polarization. From that study the effect of alloying elements (Cu and Sn in the corrosion, pitting and repassivation potentials were determined. The effect of copper and tin on the critical pitting temperature (CPT was determined by icon-time-temperature curves. The influence of these alloying elements in FeCl3 under ASTM G48-00 norm was also studied. The addition of copper favours the nucleation of pits. The addition of tin slightly improves the corrosion resistance. The synergic effect of Cu-Sn was positive at low concentrations.

    Se estudia la influencia de la adición de cobre y estaño en la resistencia a la corrosión por picadura del acero inoxidable AISI 304, en 3,5 % NaCl a 20 °C mediante medidas potenciodinámicas de polarización cíclica, con el fin de determinar el efecto de la adición de aleantes (cobre y estaño en los potenciales de corrosión, picadura y repasivación. Se ha determinado el efecto del cobre y estaño en la temperatura crítica de picadura mediante el trazado de curvas icon-tiempo. Asimismo se estudió la influencia de estos aleantes en FeCl3, según norma ASTM 048-00. La adición de cobre favorece la nucleación de picaduras. La adición de estaño presenta una tendencia a mejorar la resistencia a la corrosión. El efecto sinérgico Cu-Sn es positivo en bajas concentraciones.

  1. Transformaciones Microestructurales en Soldaduras Disímiles de Acero Inoxidable Austenítico con Acero Inoxidable Ferrítico

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    Sara María Aguilar-Sierra

    2015-03-01

    Full Text Available En este trabajo se estudian los fenómenos metalúrgicos que ocurren en la soldadura SMAW de un acero inoxidable ferrítico AISI 430 con un acero inoxidable austenítico AISI 316L. Para el estudio se utilizaron dos tipos de electrodos: austenítico AWS E309L y dúplex AWS E2209-16, ambos con un diámetro de 3,2 mm. Las uniones soldadas se realizaron con un solo pase y se variaron simultáneamente la corriente y la velocidad de soldadura; las condiciones fueron 49 A y 2,4 mm.s–1como valores bajos y 107 A y 4,3 mm.s–1como valores altos. Se evaluó la influencia del tipo de electrodo y de los parámetros de soldadura en la evolución microestructural de las zonas afectadas por el calor y de las zonas de fusión, encontrando diferencias en la morfología y cantidad de ferrita delta para todas las condiciones estudiadas. Se evidenció crecimiento y refinación de grano ferrítico y formación de martensita en la zona afectada por el calor del metal base ferrítico. Se evaluó también la resistencia a la tensión hallando similitudes en todas las soldaduras.

  2. “MEDICION DE PARAMETROS GENERADORES DE ESFUERZOS RESIDUALES DURANTE EL PROCESO DE SOLDADURA DE ACERO INOXIDABLE AUSTENITICO AISI 304L”.

    OpenAIRE

    García López, Christian Jesus

    2012-01-01

    En la actualidad los procesos de soldadura por arco eléctrico se han convertido en la técnica por excelencia para la unión del acero y sus aleaciones. Se puede mencionar que la importancia de la soldadura, es tal, que sin ella no serían posibles muchos de los productos y servicios que cotidianamente son consumidos o requeridos por las sociedades contemporáneas actuales. Cada vez con mayor longitud y diámetro se instalan líneas de tubería para la distribución y conducción de tod...

  3. Caracterización mediante la técnica EBSD de la deformación de chapa de acero inoxidable AISI 304 DDQ bajo tensiones multiaxiales típicas de la embutición

    Directory of Open Access Journals (Sweden)

    Coello, J.

    2009-10-01

    Full Text Available The main aim of this work is to evaluate AISI 304 DDQ stainless steel behaviour under deep drawing deformation condition, that is, pure shear deformation in which material suffers a typical deformation under tension-biaxial compression stresses system. The microestructural evolution has been investigated by optical microscopy and by EBSD technique. The success of the EBSD analysis has been established for the deformation conditions experimented here. It has been determined the rolling direction and the equivalent strain influence on the crystallographic orientation maps, misorientation diagrams and poles figures. The results let the authors say the low angle misorientations corresponding to 0, 45 and 90° rolling directions have an inverse correlation with the material anisotropy. Initial prestraining has been considered also and the analysis of this aspects lead to establish that the increment of the intragranular misorientations with the strain depends on the initial state of the steel; this increment is observed to be minor for samples with initial prestraining. High angle misorientation analysis (>15° indicates that the grain boundaries character distributions depends on the deformation.

    El objetivo de este trabajo es evaluar el comportamiento del acero inoxidable AISI 304 DDQ durante un proceso de deformación típico del conformado de chapa por embutición, tracción-compresión biaxial (T-CC, determinando la evolución microestructural mediante microscopía óptica y EBSD. Se ha establecido la validez del análisis efectuado por EBSD para las condiciones de deformación consideradas en este trabajo. Se ha analizado la influencia de la dirección de laminación y de la deformación equivalente sobre los mapas de orientación cristalina, diagramas de desorientación y figuras de polos inversa, determinando que las desorientaciones de ángulo bajo obtenidas en muestras deformadas a 0°, 45°, y 90° respecto a la dirección de

  4. Análisis de la deformabilidad del acero inoxidable AISI 304 DDQ en condiciones multiaxiales de embutición. Evaluación de la influencia de la acritud inicial

    Directory of Open Access Journals (Sweden)

    Ferrer, C.

    2010-10-01

    ón-compresión biaxial existentes en la zona del ala de un proceso de embutición profunda. El material estudiado es acero inoxidable AISI 304 con calidad de embutición. También se establece la influencia existente para estados de acritud inicial diferentes, laminación y tracción biaxial. Los resultados obtenidos permiten establecer la validez del ensayo realizado desde el punto de vista de la deformación que impone al material. También, se demuestra el efecto predominante de la acritud inicial del material frente al provocado en condiciones multiaxiales de embutición y se establece la variación del coeficiente de anisotropía del material con la deformación de embutición para la dirección coincidente con la de laminación del material.

  5. Characterization of gold and nickel coating on AISI 304 stainless steel for use in the fabrication of current collector plates for fuel cells; Caracterizacion de recubrimientos de oro y niquel realizados sobre acero inoxidable AISI 304 para su empleo en la fabricacion de placas colectoras de corriente para celdas de combustible

    Energy Technology Data Exchange (ETDEWEB)

    Flores Hernandez, J. Roberto [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)] e-mail: jrflores@iie.org.mx; Aguilar Gama, M. Tulio [UNAM. Facultad de Quimica, Mexico D.F. (Mexico); Cano Castillo, Ulises; Albarran, Lorena [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Olvera, J. Carlos; Orozco, German [CIDETEQ, Pedro Escobedo, Queretaro (Mexico)

    2009-09-15

    Among the different components that compose fuel cell technology (MEA, bipolar plates, seals, etc.) current collector plates play an important role in the good performance of fuel cells, since they collect all of the current generated and distribute it to the external circuit. Therefore, the most important properties that the current collector plates should have are excellent conductivity and good resistance to the corrosive conditions present in the fuel cell. This document presents results obtained during the nickel and gold electrodeposition process on AISI 304 stainless steel and the morphology and thickness of each coating, their adhesion, hardness and conductivity values. Finally, results obtained during some of the electrochemical tests performed on the coatings are shown. [Spanish] De los diferentes componentes que integran la tecnologia de celdas de combustible (MEA's, placas bipolares, sellos, etc.), las placas colectoras de corriente tienen un importante rol en el buen desempeno de la celdas de combustibles, ya que en estas placas se colecta toda la corriente generada y se distribuye al circuito externo. Debido a esto, las propiedades mas importantes que deben tener las placas colectaras de corriente son: excelente conductividad y buena resistencia a las condiciones corrosivas presentes en la celda de combustible. En este documento se presentan los resultados obtenidos en el proceso de electrodeposicion de niquel y oro sobre acero inoxidable AISI 304, asi como la morfologia y el espesor de cada recubrimiento, sus valores de adherencia, dureza y conductividad. Finalmente se muestran tambien los resultados obtenidos de algunas pruebas electroquimicas a los que fueron sometidos los recubrimientos.

  6. Comportamiento termomecánico de aceros AISI 304

    Directory of Open Access Journals (Sweden)

    El Wahabi, M.

    2001-04-01

    Full Text Available The hot deformation behaviour of three AISI 304 (H, L and HP austenitic stainless steel with different carbon contents has been studied. An analysis of the parameters describing their hot flow curves was carried out. No heavy effect of the carbon content was found on most of the latter parameters. However, the work hardening and dynamic recovery behaviour showed clear differences depending on the given alloy, especially at high temperatures and low strain rates where the high carbon steel displayed larger work hardening and dynamic recovery rates than the other steels. The high purity steel (interstitial free displayed the lower stress levels as its hardening rate was slower than in the other two steels.

    Se llevó a cabo un estudio del comportamiento termomecánico de tres aceros inoxidables austeníticos tipo AISI 304 (H, L y HP con diferentes contenido en carbono, mediante la determinación de los parámetros que describen las etapas de deformación en caliente. No se notó un fuerte efecto del carbono en dichos parámetros, excepto en los que describen los procesos de endurecimiento y de restauración dinámica que muestran una cierta dependencia con la composición química, especialmente a bajos valores del parámetro de Zener-Hollomon, donde el acero de alto carbono (304H endurece y restaura más rápido que el de bajo carbono (304L, alcanzándose valores de tensión de pico similares en ambos casos. El material de alta pureza (libre de intersticiales toma valores de tensión de pico más bajos que los otros aceros, endureciendo más lentamente y con una velocidad de restauración similar a la del 304H.

  7. Fragilización por envejecimiento de aceros inoxidables moldeados

    OpenAIRE

    Mazorra Incera, Luis; Gutiérrez-Solana Salcedo, Federico; González Martínez, Javier Jesús; Varona Ruiz, José María

    1989-01-01

    RESUMEN. En este artículo se presenta, por una parte, la exposición resumida de los modelos teóricos existentes sobre la fragilización de aceros inoxidables moldeados austenoferríticos causada por envejecimiento térmico a 280ºC y, por otra, el análisis-aplicación a un acero real fragilizado, procedente del circuito de recirculación de una central nuclear. Los resultados obtenidos advierten de una importante fragilización al prever una reducción del 50% de la tenacidad a temperatura ambiente e...

  8. Efecto del nitrógeno en la atmósfera de sinterización del acero inoxidable ferrítico AISI430L P/M

    Directory of Open Access Journals (Sweden)

    Corpas, F. A.

    2005-04-01

    Full Text Available In this paper, we have studied the nitrogen effects different sintering atmospheres (nitrogen-hydrogen, and dissociate ammonia on ferritic stainless steels (430L, fabricated by powder metallurgy process. We have carried out a study of the physical (density, porosity and dimensional variation and mechanical properties (hardness, tensile strength, and lengthening of the ferritic stainless steels sintered in the afore-mentioned atmospheres, as well as of their behaviour in pitting corrosion. We have studied, also the microstructure of the steels, which depends on the atmosphere used for sintering

    En el presente artículo, se ha estudiado el efecto del nitrógeno presente en las diferentes atmósferas de sinterización (nitrógeno-hidrógeno y amoniaco disociado en los aceros inoxidables ferríticos (430L, fabricados mediante procedimientos pulvimetalúrgicos. Por lo cual, se ha tomado como referencia la sinterización en vacío. Se han estudiado las propiedades físicas (densidad, porosidad y variación dimensional y las propiedades mecánicas (dureza, resistencia a la tracción y alargamiento de los aceros inoxidables ferríticos sinterizados en las diferentes atmósferas, así como su comportamiento a la corrosión por picaduras. Del mismo modo, se ha estudiado la microestructura de los aceros dependiendo de la atmósfera utilizada en la sinterización

  9. Effects of surface modification of thin wires of AISI 302 stainless steel by electrolytic plasma on its mechanical properties; Efecto de la modificacion superficial de alambres delgados de acero inoxidable AISI 302 mediante plasma electrolitico sobre sus propiedades mecanicas

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, A.; Camurri, C.; Carrasco, C.; Soldera, F.

    2012-07-01

    In this work different tests using electrolytic plasma (EP) on thin wires of stainless steel AISI 302 in an inert solution were performed. Tensile tests were carried out in order to measure changes in the mechanical strength of the samples; moreover, both the morphological and microstructural changes also were evaluated. It was found that after 10 s of the application of EP, the samples surface was uniformly covered by nodules-like and craters similar to those found in the melting and cooling periods of EP. The results show a significant surface grain refinement, leading to crystalline arrangements with sizes less than 200 nm and also an increase in the samples tensile strength of at least 57 % respect to steel base. (Author) 14 refs.

  10. Influence of copper and tin addition on pitting corrosion behaviour of AISI 304 Strainless Steel; Efecto de la adicion de cobre y estano en el comportamiento a la corrosion por picadura de acero inoxidable AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, A.; Merino, M. C.; Botella, J.; Matres, V.; Viejo, F.; Carboneras, M.; Arrabal, R.

    2004-07-01

    The influence of copper and tin addition on the pitting corrosion resistance of AISI 304 stainless steel in 3.5% NaCl at 20 degree centigree has been studied using potenciodinamic and cyclic polarization. From that study the effect of alloying elements (Cu and Sn) in the corrosion, pitting and re passivation potentials were determined. The effect of copper and tin on the critical pitting temperature (CPT) was determined by i{sub c}orr-time-temperature curves. The influence of these alloying elements in FeCl{sub 3} under ASTM G48-00 norm was also studied. The addition of copper favours the nucleation of pits. The addition of tin slightly improves the corrosion resistance. The synergic effect of Cu-Sn was positive at low concentrations. (Author) 10 refs.

  11. Applications of the essay at slow deformation velocity in pipes of stainless steel AISI-304; Aplicaciones del ensayo a velocidad de deformacion lenta en tuberias de acero inoxidable AISI-304

    Energy Technology Data Exchange (ETDEWEB)

    Zamora R, L.; Mora R, T. De la [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    Nowadays is carried out research related with the degradation mechanisms of structures, systems and/or components in the nuclear power plants, since many of the involved processes are those responsible for the dependability of these, of the integrity of the components and of the aspects of safety. The purpose of this work, was to determine the grade of susceptibility to the corrosion of a pipe of Austenitic stainless steel AISI 304, in a solution of Na CI (3.5%) to the temperatures of 60 and 90 C, in two different thermal treatments - 1. - Sensitive 650 C by 4 hours and cooled in water. 2. Solubilized to 1050 C by 1 hour and cooled in water.

  12. Effects of nitrogen and pulsed mean welding current in AISI 316 austenitic stainless steel solidification cracks; Efecto del nitrogeno y la corriente media pulsada de soldadura en la formacion de grietas de solidificacion en aceros inoxidables AISI 316L

    Energy Technology Data Exchange (ETDEWEB)

    Trevisan, R. E.; Braga, E.; Fals, H. C.

    2002-07-01

    An analysis of the influence of nitrogen concentration in the weld zone and the pulsed mean welding current in the solidification crack formation is presented in this paper. The AISI 316L austenitic stainless steel was employed as the metal base. The welding was done using CC+ pulsed flux cored are welding process and AWS E316L wire type. The tests were conducted using CO{sub 2} shielding gas with four different nitrogen levels (0,5; 10 and 15%) in order to induce different nitrogen weld metal concentrations. The pulsed mean welding current was varied in three levels and the. Transvarestraint tangential strain test was fixed of 5%. The results showed that the solidification cracking decreased as the pulsed mean welding current increase. It was also verified that an increase of the weld zone nitrogen level was associated with a decrease in both the total length of solidification crack and the amount of {delta} ferrite. (AUthor) 20 refs.

  13. Study of cyclic oxidation for stainless steels AISI 309 T 253 M A, with low additions of cerium; Estudio de la oxidacion ciclica de los aceros inoxidables AISI 309 T 253 MA, con pequenas adiciones de Cerio

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez F, G.L.; Martinez, M.; Ruiz, A. [Universidad Nacional Experimental Politecnica (UNEXPO) - Vicerrectorado de Puerto Ordaz, Centro de Estudios de Corrosion. Puerto Ordaz. venezuela (Venezuela)

    1998-12-31

    It has been detected that the addition of small amounts (<1%) of the so called `reactive elements` such as Cerium to Fe-Cr alloys that was utilized in oxidating environment at high temperatures improving its resistance to oxidation under isothermal and cyclic conditions. In this work, it was evaluated the behavior under cyclic oxidation conditions for an austenitic stainless steel at chromium-nickel (253MA) with cerium addition, and comparing it with the AISI 310S austenitic stainless steel. The cyclic oxidation essays consist of five cycles by 24 hours each one, following of a cooling in air until ambient temperature from the temperatures of 850, 900 and 950 Centigrade, registering the gain mass of the specimen at end of each cycle. In order to this were prepared samples with dimensions of 20 mm. x 10 mm. x 1 mm. Later to the oxidation essays was evaluated the morphology of the corrosion products layer by scanning electron microscopy. The present phases were identified by X-ray diffraction and by chemical microanalysis by Dispersive energy (EDAX). The results obtained show that the steel with cerium addition, presents a higher adherence and resistance to the spalling noting that the cerium promotes the casting anchor of the oxides layer to matrix and by reducing the grain size of the layer improving its plasticity. Additionally the cerium promotes the preferential oxidation of the forming elements of protective layers like the chromium. (Author)

  14. Crack propagation in stainless steel AISI 304L in Hydrogen Chemistry conditions (HWC); Propagacion de Grietas en Acero Inoxidable AISI 304L en Condiciones de Quimica de Hidrogeno (HWC)

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.; Fuentes C, P.; Merino C, F. [ININ, Carretera Mexico -Toluca s/n, La Marquesa, Ocoyoacac, Mexico (Mexico); Castano M, V. [Instituto de Fisica Aplicada, UNAM, Km 15.5 Carretera Queretaro-San Luis Potosi, Juriquilla, Queretaro (Mexico)]. e-mail: ads@nuclear.inin.mx

    2006-07-01

    Velocities of crack growth in samples type CT pre cracking of stainless steel AISI 304l solder and sensitized thermally its were obtained by the Rising Displacement method or of growing displacement. It was used a recirculation circuit that simulates the operation conditions of a BWR type reactor (temperature of 280 C and a pressure of 8 MPa) with the chemistry modified by the addition of hydrogen with and without the addition of impurities of a powerful oxidizer like the Cu{sup +} ion. In each essay stayed a displacement velocity was constant of 1x10{sup -9} m/s, making a continuous pursuit of the advance of the crack by the electric potential drop technique. Contrary to the idea of mitigation of the crack propagation velocity by effect of the addition of the hydrogen in the system, the values of the growth velocities obtained by this methodology went similar to the opposing ones under normal operation conditions. To the finish of the rehearsal one carries out the fractographic analysis of the propagation surfaces, which showed cracks growth in trans and intergranular way, evidencing the complexity of the regulator mechanisms of the IGSCC like in mitigation conditions as the alternative Hydrogen Chemistry. (Author)

  15. Propagation of crevices in stainless steel AISI304L in conditions of hydrogen chemistry (HWC); Propagacion de grietas en acero inoxidable AISI304L en condiciones de quimica de hidrogeno (HWC)

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.; Fuentes C, P.; Merino C, F. [ININ, 52750 Ocoyoacac, Estado de Mexico (Mexico); Castano M, V. [IFA-UNAM, Juriquilla, Queretaro (Mexico)]. e-mail: ads@nuclear.inin.mx

    2006-07-01

    Crevice growth velocities in samples of AISI 304L stainless steel thermally welded and sensitized were obtained by the Rising displacement method or of growing displacement. It was used a recirculation circuit in where the operation conditions of a BWR type reactor were simulated (temperature of 288 C and a pressure of 8 MPa) with the chemistry modified by the addition of hydrogen with and without the addition of impurities of a powerful oxidizer like the Cu{sup ++} ion. CT pre cracked specimens were used and each rehearsal stayed to one constant displacement velocity of 1 x 10{sup -9} m/s (3.6 {mu}m/hr), making a continuous pursuit of the advance of the crack by the electric potential drop technique. To the end of the rehearsal it was carried out the fractographic analysis of the propagation surfaces. The values of the growth velocities obtained by this methodology went similar to the opposing ones under normal conditions of operation; while the fractographic analysis show the cracks propagation in trans and intergranular ways, evidencing the complexity of the regulator mechanisms of the one IGSCC even under controlled ambient conditions or with mitigation methodologies like the alternative hydrogen chemistry. (Author)

  16. Characterization of welding of AISI 304l stainless steel similar to the core encircling of a BWR reactor; Caracterizacion de soldaduras de acero inoxidable AISI 304L similares a las de la envolvente del nucleo de un reactor BWR

    Energy Technology Data Exchange (ETDEWEB)

    Gachuz M, M.E.; Palacios P, F.; Robles P, E.F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    Plates of austenitic stainless steel AISI 304l of 0.0381 m thickness were welded by means of the SMAW process according to that recommended in the Section 9 of the ASME Code, so that it was reproduced the welding process used to assemble the encircling of the core of a BWR/5 reactor similar to that of the Laguna Verde Nucleo electric plant, there being generated the necessary documentation for the qualification of the one welding procedure and of the welder. They were characterized so much the one base metal, as the welding cord by means of metallographic techniques, scanning electron microscopy, X-ray diffraction, mechanical essays and fracture mechanics. From the obtained results it highlights the presence of an area affected by the heat of up to 1.5 mm of wide and a value of fracture tenacity (J{sub IC}) to ambient temperature for the base metal of 528 KJ/m{sup 2}, which is diminished by the presence of the welding and by the increment in the temperature of the one essay. Also it was carried out an fractographic analysis of the fracture zone generated by the tenacity essays, what evidence a ductile fracture. The experimental values of resistance and tenacity are important for the study of the structural integrity of the encircling one of the core. (Author)

  17. INFLUENCIA DE LA NITRURACIÓN POR PLASMA SOBRE EL COMPORTAMIENTO A LA CORROSIÓN Y LA ADHESIÓN DE RECUBRIMIENTOS DLC SOBRE ACERO INOXIDABLE AISI 420

    Directory of Open Access Journals (Sweden)

    Jorge N. Pecina

    2016-01-01

    Full Text Available En este trabajo se estudió el comportamiento a la corrosió n y la adhesión de dos rec ubrimientos DLC (“Diamond Like Carbon ” , “Soft” y “Hard”, depositados por PACVD (“Plasma Assisted Chemical Vapour Deposition” sobre acero AISI 420, templado y revenido y /o nitrurado por plasma . Se analizaron por espectroscopía Raman y midió dureza en superficie. Se observó la microestructura por OM y SEM. Se realizaron pruebas de adhesión con indentación Rockwell C . S e practicaron ensayos de Niebla Salina e inmersión en HCl . Los DLC “ Soft ” presentaron una dureza de 5 00 HV y un espesor de 2 0 μm , mientras que los “ Hard ” tuvieron 1400 HV y 2 ,5 μm. Ambos recubrimientos presentaron bajo coeficiente de fricción y buena adhesión sobre el sustrato nitrurado . También presentaron buena resistencia a la corrosión atmosférica. En HCl el DLC retardó la degradación que se presentó rápidamente en las muestras sin recubrir.

  18. Evaluación de la fuerza de doblado y de fricción en el conformado de chapa de acero inoxidable AISI 304 DDQ mediante ensayos de doblado en condiciones multiaxiales de embutición

    Directory of Open Access Journals (Sweden)

    Coello, J.

    2012-08-01

    Full Text Available Die radius is a critical area from the viewpoint of friction in forming processes. Moreover the sheet, that has been previously deformed in flange area, suffers bending and unbending stresses. Then, die-sheet contact in die radius must be especially considered in order to guarantee the suitable lubrication conditions. In the present work, a test method is carried out for evaluating an AISI 304 DDQ steel under similar conditions to those existing in the die radius area and that, usually, are not really reproduced in traditional bending under tensions tests. Deformation under pure shear condition, the bending and the radius angle have been established as variables of the tests. Results allow to obtain the apparent pressure sheet-bending tool, that increases with bending angle and decreases with tool radius. This last variable is the most significant while the bending angle has lesser influence. Although experimental results present some concordances with values obtained by analytical methods, some corrections must be considered in them in order to improve the theoretical values.

    El radio de entrada a la matriz se considera una de las zonas críticas en los procesos de conformado de chapa mediante embutición profunda. El análisis de la fuerza de fricción y de doblado existentes resulta importante para predecir el comportamiento de la chapa en dicha zona, así como para garantizar una lubricación adecuada a las condiciones de procesado. En el presente trabajo, se aplica un método de ensayo que evalúa las acciones en el proceso de doblado del acero AISI 304 DDQ bajo condiciones similares a las que sufre el material en los procesos de embutición y que no son reproducidas por los clásicos ensayos de doblado bajo tensión. Se establecen como variables la deformación experimentada previamente por el material en condiciones típicas de cortante puro, “pure shear”, el ángulo de doblado y el radio de doblado. Los resultados obtenidos

  19. Análisis de las películas pasivas generadas en aceros inoxidables implantados con cromo

    Directory of Open Access Journals (Sweden)

    Abreu, C. Mª

    2004-06-01

    Full Text Available This work studies the effect of chromium implantation on the development of passive layers generated electrochemically in alkaline medium over two stainless steels. The XPS analyses show that the layers generated on the implanted steels present less thickness together with similar composition compared to the unimplanted steels layers. However, SEM micrographs show that the layers grown on implanted steels present more defects and less adherence that the films on unimplanted steels. These changes together with the results obtained by Cyclic Voltammetry suggest an oxide structure modification, lattice structure or cristalinity state.

    En este trabajo se estudia el efecto de la implantación de cromo en el desarrollo de capas pasivas generadas electroquímicamente en medio básico sobre dos aceros inoxidables (AISI 430 y AISI 304L. Los análisis de XPS muestran que las películas desarrolladas sobre ambos aceros implantados presentan espesores menores, junto con composiciones similares, a las formadas sobre los no implantados. Sin embargo, en los resultados del examen con MEB se puede apreciar que las películas tienen más defectos (agrietamientos y peor adherencia (especialmente en el AISI 430. Este cambio, junto con los datos de voltametría cíclica, parece sugerir una modificación en la estructura de los óxidos, bien en su grado de cristalinidad o bien en la estructura de su red cristalina.

  20. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars; Evaluacion del comportamiento estructural y de resistencia a la corrosion de armaduras de acero inoxidable austenitico AISI 304 y duplex AISI 2304 embebidas en morteros de cemento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-07-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  1. Influencia de la adición de cobre y de bronce sobre las propiedades de los aceros inoxidables austeníticos sinterizados

    Directory of Open Access Journals (Sweden)

    Velasco, F.

    1997-04-01

    Full Text Available The effect that, on AISI 316L and 304L stainless steels alloyed with copper and bronze in different percentages up to a maximun of 20 % wt, produce both the alloying content and the sintering temperature over physical and mechanical properties and over the microstructure of sintered stainless steels are studied. Alloying with copper and bronze improves the density of sintered steels at the two sintering temperatures used. Copper and bronze promote liquid phase sintering (transitory or permanent, that activates sintering process. Tensile strength of stainless steel is highly improved for higher alloying contents. Moreover, tensile strength presents greater values alloying with bronze than with copper.

    Partiendo de los aceros inoxidables AISI 316L y 304L a los que se añadió cobre y bronce en diferentes porcentajes hasta el 20 % en peso, se estudia el efecto que la cantidad de aleante y la temperatura de sinterización tienen sobre las propiedades físicas y mecánicas y sobre la microestructura de los aceros inoxidables sinterizados. La aleación con cobre y con bronce aumenta la densidad de los aceros sinterizados para las dos temperaturas de sinterización utilizadas. El cobre y el bronce provocan la aparición de fase líquida (transitoria o permanente que activa el proceso de sinterización. La resistencia a la tracción del acero inoxidable experimenta un fuerte incremento para los contenidos más elevados de aleante. Además, la resistencia a la tracción alcanza mayores valores para la aleación con bronce que con cobre.

  2. Evaluación del springback mediante ensayos de doblado bajo tensión en condiciones de multiaxialidad típicas de los procesos de embutición profunda. Aplicación a chapa de acero inoxidable AISI 304 DDQ

    Directory of Open Access Journals (Sweden)

    Miguel, V.

    2013-06-01

    Full Text Available In this paper, a methodology has been developed for evaluating the springback of AISI 304 DDQ stainless steel sheet based on a bending under tension test. The main difference of the methodology herein carried out is that tests are made under the multiaxial stresses state that take place in deep drawing processes. This affects to the level of stress value in the test and to the hardening state of the sheet. Springback evaluation has been done in two different areas. Bending area has been evaluated from elastic recovery ratio defined as the ratio between the bending radius after and before bending. Bending and unbending extreme has been studied from the measured curvature radius in this area and taking into account the geometric equivalence of the test with the drawing cups process. Results found allow to state that drawing ratio or deformation ratio have a negligible influence on the springback into the range of values experimented here. Bending radius has hardly influence as well while bending angle is the most significant variable. The results obtained are compared to those measured in deep-drawn cups, finding a great agreement.En este trabajo se presenta una metodología para evaluar la recuperación elástica o springback de chapa de acero inoxidable AISI 304 DDQ basada en la realización de ensayos bajo tensión. A diferencia de los estudios existentes en la literatura, los ensayos realizados son efectuados en condiciones multiaxiales típicas de los procesos de embutición de chapa. Esto afecta fundamentalmente a las tensiones involucradas en el proceso así como al estado de endurecimiento que experimenta el material. La evaluación del springback se ha efectuado en dos áreas diferentes. En la zona de doblado se ha evaluado a partir del factor de recuperación definido como la razón entre el radio de doblado y el radio con el que queda finalmente el material. La zona de doblado y desdoblado se ha evaluado en base a la inversa del radio

  3. Tecnología para la obtención de polvos microporosos de acero inoxidable

    Directory of Open Access Journals (Sweden)

    Martínez, M.

    2001-10-01

    Full Text Available En el trabajo se trata el desarrollo de la tecnología de obtención de polvos microporosos de acero inoxidable mediante atomización y recocido de descarburación. La esencia del proceso consiste en recarburar el metal en estado líquido y, posteriormente, descarburar el polvo en estado sólido mediante recocido en hidrógeno o amoniaco disociado. Con esta tecnología se logra la formación de una microporosidad interna en la partícula, que aligera el material y mejora los procesos de conformación, ya que aumenta la deformación que puede experimentar una partícula. A su vez, se reduce el costo de producción y los gastos de inversión, para asimilar la tecnología. Además, se exponen los resultados del estudio cinético acerca de la descarburación y la caracterización del polvo de acero inoxidable obtenido.

    En el trabajo se trata el desarrollo de la tecnología de obtención de polvos microporosos de acero inoxidable mediante atomización y recocido de descarburación. La esencia del proceso consiste en recarburar el metal en estado líquido y, posteriormente, descarburar el polvo en estado sólido mediante recocido en hidrógeno o amoniaco disociado. Con esta tecnología se logra la formación de una microporosidad interna en la partícula, que aligera el material y mejora los procesos de conformación, ya que aumenta la deformación que puede experimentar una partícula. A su vez, se reduce el costo de producción y los gastos de inversión, para asimilar la tecnología. Además, se exponen los resultados del estudio cinético acerca de la descarburación y la caracterización del polvo de acero inoxidable obtenido.

  4. Estudio de la corrosión producida en aceros inoxidables 304 en procesos de soldadura

    OpenAIRE

    Terán, G.; Tovar, C.; Portocarrero, J.; Sánchez, N. A. de

    2004-01-01

    En este trabajo de investigación se analizan las probetas de aceros inoxidables 304 que después de haber sido soldadas mediante los procesos de soldadura SMAW, GMAW y GTAW, se sometieron a un ambiente corrosivo propio de las condiciones de trabajo. Se estudió la microestructura del cordón de soldadura utilizando microscopía electrónica de barrido (SEM), la interfase entre el material base y el de aporte se estudió utilizando un microscopio óptico y analizador de imágenes.

  5. Estudio de la corrosión producida en aceros inoxidables 304 en procesos de soldadura

    Directory of Open Access Journals (Sweden)

    G. Terán

    2004-01-01

    Full Text Available En este trabajo de investigación se analizan las probetas de aceros inoxidables 304 que después de haber sido soldadas mediante los procesos de soldadura SMAW, GMAW y GTAW, se sometieron a un ambiente corrosivo propio de las condiciones de trabajo. Se estudió la microestructura del cordón de soldadura utilizando microscopía electrónica de barrido (SEM, la interfase entre el material base y el de aporte se estudió utilizando un microscopio óptico y analizador de imágenes.

  6. Fenómenos de envejecimiento y oxidación a altas temperaturas en tres aceros inoxidables altamente aleados

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1999-02-01

    Full Text Available The oxidation kinetics in air up to 50 h at 1,373 and 1,473 K of three refractory stainless steels (25Cr20Ni, 21Cr11Ni(1, 21Cr11Ni(2 are studied. At 1,373 K, the best results are those of 25Cr20Ni followed by those of 21Cr11Ni(1, with 0,036 % lanthanides, and the worst behaviour is that of 21Cr11Ni(2, with 0,010 % lanthanides. A 2 h oxidation treatment at 1,323 K in air produces oxidation layers from 1 to 3 μm in thickness for the three materials. Scanning electron microscopy and energy dispersive microanalysis (SEM-EDX and X-ray diffraction (XRD characterisation of the oxidation layers give the same characteristics for the three steels: Mn Cr2O4 spinel type in the outer part, Cr2O3 in the inner one, with a SiO2 barrier in the oxide-metal interface and a large amount of internal and intergranular precipitates (also Si02 in 21Cr11Ni materials. After ageing tests, at 1,073 K for 400 h, about 10 vol. % of the σ-phase is present in the 25Cr20Ni (AISI 310 S material, while no a-phase is present in the 21Cr11Ni materials perhaps due to the high nitrogen content. The application of field emission SEM with EDX allows the analysis of σ-phase and carbides, nitrides and carbonitrides present. The steel 25Cr20Ni only forms, in addition to the σ-phase, M23C6 type carbides, while the steel 21Cr11Ni(1 forms these carbides and M15N nitrides (M8N in the surface and the steel 21Cr11Ni(2 forms mainly carbonitrides M6(CN. The relatively higher nitrogen level in the 21Cr11Ni(1 alloy could explain the different behaviour of both 21Cr11Ni steels.

    Se parte de tres aceros inoxidables austeníticos refractarios (25Cr20Ni, 21Cr11Ni(1, 21Cr11Ni(2 y se estudian las cinéticas de oxidación al aire, hasta 50 h a 1.373 y 1.473 K. El mejor comportamiento a 1

  7. Detección de la corrosión por picadura en aceros inoxidables empleando ultrasonidos

    Directory of Open Access Journals (Sweden)

    Rodríguez, Cristina

    2014-03-01

    Full Text Available Passive metallic systems are able to develop in a spontaneous way a protective layer on the metallic surface that offers excellent corrosion resistance since really in a physical barrier for the reaction with the environment. However, some factors can break locally this layer, promoting one of the most insidious attack, pitting corrosion, which produces local chemical conditions that favouring the corrosive process causing defects in the material, as externals and internals ones, with a random distribution on the metal surface. In this work, ultrasounds non destructive technique has been employed using as variable the maximum amplitude of the backwall echo in order to detect this type of attack. The material employed is an austenitic stainless steel AISI 304, wherein appear several defectology distributions as superficial such as depths simulating pits.Los sistemas pasivables, capaces de desarrollar una capa protectora, delgada, adherente y continua sobre el substrato metálico, presentan excelente resistencia a la corrosión ya que dicha capa se produce instantáneamente al reaccionar con el medio. Ahora bien, en determinadas circunstancias, esa capa se puede romper localmente, dando lugar a uno de los ataques más insidiosos que se conocen, corrosión por picadura, que producen unas condiciones químicas locales que aceleran el proceso corrosivo provocando defectos en el material, tanto externos como internos, con una distribución aleatoria en la superficie metálica. En este trabajo se ha planteado el empleo de técnicas de ensayos no destructivas mediante ultrasonidos para detectar este tipo de ataque en un acero inoxidable austenítico AISI 304, con distinta distribución superficial de defectología y profundidades de ataque, que simulan picaduras, tomando como variable fundamental de la onda ultrasónica la amplitud máxima del eco de fondo.

  8. Comportamiento del desgaste del flanco en el torneado en seco de alta velocidad del acero AISI 316L//Flank wear behavior in the dry high‐speed turning of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Yoandrys Morales-Tamayo

    2013-09-01

    Full Text Available El presente estudio experimental se centra en investigar los efectos de los parámetros corte en el desgaste de flanco con dos insertos recubiertos durante el torneado de acabado en seco a altas velocidades del acero inoxidable AISI 316L. Los efectos de los parámetros de corte fueron determinados utilizando un análisis de varianza y de regresión simple. Como principal resultado se obtuvo el efectosignificativo del avance y del tiempo de maquinado en el desgaste del flanco. El inserto de tres capas no sobrepasó el criterio de fin de vida del desgaste, mientras que el inserto de una capa sufrió un desgaste catastrófico para la mayor velocidad de corte. El desgaste del flanco tuvo mejor comportamiento para el avance de 0,08 mm/rev en todas las velocidades empleadas en este estudio.Palabras claves: torneado de alta velocidad, desgaste de flanco, acero inoxidable AISI 316L, estudio experimental, análisis de varianza y regresión.______________________________________________________________________________AbstractThe current experimental study is focused on investigating the effects of cutting parameters on flank wear in two coated carbide inserts during dry high speed finish turning of AISI 316L stainless steel. The effects of cutting parameters were determinate using analysis of variance and simple regression. As a main resulta significant effect of cutting feed and the machining time on flank wear was found. The three coating layers insert did not exceed the criterion of end of life of wear while the insert with one layer suffered a catastrophic wear at the highest cutting speed. The flank wear showed the best performance for the cuttingfeed of 0,08 mm/rev at all the speeds used in the study.Key words: high speed turning; flank wear; AISI 316L stainless steel, experimental study; analysis of variance and regression.

  9. Caracterización microestructural de uniones soldadas de acero AISI 316L en tuberías

    Directory of Open Access Journals (Sweden)

    Tomás H. Fernández-Columbié

    2016-03-01

    Full Text Available Se analizó el comportamiento microestructural de uniones soldadas de acero AISI 316L empleado en la fabricación de tuberías, las cuales se ven afectadas por agrietamiento en el cordón de soldadura. Se emplearon electrodos revestidos de acero inoxidables de los tipos E 309–16; 310–16 y E 316L–16, según norma de la AWS, los que fueron evaluados por su depósito en uniones a tope preparadas con biseles en V, soldadas por un solo lado del material de la tubería, así como la selección y preparación de muestra en zonas donde la tubería presenta daños mecánicos, fisuras y corrosión severa con pérdida del espesor de pared crítica para soportar las presiones de trabajo. Se caracterizó la microestructura de la zona fundida y la zona de influencia térmica de cada cordón luego de realizado el proceso de soldadura. Se concluye que la soldadura con electrodos del tipo E 309-16 y del tipo E 316-16 no son recomendables debido a que se obtiene una microestructura sensible al agrietamiento.

  10. Análisis económico de la utilización de armaduras de acero inoxidable en estructuras de hormigón

    OpenAIRE

    Medina Sanchez, Eduardo; Cobo Escamilla, Alfonso; Martínez Bastidas, David

    2012-01-01

    La utilización de armaduras de acero inoxidable, de los tipos austeníticos y dúplex, con el objetivo de prolongar la vida útil de las estructuras de hormigón, es una alternativa que está recibiendo cada vez más consideración. Los aceros inoxidables son aleaciones fundamentalmente de cromo y níquel, con muy alta resistencia a la corrosión, especialmente frente a cloruros. El elevado coste del níquel y sus grandes fluctuaciones en el mercado, han favorecido la aparición de nuevos aceros inoxida...

  11. “CARACTERIZACION NO DESTRUCTIVA DE TRATAMIENTOS TÉRMICOS DE ENVEJECIMIENTO EN ACERO INOXIDABLE DÚPLEX 2205”

    OpenAIRE

    Ortiz Lara, Noemí

    2012-01-01

    Los aceros inoxidables dúplex presentan una microestructura de dos fases con cantidades aproximadamente iguales de ferrita (α) y austenita (γ) lo cual le dan una combinación de buenas propiedades mecánicas y excelente resistencia al agrietamiento por corrosión lo cual los hace atractivos para ser usados en la industria petrolera, química y nuclear. La buena relación entre propiedades mecánicas y resistencia a la corrosión que presenta este tipo de aceros puede ser perdida por l...

  12. Comportamiento Tribológico de Aceros Inoxidables para Cubertería Tribologic Behavior of Stainless Steels for Cutlery

    OpenAIRE

    José D.B de Mello; Paulo S. de S Bálsamo

    2006-01-01

    Se estudió el comportamiento tribológico de los aceros inoxidables utilizados en cubertería. Se sometieron aceros martensíticos y ferríticos con diferentes contenidos de carbono y cromo a ensayos con micro-abrasión y desgaste por deslizamiento alternado. A pesar de que la composición química haya afectado considerablemente la micro estructura y dureza de las aleaciones, el comportamiento en la abrasión y en el coeficiente de fricción no fueron afectados por estos factores. La velocidad de des...

  13. Deformability analysis of the AISI 304 DDQ stainless steel under deep drawing multiaxial condition. Evaluation of the initial strain influence; Analisis de la deformabilidad del acero inoxidable AISI 304 DDQ en condiciones multiaxiales de embuticion. Evaluacion de la influencia de la acritud inicial

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J.; Miguel, V.; Calatayud, A.; Martinez, A.; Ferrer, C.

    2010-07-01

    The deep drawing formability of a material is established as a function of standard indexes, as strength coefficient and anisotropy coefficient. But these indexes are determined in different conditions to those that take place in the forming process. The simulative assays do not separate the actions due to the different variables that work in the process, as for example, the rolling direction. In the present work a test that uses a wedge shape die is considered in order to obtain the strength and anisotropy coefficients as a function of rolling direction. This way, the assays are carried out under a tensile-biaxial compression stress state similar to that one taking place in the flange zone in deep drawing. The experimented material is a deep drawing quality stainless steel AISI 304. The influence of initial strengthened states, rolling and uniaxial tensile on the steel behaviour are also studied. The results permits the authors establish the validity of the assay from the point of view of the strains produced in the sheet. The initial strain has a higher effect on the material than that one obtained from the tensile-biaxial of the state than the tensile-biaxial compression causes. The anisotropy coefficient changes with the strain for the sheet rolling direction. (Author).

  14. Friction and bending forces evaluation of AISI 304 DDQ steel sheet forming by bending tests under deep-drawing multiaxial stresses; Evaluacion de la fuerza de doblado y de friccion en el conformado de chapa de acero inoxidable AISI 304 DDQ mediante ensayos de doblado en condiciones multiaxiales de embuticion

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatayud, A.; Martinez, A.

    2012-11-01

    Die radius is a critical area from the viewpoint of friction in forming processes. Moreover the sheet, that has been previously deformed in flange area, suffers bending and unbending stresses. Then, die-sheet contact in die radius must be especially considered in order to guarantee the suitable lubrication conditions. In the present work, a test method is carried out for evaluating an AISI 304 DDQ steel under similar conditions to those existing in the die radius area and that, usually, are not really reproduced in traditional bending under tensions tests. Deformation under pure shear condition, the bending and the radius angle have been established as variables of the tests. Results allow to obtain the apparent pressure sheet-bending tool, that increases with bending angle and decreases with tool radius. This last variable is the most significant while the bending angle has lesser influence. Although experimental results present some concordances with values obtained by analytical methods, some corrections must be considered in them in order to improve the theoretical values. (Author) 18 refs.

  15. Spring back evaluation by bending under tension tests in conditions of multiaxial stresses corresponding to deep drawing processes. Application to AISI 304 DDQ stainless steel sheet; Evaluacion del springback mediante ensayos de doblado bajo tension en condiciones de multiaxialidad tipicas de los procesos de embuticion profunda. Aplicacion a chapa de acero inoxidable AISI 304 DDQ

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, V.; Coello, J.; Martinez, A.; Calatayud, A.

    2013-09-01

    In this paper, a methodology has been developed for evaluating the spring back of AISI 304 DDQ stainless steel sheet based on a bending under tension test. The main difference of the methodology herein carried out is that tests are made under the multiaxial stresses state that take place in deep drawing processes. This affects to the level of stress value in the test and to the hardening state of the sheet. Springback evaluation has been done in two different areas. Bending area has been evaluated from elastic recovery ratio defined as the ratio between the bending radius after and before bending. Bending and unbending extreme has been studied from the measured curvature radius in this area and taking into account the geometric equivalence of the test with the drawing cups process. Results found allow to state that drawing ratio or deformation ratio have a negligible influence on the springback into the range of values experimented here. Bending radius has hardly influence as well while bending angle is the most significant variable. The results obtained are compared to those measured in deep-drawn cups, finding a great agreement. (Author)

  16. Characterization by EBSD technique of AISI 304 DDQ stainless steel sheet deformed under typical deep drawing multiaxial stress system; Caracterizacion mediante la tecnica EBSD de la defromacion de chapa de acero inoxidable AISI 304 DDQ bajo tensiones multiaxiales tipicas de la embuticion

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J.; Miguel, V.; Calatayud, A.; Ferrer, C.; Martinez, A.

    2009-07-01

    The main aim of this work to evaluate AISI 304 DDQ stainless steel behaviour under deep drawing deformation condition, that is pure shear deformation in which materials suffers a typical deformation under tension-biaxial compression stresses system. The microstructural evolution has been investigated by optical microscopy and by EBSD technique. The success of the EBSD analysis has been established for the deformation conditions experimented here. It has been determined the rolling direction and the equivalent strain influence on the crystallographic orientation maps, misorientation diagrams and poles figures. The results let the authors say the low angle misorientation corresponding to 0,45 and 90 degree centigrade rolling directions have an inverse correlation with the material anisotropy. Initial pre-straining has been considered also and the analysis of this aspects lead to establish that the increment of the intragranular misorientation with the strain depends on the initial state a of the steel; this increment is observed to be minor for samples with initial prestraining. High angle misorientation analysis (>15 degree centigrade) indicates that the grain boundaries character distributions depends on the deformation. (Author) 20 refs.

  17. Behavior to the fracture of an AISI 304 stainless steel sensitized in BWR reactor conditions (288 degrees Centigrade and 80 Kg/cm{sup 2}); Comportamiento a la fractura de un acero inoxidable AISI 304 sensibilizado en condiciones de reactor BWR (288 grados Centigrados y 80 Kg/cm{sup 2})

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez C, R.; Diaz S, A.; Garcia R, R.; Aguilar T, A.; Gachuz M, M.; Arganis J, C.; Merino C, J. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    It is a knew fact that ductility of a lot of structural alloys can be deteriorated by the environment effect which are exposed, and that their consequent embrittlement can put in doubt the safety of their functioning; such is the case of austenitic stainless steels used in internal components of the BWR type reactors which not only is subjected to the effect combined of the aggressive environment which surround it (pressure, temperature, corrosion potential, conductivity medium, local state of efforts, etc.), but also to the action of present neutron radiation, manifesting microstructural changes which are reflected in the augmentation of its susceptibility to the intergranular cracking, phenomena generally known as IASCC ''Irradiation Assisted Stress Corrosion Cracking''. Once appeared the cracking in the material, the useful life of a component is limited by the rapidity to growth of these cracking, making necessary evaluations which can to predict its behavior, therefore the present work shows the preliminary results for determining the behavior to the fracture of an AISI 304 stainless steel sensitized, in a dynamic recirculation circuit which allows to simulate the operation conditions of a BWR reactor (288 Centigrade and 80 kg/cm{sup 2}). (Author)

  18. Ensayos de rozamiento plano sobre aceros inoxidables austeníticos con diferente acabado superficial. Determinación de las condiciones de adhesión en el rozamiento

    Directory of Open Access Journals (Sweden)

    Coello, J.

    2008-12-01

    Full Text Available The main purpose of this work is to evaluate the tribological behaviour of austenic stainless steels AISI 304 with bright annealed surface finishing (BA (ASTM a 240; AISI 304 DDQ and AISI 316 with bright surface finishing (B. The assays have been carried out in flat faced dies system with mineral oil of 200 cts viscosity, S2Mo grease and in dry conditions.. The relationship between friction coefficient and pressure and velocity has been established for the mineral oil as lubricant. In these conditions, a strong adhesive tendency has been found in boundary lubrication regime. The results obtained here, show us that S2Mo grease leads to lowest values for the friction coefficient. A minor adhesive behaviour tendency for AISI 316 steel, harder than 304 grades, has been found. A relevant plowing phenomena has been observed for the more critical friction conditions tried out. A surface hardener is produced as a consequence of that.

    El objetivo de este trabajo es determinar el comportamiento tribológico de los aceros inoxidables austeníticos 304 con acabado brillante BA (ASTM A 240, 304 DDQ y 316 con acabado mate 2B, en sistemas de contacto plano, con el fin de simular el rozamiento en la zona del flanco en los procesos de embutición de acero inoxidable. Para ello, se ha estudiado la influencia del acabado superficial del acero, la velocidad de deslizamiento y la presión normal sobre el coeficiente de rozamiento, utilizando un ensayo de fricción con matrices planas. Los ensayos se han realizado con aceite mineral de 200 cst, grasa de bisulfuro de molibdeno y en seco. En presencia de aceite, se ha establecido una correlación de m con la velocidad de deslizamiento y la presión de contacto con comportamiento fuertemente adhesivo en las condiciones de lubricación límite consideradas. Los resultados obtenidos muestran que la grasa de bisulfuro de molibdeno disminuye en un 50 % los valores del coeficiente de rozamiento

  19. “ESTUDIO DEL EFECTO DEL NITROGENO ADICIONADO AL GAS DE PROTECCION MEDIANTE EL PROCESO DE SOLDADURA GMAW, SOBRE UN RECARGUE DE ACERO INOXIDABLE 410”

    OpenAIRE

    Avila Cruz, Luis Adrian

    2012-01-01

    Los aceros inoxidables martensíticos de la serie 400, son utilizados en la industria del gas, tuberías de vapor, álabes de turbinas de vapor, los rodillos de colada continua y otras piezas de aplicación industrial. Debido a las condiciones de trabajo a los que está sometido el acero inoxidable martensítico, este puede ser reforzado para un mejor funcionamiento, ya que las condiciones a los que esta sometidos con el tiempo inducen la falla en el recargue y por consiguiente una r...

  20. PRECIPITACIÓN DE LA FASE SIGMA BAJO LA APLICACIÓN DE CICLOS TERMICOS EN UN ACERO INOXIDABLE SUPERDÚPLEX SAF 2507

    OpenAIRE

    Villalobos Vera, Doris Ivette

    2012-01-01

    El acero inoxidable superdúplex es utilizado principalmente en la industria química, petroquímica y del petróleo ya que consiste aproximadamente de 50% ferrita y 50% austenita, lo que permite una combinación de excelentes propiedades mecánicas y una elevada resistencia a la corrosión. Las características y propiedades que ofrecen los aceros inoxidables superdúplex, se deben a los contenidos de Cr, Mo, Ni y N, los cuales también promueven la formación de fase sigma. Esta fase...

  1. Efectos gammágenos del cobre en los aceros inoxidables 18Cr8Ni

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1997-10-01

    Full Text Available From a series of 22 typical 18Cr8Ni stainless steel 40 kg ingots, with copper variable concentrations from 0.6 to 3.0 weight %, δ-ferrite is measured with a ferrite-meter device, calculating a nickel equivalent of 0.27 for copper. Some differences between the 8-ferrite and that on calculated by DeLong -excluding the copper γ-gene action- have been found because of different solidification and cooling regimes in ingot and weld cases.

    A partir de una serie de 22 lingotes de 40 kg de aceros inoxidables típicos 18Cr8Ni, con concentraciones variables de cobre entre 0,6 y 3,0 % en masa, se mide la ferrita δ mediante un medidor de ferrita y se deduce para el cobre un equivalente en níquel de 0,27, a la vez que se establecen ciertas diferencias entre los contenidos de ferrita δ medida y la deducida según DeLong -excluida la acción gammágena del cobre- por el hecho de solidificar en lingotes en vez de la típica solidificación de soldaduras.

  2. Estructura cristalina del acero AISI 1045 deformado plásticamente

    Directory of Open Access Journals (Sweden)

    Tomás Fernández Columbié

    2008-01-01

    Full Text Available Se abordó el comportamiento microestructural del acero AISI 1045 endurecido mediante la Deformación Plástica Superficial por rodillo, Se establece el mecanismo de endurecimiento del acero por el deslizamiento de los granos en la red cristalina y se demuestra el fenómeno de la acritud, la cual es producto del tensionamiento de los granos cuando el material es sometido al tensionamiento de su estructura cristalina. Se establece el procedimiento experimental realizado después que las probetas fueron sometidas al proceso de deformación.

  3. Estructura cristalina del acero AISI 1045 deformado plásticamente

    OpenAIRE

    Tomás Fernández Columbié; Isnel Rodríguez González; Dayanis Alcántara Borges

    2008-01-01

    Se abordó el comportamiento microestructural del acero AISI 1045 endurecido mediante la Deformación Plástica Superficial por rodillo, Se establece el mecanismo de endurecimiento del acero por el deslizamiento de los granos en la red cristalina y se demuestra el fenómeno de la acritud, la cual es producto del tensionamiento de los granos cuando el material es sometido al tensionamiento de su estructura cristalina. Se establece el procedimiento experimental realizado después que las probetas fu...

  4. Variación microestructural del acero AISI 1045 endurecido por rodadura

    OpenAIRE

    Esther Fernández-Guilarte; Dayanis Alcántara-Borges; Isnel Rodríguez-González; Tomás Fernández-Columbié

    2010-01-01

    En este trabajo se analiza el comportamiento microestructural del acero AISI 1045, endurecido mediante deformación plástica superficial por rodillo, empleando como variables en el proceso de endurecimiento el número de revoluciones, avance y fuerza del torno 16D20. Se empleó el análisis espectral para determinar la composición química del acero y el Nital como reactivo químico para resaltar la estructura metalográfica después de pulida. Se establecen los parámetros de los regímenes de la defo...

  5. Metalografía en color de los aceros inoxidables mediante la técnica de ataque coloreado

    Directory of Open Access Journals (Sweden)

    Fosca, C.

    1996-08-01

    Full Text Available The color metallography by tint etching allows the identification and quantification by optical microscopy of phases and constituents present in the microstructure of a great number alloys. The principle of this technique consists of the build up of an interference film on the alloy surface as consequence of electrochemical reactions between the metallic surface and the tint etching reagent. The application of the tint etching to the metallographic analysis of stainless steels enable the identification and quantification, by image analysis, of secondary phases, as ferrite in the austenitic stainless steels, or secondary austenite and sigma phase in the duplex stainless steels.

    La metalografía en color mediante la técnica de ataque coloreado permite la identificación y cuantificación, por el contraste de color, de diversas fases y constituyentes presentes en la microestructura de un gran número de aleaciones. La técnica consiste en depositar una película de interferencia en la superficie del material como consecuencia de reacciones electroquímicas entre el metal y el reactivo de ataque coloreado. La aplicación de la técnica de ataque coloreado en los aceros inoxidables permite la identificación y cuantificación, mediante análisis de imagen, de fases secundarias como la ferrita en los aceros inoxidables austeníticos o la austenita secundaria y la fase sigma en los aceros inoxidables dúplex.

  6. Precipitación de la fase sigma bajo la aplicación de ciclos térmicos en un acero inoxidable superduplex SAF 2507

    OpenAIRE

    Villalobos Vera, Doris Ivette

    2011-01-01

    El acero inoxidable superdúplex es utilizado principalmente en la industria química, petroquímica y del petróleo ya que consiste aproximadamente de 50% ferrita y 50% austenita, lo que permite una combinación de excelentes propiedades mecánicas y una elevada resistencia a la corrosión.

  7. Estudio de corrosión galvánica en pares latón/acero inoxidable y latón/fundición de hierro

    Directory of Open Access Journals (Sweden)

    Ohanian, M.

    2011-08-01

    Full Text Available Corrosion attack in heat exchanger systems is a topic of main interest for the maintenance in each industrial plant. These are multigalvanic systems with particular geometric and fluidodynamic complexity. Corrosive damages include zinc selective dealeation in copper alloys. In order to explain zinc dealeation attack, this paper deals with laboratory scale testing, characterization and interactions between two copper and zinc alloys (Yellow brass –UNS C268– and Admiralty brass –UNS C443– compared to AISI 316 stainless steel and cast iron. The tests were performed at 20 °C in 1.5 % NaCl and 1.5 % Na2SO4 solutions, pH 8 and each material was characterized by potentiodynamic sweeps. The couples are analyzed by studying transient galvanic currents. We conclude about the cause of the analyzed pathology, brass protection potential ranges and its coupling compatibility with other metals.

    El ataque por corrosión en los sistemas intercambiadores de calor constituye un problema para el mantenimiento de cualquier planta industrial. Se trata de sistemas multigalvánicos con particular complejidad geométrica y fluidodinámica. Las patologías corrosivas incluyen el fenómeno de dealeación selectiva de cinc en las aleaciones de cobre. A fin de explicar un caso particular de ataque por decinficación (deterioro en placa de intercambiador de calor de tubos de inoxidable, el presente trabajo aborda en ensayos a escala de laboratorio, la caracterización e interacciones entre dos aleaciones de cobre y cinc, (Yellow brass –UNS C268– y Admiralty brass –UNS C443–, respecto a acero inoxidable AISI 316 y fundición gris de hierro. Los ensayos se realizan a 20 °C en disoluciones de NaCl 1,5 % y Na2SO4 1,5 % y pH 8. Se caracterizan electroquímicamente las aleaciones y materiales involucrados mediante barridos potenciodinámicos. Los pares galvánicos formados se analizan mediante el

  8. Identificación de Fases y Precipitados por MFA en Uniones de Acero Inoxidable Dúplex

    Directory of Open Access Journals (Sweden)

    María Eugenia Herrera López

    Full Text Available Resumen La Microscopía de Fuerza Atómica (MFA, técnica de caracterización que genera imágenes topográficas de superficies a muy altas resoluciones, opera registrando los detalles de relieve superficial del material con un cantiléver que se mueve sobre la muestra, mientras un detector piezoeléctrico monitorea los cambios de altura. Ésta técnica, adquiere relevancia en el campo de la identificación de fases, partículas y precipitados a niveles de nanoescala por lo que se propone para su identificación en la zona de fusión de componentes soldados y para la identificación temprana de fallas por agrietamiento. Es una técnica que no requiere de muestras conductoras, o la especial preparación metalográfica de probetas como es el caso de la microscopia electrónica. El material de estudio es un acero inoxidable dúplex 2205, unido por arco metálico y electrodo de tungsteno (GTAW. Al material soldado se le practicó ensayo de tensión. Las probetas fueron caracterizadas mediante microscopia óptica, microscopía electrónica de barrido, microscopía de fuerza atómica y pruebas de nanoindentación. Los resultados se concentran en la identificación de las características magnéticas, topográficas y dureza específicos de cada una de las fases, partículas y regiones presentes en el metal base, zona de fusión y la zona deformada por la fractura.

  9. Comportamiento Tribológico de Aceros Inoxidables para Cubertería Tribologic Behavior of Stainless Steels for Cutlery

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    José D.B de Mello

    2006-01-01

    Full Text Available Se estudió el comportamiento tribológico de los aceros inoxidables utilizados en cubertería. Se sometieron aceros martensíticos y ferríticos con diferentes contenidos de carbono y cromo a ensayos con micro-abrasión y desgaste por deslizamiento alternado. A pesar de que la composición química haya afectado considerablemente la micro estructura y dureza de las aleaciones, el comportamiento en la abrasión y en el coeficiente de fricción no fueron afectados por estos factores. La velocidad de desgaste por deslizamiento crece con el potencial de contacto, sugiriendo que el desgaste por deslizamiento de estos aceros se asocia con la formación de una capa protectora de óxidos.A study was made of the tribologic behavior of stainless steel used in cutlery. Abrasive and sliding wear tests were carried out on martensitic and ferritic stainless steels which had different contents of carbon and chromium. Although the chemical composition and heat treatment considerably modified the microstructure and hardness of the steels, these treatments had no significant effect on abrasion resistance and the friction coefficient. The sliding wear rate grows with the contact potential, suggesting that sliding wear in these steels is associated with the formation of protective oxide coatings

  10. Efecto de la biopelícula en la corrosión de aceros inoxidables

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    Bethencourt, M.

    2010-02-01

    Full Text Available In this work, the influence of the biofilms in the corrosion process of different alloys of stainless steel was studied in two sampling points in a wastewater treatment plant during 4 years. The physicochemical microenvironment within the biofilms was characterized through O2, H2S and pH microelectrodes. Corrosion rates were quantified from the number, diameter and depth of pits. The results show a remarkable development of the biofilm and a significantly greater number of pits in the grit removal channel than in the sludge recirculation channel. Based on the characteristics of the water phase and microelectrode measurements, our results suggest that biofilms induced corrosion throughout 3 mechanisms: creation of differential aeration cells, areas with different pH and areas having high sulphide production which may react with metal ions.

    En este trabajo se ha estudiado la influencia de las biopelículas en los procesos de corrosión de diferentes aleaciones de acero inoxidable, situadas durante 4 años en dos puntos de una estación depuradora de aguas residuales. Se caracterizó el microambiente físico-químico en el interior de las biopelículas mediante microelectrodos de O2, H2S y pH, y se cuantificaron las tasas de corrosión a partir del número, diámetro y profundidad de picadura. Los resultados obtenidos muestran un desarrollo más notable de las biopelículas y un número de picaduras significativamente mayor en el canal de salida de desbastes que en el canal de recirculación de fangos. Con base en las características del agua sobrenadante y en las medidas realizadas con microelectrodos, se sugiere que la biopelícula induce la corrosión a través de tres posibles mecanismos: creación de celdas de aireación diferencial, zonas con diferente pH y zonas con elevada producción de sulfuro capaz de reaccionar con iones metálicos.

  11. Propiedades mecánicas de las uniones por láser de aceros inoxidables dúplex

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    Amigó, V.

    2005-04-01

    Full Text Available The welded joints of stainless steels always present problems for the microstructural modifications that occur in the heat affected zone. Particularly, duplex stainless steels present very important changes when the weld pool solidifies forming fundamentally ferritic structures with some austenite in grain boundaries. These microstructural modifications, and those which occur in the HAZ, justify the mechanical properties of the joint and mainly those of plasticity, being all of them influenced by the processing conditions. In this work the influence of the laser welding speed on the tensile behaviour of duplex stainless steel welded joints is presented. The microstructure of the obtained seams and of the heat affected zone will be evaluated by means of optic and scanning electron microscopy. Also, different microhardness profiles have been obtained to evaluate the modifications in the mechanical properties both in the seam and the zone of thermal affection.

    Las uniones soldadas de aceros inoxidables siempre presentan problemas por las modificaciones microestructurales que suceden en la zona afectada por el calor. Particularmente, los aceros inoxidables dúplex presentan cambios microestructurales muy importantes al solidificar el cordón y formar estructuras, fundamentalmente ferríticas, con formación de austenita en borde de grano. Estas modificaciones microestructurales, junto a las que suceden en la ZAC, son las que justifican las propiedades mecánicas de la unión y fundamentalmente las de plasticidad. Y todo ello en función de las condiciones de procesado. En este trabajo se presenta la influencia de la velocidad de soldeo en las propiedades a tracción de uniones soldadas por láser de chapas de acero inoxidables dúplex. La microestructura de los cordones obtenidos y de la zona afectada por el calor se ha evaluado mediante microscopía óptica y electrónica de barrido, y se han obtenido diferentes perfiles de microdureza que

  12. Variación microestructural del acero AISI 1045 endurecido por rodadura

    Directory of Open Access Journals (Sweden)

    Esther Fernández-Guilarte

    2010-03-01

    Full Text Available En este trabajo se analiza el comportamiento microestructural del acero AISI 1045, endurecido mediante deformación plástica superficial por rodillo, empleando como variables en el proceso de endurecimiento el número de revoluciones, avance y fuerza del torno 16D20. Se empleó el análisis espectral para determinar la composición química del acero y el Nital como reactivo químico para resaltar la estructura metalográfica después de pulida. Se establecen los parámetros de los regímenes de la deformación plástica superficial por rodillo para evaluar la dureza de los pasadores utilizados en las esteras de los equipos de laboreo minero y se expone una metodología para determinar el tiempo de ejecución del corte de las muestras.

  13. Estudo comparativo entre os aços inoxidáveis dúplex e os inoxidáveis AISI 304L/316L

    Directory of Open Access Journals (Sweden)

    Marcelo Senatore

    2007-03-01

    Full Text Available Os aços inoxidáveis dúplex ferríticos-austeníticos fazem parte de uma classe de materiais com microestrutura bifásica, composta por uma matriz ferrítica e ilhas de austenita, com frações volumétricas aproximadamente iguais dessas fases. Essa classe de materiais é caracterizada por apresentar interessante combinação de elevadas propriedades mecânicas e de resistência à corrosão e, por isso, é considerada bastante versátil. Os aços inoxidáveis dúplex são, freqüentemente, utilizados nas indústrias química e petroquímica, de papel e celulose, siderúrgicas, alimentícias e de geração de energia. O presente trabalho estabelece um comparativo entre as propriedades físicas, mecânicas e de resistência à corrosão dos aços inoxidáveis duplex e os tradicionais aços inoxidáveis austeníticos AISI 304L e 316L, largamente utilizados na indústria brasileira. Resultados de ensaios laboratoriais e dados relevantes de experiências práticas desses materiais também são apresentados.Ferritic-austenitic duplex stainless steels are part of a class of material having a two-phase microestructure, comprised of a ferritic matrix and austenitic islands, with the volumetric fractions approximately the same in these phases. This class of material is characterized by the presentation of an interesting combination of high mechanical properties and corrosion resistance and is therefore considered quite versatile. The duplex stainless steels are often used in the chemical, petrochemical, pulp & paper and food industries, as well as in steel foundaries and energy power plants. This paper shows a comparison between the physical, mechanical and corrosion resistance properties of duplex stainless steels and the traditional austenitic stainless steels 304L and 316L, largely used in the Brazilian industry. Results of laboratory tests and relevant data on practical experiments on these materials are also presented.

  14. Formación de microporosidad interna en polvos de acero inoxidable: cinética y mecanismo

    Directory of Open Access Journals (Sweden)

    Martínez, M.

    2002-06-01

    Full Text Available The internal microporosity of stainless steel powders is obtained by a technology developed in the Metallurgical Research Center (CIME in collaboration with ISPETP, which consists of carbon enrichment of alloy during the fusion process, and after powder atomization a subsequent decarburization annealing. The internal microporosity, which can reach up to 10 volume percent of the steel particle, reduces powder density and improves powder compressibility, while costs for technology installation are also reduced. In this paper the technology for obtaining the microporosity, the mathematical models of the process, and the structural transformations undergone by stainless steel powder are shown. It is concluded that for carbon contents lower than 0.05% internal microporosity tends to disappear.

    El Centro de Investigaciones Metalúrgicas (CIME de La Habana, en colaboración con el Instituto Superior Pedagógico para la Educación Técnica Profesional (ISPETP, ha desarrollado una tecnología para la obtención de los polvos de acero inoxidable con microporosidad interna. La tecnología consiste en enriquecer la aleación con carbono durante la fusión y, una vez atomizado el polvo, someterlo a un recocido de descarburación. La microporosidad interna, que puede alcanzar hasta un 10 % en volumen de la partícula, reduce la densidad de los polvos y mejora su compresibilidad, al tiempo que reduce los costes de instalación. El presente trabajo muestra la tecnología de obtención de la microporosidad, los modelos matemáticos del proceso y las transformaciones estructurales que sufre el polvo de acero inoxidable. Se concluye que la microporosidad tiende a desaparecer para contenidos de carbono menores de 0,05 %.

  15. Diseño, construcción y puesta en funcionamiento de un alambique modificado de acero inoxidable a nivel de laboratorio

    OpenAIRE

    Otiniano Cáceres, Manuel Eduardo; Departamento Académico de Operaciones Unitarias, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Romero y Otiniano, P.; Departamento de Análisis y Diseño de Procesos, Facultad de Química e Ingeniería Química, UNMSM.; Garrido, A.; Departamento Académico de Operaciones Unitarias, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Flores, R.; Departamento Académico de Química Inorgánica, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Deza, E.; Departamento Académico de Química Inorgánica, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Cárdenas, J.; Departamento de Análisis y Diseño de Procesos, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Lombira, J.; Departamento Académico de Operaciones Unitarias, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos; Mori, V.; Estudiante de la E.A.P. de Ingeniería Química, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos.; Meneses, K.; Estudiante de la E.A.P. de Ingeniería Química, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos.

    2016-01-01

    Se presenta en el presente trabajo las características principales del alambique modificado de acero inoxidable a nivel de laboratorio, construido en un proyecto de investigación del año 2014. La puesta en funcionamiento se hicieron con ensayos de mosto fermentado de uva quebranta proveniente del Valle de Lunahuana, Cañete, obteniéndose pisco de aceptable calidad.

  16. DEFORMACIÓN ELÁSTICA RESIDUAL EN LÁMINAS DE ACERO AISI 304 RECUBIERTAS CON UNA PELÍCULA DE NITRURO DE TITANIO DEPOSITADA POR PVD-MAGNETRON SPUTTERING

    OpenAIRE

    COLORADO, H. A.; SALVA, H. R.; GHILARDUCCI, A. A.

    2009-01-01

    se realizó una caracterización mediante difracción de rayos x (DRX) en láminas de acero inoxidable AISI 304 recubierto con una capa de nitruro de titanio de 3 mm de espesor, obtenida mediante deposición física de vapor (PVD-magnetron sputtering) a una temperatura de 200 ˚C. se tomaron imágenes de microscopía electrónica de barrido (MEB), microscopía óptica (MO) y microscopía de fuerza atómica (MFA) para caracterizar el sustrato, la capa y la zona cercana a la intercara. adicionalmente se dete...

  17. DEFORMACIÓN ELÁSTICA RESIDUAL EN LÁMINAS DE ACERO AISI 304 RECUBIERTAS CON UNA PELÍCULA DE NITRURO DE TITANIO DEPOSITADA POR PVD-MAGNETRON SPUTTERING

    Directory of Open Access Journals (Sweden)

    H. A. COLORADO

    2009-01-01

    Full Text Available Se realizó una caracterización mediante difracción de rayos x (DRX en láminas de acero inoxidable AISI 304 recubierto con una capa de nitruro de titanio de 3 um de espesor, obtenida mediante deposición física de vapor (PVD-MAGNETRON SPUTTERING a una temperatura de 200 °C. se tomaron imágenes de microscopía electrónica de barrido (MEB, microscopía óptica (MO y microscopía de fuerza atómica (MFA para caracterizar el sustrato, la capa y la zona cercana a la intercara. adicionalmente se determinó la deformación elástica residual asociada con el ensanchamiento de los picos de DRX.

  18. Microestrutura de uma Solda Dissimilar entre o Aço Inoxidável Ferrítico AISI 410S e o Aço Inoxidável Austenítico AISI 304L Soldado pelo Processo FSW

    OpenAIRE

    Tathiane Caminha Andrade; Cleiton Carvalho Silva; Hélio Cordeiro de Miranda; Marcelo Ferreira Motta; Jesualdo Pereira Farias; Luciano Andrei Bergman; Jorge Fernandes dos Santos

    2015-01-01

    Resumo O presente trabalho visa investigar a microestrutura formada na soldagem dissimilar entre chapas de aços inoxidáveis ferríticos AISI 410S e aços inoxidáveis austeníticos AISI 304L pelo processo friction stir welding. A soldagem foi realizada com o ajuste dos seguintes parâmetros: rotação 450 rpm; velocidade de soldagem de 1,0 mm/s; e força axial 40 kN. O aço AISI 410S foi posicionado no lado de avanço enquanto que o aço AISI 304L foi posicionado no lado de retrocesso. A análise consist...

  19. Evolución de las características de dureza del acero AISI 304 con el tratamiento térmico

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    López, A.

    2001-04-01

    Full Text Available The evolution of the microstructure and hardness of commercial AISI 304 stainless-steel samples with the heat treatment has been studied. Steel specimens in the as-received condition, and after 50% cold rolling, were soaked for 1 hour at various temperatures between 650 and 1200 °C. Samples, maintain their grain size and hardness until about 900 °C; thereafter, size increases with temperature, while hardness lightly-diminishes. Recrystallization of cold-rolled specimens begins at 650 °C, and finishes around 850 °C. Recrystallized grain-size reaches the value found in the as received material after the treatment at 900 °C. For high her annealing temperatures both grain growth and hardness decrease following the same trent in cold-worked and non-deformed materials.

    Se ha estudiado la evolución que experimenta la microestructura y las propiedades mecánicas (dureza de un acero inoxidable austenítico AISI 304 de calidad comercial, cuando se somete a tratamientos térmicos tras una deformación en frío, por laminación, del 50%. En tratamientos isócronos, de una hora de duración, la recristalización del acero y su ablandamiento comienza a los 650 °C, completándose alrededor de los 825 °C. Entre 650 y 900 °C, se produce un crecimiento de grano recristalizado cuyo tamaño no alcanza el del grano original hasta los 925 °C, aproximadamente. A mayores temperaturas, hasta 1.200 °C, tiene lugar un manifiesto crecimiento del grano austenítico con un ligero descenso en los valores de dureza. El comportamiento del acero laminado y tratado se ha comparado con el de muestras calentadas, en las mismas condiciones, pero sin deformación previa en frío.

  20. Thermomechanical behaviour of AISI 304 steels; Comportamiento termomecanico de aceros AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    El Wahabi, M.; Garcia, V. G.; Cabrera, J. M.; Prado, J. M.

    2001-07-01

    The hot deformation behaviour of three AISI 304 (H, L and HP) austenitic stainless steel with different carbon contents has been studied. An analysis of the parameters describing their hot flow curves was carried out. No heavy effect of the carbon content was found on most of the latter parameters. However, the work hardening and dynamic recovery behaviour showed clear differences depending on the given alloy, especially at high temperatures and low strain rates where the high carbon steel displayed larger work hardening and dynamic recovery rates than the other steels. The high purity steel (interstitial free) displayed the lower stress levels as its hardening rate was slower than in the other two steels. (Author) 16 refs.

  1. Influencia de la temperatura en las propiedades a tracción de un acero inoxidable superdúplex

    Directory of Open Access Journals (Sweden)

    Gironès, A.

    2001-04-01

    Full Text Available Tensile tests, at temperatures ranging between 275 and 475 °C were performed in a superduplex stainless steel EN 1.4410. The dependence of yield stress and ultimate tensile strength on temperature indicates the existence of dynamic strain aging (DSA. In order to evaluate the influence of strain rate on this phenomenon, tests were conducted at two different strain rates, both at 325 °C, temperature at which DSA is maximum for this material. The results show that the flow stress has an inverse strain rate sensitivity which confirms the existence of DSA in the steel under study.

    Un acero inoxidable superduplex tipo EN 1.4410 se ensayó a tracción en el rango de temperaturas de 275 a 475 °C. La evolución, en función de la temperatura, de los valores de límite elástico y resistencia máxima indica la existencia de un fenómeno de envejecimiento por deformación (Dynamic Strain Aging, DSA. Para evaluar la influencia de la velocidad de deformación sobre dicho comportamiento se realizaron ensayos de tracción a dos velocidades diferentes, ambos a la temperatura de 325 °C, para la cual se había registrado la máxima manifestación de DSA. Dichos ensayos reflejaron una sensibilidad inversa a la velocidad de deformación lo que confirma la presencia de DSA en el acero bifásico estudiado.

  2. Formación de maclas durante el enfriamiento en aceros inoxidables superferríticos envejecidos

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    Salán, M. N.

    2005-12-01

    Full Text Available Superferritic stainless steels show a BCC structure free of austenite at any temperature. Intermediate ageing temperatures, close to 475 °C, induce a-chromium content modulation and only after long periods of time, it is possible to detect chromium rich α' phase, which is responsible for embrittlement (475 °C embrittlement. In this work, ageing thermal treatments at intermediate temperatures in the superferritic stainless steel DIN 1.4575, have allowed to relate the associated hardness increase with time and temperature by means of a relationship that is compatible with a thermally activated process. After quenching from ageing temperature, twinning formation has been observed, and the extent of twinning is proportional to the increase in hardness, showing in this way that twinning density is proportional to embrittlement level.

    Los aceros inoxidables superferríticos se caracterizan por su estructura cúbica centrada, libre de austenita a cualquier temperatura. Sometidos a temperaturas intermedias, próximas a 475 °C, revelan una modulación del contenido en Cr de la red. Después de tiempos prolongados se forma fase α', fragilizante y rica en cromo, fenómeno conocido como fragilización a 475 °C. En este trabajo, los tratamientos de envejecimiento realizados a temperaturas intermedias para un superferrítico DIN 1.4575 han permitido relacionar el incremento de dureza asociado a éstos con el tiempo de tratamiento, mediante una expresión coherente con un proceso térmicamente activado. Por otra parte, se ha detectado la presencia de maclas en el acero envejecido y templado en agua, siendo proporcional su densidad al grado de endurecimiento provocado por el tratamiento.

  3. “IDENTIFICACIÓN DE LA CORROSIÓN EN LOS ALAMBRES DE NIQUEL TITANIO Y ACERO INOXIDABLE Y LA PRESENCIA DE BACTERIAS ASOCIADAS EN UNA MUESTRA DE ARCOS UTILIZADOS EN PACIENTES DE LA CLÍNICA DE ORTODONCIA”.

    OpenAIRE

    Vargas Morales, Karla Odette

    2012-01-01

    El propósito de este trabajo de investigación fue identificar la presencia de corrosión en alambres de Níquel Titanio y Acero Inoxidable, así como presencia de bacterias asociadas en los mismos colocados en boca durante 4 meses en pacientes de la clínica de ortodoncia de la Universidad Michoacana de San Nicolás Hidalgo. En el tamaño de la muestra del presente estudio se utilizaron diez arcos: cinco de níquel titanio termoactivados y cinco de acero inoxidable. Los siguientes ...

  4. Caracterización mecánica de recubrimientos de aluminio por CVD-FBR sobre aceros inoxidables y resistencia a la oxidación en vapor de agua

    Directory of Open Access Journals (Sweden)

    Diego Pérez-Muñoz

    2015-09-01

    Full Text Available Los recubrimientos de aluminio depositados sobre el acero inoxidable austenítico AISI 317 por Deposición Química de Vapor en Lecho Fluidizado (CVD-FBR presentan a altas temperaturas una reducción de la velocidad de corrosión de más de 80 veces. Se realizó la caracterización mecánica de los recubrimientos por medio de microdureza, nanoindentación, para conocer cómo se vieron afectas las propiedades mecánicas (en especial la dureza y el módulo de Young del recubrimiento y del sustrato luego de ser sometidos a la oxidación a alta temperatura. También se hicieron análisis por medio de Microscopia Electrónica de Barrido (MEB, para observar los cambios microestructurales, y de Microscopia de Fuerza Atómica (MFA, para observar cómo varía la topografía y el gradiente de rugosidad en función de la distancia recorrida por la punta del cantiléver durante los barridos.

  5. Simulación del efecto de la irradiación mediante el trabajado en frío y los tratamientos térmicos en dos aceros inoxidables austeníticos

    Directory of Open Access Journals (Sweden)

    de Diego, G.

    1998-10-01

    Full Text Available In the present study, annealed type 304 SS was cold worked and heat treated to simúlate irradiation hardening, ductility loss and grain boundary segregation. Constant Extension Rate Tensile (CERT tests were conducted to reproduce Irradiation Assisted Stress Corrosion Cracking (IASCC in BWR (Boiling Water Reactor environment.

    En este trabajo se simulan los efectos que produce la irradiación, pérdida de ductilidad y segregación de impurezas en borde de grano, mediante trabajado en frío y posterior tratamiento térmico, para aceros inoxidables austeníticos AISI 304. Mediante ensayos de velocidad de extensión constante y en medios similares a los de los reactores de agua en ebullición se intenta relacionar la susceptibilidad a la corrosión bajo tensión con la susceptibilidad a la corrosión asistida por irradiación.

  6. Corrosión de la soldadura de un acero inoxidable supermartensítico mediante una minicelda electroquímica

    OpenAIRE

    Bilmes, Pablo David; Llorente, Carlos Luis; Gervasi, Claudio Alfredo; Pereda, María Dolores

    2011-01-01

    En el presente trabajo se investigó la influencia de los ciclos térmicos de una soldadura en la corrosión localizada de aceros inoxidables martensíticos de bajo carbono. A tal fin se utilizó una minicelda electroquímica (MCE) y se evaluó separadamente el metal de soldadura (MS), el metal base (MB) y la zona afectada por el calor (ZAC) como también diferentes áreas dentro del cordón de soldadura multipasada.

  7. Efecto de los ciclos térmicos sobre la ZAT de una soldadura multipasos de un acero inoxidable superdúplex SAF 2507

    OpenAIRE

    Villalobos,D.; C. Maldonado; Albiter,A.; Robles-Piedras,E.

    2010-01-01

    Los ciclos térmicos de una soldadura multipasos que experimenta un acero inoxidable superdúplex SAF 2507, pueden promover la precipitación de fases secundarias reduciendo significativamente las propiedades mecánicas y la resistencia a la corrosión. Debido a su aplicación en la industria petroquímica, el estudio de las aleaciones superdúplex es de suma importancia para predecir su comportamiento en servicio cuando están involucrados procesos de soldadura por arco eléctrico. En este trabajo, se...

  8. Metodología de detección de óxido residual en superficies de acero inoxidable mediante visión por computador

    OpenAIRE

    Cañero Nieto, Juan Miguel

    2016-01-01

    La presente tesis doctoral es una investigación que propone una alternativa basada en visión por computador a la detección, por parte de un operador humano, de un defecto superficial denominado óxido residual que puede producirse durante el procesamiento de bobinas de acero inoxidable en una línea de recocido y decapado de la industria siderúrgica. Se trata de un defecto cuya eliminación incompleta puede producir problemas operativos durante el procesamiento posterior que va a sufrir la bob...

  9. Estudio comparativo de la cavidad de acceso radicular en conductos curvos con limas de níquel-titanio y taladros de acero inoxidable

    OpenAIRE

    Oncins Rodríguez, J.; Pumarola Suñé, José; Canalda Sahli, Carlos

    2005-01-01

    El propósito de este estudio fue comparar la cantidad de dentina radicular removida y evaluar el mantenimiento de la forma del conducto tras la instrumentación de los dos tercios coronarios radiculares, utilizando instrumentos de acero inoxidable (taladros de Gates Glidden) y de níqueltitanio (limas GT Flare y limas Orifice Shaper). Un total de 42 dientes humanos extraídos con conductos radiculares curvos fueron divididos en tres grupos. Los conductos se instrumentaron mecánicamente usando ta...

  10. ESTUDIO EXPERIMENTAL PRELIMINAR DE LA DESHIDRATACIÓN DEL ETANOL CON CLORURO DE SODIO EN UN EQUIPO DE DESTILACIÓN DISCONTINUA CON COLUMNA EMPACADA DE ACERO INOXIDABLE

    OpenAIRE

    Otiniano Cáceres, Manuel Eduardo; Departamento de Operaciones Unitarias, Facultad de Química e Ingeniería Química UNMSM; Romero y Otiniano, P.; Departamento de Análisis y Diseño de Procesos, Facultad de Química e Ingeniería Química, UNMSM.; Guerrero, M.; Departamento de Química Orgánica,Facultad de Química e Ingeniería Química,Universidad Nacional Mayor de San Marcos,Lima,Perú.; Linares, T.; Departamento de Química Orgánica, Facultad de Química e Ingeniería Química, UNMSM.; Salas, G.; Departamento de Operaciones Unitarias, Facultad de Química e Ingeniería Química UNMSM; Lombira, J.; Departamento de Operaciones Unitarias, Facultad de Química e Ingeniería Química UNMSM; Helfer, H.; Departamento de Análisis y Diseño de Procesos, Facultad de Química e Ingeniería Química, UNMSM.; Cárdenas, J.; Departamento de Análisis y Diseño de Procesos, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos

    2015-01-01

    Se presentan los resultados preliminares de los ensayos experimentales realizados para la obtención del etanol anhidro utilizando destilación discontinua extractiva con una sal disuelta como el cloruro de sodio. Para los ensayos se utilizaron una planta piloto de destilación discontinua de acero inoxidable que cuenta con un sistema de adquisición de datos.  Los resultados muestran que no se alcanza la composición del azeótropo que es de 95.6 % en peso de etanol.

  11. Efecto de la velocidad y ángulo de impacto en la resistencia a corrosión - erosión de aceros inoxidables recubiertos con TiN

    Directory of Open Access Journals (Sweden)

    José Ricardo Cano Rodas

    2004-01-01

    Full Text Available Fueron estudiados los mecanismos de degradación superficial en aceros inoxidables austenítico AISI 304 y martensítico AISI 420, con y sin recubrimiento cerámico de TiN, aplicado mediante técnica de deposición física de vapor PVD por arco pulsado, sometidos a erosión (solución de agua destilada con 30% en peso de partículas de sílice, corrosión (solución ½ M H2SO4 + 3.5% NaCl y efectos sinérgicos corrosión - erosión. Fue construido un dispositivo para realizar los ensayos descritos con la posibilidad de variar la velocidad y el ángulo medio de impacto de las partículas sobre la superficie de las muestras. Marcas características fueron observadas en las superficies desgastadas, siendo la condición de ángulo rasante la de mayor efecto nocivo tanto para las superficies desnudas como para las recubiertas con TiN. El nivel de deterioro superficial aumentó con la velocidad de impacto, al tiempo que se evidenció la importancia de la adherencia de las películas protectoras al substrato para la obtención de una buena resistencia a corrosiónerosión. La sinergia corrosión-erosión presentó, en algunas ocasiones, un efecto positivo para la superficie, ya que el impacto de las partículas duras causó intensa deformación plástica pero no consiguió remover material de la superficie.

  12. Oxidación cíclica de un acero refractario AISI 310 a alta temperatura en atmósferas con contenidos de oxígeno variables

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    Higuera-Hidalgo, V.

    2005-06-01

    Full Text Available High temperature oxidation tests of an AISI 310 stainless steel was performed in two different environments: in an standard atmosphere (21 % oxygen at 704, 800, 884 and 1,000 °C and in the typical environment of a gas turbine and vapor generator of a combined-cycle electric generation unit (10 % oxygen at 800 and 1,000 °C. The oxidation kinetics was determined by means of the measurement of the weight gain per unit surface of the specimen and also determining the thickness of the oxide layer. Comparable results have been obtained using both methodologies and the effect of the oxygen content along with the other experimental differences were determined observing the oxidation kinetics in both environments. The cyclic oxidation of AISI 310 deteriorates at temperatures higher than 1,000 °C.

    Se ha llevado a cabo un estudio experimental sobre la oxidación a altas temperaturas de un acero inoxidable refractario AISI 310, en dos ambientes diferentes: en una atmósfera convencional (21 % de O2, a 704, 800, 884 y 1.000 °C y en un ambiente simulativo de una turbina de gas y del generador de vapor de uña central eléctrica de ciclo combinado (10-11 % de O2, a 800 y 1.000 °C. La cinética de la oxidación del material se ha determinado a partir, tanto de la ganancia de peso por unidad de superficie experimentada por las probetas objeto de ensayo como por la determinación de los espesores de las capas de óxido formados. Se han obtenido resultados comparables con ambas metodologías y se ha puesto de manifiesto el efecto del contenido de oxígeno y de las demás diferencias experimentales a partir de la comparación de las cinéticas de oxidación del acero en los dos medios oxidantes analizados. La oxidación del acero AISI 310 en situaciones térmicas cíclicas empieza ya a ser importante a partir de una temperatura de 1.000 °C.

  13. Influencia de la microestructura en el comportamiento a fatiga de aceros inoxidables austeníticos con alto contenido en molibdeno

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    Oñoro, J.

    2006-02-01

    Full Text Available Austenitic stainless steels with molybdenum present high mechanical properties and corrosion resistance to aggressive environments. These steels have been used to tank and vessel components for high corrosive liquids as phosphoric, nitric and sulphuric acids. These materials with low carbon and nitrogen addition have been proposed candidates as structural materials for the international thermonuclear experimental reactor (ITER in-vessel components. Molybdenum addition in austenitic stainless steel improves mechanical and corrosion properties, but with it can produce the presence of nitrogen microstructure modifications by presence or precipitation of second phases. This paper summarises the fatigue and corrosion fatigue behaviour of two 317LN stainless steels with different microstructure. Fully austenitic steel microstructure show better fatigue, corrosion fatigue resistance and better ductility than austenitic steel with delta ferrite microstructure, mainly at low stresses.

    Los aceros inoxidables austeníticos con elevados contenidos en molibdeno presentan alta resistencia mecánica y resistencia a los medios corrosivos. Se utilizan en la construcción de depósitos y recipientes para el almacenamiento y transporte de líquidos altamente corrosivos, tales como ácido fosfórico, nítrico o sulfúrico. Estos materiales con bajo carbono y adiciones de nitrógeno han sido propuestos como candidatos para materiales estructurales en la fabricación de la vasija del reactor experimental termonuclear internacional (ITER. La adición de molibdeno mejora las propiedades frente a la corrosión de los aceros inoxidables austeníticos. Sin embargo, este aumento del contenido en molibdeno, junto con la presencia de nitrógeno, puede producir modificaciones microestructurales, por la aparición de fases precipitadas o segundas fases. En este trabajo, se analiza el comportamiento la fatiga y corrosión-fatiga de dos aceros inoxidables austen

  14. Efecto del boro en la sinterización de un acero inoxidable ferrítico

    Directory of Open Access Journals (Sweden)

    Cabral-Miramontes, J. A.

    2008-12-01

    Full Text Available This work studies the effect of boron on the density of a 409Nb ferritic stainless steel obtained by powder metallurg during the process of sintering. The purpose of adding boron is to promote the formation of a liquid phase during sintering at temperatures below 1200 °C. The boron contents varied from 0.0 to 1.5%wt. Specimens were compacted at 700MPa, and sintering was made at 1075 and 1150 ºC during 60 minutes under a hydrogen atmosphere, using a heating rate of 20 ºC/min. Density values were determined by the Archimedes method, and the samples were analyzed using scanning electron microscopy. This work shows the dependence of the steel density and morphology of the microestructure as a function of boron content and the temperature of sintering.

    En este trabajo se analiza el efecto del boro sobre la densidad del acero inoxidable ferrítico 409Nb en el proceso de sinterización. La finalidad de adicionar boro es promover la formación de una fase líquida durante la sinterización, a una temperatura por debajo de 1.200 °C. Las adiciones de boro variaron entre 0,0 y 1,5 % en peso. Las muestras se compactaron a 700 MPa y las sinterizaciones se realizaron a 1.075 y 1.150 ºC, durante 60 min en una atmósfera de hidrógeno, calentando a una velocidad de 20 ºC/min. La densidad se determinó por el método de Arquímedes y las muestras se analizaron en el microscopio electrónico de barrido. Este trabajo muestra la dependencia de la densidad del acero y morfología de la microestructura, en función del contenido de boro y la temperatura de sinterización.

  15. Evolución microestrutural durante la soldaddura flerte de um acero inoxidablesúper dúplex UNS S32705 usando Ni-P como metal de aporte

    OpenAIRE

    Andrade Centeno, Dany Michell; Brandi, Sergio Duarte

    2014-01-01

    Los aceros inoxidables dúplex (AID), al ser sometidos a ciclos térmicos, pueden tener sus propiedades alteradas, sobre todo cuando se emplean procesos de soldadura o unión en altas temperaturas. Por lo tanto, muchas investigaciones se han desarrollado con respecto a la soldabilidad de estos aceros. Una de estas opciones de soldadura se viene dando con la soldadura fuerte de estos aceros. En este trabajo se realizó la soldadura fuerte, en horno continuo con atmósfera de hidrógeno, de cuerpos d...

  16. Evaluación electroquímica de soldaduras en tubos capilares de acero inoxidable

    OpenAIRE

    Javier E. Rodríguez-Yáñez; Ericka Saborío-Leiva; Daniel Mora-Montoya

    2014-01-01

    La recuperación de capilares de acero 316L utilizados en pozos geotérmicos neutros, por medio de soldadura orbital autógena, se evalúa desde el punto de vista de su resistencia a la corrosión en las condiciones de utilización, mediante técnicas electroquímicas básicas. En el pretratamiento se encuentra que es más conveniente realizar un decapado químico previo a la soldadura por 5 minutos. Mientras que posteriormente a la soldadura, la aplicación de tratamiento térmico de reducción de ten...

  17. Microestrutura de uma Solda Dissimilar entre o Aço Inoxidável Ferrítico AISI 410S e o Aço Inoxidável Austenítico AISI 304L Soldado pelo Processo FSW

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    Tathiane Caminha Andrade

    2015-12-01

    Full Text Available Resumo O presente trabalho visa investigar a microestrutura formada na soldagem dissimilar entre chapas de aços inoxidáveis ferríticos AISI 410S e aços inoxidáveis austeníticos AISI 304L pelo processo friction stir welding. A soldagem foi realizada com o ajuste dos seguintes parâmetros: rotação 450 rpm; velocidade de soldagem de 1,0 mm/s; e força axial 40 kN. O aço AISI 410S foi posicionado no lado de avanço enquanto que o aço AISI 304L foi posicionado no lado de retrocesso. A análise consistiu de preparação metalográfica e caracterização microestrutural por microscopia ótica e microscopia eletrônica de varredura. Para o aço AISI 410S foi observada a formação de martensita associada com ferrita na zona de mistura (ZM, zona termomecanicamente afetada (ZTMA e na zona afetada pelo calor (ZAC. As características do processo de soldagem FSW resultaram num refino de grão para o aço inoxidável ferrítico, posicionado no lado de avanço, tanto na ZM quanto nas ZTMA e ZAC. O mesmo comportamento não foi observado para o lado austenítico.

  18. Resistência à corrosão de junta dissimilar soldada pelo processo TIG composta pelos aços inoxidáveis AISI 316L e AISI 444

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    Luis Henrique Guilherme

    2014-03-01

    Full Text Available O aço inoxidável AISI 444 tornou-se uma opção para substituir a liga AISI 316L devido ao seu menor custo e satisfatória resistência à corrosão. Entretanto, o uso da liga AISI 444 no feixe tubular de trocadores de calor acarreta na soldagem de uma junta dissimilar. O presente estudo teve por objetivo avaliar a resistência à corrosão da junta tubo-espelho soldada pelo processo TIG composta pelas ligas AISI 316L e AISI 444. A manufatura das amostras consistiu em replicar o projeto da junta tubo-espelho de trocadores de calor. Realizou-se em juntas soldadas ensaios de sensitização, perda de massa por imersão desde a temperatura ambiente até 90 ºC, e ensaios eletroquímicos de polarização potenciodinâmica nos eletrólitos 0,5 mol/L de HCl e 0,5 mol/L de H2SO4. Os resultados mostraram que a junta dissimilar sofreu corrosão galvânica com maior degradação na zona afetada pelo calor (ZAC do tubo AISI 444. Porém, os mecanismos de corrosão localizada (pite e intergranular demonstraram ser mais ativos para a liga AISI 316L. Conclui-se que a junta dissimilar apresentou melhor resistência à corrosão do que a junta soldada composta unicamente pela liga AISI 316L em temperaturas de até 70 ºC, conforme as condições observadas neste trabalho.

  19. Evaluación electroquímica de soldaduras en tubos capilares de acero inoxidable

    Directory of Open Access Journals (Sweden)

    Javier E. Rodríguez-Yáñez

    2014-02-01

    Full Text Available La recuperación de capilares de acero 316L utilizados en pozos geotérmicos neutros, por medio de soldadura orbital autógena, se evalúa desde el punto de vista de su resistencia a la corrosión en las condiciones de utilización, mediante técnicas electroquímicas básicas. En el pretratamiento se encuentra que es más conveniente realizar un decapado químico previo a la soldadura por 5 minutos. Mientras que posteriormente a la soldadura, la aplicación de tratamiento térmico de reducción de tensiones no se justifica desde el punto de vista de la resistencia a la corrosión. También se plantea la comparación de los capilares soldados respecto a capilares nuevos y usados, teniendo los capilares soldados un comportamiento intermedio entre ambos.

  20. Diseño y puesta a punto de un sistema de vacío para sinterización de probetas pulvimetalúrgicas de acero

    OpenAIRE

    Álvaro Perrote, Óscar; Ferrero Peña, Carlos

    2013-01-01

    El objetivo principal del proyecto es diseñar y poner en funcionamiento un sistema de vacío de dos bombas (rotativa y difusora) para sinterizar probetas pulvimetalúrgicas de los aceros inoxidables AISI 316L, AISI 430L y DÚPLEX 50/50 a las que se practicarán ensayos de tracción para conocer su comportamiento mecánico. Una vez optimizado el proceso, se estudian las propiedades mecánicas. El comportamiento de estos aceros frente a la corrosión se evaluará de forma cualitativa mediante la práctic...

  1. Evaluación del coeficiente de endurecimiento del acero AISI 1045 deformado por rodillo

    Directory of Open Access Journals (Sweden)

    D. Alcántara

    2011-12-01

    Full Text Available El objetivo del trabajo es determinar el comportamiento del coeficiente de endurecimiento n por la ecuación de Hollomon en muestras cilíndricas de acero AISI 1045, las cuales, después de ser deformadas, se sometieron a ensayos de tracción. Se utiliza un diseño de experimento donde se tienen en cuenta las variables número de revolución (n con 27, 54 y 110 rev/min, fuerza de compresión (P de 500, 1 500 y   2 500 N y avance (S de 0,075; 0,125 y 0,25 mm/rev. Finalmente, aplicando el método de regresión se obtuvo un coeficiente de endurecimiento, el cual se aproxima a la linealidad cuando restringimos el cálculo a rangos de deformación elevados. Este coeficiente de endurecimiento se aplica en la ecuación de Hollomon para determinar el nuevo valor de tensión de fluencia y aplicarlo para el cálculo del trabajo mínimo a realizar en un proceso de deformación en frío empleando rodillo simple.   Palabras clave: Deformación Plástica; tensión; deformación; endurecimiento.The objective of the work is to determine the behavior of the hardening coefficient n by the equation of Hollomon, in cylindrical samples of steel AISI 1045, those which, after the deformed, were subjected to traction rehearsals. He used an experiment design where are kept in mind the revolution number (n with 27, 54 and 110 rev/min, it compression forces (P of 500, 1 500 and 2 500 N and feed (S of 0.075; 0.125 and 0.25 mm/rev. Finally, applying the regression method a hardening coefficient was obtained, which approaches to the linearity when restrict the calculation to high ranges of deformation. This hardening coefficient is applied in the equation of Hollomon for determine the new value of flow tension and to apply in the calculation of the minimum work to carry out in a cold process of deformation using simple roller.   Keywords: Plastic deformation; stress; deformation; hardening.

  2. Caracterización y propiedades mecánicas a alta temperatura de un acero inoxidable dúplex

    Directory of Open Access Journals (Sweden)

    Jiménez, J. A.

    1998-05-01

    Full Text Available The microstructure and mechanical behavior at high temperature of a thermomechanical processed duplex stainless steel have been studied. Recrystalization of the material takes place during heating to test temperature, and a microstructure consisting of islands of austenitic grains of about 10-15 μm in size included in a more or less continuous matrix of ferrite is observed. Tensile tests at temperatures above 1,000°C and at low strain rates show a stress exponent of about 2 and elongations to failure up to 290 %. These values suggest that deformation is controlled by a grain boundary sliding mechanism, which causes a decrease in the size of the islands during deformation. Finally, an activation energy for plastic deformation of 167 kJ/mol was observed that was related to the activation energy for grain boundary diffusion of iron.

    Se ha estudiado la microestructura y el comportamiento mecánico a alta temperatura de un acero inoxidable dúplex procesado termomecánicamente. Durante el calentamiento a la temperatura de ensayo, el material recristaliza y se obtiene una microestructura de granos austeníticos de tamaños comprendidos entre 10 y 15 μm agrupados en islas incluidas en una matriz más o menos continua de ferrita. Ensayos de tracción a temperaturas superiores a 1.000°C y bajas velocidades de deformación muestran un exponente de la tensión igual a 2 y alargamientos a rotura de hasta 290 %. Estos valores permiten asociar el mecanismo de deformación al deslizamiento de fronteras de grano, el cual determina la desaparición progresiva de las islas de granos austeníticos durante la deformación. Finalmente, se encontró un valor de 167 kJ/mol para la energía de activación de la deformación plástica, la cual se relacionó con la energía de autodifusión del hierro a lo largo de las fronteras de grano.

  3. Recubrimientos de (ti,aln sobre acero aisi 4140 por sputtering reactivo

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    DANNA GARCIA

    2007-01-01

    Full Text Available Empleando la técnica de Pulverización catódica con radiofrecuencia y magnetrón (Magnetron Sputtering RF, se prepararon películas de (Ti,AlN sobre sustratos de acero AISI 4140. Se utilizó un blanco formado con polvos metálicos de Ti y Al, con composición nominal 60% Ti y 40% Al (porcentaje en átomos y una razón de presiones parciales de nitrógeno - argón, PN2/PAr de 0,1 aproximadamente; la temperatura del sustrato se varió entre 260 y 330 ºC y el tiempo de deposición entre 2 y 4,5 horas para obtener películas con diferentes espesores. La composición química de las películas se determinó mediante la técnica de energía dispersada de rayos X (EDX, y su topografía mediante microscopía de fuerza atómica (AFM. Igualmente se midió micro dureza, y se determinó su comportamiento electroquímico mediante espectroscopia de impedancia electroquímica EIS y ensayos TAFEL. Las películas obtenidas presentaron granos globulares, uniformes y de pequeño diámetro, con características electroquímicas de protección al sustrato frente a procesos de corrosión.

  4. Desarrollo de un modelo matemático de diferencias finitas para el análisis del campo de temperaturas en la soldadura por arco de chapas finas de acero inoxidable

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    Miguel, V.

    2010-12-01

    Full Text Available This work develops a finite difference method to evaluate the temperature field in the heat affected zone in butt welding applied to AISI 304 stainless steel thin sheet by GTAWprocess. A computer program has been developed and implemented by Visual Basic for Applications (VBA in MS-Excel spreadsheet. The results that are obtained using the numerical application foresee the thermal behaviour of arc welding processes. An experimental methodology has been developed to validate the mathematical model that allows to measure the temperature in several points close to the weld bead. The methodology is applied to a stainless steel sheet with a thickness lower than 3 mm, although may be used for other steels and welding processes as MIG/MAG and SMAW. The data which has been obtained from the experimental procedure have been used to validate the results that have been calculated by the finite differences numerical method. The mathematical model adjustment has been carried out taking into account the experimental results. The differences found between the experimental and theoretical approaches are due to the convection and radiation heat losses, which have not been considered in the simulation model.With this simple model, the designer will be able to calculate the thermal cycles that take place in the process as well as to predict the temperature field in the proximity of the weld bead.

    En este trabajo se desarrolla un método de diferencias finitas para calcular el campo de temperaturas en la zona afectada por el calor en la soldadura de dos chapas de acero inoxidable AISI 304, soldadas mediante el procedimiento GTAW. Se ha desarrollado un programa informático implementado en libros de cálculo MS-Excel con Visual Basic para Aplicaciones (VBA. Los experimentos modelizados a través de la aplicación numérica predicen el comportamiento térmico de un procedimiento de soldadura. Para la validación del modelo matemático se ha desarrollado un

  5. Análisis experimental del torneado de alta velocidad del acero AISI 1045 // Experimental analysis of high speed turning of AISI 1045 steel gears

    Directory of Open Access Journals (Sweden)

    Luís Wilfredo Hernández‐González

    2012-01-01

    Full Text Available El objetivo de este trabajo es el estudio experimental de la evolución del desgaste del flanco de dosinsertos de carburo recubiertos y un cermet, durante el torneado en seco del acero AISI 1045 con 500 y600 m/min de velocidad de corte. Los resultados fueron comparados utilizando el análisis de varianza y deregresión. La investigación mostró un efecto significativo de la velocidad de corte y del tiempo demaquinado en el desgaste del flanco. El mejor desempeño fue para el carburo recubierto con tres capas,mientras que a elevada velocidad de corte el carburo con dos capas sufrió el mayor desgaste, lo cual sedebe a que cuando pierde sus recubrimientos el substrato del inserto queda desprotegido y el desgastecrece rápidamente por la extremas condiciones del mecanizado por alta velocidad. Además, se planteanrecomendaciones del tiempo de maquinado de los insertos dadas las condiciones de elaboración por altavelocidad.Palabras claves: torneado de alta velocidad, desgaste del flanco, acero AISI 1045, estudio experimental.__________________________________________________________________________AbstractThis work deals with the experimental study of the flank wear evolution of two coating carbide inserts and acermet insert during the dry turning of AISI 1045 steel with 500 and 600 m/min cutting speed. The resultswere compared using the variance and regression analysis. The investigation showed a significant effectof cutting speed and machining time on the flank wear in high speed machining. The three coating layersinsert showed the best performance while the two layers insert had the worst behaviour of the cutting toolwear at high cutting speed, this is because once the coating film is peeled off, the substrate of the insertbecomes uncovered and the wear grows rapidly due to the extreme machining conditions for high speed.Besides, the machining time recommendations of inserts for the cutting conditions at high speed areexposed.Key words: high

  6. Predicción del desgaste del flanco de la herramienta de corte durante el torneado en seco de alta velocidad para piezas de acero AISI 316L en la industria minera

    Directory of Open Access Journals (Sweden)

    Yusimit K. Zamora-Hernández

    2015-07-01

    Full Text Available Se realizó un estudio experimental sobre la influencia de los parámetros de corte en el torneado del acero inoxidable AISI 316L con insertos recubiertos de TiCN, Al2O3, TiN. Un microscopio electrónico de barrido fue utilizado para medir y analizar el desgaste de las herramientas de corte. Los resultados fueron comparados utilizando el análisis de varianza y el análisis de regresión múltiple para describir la relación entre el desgaste del flanco de las herramientas de corte, el tiempo de maquinado y el avance de corte, obteniéndose las ecuaciones de los modelos ajustados. La investigación demostró el efecto significativo del avance y del tiempo de maquinado en el desgaste del flanco. El inserto de tres capas no sobrepasó el criterio de fin de vida del desgaste, mientras que el inserto de una capa sufrió un desgaste elevado para la mayor velocidad de corte. El desgaste del flanco tuvo mejor comportamiento para el avance de 0,08 mm/rev en todas las velocidades empleadas en este estudio. Los errores medios absolutos no superaron el 15 %.

  7. Efecto del nitrógeno y la corriente media pulsada de soldadura en la formación de grietas de solidificación en aceros inoxidables AI5I 316L

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    Trevisan, R. E.

    2002-08-01

    Full Text Available An analysis of the influence of nitrogen concentration in the weld zone and the pulsed mean welding current in the solidification crack formation is presented in this paper. The AISI 316L austenitic stainless steel was employed as the metal base. The welding was done using CC+ pulsed flux cored arc welding process and AWS E316LT-1 wire type. The tests were conducted using CO2 shielding gas with four different nitrogen levels (0, 5, 10 and 15 % in order to induce different nitrogen weld metal concentrations. The pulsed mean welding current was varied in three levels and the Transvarestraint tangential strain test was fixed of 5 %. The results showed that the solidification cracking decreased as the pulsed mean welding current increase. It was also verified that an increase of the weld zone nitrogen level was associated with a decrease in both the total length of solidification crack and the amount of δ ferrite.

    En este trabajo se expone un análisis de la influencia de la concentración de nitrógeno y de la corriente media pulsada de soldadura en la formación de grietas de solidificación. Como metal base se usó el acero inoxidable austenítico AISI 316L. Las soldaduras se realizaron con el proceso de almbre tubular con pulsación del arco en CC+ y metal de aporte del tipo AWS E316LT-1. Se usó CO2 como gas de protección, añadiéndole cuatro diferentes porcentajes de nitrógeno 0, 5, 10 y 15 %, para inducir diferentes concentraciones de este elemento en la zona fundida. La corriente media de pulso se varió en tres niveles. La deformación tangencial de las probetas se mantuvo constante en 5 %, empleando el ensayo Transvarestraint. Los resultados indican que la longitud total de las grietas de solidificación es inversamente proporcional al aumento de la corriente media de pulso, comprobándose, además, que el incremento del nivel de nitrógeno en la zona fundida provocó una disminución en las grietas de

  8. Influencia de los tratamientos térmicos en la deformación en frío de los aceros inoxidables dúplex

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    Fargas, G.

    2004-06-01

    Full Text Available The purpose of this paper is to study the compression behavior of a duplex stainless steel after several annealing conditions, in order to simulate the response during cold rolling in the industrial process. For each studied condition, stress-strain curves present serrations in the flow zone due to austenite and ferrite twinning and the austenite phase transformation to martensite. At the same time, it is shown that sigma phase increases the strength and diminish the cold deformation capacity of the steel.

    Se realizó un estudio del comportamiento a compresión de un acero inoxidable dúplex sometido a distintos tratamientos térmicos de recocido, con el fin de simular su respuesta durante la laminación en frío que tiene lugar en el proceso industrial. Para todas las condiciones estudiadas, las curvas esfuerzo-deformación presentan inestabilidades en la zona plástica, provocadas por el maclado de ambas fases y la transformación de la austenita a martensita. Al mismo tiempo, puede observarse cómo la presencia de fase sigma endurece el acero y limita su capacidad de deformación.

  9. Corrosión en caliente de un acero inoxidable 304h para calderas en presencia de sales fundidas de vanadatos y sulfatos

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    Sonia Rincón

    2003-01-01

    Full Text Available El presente trabajo busca indagar y establecer el tipo de mecanismo de daño que sufre el acero inoxidable 304H en contacto con depósitos de sal fundida, junto con un estudio preliminar de la cinética de la corrosión. Para ello, se analizarán los depósitos fundidos, la composición química de éstos y se medirá la pérdida de material luego de ser sometido a períodos continuos de ataque, con el uso de la técnica gravimétrica en crisol. Con esto se pretende conocer las variables que influyen directamente sobre el deterioro del acero 304H, para en un futuro, adoptar medidas predictivas y/o preventivas que incrementen su vida útil, aumentando de ésta manera la eficiencia de las calderas y disminuyendo el tiempo entre paradas programadas.

  10. COMPARACIÓN DEL COMPORTAMIENTO AL DESGAS TE DE UN ACERO AISI 1045 NITRURADO Y SEGUIDO DE UN TEMPLE POR INDUCCIÓN

    OpenAIRE

    Gonzalo J. Schierloh; Matías Regis; Raúl Charadia; Eugenia L. Dalibon; Sonia P. Brühl

    2016-01-01

    Se estudió el comportamiento al desgaste de l acero AISI1045 con un tratamiento de nitruración iónica y posterior temple por inducción. Se midió dureza en superficie y perfil en profundidad. Se analizó la microestructura y evaluó el comportamiento al desgaste . Como resultado de la nitruración se obtuvo una zona formada por una capa de compuestos seguida por una zona de difus ión de nitrógeno. L a dureza superficial del acero templado y revenido aumentó en un...

  11. Análisis térmico de soldadura GTAW sobre placa de acero AISI 316L empleando el método de elementos finitos GTAW welding thermal analysis on AISI 316L steel plate using the finite elements method

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    Juan A. Pozo-Morejón

    2011-09-01

    Full Text Available En el presente trabajo se realiza la modelación térmica de soldadura GTAW sobre placa de acero inoxidable AISI 316L. Se analizan los aspectos teóricos más relevantes a considerar durante la ejecución de un análisis de este tipo. En la simulación se emplea un software de análisis por elementos finitos de uso general y se enriquece una metodología, previamente desarrollada, para la modelación en 3D no lineal transitoria del proceso de soldeo. En dicha metodología se implementa una subrutina en lenguaje APDL, programada con el modelo volumétrico de fuente calor de doble elipsoide, en un sistema de coordenadas cartesiano. Se analiza la influencia del paso de tiempo seleccionado sobre los resultados de la simulación. Finalmente se valida la metodología enriquecida, en base a la correlación de los resultados del modelo respecto a los resultados experimentales.In the present work, thermal modeling of GTAW welding on AISI 316L stainless steel plate is presented. More relevant theoretical aspects to be considered during the implementation of an analysis of this type are discussed. For the simulation a general purpose finite element analysis software has been used. A previously developed methodology for 3D nonlinear transient modeling of welding process has also been improved. In this methodology a subroutine in APDL language is implemented, programmed with the double ellipsoid volumetric heat source model, in a Cartesian coordinated system. The influence of the selected time step on the simulation results is analyzed. The good correlation obtained among the results calculated by means of the model and the experimental data validates this improved methodology.

  12. Determinación de tensiones por rayos x del acero AISI 1045 deformado por rodillo // Determination of stress for x‐ray of the steel AISI 1045 deformed for roller

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    Tomás Fernández‐Columbié

    2012-01-01

    Full Text Available El objetivo del trabajo es realizar el análisis de las tensiones a muestras de acero AISI 1045 endurecidasen frío por rodillo. Con empleo del método de Willianson–Hall se determinó las macro ymicrodeformaciones; la deformación reticular del parámetro de red; el tamaño de las cristalitas; losesfuerzos en la red cristalina y la reducción del tamaño promedio de los granos, lo que permitió establecerlos mecanismos de endurecimiento del acero AISI 1045, deformado por rodadura. Fueron medidos yanalizados diferentes puntos teniendo en cuenta los índices de Miller para la fase ferrítica del acero. Losmodelos lineales obtenidos, son estadísticamente significativos, que muestran una tendencia creciente delas propiedades mecánicas y metalúrgicas, según se incrementan las variables independientes delproceso de experimentación.Palabras claves: rodillo, rodadura, deformación plástica.__________________________________________________________________AbstractThe objective of the paper is to carry out the analysis from the tensions to steel samples AISI 1045hardened cold for roller. With employment of the method of Willianson-Hall was determined the macro andmicro deformations; the reticular deformation of the net parameter; the size of the crystallites; the efforts inthe crystalline net and the reduction of the size average of the grains, what allowed to establish themechanisms of hardening of the steel AISI 1045, deformed by rolling. They were measured and analyzeddifferent points keeping in mind the indexes of Miller for the phase ferrite of the steel. The obtained linealmodels, they are statistically significant that they show a growing tendency of the mechanical estates andmetallurgical, as the independent variables of the experimentation process are increased.Key words: roller, rolling, plastic deformation.

  13. Síntesis y caracterización de recubrimientos de tin, tic y ticn sobre acero aisi 4340

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    Héctor E. Jaramillo Suárez

    2004-01-01

    Full Text Available En este trabajo se crecieron películas de TiN, TiC y TiCN sobre aceros AISI 4340, con el objeto de comparar los resultados estructurales, morfológicos y mecánicos al crecerlos sobre un mismo substrato. Se utilizó un láser pulsado Nd: YAG con energía de 500mJ, longitud de onda de 1064 nm y tasa de repetición de 10 Hz. Mediante microscopia de Fuerza Atómica AFM, se observó que los recubrimientos presentan alta homogeneidad y tamaño de grano fino. Por Microscopía Electrónica de Barrido se determinó presencia de microgotas en los recubrimientos. Se aplicó prueba de tensión para determinar la adhesión de las películas; aplicando cargas máximas de 60 Kgf, los recubrimientos no mostraron señales de desprendimiento del substrato. A todos los recubrimientos se les sometió a prueba de dureza Rockwell C, con el fin de determinar la resistencia a la fractura, indicando que estos recubrimientos son aptos para diferentes aplicaciones en la industria.

  14. Decapado de un acero inoxidable austenítico mediante mezclas ecológicas basadas en H2O2 - H2SO4 - iones F-

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    Narváez, L.

    2013-04-01

    Full Text Available This study reports the pickling of 316L stainless steel using mixtures of hydrogen peroxide (H2O2, sulphuric acid (H2SO4 and fluoride ions as hydrofluoric acid (HF, sodium fluoride (NaF and potassium fluoride (KF. The decomposition of H2O2 in the mixtures was assessed at different temperatures 25 °C to 60 °C, with ferric ion contents from 0 to 40 g/l. According to the results obtained, were established the optimal condition pickling at 20 g/l of ferric ions, 25 °C and p-toluensulphonic acid as stabilizer of H2O2. The HF pickling mixture was the only capable to remove totally the oxide layer from the 316L stainless steel after 300 s. The fluoride salts pickling mixtures only remove partially the oxide layer (20 to 40 % aprox. after 300 s. When the pickling time was increased until 1200 s, the removal percentages were around to 80 %.En este estudio se presenta el decapado del acero inoxidable austenítico 316L utilizando mezclas de peróxido de hidrógeno (H2O2/ácido sulfúrico (H2SO4/iones fluoruro; los iones fluoruro provienen del ácido fluorhídrico (HF, fluoruro de sodio (NaF y fluoruro de potasio (KF. La estabilidad del H2O2 fue valorada modificando las concentraciones del ión férrico de 0 a 40 g/l y las temperaturas de 25 °C a 60 °C en las mezclas decapantes. Se establecieron las condiciones óptimas de decapado utilizando 20 g/l de iones férrico a 25 °C empleando el ácido p-toluensulfónico como estabilizante del H2O2. La mezcla que contenía HF fue la única capaz de eliminar completamente los óxidos superficiales del acero a tiempos de 300 s. Las mezclas a base de sales fluoradas eliminaron parcialmente los óxidos (20 y 40 % aprox. en 300 s. Al incrementar el tiempo de decapado hasta 1200 s se obtuvieron porcentajes de eliminación alrededor de un 80 %.

  15. Comportamiento a altas temperaturas de aceros inoxidables austeníticos refractarios: Formación de fase σ y oxidación al aire

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    Botella, J.

    1998-05-01

    Full Text Available Three stainless steels: 25Cr20Ni, 21Cr11Ni(1 and 21Cr11Ni(2 have been oxidised in air at 1,323 K for 2 h. The three materials form oxide layers 1 to 3 μm thick with MnCr2O4 external crystals and Cr2O3 inner ones. There are a SiO2 barrier below Cr2O3, in the oxide-metal interface. SiO2 also forms intra and intergranular precipitates in the metal, which are specially abundant in 21Cr11Ni materials. The theoretical predictions about σ-phase formation tendencies are confirmed after a treatment at 1,073 K for 400 h: 25Cr20Ni forms 10 % vol. σ-phase, while both 21Cr11Ni form few σ-phase or they do not form it at all.

    Se oxidan al aire durante 2 h a 1.323 K tres aceros inoxidables: 25Cr20Ni, 21Cr11Ni(1 y 21Cr11Ni(2. Los tres materiales forman capas de óxido de 1 a 3 μm de espesor, con cristales externos de MnCr2O4 e internos de Cr2O3. Debajo del Cr2O3, en la intercara óxido-metal, se forma SiO2, en forma de precipitados intra e intergranulares en el metal, especialmente abundantes en los 21Cr11Ni. Las predicciones teóricas sobre las tendencias a la formación de fase σ se ven confirmadas tras un tratamiento de 400 h a 1.073 K; el 25Cr20Ni forma un 10 % en volumen de σ, mientras que los aceros 21Cr11Ni o no forman σ, o lo hacen escasamente.

  16. Influencia del material de aporte en la resistencia a corrosión por picadura en uniones soldadas de un acero inoxidable dúplex 2205

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    Múnez, C. J.

    2007-08-01

    Full Text Available In this work, it has been studied the pitting corrosion resistance of welding duplex stainless steel 2205. Unions were made by GMAW process with different fillers: duplex ER 2209 and two austenitic (ER 316LSi and ER 308LSi. The microstructure obtained with the duplex ER 2209 filler is similar to the duplex 2205 base material, but the unions produced with the austenitic fillers cause a decrease of the phases relation a/g. To evaluate the influence of the filler on the weld, the pitting corrosion resistance was determined by electrochemical critical pitting temperature test (TCP and the mechanical properties by the hardness. The phases imbalance produced for the dissimilar fillers bring out a variation of the pitting corrosion resistance and the mechanical properties.

    En este trabajo se ha estudiado la resistencia a la corrosión localizada por picadura, de soldaduras realizadas sobre un acero inoxidable dúplex 2205. Se hicieron uniones mediante el proceso GMAW, utilizando como material de aporte un hilo dúplex ER 2209 y dos austeníticos ER 316LSi y ER 308LSi. Metalúrgicamente, se observa como para el hilo ER 2209 las microestructuras que se obtienen son similares a la del dúplex 2205, mientras que en las uniones con hilo austenítico, pueden verse microestructuras muy diferentes en las que la relación de fases a/g disminuye. Al evaluar la resistencia a la corrosión por picadura, mediante la Temperatura Crítica de Picadura (TCP, se comprobó como el desequilibrio entre las fases, generado por el aporte, provoca la variación en la resistencia a la corrosión localizada por picadura. También, se estudió la variación en las propiedades mecánicas del material mediante ensayos de dureza.

  17. Recuperación de ácidos y metales en baños agotados del decapado de aceros inoxidables

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    Frías, C.

    1998-05-01

    Full Text Available During the pickling of stainless steels around 300.000 m3/year of effluents from spent baths are produced in Europe. The usual treatment of these effluents by neutralisation and slurry disposal gives important disadvantages which are necessary to solve. A new process is being developed, called PIBARE, which shows a good future market in base of a preliminary technical-economical study for a plant of 10.000 m m3/year, where a pay-back period of two years is obtained. Furthermore, other environmental advantages are produced, as free and complex acids recycling and metals recovery as commercial by-products or recycled alloys. This article shows a general review of PIBARE project and the results obtained in the laboratory step which is been developed at the moment.

    En la operación del decapado de los aceros inoxidables se producen anualmente en Europa unos 300.000 m3/año de efluentes de baños agotados. El tratamiento normal de estos efluentes mediante neutralización y depósito de los lodos generados presenta graves inconvenientes que requieren ser subsanados, para lo cual se ha comenzado a desarrollar un nuevo proceso denominado proceso PIBARE, que presenta una gran potencialidad comercial basado en el análisis técnico-económico preliminar para una planta de 10.000 m3/año, donde se obtiene un "pay back period" de unos dos años, con otras ventajas medioambientales, ya que se reciclarían los ácidos libres y complejos y se recuperarían los metales como subproductos comerciales o aleaciones reciclables. Se presenta una visión general del proyecto PIBARE y los resultados obtenidos en la etapa de laboratorio que se desarrolla actualmente.

  18. Separación selectiva de hierro y cromo de las lejías agotadas del decapado de acero inoxidable

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    Gálvez, J. L.

    2005-12-01

    Full Text Available Stainless steel spent pickling baths are very complex solutions of metals and acids (HNO3 and HF and are a very important environmental concern. Several processes have been developed for acid recovery (free and bounded acid with techniques like acid retardation, solvent extraction, evaporation and dialysis diffusion. In these processes, metallic content is precipitated and treated for its disposal. We have developed a process that permits the separation of metals by means of a selective precipitation, induced by adding free fluoride. Iron (Fe and chromium (Cr precipitate as pentafluorides and nitrogennickel (Ni remains in solution. After this stage, complex fluorides can be hydrolized with alkali to give iron and chromium hydroxides, releasing fluoride in solution

    Los baños ácidos agotados del decapado de acero inoxidable son disoluciones muy complejas debido al alto contenido de metales y ácidos (HNO3 y HF, por lo que constituyen un grave problema medioambiental. Existen tratamientos comerciales para la recuperación del ácido (libre o complejado que se basan en técnicas de retardo ácido, extracción con disolventes, evaporación o membranas. En estos procesos el contenido metálico es precipitado y tratado como un residuo. El grupo de investigación formado por los autores del presente trabajo ha desarrollado un procedimiento que permite el aprovechamiento de dichos metales mediante su recuperación selectiva con una técnica de precipitación modificada inducida por fluoruro libre. Se consigue la precipitación de hierro (Fe y cromo (Cr como pentafluoruros (pH 3-4,5 dejando el níquel en disolución. Posteriormente, los fluoruros complejos son hidrolizados con álcali dando lugar a hidróxidos de hierro y cromo, mientras que el fluoruro es redisuelto.

  19. Influencia de la composición química, del tratamiento térmico y del acabado superficial en el bioensuciamiento de aceros inoxidables austeníticos

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    Sarró, M.

    2004-02-01

    Full Text Available The main objective of this study was to analyse the biofouling processes in three kinds of stainless steels used normally in industry (UNS S30400, UNS S30403 and UNS S31600, with different surface treatments after grinding and polishing. The study was developed using two microscopy techniques. Scanning Electron Microscopy (SEM was used to evaluate the microorganisms distribution in the materials, and Epifluorescence Microscopy was used to evaluate the viability of cells in the biofilm. The results revealed the influence of the material, heat treatment, surface treatment and roughness in the biofouling processes in the stainless steel assays.

    El objetivo de este estudio es analizar el comportamiento frente al bioensuciamiento de tres aceros inoxidables austeníticos, utilizados habitualmente en la industria (UNS S30400, UNS S30403, UNS S31600, con diferentes tratamientos térmicos y acabados superficiales de lijado y pulido. Para ello, se utilizaron diferentes técnicas de microscopía. Por microscopía electrónica de barrido se evaluó la distribución de los microorganismos en la superficie del material, y por microscopía de epifluorescencia se analizó la viabilidad de los mismos. Los resultados obtenidos revelan una influencia del material, del tratamiento térmico, del acabado superficial y de la rugosidad en el bioensuciamiento de los aceros inoxidables austeníticos.

  20. The influence of cutting speed and feed rate in surface integrity of aisi 1045//Influencia de la velocidad de corte y la velocidad de avance en la integridad superficial del acero aisi 1045

    OpenAIRE

    Mario Jacas-Cabrera; Tania Rodríguez - Moliner; José Luís Lopes-Da Silveira

    2015-01-01

    El objetivo de esta investigación es el estudio de la influencia de la velocidad de corte y la velocidad de avance en la integridad superficial del acero AISI-1045, sometido a un proceso de torneado. Las probetas se sometieron a un tratamiento térmico de recocidos (81 HRB). En el trabajo se empleó un diseño experimental 32, con dos variables a tres niveles experimentales, para un total de nueve experimentos, los que fueron replicados. La integridad superficial fue evaluada con la medición de ...

  1. Comportamiento tribológico del acero AISI W112 con endurecimiento lineal mediante laser de ND:YAG.L. // Tribological behavior of AISI W112 steel with lineal hardening by means of ND:YAG laser.

    Directory of Open Access Journals (Sweden)

    R. Sagaró

    2001-07-01

    Full Text Available Para disminuir el desgaste en los sistemas tribológicos frecuentemente se acostumbra a endurecer localmente aquellaszonas sometidas a desgaste. En el presente trabajo, para incrementar la dureza y la resistencia al desgaste del acero AISIW112 se empleó un láser de Nd:YAG. Las características de fricción y desgaste del acero AISI W112 en condiciones decontacto deslizante en fricción seca con el acero 65MN4 fueron evaluadas para tratamientos convencionales luego de suirradiación con láser. En el trabajo se presentan además las transformaciones que ocurren durante el tratamiento con láser,así como la influencia de los parámetros operacionales del láser en la profundidad de la capa endurecida y lascaracterísticas tribológicas. El trabajo experimental corroboró que la resistencia al desgaste del acero AISI W112 es variasveces superior en comparación con los tratamientos convencionales.Palabras claves: Comportamiento tribológico, endurecimiento lineal, tratamiento superficial con láser._______________________________________________________________________________Abstract.Diminishing wear in tribological systems is usually done by locally hardening those areas subject to wear. In this paper ispresented the increasing of hardness and resistance to wear of AISI W112 steel by means of a Nd:YAG laser. Thecharacteristics of friction and wear of AISI W112 steel under sliding contact in dry friction conditions with the 65MN4steel were evaluated for conventional treatments and after laser irradiation. In the work are presented the transformationsthat take place during the laser treatment, as well as the influence of the laser operational parameters in the depth of thehardened layer and the tribological characteristics. The experimental work corroborated that the resistance to wear of AISIW112 steel is several times superior in comparison with conventional treatments.Key words: Tribological behavior , lineal hardening, laser superficial

  2. Efecto del contenido de azufre y del grado de desoxidación sobre la ductilidad en caliente de aceros inoxidables austeníticos resulfurados en estado de solidificación

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    Botella, J.

    1998-05-01

    Full Text Available The manufacture of free machining austenitic stainless steels features a specific drawback derived from their high sulphur content, which is needed for generating, into the austenitic matrix, inclusions to optimize the different machining operations. However, sulphur has a harmful effect on hot workability. This paper deals with assessing the effect of sulphur content and deoxidation level on the hot ductility of resulphurized austenitic stainless steels in as cast condition. Hot tensile tests were conducted on a Gleeble machine, at temperatures between 1,150 and 1,250°C, studying a ductility factor as a function of sulphur content, deoxidation degree, as well as type, size and distribution of sulfides. Results point out the harmful effect of increasing sulphur and oxygen contents on the hot workability of resulphurized austenitic stainless steels, and the need to control carefully the level of oxides of these steels.

    La fabricación de aceros inoxidables austeníticos de alta maquinabilidad presenta una problemática específica derivada de su elevado contenido de azufre; elemento necesario para generar en la matriz austenítica inclusiones que faciliten las diferentes operaciones de mecanizado, pero perjudicial en cuanto al deterioro que produce en la deformabilidad en caliente. Este artículo describe el estudio realizado para evaluar el efecto del contenido de azufre y el grado de desoxidación sobre la ductilidad en caliente de aceros inoxidables austeníticos resulfurados, partiendo de una estructura de solidificación (as cast condition. Se realizaron ensayos de tracción en un sistema Gleeble, a temperaturas entre 1.150 y 1.250°C, analizándose el parámetro de ductilidad en función del contenido de azufre, nivel de desoxidación, y del tipo, tamaño y distribución de los sulfuros presentes. Los resultados ponen de manifiesto el efecto perjudicial de los contenidos de azufre y oxígeno sobre la deformabilidad en

  3. Tensiones de contacto por el método de elementos finitos del acero AISI 1045 endurecido por rodillo

    Directory of Open Access Journals (Sweden)

    Fernández-Columbié, T.

    2012-02-01

    Full Text Available In this paper, the tense-deformational behavior is analyzed by means of simulation using the finite element method for AISI 1045 cold rolled deformed steel. ANYSYS V.10 software was used in this study. Revolution number, compressive strength and tool feed rate were the variables considered in the deformation process. They allowed determining the contact stress of the deformed material. The material used was 30 mm diameter and 100 mm length. Samples of 30 mm diameter and 3 mm thickness were prepared for the optical microscopic observation, which were compared to the results obtained from the simulation. The tensile status of the deformed samples was evaluated as from the reduction of the average size of the grains as per the strength applied. This study intends to show that the cold hardening method is a surface hardening option.

    En el trabajo se analiza el estado tenso-deformacional mediante la simulación por el método de los elemento finitos del acero AISI 1045 deformado en frío empleando rodillo simple, para ello se utilizó el software ANSYS V.10. En el proceso de deformación se consideran las variables número de revolución, la fuerza compresiva y el avance de la herramienta, lo que permitió determinar las tensiones de contacto del material deformado. El diámetro del material empleado fue de 30 mm con una longitud de 100 mm. Para la observación de la microscopía óptica, se prepararon muestras de 30 mm de diámetro por 3 mm de espesor, las que fueron comparadas con los resultados obtenidos de la simulación. El estado tensional de las muestras deformadas se evaluó a partir de la reducción del tamaño promedio de los granos según la fuerza empleada. Con el desarrollo del trabajo se trata de demostrar que el empleo del método de endurecimiento en frío es una alternativa de endurecimiento superficial.

  4. Caracterización mediante HRTEM de un acero AISI4140 nitrurado por postdescarga micro-ondas

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    Béjar-Gómez, L.

    2005-12-01

    Full Text Available An analysis of the nitrides formed in an AISI 4140 steel nitrided by postdischarge microwave nitriding treatment was carried out by high resolution transmission electron microscopy (HRTEM, fast Fourier transform (FFT and nanoanalysis. The steel samples were nitrided below of the eutectoid transformation point (590 °C, after nitriding the samples were cooling slowly inside in the reactor whit an argon atmosphere. The analysis were carried out in a FEG-TEM PHILIPS TECNAI F20 at 200 Kv. The results showed the morphology and size of the nitrides ε-Fe2-3N and γ’-Fe4N, which had coherency whit the matrix. By other hand the following crystallographic relations were determined: (110 Fe-α ║ (1001 ε-Fe2-3N ║ (110 γ’-Fe4N and [1-1 0]Fe-α ║ [1 0-1 0] ε-Fe2-3N ║ [0 1 1] Fe4N.

    Un análisis de las fases de nitruros formados en un acero AISI 4140, nitrurado mediante condiciones de postdescarga micro-ondas, se llevó a cabo por microscopía electrónica de transmisión de alta resolución (HRTEM, rápida transformada de Fourier (FFT y nanoanálisis. Las muestras de acero fueron nitruradas por debajo del punto de transformación eutectoide (590 °C; después del tratamiento de nitruración las piezas fueron enfriadas lentamente dentro del reactor con una atmósfera de argón. Los análisis se realizaron en un microscopio Philips con cañón de emisión de campo Tecnai F20 a 200 Kv (PHILIPS FEG-TEM TECNAI F20. Los resultados mostraron la morfología y tamaño de los nitruros de hierro ε-Fe2-3N y γ’-Fe4N, los cuáles mostraron coherencia con la matriz. Además, se obtuvo la siguiente relación de coherencia entre precipitados y matriz: (110 Fe-α ║ (1001 ε-Fe2-3N ║ (110 γ’-Fe4N y [1-1 0]Fe-α ║ [1 0-1 0] ε-Fe2-3N ║ [0 1 1] Fe4N.

  5. Evolución microestructural de un acero inoxidable superdúplex bajo ciclos térmicos de corta duración Microstructural evolution of a superduplex stainless steel under short duration thermal cycles

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    Ivan Mendoza Bravo

    2010-09-01

    Full Text Available Este trabajo investiga el efecto de los ciclos térmicos sobre la microestructura de un acero inoxidable superdúplex específicamente sobre la formación de fase sigma. Los ciclos térmicos examinados son similares a los que se producen en la zona afectada térmicamente del acero inoxidable cuando se aplica el proceso de soldadura GTAW. Las temperaturas y tiempo de permanencia para el ciclo térmico se determinan usando un modelo de distribución de temperatura típico. La aplicación de los ciclos térmicos permite conocer la evolución microestructural del acero en el rango de 475ºC a 1100ºC con un tiempo corto de calentamiento y determinar la temperatura de formación y disolución de la fase sigma, pasando por su temperatura de máxima formación. Se examina la formación preferencial y la composición química de la fase sigma.This work investigates the effect of thermal cycling on the microstructure of a stainless steel superduplex, specifically on the sigma phase formation. The examined thermal cycles are similar to those produced in the heat affected zone of stainless steel when applying GTAW welding process. The temperatures and residence time for the cycle was determined using a typical thermal model of temperature distribution. The application of thermal cycles shows the microstructural evolution of steel in the range of 475ºC to 1100ºC with a short heating time and determines the temperature of formation and disolution of the sigma phase, and its maximum temperature of formation. The formation mechanism and chemical composition of the sigma phase is also examined.

  6. Pitting corrosion detection in stainless steels using ultrasounds; Deteccion de la corrosion por picadura en aceros inoxidables empleando ultrasonidos

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, C.; Biezma, M. V.

    2014-04-01

    Passive metallic systems are able to develop in a spontaneous way a protective layer on the metallic surface that offers excellent corrosion resistance since really in a physical barrier for the reaction with the environment. However, some factors can break locally this layer, promoting one of the most insidious attack, pitting corrosion, which produces local chemical conditions that favouring the corrosive process causing defects in the material, as externals and internals ones, with a random distribution on the metal surface. In this work, ultrasounds non destructive technique has been employed using as variable the maximum amplitude of the back wall echo in order to detect this type of attack. The material employed is an austenitic stainless steel AISI 304, wherein appear several defectology distributions as superficial such as depths simulating pits. (Author)

  7. Influencia de los regímenes de lubricación en la vida de la herramienta y el acabado superficial del fresado de aceros endurecidos AISI D2 y AISI D6

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    Maritza Mariño-Cala

    2015-10-01

    Full Text Available Se realizó un análisis de la calidad superficial y la vida de la herramienta durante el mecanizado con altas velocidades de los aceros endurecidos AISI D2 y AISI D6, en dos regímenes de lubricación. Los ensayos fueron realizados en un centro de mecanizado MORI SEIKI SV 40 y se emplearon herramientas intercambiables de metal duro recubiertas. La evaluación de la calidad superficial se realizó mediante el monitoreo off-line de la rugosidad superficial media Ra en el sentido del avance y perpendicular a este. La progresión del desgaste en las herramientas se analizó a través de un estereoscopio montado en conjunto con una cámara fotográfica digital interconectada a un programa analizador de imágenes. La aplicación de corte seco en operaciones de fresado de aceros endurecidos con altas velocidades apunta hacia una disminución de los costos del proceso asociados al uso de líquidos lubricantes y su reciclaje y a un aumento de la calidad superficial de la pieza y la vida de la herramienta.

  8. Estudio de la influencia de la microestructura sobre la deformabilidad en caliente de un acero inoxidable dúplex

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    Iza-Mendia, A.

    1998-05-01

    Full Text Available The complexity of the hot deformation behaviour of the ferrite and austenite in a duplex structure is increased as compared with that of single phase ferritic or austenitic steels. Important factors are: the spatial phase distribution with respect to the direction of the imposed deformation, the codeformation of both phases having considerably different mechanical properties, and the nature of the interface between austenite and ferrite. In the present study, the influence of these factors on the crack formation during the hot deformation is analyzed.

    El comportamiento frente al conformado en caliente de la ferrita y de la austenita, en una estructura dúplex, es muy diferente al que presentan ambas fases por separado en los aceros monofásicos austeníticos o ferríticos. A ello contribuyen, entre otros, la distribución espacial de las fases con respecto a la deformación impuesta, la codeformación de dos fases, con propiedades mecánicas muy diferentes, y la naturaleza de la intercara. En el presente trabajo se analiza la influencia de estos factores en la formación de daño bajo condiciones de deformación en caliente.

  9. Estudio in vitro de la citotoxicidad y genotoxicidad de los productos liberados del acero inoxidable 316L con recubrimientos cerámicos bioactivos Cytotoxic and genotoxic study of in Vitro released products of stainless Steel 316l with bioactive ceramic Coatings

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    María Elena Márquez Fernández

    2007-03-01

    Full Text Available El acero inoxidable AISI 316L es el biomaterial mas utilizado para la fabricación de implantes temporales, pero presenta limitaciones para implantes permanentes debido a la liberación de iones metálicos hacia los tejidos circundantes, produciendo especies reactivas de oxígeno (ERO y daño en ADN, factores que aumentan el riesgo de aparición de tumores locales y fallas mecánicas del implante. Una estrategia utilizada para disminuir la liberación de iones es la modificación superficial de los implantes metálicos por medio de recubrimientos inorgánicos, cerámicos o vítreos, aplicados por el método sol-gel, el cual presenta una serie de ventajas comparativas con otras técnicas de deposición, como buena adherencia, aplicación sencilla, mínimos problemas de secado, bajas temperaturas de densificación y posibilidad de agregar partículas y/o grupos orgánicos que mejoran la adherencia celular al implante aumentando su biocompatibilidad. En el presente trabajo se evaluaron los efectos citotóxico por medio de la técnica MTT, y genotóxico por electroforesis en gel de células individuales (Ensayo Cometa, sobre células de la línea celular CHO, de los productos liberados en medio MEM por el acero inoxidable 316L sin recubrir, recubierto con una monocapa de vidrio de sílice (MC, o con doble capa que contiene partículas bioactivas de hidroxiapatita (HA, vidrio (V o vitrocerámico (VC, después de un periodo de 30 días. Los resultados muestran que a los 30 días de envejecimiento en medio MEM no se encuentra ningún efecto citotóxico, pero se encontró efecto genotóxico en las probetas de A y MC que no representa un peligro inminente a sistemas celulares. The stainless steel AISI 316L is the must used biomaterial for the making of temporal prosthesis, but it presents severe limitations for permanent implants due to the generation and migration of metallic ions to the surrounding peripheral tissues, which produces oxygen reactive

  10. Formación de fase sigma en uniones soldadas de acero inoxidable súper dúplex fundido

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    Garin, J. L.

    2011-08-01

    Full Text Available This paper decribes the microstructural characteristics of weldments of cast super duplex stainless steel (J93404, being subjected to annealing processes to induce formation of sigma-phase at high temperatures. The influence of heating time at 1073 K, 1123 K and 1173 K upon precipitation of sigma in the heat affected zone, base metal and fusion zone of the weldments was analyzed. The experimental results revealed the formation of this intermetallic compound throughout decomposition of the ferritic phase into austenite and sigma. At earlier stages of the transformation the phase rapidly nucleates and growth along the ferrite-austenite grain boundaries, and then massively advances towards the bulk of the ferritic zone with greater effectiveness as temperature increases. The formation of sigma-phase in all weldments resembles the Johnson-Mehl-Avrami’s mechanism stated for nucleation and growth.

    El presente trabajo describe las características microestructurales de uniones soldadas de acero súper dúplex fundido (J93404, al ser sometidas a procesos de recocido para inducir la formación de fase sigma a altas temperaturas. Se analizó la influencia del tiempo de calentamiento a 1.073 K, 1.123 K y 1.173 K sobre la precipitación de fase sigma en la zona afectada térmicamente, metal base y zona de fusión de los conjuntos soldados. Los resultados experimentales evidenciaron la formación de este compuesto intermetálico por descomposición de la fase ferrítica en austenita y sigma. Al comienzo de la transformación la fase nuclea y crece rápidamente en los bordes de grano austenita-ferrita, extendiéndose luego masivamente hacia el seno de la zona ferrítica, con mayor efectividad en términos del aumento de la temperatura de proceso. La formación de sigma en todas las uniones soldadas obedece a un mecanismo de nucleación y crecimiento del tipo Jonson-Mehl-Avrami.

  11. Análisis experimental del desgaste entre UHMWPE y acero inoxidable 316l empleados en la manufactura de prótesis coxofemorales

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    Ricardo Gustavo Rodríguez Cañizo

    2010-10-01

    Full Text Available Título en inglés: Experimental wear analysis of UHMWPE and stainless 316l used in the manufacturing of coxofemoral prosthesis. Resumen La causa más común de falla en prótesis coxofemorales es el aflojamiento entre los componentes que conforman el sistema, de manera específica la copa acetabular y la cabeza femoral. En esta investigación se presenta un análisis tribológico del desgaste en los componentes mencionados, ya que cuando las superficies en contacto se desgastan, la funcionalidad mecánica del sistema se compromete, debido al cambio de geometría de los mismos, dando como resultado un juego mecánico entre la copa y la cabeza. Los materiales considerados en este estudio son el polietileno de ultra elevado peso molecular (UHMWPE, por sus siglas en inglés para la copa acetabular, y acero inoxidable 316L para la cabeza femoral. Esta combinación de materiales representa hoy en día la recomendación más usual por parte de los cirujanos para pacientes de la tercera edad. La tasa anual de desgaste se determinó de manera experimental y se cuantificó la cantidad de material desprendido durante el contacto. Se establecieron las condiciones de carga de forma analítica, considerando las que actúan sobre la cabeza femoral a lo largo del área de desgaste durante la marcha humana. Posteriormente, se realizó el análisis experimental de desgaste utilizando una máquina tribológica de configuración perno-sobre-disco (pin-on-disk, diseñada de manera específica para este estudio. Las pruebas para determinar la pérdida volumétrica de los componentes se realizaron bajo tres condiciones de operación: en seco, lubricada con agua destilada y lubricada con suero bovino. El marco experimental considerado consistió en pernos de UHMWPE sobre discos de acero inoxidable 316L simulando el desgaste equivalente a diez años de uso de la prótesis. Finalmente, de los resultados obtenidos se puede establecer que el desgaste y la cantidad de part

  12. Evaluación del comportamiento a fatiga de una unión soldada a tope de acero AISI 1015//Evaluation of the fatigue behaviour of a butt welded joint of AISI 1015 steel

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    Pavel Michel Almaguer‐Zaldivar

    2015-01-01

    Full Text Available Las uniones soldadas son un componente importante de una estructura, por lo que siempre es necesario conocer la respuesta de las mismas sometidas a cargas cíclicas. El objetivo de este trabajo es obtener la curva S-N de una unión soldada a tope de acero AISI 1015 y electrodo E6013 como material de aporte. Los ensayos a fatiga se realizaron de acuerdo a la norma ASTM en una máquina universal MTS810. Se utilizaron probetas de sección rectangular. El ciclo de carga fueasimétrico a tracción, con un coeficiente de asimetría de 0,1. Se obtuvo que la unión estudiada tiene un límite de resistencia a la fatiga de 178 MPa, a un punto de corte de 2 039 093 ciclos.Palabras claves: unión soldada, fatiga, curva S-N, AISI 1015, electrodo E6013._______________________________________________________________________________AbstractWelded joints are an important component in structures, by this reason is necessary to know the behaviour of these elements under cyclic loads. The objective of this work is to obtain the S-N curve of the butt welded joint of AISI 1015 steel and electrode E6013 as the contribution material. Fatiguetest was realized within the ASTM standard in the MTS810 testing machine. Rectangular cross section specimens was used. Cyclic loads was asymmetric tensile and the asymmetry ratio used was 0,1. In this study was obtained the fatigue limit equal to 178 MPa, at the cut point of 2 039 093 cycles.Key words: welded joint, fatigue, S-N curve, AISI 1015 steel, electrode E6013.

  13. Estudio de la susceptibilidad de un acero inoxidable austenítico estabilizado con niobio al dañado por tensocorrosión en medio H2S (SSC y corrosión intergranular (IGC en otros medios agresivos

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    Gutiérrez de Saiz-Solabarría, S.

    1998-05-01

    Full Text Available Behavior to hydrogen damage caused by stress corrosion in a H2S medium (SSC and to intergranular corrosion (IGC in different mediums, such as oxalic acid (C2H2O4-2H20, iron sulphate-50 % sulfuric acid [Fe2(SO43-50 % H2SO4], nitric acid (HNO3, copper sulphate-16 % sulfuric acid (CuSO4-5H2O-16 % H2SO4 and cooper sulphate-50 % sulfuric acid (CuSO4-5H2O-50 % H2SO4, is studied in an AISI 347 austenitic stainless steel stabilized with 0.61 mass % Nb and hot rolled to a seamless pipe with 273.1 mm in diameter and 18.2 mm in thickness.

    Se estudia el comportamiento de un acero inoxidable austenítico del tipo AISI 347 estabilizado con un 0,61 % en masa de Nb, laminado en caliente para producir una tubería sin soldadura de 273,1 mm de diámetro y 18,2 mm de espesor, frente al dañado por hidrógeno generado por tensocorrosión en medio H2S (SSC y frente a la corrosión intergranular (IGC en diferentes medios agresivos tales como ácido oxálico (C2H2O4∙2H2O, sulfato de hierro-50% ácido sulfúrico [Fe2 (SO43-50 % H2SO4], ácido nítrico (HNO3, sulfato de cobre-16% ácido sulfúrico (CuSO4-5H2O-16 % H2SO4 y sulfato de cobre-50 % ácido sulfúrico (CuSO4-5H2O-50 % H2SO4, respectivamente.

  14. RESISTENCIA A LA CORROSIÓN DE LAS MULTICAPAS DE [TIN/ALTIN]n DEPOSITADAS SOBRE ACERO AL CARBONO AISI 1045

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    WILLIAM APERADOR

    2011-01-01

    Full Text Available En este artículo se presenta el mejoramiento frente a la corrosión de los recubrimientos multicapas de [TiN/AlTiN]n con periodos de 2, 6, 12 y 24 bicapas depositados mediante la técnica de PVD magnetrón Sputtering sobre acero al carbono AISI 1045. La evaluación electroquímica se realizó mediante las técnicas espectroscopia de impedancia electroquímica (EIS y curvas de polarización Tafel, en una solución de 0.5M de H2SO4 + 3.5% wt. de NaCl. La resistencia a la corrosión aumentó de forma gradual en función del número de bicapas en comparación al sustrato encontrando valores de velocidad de corrosión de 18.51 mpy para el sustrato sin recubrir y de 1x10 6 mpy para la muestra con 24 bicapas. Los resultados electroquímicos revelan el efecto positivo en cuanto a la protección superficial del acero 1045 con el incremento del periodo en las multicapas de [TiN /AlTiN]n.

  15. Microstructural characterization of an AISI-SAE 4140 steel without nitridation and nitrided; Caracterizacion microestructural de un acero AISI-SAE 4140 sin nitrurar y nitrurado

    Energy Technology Data Exchange (ETDEWEB)

    Medina F, A.; Naquid G, C. [Gerencia de Ciencia de Materiales, Depto. de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    It was micro structurally characterized an AISI-SAE 4140 steel before and after of nitridation through the nitridation process by plasma post-unloading microwaves through Optical microscopy (OM), Scanning electron microscopy (SEM) by means of secondary electrons and retrodispersed, X-ray diffraction (XRD), Energy dispersion spectra (EDS) and mapping of elements. (Author)

  16. Aplicación del ensayo miniatura de embutido para la evaluación de la tenacidad a temperaturas criogénicas de aceros inoxidables austeníticos envejecidos isotérmicamente

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    Saucedo-Muñoz, M. L.

    2003-10-01

    Full Text Available Two types of austenitic stainless steels JJl and JNl were isothermally aged at temperatures from 873 to 1173 K for 10 to 1000 min in order to study the microstructural evolution and its effect on fracture toughness at cryogenic temperatures. The Charpy V-Notch (CVN and Small-Punch (SPTesting methods were conducted at 77 K to evaluate the toughness of both solution treated and aged specimens. The fracture energy at 77 K determined for both methods showed a significant decrease with aging time for both steels. A linear correlation between the fracture energies of both methods was found. The intergranular precipitation of carbides and nitrides was responsible for the fracture toughness deterioration. The scanning electron microscope fractographs showed an intergranular brittle fracture and its fraction also increased with aging time and temperature. The presence of a more abundant intergranular precipitation resulted in a more rapid decrease in fracture toughness with aging time in JNl steel due to its higher content of C and N, compared to that of JJl steel.

    Dos tipos de aceros inoxidables austeníticos, JJl y JNl, se envejecieron isotérmicamente a temperaturas entre 873 y 1.173 K por tiempos de 10 a 1.000 min, para estudiar la evolución microestructural y su efecto sobre la tenacidad a la fractura a temperaturas criogénicas. Los métodos de ensayo de impacto Charpy y el ensayo miniatura de embutido se llevaron a cabo a 77 K para evaluar la tenacidad de las muestras tratadas térmicamente. La energía de fractura determinada por ambos métodos mostró una disminución con el tiempo de envejecido para ambos aceros. Se encontró una relación lineal entre ambos valores de energía. La precipitación intergranular de carburos y nitruros fue la responsable de la pérdida de la tenacidad en las muestras envejecidas. La fractografía indicó que la fractura intergranular se incrementa con la temperatura y el tiempo de envejecido. La presencia

  17. Efecto de las condiciones de corte de un láser de Nd:YAG sobre la estructura y microcomposición de la superficie de aceros inoxidables

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    Ramírez, A.

    1998-04-01

    Full Text Available A study is presented of the effect of laser parameters (time distribution, spatial distribution and speed on both the finishing quality of austenitic stainless steel and its microstructure. An Nd-YAG laser with nitrogen as protection gas has been used. The samples were studied by SEM, metallography and microprobe analysis. At 500 Hz and 10 % of the spatial distribution, any increase of the time distribution produces higher power; this effect allows working at higher speed. Quality increases with the cutting speed. The laser cutting of 304 stainless steel using speeds higher than 200 mm/min and power lower than 1,000 W and a nitrogen flow of 18 bar of pressure do not produce significative changes in the structure.

    Se presenta un estudio de la influencia de los parámetros de procesado láser (distribución temporal, distribución espacial y velocidad en la calidad de acabado y microestructura de aceros inoxidables austeníticos. Se ha utilizado un láser Nd:YAG con nitrógeno como gas de protección, analizándose los resultados mediante SEM, microsonda electrónica y análisis metalográfico. Para una distribución espacial fija (10 %, y una frecuencia de 500 Hz, el aumento de la distribución temporal produce mayor potencia, lo que permite trabajar a velocidades más altas. La calidad del acabado aumenta al hacerlo la velocidad de corte. El corte de acero 304 con láser a velocidades superiores a 0,0033 m/s y potencias inferiores a 1.000 W usando nitrógeno a 18 bar no produce modificaciones apreciables en la estructura.

  18. Aluminum coating by fluidized bed chemical vapor deposition on austenitic stainless steels AISI 304 and AISI 316

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    Jose Luddey Marulanda-Arevalo

    2015-01-01

    Full Text Available Los revestimientos de aluminio f ueron depositados sobre aceros inoxidables AISI 304 y AISI 316 en el rango de temperatura de 5 60 a 600 °C por deposición química de vapor en lecho fluidizado(CVD – FBR. Se utilizó un lecho que consistía en 10 % de aluminio en polvo y 90 % de lecho inerte (alúmina, el cual fue fluidizado con Ar y como ga ses activadores se utilizó una mezcla de ácido clorhídrico con hidrógeno (HCl/H 2 . En el recubrimiento si n tratamiento térmico están las siguiente s especies: Al 13 Fe 4 , Fe 2 Al 5 , FeAl 2 y Al 5 FeNi, las cuales están presentes para ambos aceros. Además, el tratamiento térmico provoca la difusa de alu minio hacia el sustrato y la difusa de hierro del sustrato haci a la superficie del recubrimiento, haciendo la trans formación de los compuestos ant eriores a FeAl, Fe 2 Al 5 , FeAl 2 , Al 0.99 Fe 0.99 Ni 0.02 , AlNi y el Fe 2 AlCr. Se realizó la simulación termodinámica con el s oftware Thermo Calc para obt ener información de la posible composición y la cantidad de mat erial depositado, para condiciones seleccionadas. Las muestras recubi ertas y sin recubrir, se expus ieron a 750 ºC en una atmósfera d onde el vapor agua se transporta a las muestras usando un flujo de N 2 de 40 ml/min, más 100 % vapor de agua (H 2 O. Los dos sustratos sin revestir se comportaron de manera diferente, ya que el acero AISI 304 soportó bien el a taque y ganó poco peso (0.49 mg/cm 2 , en comparación con el acero AISI 316 que perdió mucho peso (25.4 mg/cm 2 . Los aceros recubiertos ganaron poco de peso durante las mil horas de exposición (0.26 mg/cm 2 y soportaron muy bien el ataque corrosivo en c omparación con sustratos sin r ecubrimiento.

  19. Estudio de los tipos de cráteres obtenidos en el impacto de proyectiles 5,56 SS109, sobre blancos de acero AISI-SAE 1045

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    Castro, Álvaro

    2000-02-01

    Full Text Available The present work describes the morphology and formation of the types of craters obtained with the impact of projectiles 5,56 SS109 over seven steel plates AISI-SAE 1045 that received different cycles of heat treatment. A comparison between the type of deformation and fracture structures and the ones generated by the impact of this projectile over one steel armor plate was made. Each one of the craters was characterized by visual and metallography observation. The influence of the plate microstructure on the efficiency for stopping the projectile and the mechanism of craters formation was evaluated.

    En el presente trabajo se describe la morfología y formación de los tipos de cráteres obtenidos, en el impacto de proyectiles 5,56 SS109, sobre siete chapas de acero AISI-SAE 1045 que fueron sometidas a diferentes tratamientos térmicos, comparando el tipo de estructuras de deformación y fractura obtenidas con las formadas por el impacto de uno de estos proyectiles sobre una chapa comercial para blindaje. Cada uno de los cráteres se caracterizó mediante ensayos de inspección visual y metalografía evaluándose, a partir de los resultados, el papel que ejerce la microestructura obtenida sobre el nivel de eficiencia en la detención del proyectil por parte de la chapa y el mecanismo de formación de los cráteres.

  20. Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

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    Hernández-González, L. W.

    2011-06-01

    Full Text Available This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds.

    El objetivo de este trabajo es el estudio experimental de la evolución del desgaste del flanco respecto al tiempo de dos insertos de carburo recubiertos y un cermet durante el torneado de acabado en seco del acero AISI 1045 con velocidades de corte de 400, 500 y 600 m/min. Los resultados fueron comparados utilizando el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste del flanco y el tiempo de maquinado, obteniéndose la ecuación del modelo ajustado. La investigación demostró un efecto significativo de la velocidad de corte y del tiempo de maquinado en el desgaste del flanco en el maquinado de alta velocidad. El mejor desempeño se obtuvo para el carburo recubierto con tres capas, mientras que el carburo con dos capas sufrió el mayor desgaste a elevadas velocidades de corte.

  1. MODELOS EMPÍRICOS PARA LA PREDICCIÓN DE LA GEOMETRÍA DEL CORDÓN EN SOLDADURAS A TOPE DE UN ACERO INOXIDABLE DÚPLEX 2205

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    MINERVA DORTA ALMENARA

    2011-01-01

    Full Text Available La presente investigación muestra dos modelos empíricos que permiten predecir la geometría del cordón de soldadura a tope de un acero inoxidable dúplex tipo 2205. Para obtener dichos modelos se empleó una metodología que permite utilizar los parámetros operacionales más importantes de la soldadura, como son: la intensidad de corriente (I, el voltaje (E, la velocidad de pasada (v y calor aportado (HI. Se realizaron diferentes combinaciones de dichos parámetros para realizar la soldadura por arco sumergido (SAW. A cada muestra se le realizó la medición de la geometría del cordón a través de un barrido de 360° con 38 mediciones para obtener los modelos, los cuales luego fueron validados a través de gráficas de control. Se pudo observar que al aumentar la intensidad de corriente y el calor aportado, aumenta la geometría del cordón, es decir, la penetración, el ancho y la altura, mientras que lo inverso ocurre cuando se incrementa la velocidad de pasada.

  2. Soldadura TIG de los aceros inoxidables dúplex del tipo 22-05 (Uranus 45N y Avesta. Estudio de la microestructura y de las propiedades mecánicas

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    Gómez de Salazar, J. M.

    1998-05-01

    Full Text Available TIG welding of two different duplex stainless steels is carried out. Arc-discharge on base-material plates by means of the TIG technique without filler metal and varying the energetic conditions (E.N.A. has been performed, A comparative study concerning the microstructural evolution as well as mechanical properties is carried out, The relation between hardness profiles, the microstructural variations and the ferrita δ concentration is established. Further, the above mentioned properties are related to the E.N.A. for each welded joint.

    Se estudia la soldadura TIG de dos aceros inoxidables dúplex. Para ello, se ha descargado un arco sobre las chapas de material base mediante la técnica TIG, sin aportación de material y variando las E.N.A. Se realiza un estudio comparativo de la evolución microestructural, así como de las propiedades mecánicas. Se establece la relación entre los perfiles de dureza obtenidos y la variación microestructural y de la concentración de ferrita δ, así como estas propiedades con el E.N.A, de cada cordón.

  3. Resistencia a la corrosión de recubrimientos de nitruros metálicos depositados sobre acero AISI M2

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    Jhon Jairo Olaya Florez

    2012-01-01

    Full Text Available En este trabajo se estudia el comportamiento frente a la corrosión de películas de nitruro de zirconio (ZrN, nitruro de titanio (TiN, nitruro de cromo (CrN, nitruro de niobio (NbN y nitruro de tantalio (TaN depositadas sobre acero para herramientas AISI M2 mediante la técnica de sputtering con magnetrón desbalanceado (UBM. La resistencia a la corrosión fue evaluada con ensayos de espectroscopía de impedancia electroquímica (EIS en una solución al 3% de NaCl variando el tiempo de ensayo desde 1 h hasta 7 d. En general, los mejores resultados de resistencia a la corrosión se presentaron en las películas de ZrN y NbN cuando son producidas en la configuración de menor bombardeo iónico en un sistema UBM. Los recubrimientos muestran degradación en el tiempo de ensayo debido a los defectos presentes en su microestructura, que se convierten en canales de difusión por los que la solución corrosiva llega a la superficie del sustrato. Los mecanismos de corrosión para los recubrimientos producidos son discutidos en esta investigación.

  4. Efecto del volumen de metal cortado y de la velocidad de corte en el desgaste de la herramienta durante el torneado de alta velocidad del acero AISI 1045

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    Luis W. Hernández González

    2011-01-01

    Full Text Available En este trabajo se aborda el estudio experimental del efecto del volumen de metal cortado y de la velocidad de corte en el desgaste del flanco de dos insertos de carburos recubiertos y un cermet, durante el torneado de acabado en seco del acero AISI 1045 a velocidades de corte moderada, intermedia y alta. Los resultados fueron comparados utilizando la dimensión volumétrica de la vida útil de la herramienta, el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste y el volumen removido, según las ecuaciones del modelo ajustado. La investigación mostró un efecto significativo de la velocidad de corte y del volumen cortado en el desgaste del flanco, pues se logró el mejor desempeño para la alta velocidad con el carburo recubierto con tres capas y el peor funcionamiento con el carburo recubierto con dos capas.

  5. Problemas en la reparación por laser cladding de superficies de acero AISI D2 tratado térmicamente

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    Busquets, D.

    2010-08-01

    Full Text Available The aim of the present work is to establish the relationship between laser cladding process parameters (Power, Process Speed and Powder feed rate and AISI D2 tool steel metallurgical transformations, with the objective of optimizing the processing conditions during real reparation. It has been deposited H13 tool steel powder on some steel substrates with different initial metallurgical status (annealed or tempered using a coaxial laser cladding system. The microstructure of the laser clad layer and substrate heat affected zone (HAZ was characterized by Optical microscopy, Scanning Electron Microscopy (SEM and Electron Backscattered Diffraction (EBSD. Results show that the process parameters (power, process speed, feed rate… determine the dimensions of the clad layer and are related to the microstructure formation. Although it is simple to obtain geometrically acceptable clads (with the right shape and dimensions in many cases occur some harmful effects as carbide dilution and non-equilibrium phases formation which modify the mechanical properties of the coating. Specifically, the presence of retained austenite in the substrate-coating interface is directly related to the cooling rate and implies a hardness diminution that must be avoided. It has been checked that initial metallurgical state of the substrate has a big influence in the final result of the deposition. Tempered substrates imply higher laser absorption and heat accumulation than the ones in annealed condition. This produces a bigger HAZ. For this reason, it is necessary to optimize process conditions for each reparation in order to improve the working behaviour of the component.Se ha depositado polvo de acero de herramienta (H13 sobre diferentes sustratos de acero que se encuentran en estado metalúrgico diferente (recocido o de temple y revenido para comparar los resultados y se ha analizado la microestructura del recubrimiento y de la zona afectada por el calor (ZAC mediante

  6. El tratamiento de QPQ en el mejoramiento mecánico y químico de los aceros para moldes de plástico: caso de AISI P20

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    Rónald Jiménez Salas

    2010-12-01

    Full Text Available El QPQ es un tratamiento termoquímicoaplicado principalmente a las aleacionesferrosas y de níquel para mejorar sucomportamiento mecánico y su resistenciaa la corrosión.En este artículo se presentanlos primeros resultados del proyecto dela validación de las propiedades de losaceros de herramientas para la industriade procesamiento de plásticos en CostaRica, obtenidas al aplicarle el tratamientotermoquímico de QPQ, y particularmentelos resultados de durezas y espesores decapa obtenidos en aceros AISI P20.Para el desarrollo de la investigación, seprepararon probetas pulidas y se tratarona diferentes tiempos; luego, se realizaronestudios metalográficos y de microdurezapara caracterizar las propiedades obtenidas.Por último, los resultados muestran valoresde dureza y espesores de capa acordes conlos esperados para este tipo de aceros debaja aleación.

  7. “ESTUDIO DE CORROSIÓN DE LOS ACEROS DÚPLEX 2205, AISI 1018 Y LA UNIÓN SOLDADA, EN UN DIGESTOR PARA LA FABRICACIÓN DE PAPEL”

    OpenAIRE

    Vázquez Navarro, Brenda Alondra

    2012-01-01

    El presente trabajo, se realizó en el laboratorio del departamento de corrosión, del Instituto de Investigaciones Metalúrgicas, de la Universidad Michoacana de San Nicolás de Hidalgo. Se estudió la corrosión en el digestor de cocción continua modificada, que se ubica en la planta de papel de la Corporación Scribe en la Ciudad de Morelia, Michoacán. El digestor en estudio, está fabricado principalmente de acero al carbono AISI 1018. En la zona media inferior de este equipo, p...

  8. The influence of cutting speed and feed rate in surface integrity of aisi 1045//Influencia de la velocidad de corte y la velocidad de avance en la integridad superficial del acero aisi 1045

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    Mario Jacas-Cabrera

    2015-09-01

    Full Text Available El objetivo de esta investigación es el estudio de la influencia de la velocidad de corte y la velocidad de avance en la integridad superficial del acero AISI-1045, sometido a un proceso de torneado. Las probetas se sometieron a un tratamiento térmico de recocidos (81 HRB. En el trabajo se empleó un diseño experimental 32, con dos variables a tres niveles experimentales, para un total de nueve experimentos, los que fueron replicados. La integridad superficial fue evaluada con la medición de la rugosidad superficial, las tensiones residuales superficiales, la medición de dureza por nano–indentación y por el análisis de la de formación terciaria. Los resultados determinaron la gran influencia de la velocidad de avance en la rugosidad superficial. La medición de las tensiones residuales mostró la influencia de las variables de corte. Del análisis microestructural se observó la existencia de dos zonas de deformación determinándose que el espesor de la zona endurecida llegó a 50 µm. Palabras claves: integridad superficial, rugosidad superficial, nano-indentación; superficie deformada____________________________________________________________________________AbstractThe aim of this research is to study the influence of cutting speed and feed rate on surface integrity of AISI-1045 subjected to a turning process. The specimens were in annealed condition (81 HRB. A 32 factorial experiment design was employed using low, medium and high levels of the two variables in study, performing 9 experiments with a replica. The surfaces were evaluated through the measurements of surface roughness, surface residual stresses, nano-indentation hardness and analyzing the deformed layer. Results corroborated the great influence of feed rate on surface roughness. The results of the residual stresses have shown the influence of cutting speed as well as feed rate in the behavior of circumferential and axial stress respectively. From the analysis of the

  9. Resistencia a la oxidación de aleaciones Ni-Cr-Al plaqueadas por láser sobre aceros al carbono e inoxidables austeníticos

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    de Damborenea, J.

    1995-04-01

    Full Text Available Laser surface cladding has been carried out by means of a 5 kW CO2 continuous wave laser on both a mild and a stainless steel. A powder injection technique has been used to deliver a Ni-Cr-Al alloy onto the steel molten pool. After processing, samples were analyzed by optical and scanning electron microscopy in order to know the microstructure and composition of present phases. High temperature corrosion resistance tests were done in an oxidant environment at temperatures of 950 °C. Phase transformations and corrosion behaviour are discussed. A general conclusion is the suitability of these alloys to bear oxidation due to the formation of protective oxide layers on their surface.

    Se realiza un estudio sobre la obtención de recubrimientos de superficie mediante un láser continuo de CO2 de 5 kW de potencia de salida. Mediante la técnica de inyección de partículas, se realizaron plaqueados en superficie de Ni-Cr-Al sobre un acero suave y otro inoxidable de tipo 316. Tras el procesado, se estudió la microestructura de las probetas obtenidas. Posteriormente, se procedió a su ensayo en atmósfera oxidante a 950 °C, observándose la evolución de la microestructura, la formación de las capas de óxido y la cinética del proceso. Como conclusión general, destaca, independientemente de la base sobre la que se obtienen los recubrimientos, la gran resistencia del material a la oxidación, seguramente debida a la formación de capas de alúmina que actúan como barreras frente al ataque del oxidante.

  10. Análisis de los transitorios de ruido electroquímico para aceros inoxidables 316 Y – DUPLEX 2205 en NaCl Y FeCl

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    Almeraya-Calderón, F.

    2012-04-01

    Full Text Available This work shows the results obtained from electrochemical noise measurements for different materials exhibiting pitting corrosion. The transients presented in the potential and current time, correlates with the scanning electron microscopy (SEM surface analysis. Electrochemical measurements were made at different exposure times to obtain the correlation. The materials used were stainless steel austenitic 316 and duplex 2205, immersed in ferric chloride (FeCl3 and sodium chloride (NaCl electrolytes. SEM analysis shows that the transients observed in the time series, really correspond to the activity of pit nucleation developed over the surface of the electrodes.

    En este trabajo se muestran los resultados obtenidos de las mediciones de ruido electroquímico para diferentes materiales que exhiben corrosión por picaduras. Los transitorios presentados en las series de tiempo en corriente y en potencial, se correlacionan con el análisis superficial de microscopía electrónica de barrido (MEB. Las mediciones electroquímicas fueron realizadas a diferentes tiempos de exposición, para obtener una correlación. Los materiales usados fueron los aceros inoxidables 316 y dúplex 2205, inmersos en cloruro férrico (FeCl3 y cloruro de sodio (NaCl como electrolitos. Los análisis por MEB, muestran que los transitorios observados en las series de tiempo, corresponden realmente con la actividad de la nucleación de picaduras desarrollada sobre la superficie de los electrodos.

  11. Comportamiento del acero AISI-SAE 8615 frente al proceso de nitrocarburación ferrítica, utilizando urea-metanol

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    Barrena, M. I.

    1998-06-01

    Full Text Available The present work shows the behaviour of low carbon alloyed steels as AISI-SAE 8615, after a ferritic nitrocarburizing process. Nitrocarburizing takes place at 570ºC for 3 h in an atmosphere by combustion of methanol and urea under different flow rates. Metallographic studies were performed by optical microscopy. Hardness profiles were measured and carbon percentages were also analized by emission spectrometry in order to determine the extension of the nitrocarburizing process. Optimal flow conditions have been found. The influence of the flow rate on the nitrocarburizing layer thickness has been also studied.

    El presente trabajo muestra el comportamiento del acero aleado de bajo contenido de carbono, AISISAE 8615, cuando se somete a un proceso de nitrocarburación ferrítica, a la temperatura de 570ºC y un tiempo de 3 h. La atmósfera reactiva ha sido generada mediante goteo variable de metanol y urea dentro del horno, utilizando distintas velocidades de flujo. Las capas nitrocarburadas fueron evaluadas mediante técnicas de microscopía óptica. Con el fin de conocer la extensión de las capas nitrocarburadas obtenidas, se realizaron medidas de microdureza y se determinaron los porcentajes de carbono en el proceso mediante espectroscopia de emisión. Se han encontrado las condiciones de flujo óptimo de la mezcla anteriormente comentada y se ha observado cómo su variación influye en el espesor de la capa nitrocarburada.

  12. Evaluación de la corrosión del acero AISI-SAE 1020 en un ambiente multifásico de salmuera CO2-H2S

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    Darío Yesid Peña Ballesteros

    2010-01-01

    Full Text Available La corrosión por CO2/H2S en la producción de gas y petróleo es una de las áreas de investigación más importantes, debido a la necesidad de evaluar la severidad de la corrosión, disminuir el riesgo de problemas en operación y además bajar los costos de producción. En Colombia, las investigaciones se orientan hacia la corrosión por CO2, a pesar de la existencia de trazas de H2S, que son un peligro potencial para los materiales de las líneas de transporte de hidrocarburos. En este artículo se analiza la experimentación y los resultados del acero expuesto a un sistema Salmuera/CO2/H2S en un cilindro rotatorio. En esta geometría se determinaron las velocidades de corrosión sobre el acero AISI 1020, así como los coeficientes de transferencia de masa y capas viscosas de las especies más representativas del sistema. Adicionalmente, se caracterizó la morfología de los productos de corrosión formados en estos ambientes. El estudio permitió concluir que las especies relacionadas con el CO2 (H2CO3 son las que influyen sobre el mecanismo de deterioro del acero AISI 1020, que está fuertemente influenciado por la variación de la velocidad, la temperatura y el pH.

  13. Análisis del Comportamiento Mecánico de Recargues de Inoxidable Sobre Acero de Baja Aleación en Reactores de Proceso Analysis of Mechanical Behavior of Cladding of Stainless Steel over Low Alloyed Steel in Process Reactors

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    B.Y. Moratilla

    2005-01-01

    Full Text Available Se realiza un estudio simple de tensiones considerando dos materiales, acero inoxidable y acero de baja aleación. El estudio es motivado porque en la industria petroquímica es práctica habitual, para reducir costes de materiales, utilizar recargues de inoxidable sobre una pared de acero de baja aleación para la construcción de la pared de reactores. Se determina el coeficiente de dilatación térmica y su evolución a lo largo del espesor de la zona afectada térmicamente, usando una probeta extraída durante la construcción de un reactor. Luego se aplican los resultados obtenidos a un modelo de la pared del reactor usando el método de los elementos finitos. Los resultados muestran que el uso del recargue está científica y tecnológicamente justificado.A simple study of tensions was carried out on stainless steel and low alloyed steel. The reason for the study was that a typical practice in the petrochemical industry for materials cost reduction is the use of layers of stainless steel cladding over low alloy steel in the construction of reactor walls. The coefficient of thermal dilatation and its' evolution throughout the thickness of the thermally affected zone was determined using a test sample obtained during the construction of a reactor. Later, the results obtained were applied to a model of the reactor wall using the finite element method. The results suggested that the use of the cladding was scientifically and technologically justified.

  14. Comparación entre los diagramas TTS obtenidos mediante los ensayos normalizados Huey y Strauss modificado para el acero inoxidable AISI 304

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    Otero, E.

    1996-04-01

    Full Text Available This work presents a comparison of Temperature-Time-Sensitization TTS diagrams obtained by Huey and modified Strauss standard, for detecting susceptibility to intergranular attack. The difference between these tests is the use of a strong or a slightly smooth oxidizing electrolyte. The diagrams obtained are different and if a sample tested by modified Strauss is sensitized, then it will be sensitized in the Huey test, but the contrary is not always true. This difference is because a sensitized sample has to have a continuous band lacking in chromium along the grain boundary in order to be sensitized in the modified Strauss test. This condition is not necessary in the Huey test.

    Se comparan los diagramas Temperatura-Tiempo-Sensibilización TTS, obtenidos mediante los ensayos normalizados de corrosión intergranular Huey y Strauss modificado, que, respectivamente, utilizan electrólitos fuerte y suavemente oxidantes, mostrándose que los diagramas obtenidos son diferentes. Si una muestra evaluada mediante el ensayo Strauss modificado se encuentra sensibilizada, entonces lo estará también en el ensayo Huey, pero no necesariamente ocurrirá lo contrario; esta diferencia se asocia a la necesidad de la existencia de una zona continua empobrecida en cromo a lo largo del límite de grano para que el material se sensibilice con respecto al ensayo Strauss modificado, condición innecesaria para el caso del ensayo Huey.

  15. Estudio de la resistencia a la corrosión localizada del acero inoxidable superaustenítico 24,1Cr22Ni7,1Mo en mezclas que contienen iones cloruro y cloruro-fluoruro

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    Pardo Gutiérrez del Cid, Angel

    2001-08-01

    Full Text Available The localised corrosion resistance (pitting and crevice corrosion of the high alloy 24.1Cr22Ni7.1Mo superaustenitic stainless steel has been studied in solutions with chloride concentrations between 200 and 6.000 ppm. A similar study has been carried out using mixtures of equal concentrations of chloride and fluoride ions in the range of 400 to 12.000 ppm. pH values varied from 2 to 6.5. The critical temperatures for pitting and crevice corrosion have been calculated for these test media using electrochemical techniques (direct current. From the results obtained by cyclic polarisation, the critical pitting temperature (CPT and the critical crevice temperature (CCT have been determined for this material in each of tested media. The resistance of this material to localised corrosion is high, mainly due to the high repassivation rate in the tested media. At the highest tested concentration of chloride and fluoride ions and at pH 6.5, the material undergoes a generalised attack.

    Se estudia la resistencia a la corrosión localizada (picadura y resquicio del acero inoxidable superaustenitico 24,1Cr22Ni7,1Mo, cuando opera en soluciones que contienen concentraciones de iones cloruro entre 200 y 6.000 ppm. Así mismo se estudia el comportamiento en mezclas que contienen concentraciones iguales de iones cloruro y fluoruro entre 400 y 12.000 ppm. El intervalo de pH utilizado se situó entre 2 y 6,5. Las temperaturas críticas de picadura y resquicio se calcularon mediante técnicas electroquímicas de corriente continua. A partir de los resultados obtenidos mediante polarización cíclica, se han obtenido tanto las temperaturas críticas de picadura (TCP como las de resquicio (TCR para el material en cada uno de los medios ensayados. La resistencia de este material a la corrosión localizada es alta, debido principalmente a la elevada capacidad de repasivación en los medios de ensayo empleados. Para la mayor concentración de iones cloruro y

  16. Estudio de corrosión bajo tensión en los aceros inoxidables 17-4PH y 17-7PH en presencia de NaCl y NaOH (20 % a 90 °C

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    Gaona-Tiburcio, Citlalli

    2000-04-01

    Full Text Available One of the problems that affects to the electric industry is the not programmed stoppages in the power plants, due to the failure of any main component: boiler, turbine and generator. In the turbine, the combined action of a corrosive agent (humid polluted vapor and a mechanical effort generally will result in Stress Corrosion Cracking (SCC. In this work the SCC susceptibility of the precipitation hardening stainless steels 17-4PH and 17- 7PH, thoroughly used in steam turbine blades of power stations is analyzed. The specimens were tested in the presence of NaCl and NaOH (20 % to 90 °C and different pH. The CERT test (Constant Extension Rate Test was used, at 10-6 s-1 supplementing it with electrochemical noise; the aim was to identify the conditions of maximum susceptibility and the performance of the studied materials. The fractographic analysis revealed ductile and brittle fracture. Intergranular crackings, characteristic of the anodic dissolution mechanism of the material was observed. Nevertheless, the main mechanism responsible the failure was hydrogen embrittlement.

    Uno de los problemas que afecta a la industria eléctrica es el de los paros no programados en las plantas generadoras de electricidad, debidos al fallo de algún componente principal: caldera, turbina y generador. En la turbina, la acción combinada de un agente corrosivo (vapor húmedo contaminado y un esfuerzo mecánico, generalmente provocará corrosión bajo tensión (CBT. En este trabajo se analiza la susceptibilidad a la CBT de los aceros inoxidables, endurecibles por precipitación, 17-4PH y 17-7PH, ampliamente usados en alabes de turbina de vapor de centrales termoeléctricas. Las muestras se ensayaron en presencia de NaCl y NaOH (20 % a 90 °C, y distintos valores de pH. Se empleó el ensayo CERT (Constant Extensión Rate Test, a velocidades de 10-6 s-1, complementándolo con ruido electroquímico, buscando

  17. Estudo do comportamento eletroquímico de azóis para o aço inoxidável AISI 430 em H2SO4 1 mol L-1 Study of electrochemical behavior of azoles for AISI 430 stainless steel in H2SO4 1 mol L-1

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    Martha Tussolini

    2010-03-01

    Full Text Available A corrosão é um processo indesejável que ocorre em materiais metálicos. Nesse trabalho, estudou-se o efeito inibidor do benzotriazol (BTAH, benzimidazol (BZM e indol em diferentes concentrações para o aço inoxidável AISI 430 em H2SO4 1 mol L-1. Foram empregadas as técnicas de: polarização potenciostática anódica, espectroscopia de impedância eletroquímica, microscopia óptica e eletrônica de varredura. As curvas de polarização potenciostática anódica mostraram que o BTAH, BZM e Indol atuam como inibidores de corrosão para o aço AISI 430, nas concentrações de 1x10-3 e 5x10-4 mol L-1, não apresentando inibição significativa para as concentrações iguais ou inferiores a 1x10-4 mol L-1. O aumento da eficiência inibidora em relação às substâncias estudadas seguiu a seguinte ordem: Indol Corrosion is an undesirable process that occurs in metallic materials. Studied was the effect of inhibiting Benzotriazole (BTAH, Benzimidazole (BZM and Indole in different concentrations for the stainless steel (SS AISI 430 in H2SO4 1 mol L-1. The techniques employed this research were: anodic potenciostatic polarisation, electrochemical impedance spectroscopy, optical microscopy and scanning electron microscopy. The curves of anodic polarisation showed that BTAH, BZM and Indol act as corrosion inhibitors for 430 SS, at concentrations of 1x10-3 and 5x10-4 mol L-1, but do not inhibit corrosion for concentrations equal to or less than 1x10-4 mol L-1. The in-crease of the efficiency in relation to the inhibitory substances studied followed this order: Indol

  18. Efecto de los ciclos térmicos sobre la ZAT de una soldadura multipasos de un acero inoxidable superdúplex SAF 2507 Effect of thermal cycles on the HAZ of a stainless steel multipass weld of superduplex SAF 2507

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    D. Villalobos

    2010-09-01

    Full Text Available Los ciclos térmicos de una soldadura multipasos que experimenta un acero inoxidable superdúplex SAF 2507, pueden promover la precipitación de fases secundarias reduciendo significativamente las propiedades mecánicas y la resistencia a la corrosión. Debido a su aplicación en la industria petroquímica, el estudio de las aleaciones superdúplex es de suma importancia para predecir su comportamiento en servicio cuando están involucrados procesos de soldadura por arco eléctrico. En este trabajo, se estudia el cambio microestructural de la zona afectada térmicamente correspondiente al primer cordón depositado de una unión multipasos de acero inoxidable superdúplex SAF 2507 mediante el proceso GTAW y bajo tres temperaturas de interpasos. Los resultados muestran que la temperatura de interpasos tiene una influencia sobre la precipitación de fase sigma en la zona afectada térmicamente del primer cordón depositado.Thermal cycles experienced by a superduplex stainless steel SAF 2507 when is welded, can promote the precipitation of secondary phases which decrease the mechanical properties as well as the corrosion resistance. Due to the application of the duplex alloys in the petrochemical industry, the study of these alloys has become very important in order to predict its service behavior. The aim of this work is to study the microstructural changes in the superduplex stainless steel weld joint after applying the GTAW process under three interpass temperatures after the deposition of every single pass. The results showed that slow cooling rates promoted by the deposition of the subsecuent passes and the higher interpass temperature, promote the precipitation of sigma phase in the HAZ while rapid cooling rates promoted by the lower interpass temperature do not promote the sigma phase precipitation.

  19. Evaluación del coeficiente de fricción y las propiedades mecánicas de los recubrimientos 140MXC-530AS Y 140MXC-560AS sobre acero AISI-SAE 4340 utilizando la técnica de proyección térmica

    OpenAIRE

    Patiño Infante, Maritza

    2015-01-01

    En este trabajo se produjeron recubrimientos mediante la técnica de proyección térmica por arco, se depositaron tres materiales diferentes: acero de bajo carbono (530 AS), acero inoxidable (560 AS) y una aleación a base de FeCrNbW (140 MXC). Con el fin de mejorar la adhesión, mediante la misma técnica se aplicó al sustrato una aleación de NiAl (500 AS) cuya aplicación está recomendada para mejorar esta propiedad. Se caracterizaron las fases cristalinas del recubrimiento mediante difracción de...

  20. TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

    Directory of Open Access Journals (Sweden)

    Sánchez, A.

    2010-12-01

    Full Text Available This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal.

    En este estudio se analiza la influencia que el uso de una cámara de soldadura de gas inerte tiene sobre la microestructura y las propiedades mecánicas de las soldaduras TIG en el acero inoxidable austenítico AISI-316L cuando se emplean AISI ER316L, AISI 308L e Inconel 625 como materiales de aporte. Cuando se compara con el típico proceso de TIG, el uso de una cámara de gas inerte induce cambios en la microestructura, incrementando la presencia de ferrita vermicular y de laminillas de ferrita, resultando en un aumento del límite elástico y una pérdida de dureza. Su influencia sobre otras características de las soldaduras como la carga de rotura depende de la composición del material de aporte. La mejor combinación de propiedades mecánicas se obtuvo usando el Inconel 625 como material de aporte y soldando en la cámara de gas inerte.

  1. Recubrimiento de Stellite 6 sobre acero inoxidable realizado con láser de CO2 para válvulas de escape de motores diesel

    Directory of Open Access Journals (Sweden)

    Cadenas, M.

    2002-12-01

    Full Text Available To reduce the recovery or the replacement costs of diesel engine exhaust valves, they are manufactured with an economic base material, and a coating which is deposited on the seat valve in order to reach high hardness and good impact, corrosion and high temperature wear resistance (>550 °C and without lubrication. In this work, appropriate laser cladding parameters have been determined to obtain Stellite 6 coatings over AISI 304 steel (as plane test specimens and SAE EV8 steel (as valves substrates. One and two superimposed tracks were deposited on the seat valves, and modifying the laser power as a function of the rotated angle at the beginning and the end of the circular tracks, pores and cracks have been minimized and the thickness of the track were made uniform. Hardness, dilution and final microstructure of the different coatings have been analysed. A 10 % dilution and 550 HV in the tracks over plane test specimens was observed, while valves with one track showed 25 % and 430 HV respectively. With two superimposed tracks the hardness was up to 470 HV in the upper track.

    Para abaratar el coste de recuperación o sustitución de válvulas de escape en motores diesel, estas se fabrican con un material base económico, recubriéndose el asiento de la válvula con otro material al que se exigirá elevada dureza y buena resistencia al impacto, a la corrosión y al desgaste erosivo en caliente (>550 °C y sin lubricación. Partiendo de esta idea, en el presente trabajo se han determinado los parámetros adecuados para realizar, mediante la técnica de plaqueado láser, un recubrimiento con Stellite 6, sobre sustratos de acero AISI 304 (probetas planas y SAE EV8 (válvulas reales. Sobre las válvulas, se depositaron uno y dos cordones superpuestos, se minimizó la presencia de poros y grietas, modificando el grado de solape inicial y final de los cordones circulares y la potencia en función del ángulo girado. Así, se

  2. Microbiologically influenced corrosion evaluation on brass (UNS C68700, UNS C443) and AISI 316 stainless steel; Estudio de la influencia microbiologica en la corrosion de latones (UNS C68700, UNS C443) y acero inoxidable AISI 316

    Energy Technology Data Exchange (ETDEWEB)

    Ohanian, M.; Diaz, V.; Corengia, M.; Russi, P.; Pianzzola, M. J.; Menes, R. J.

    2014-10-01

    Microorganisms may play an important role in the corrosion process and generate conditions which affect the rate and/or the mechanism of deterioration. They become visible by the formation of bio films: clusters of microorganisms and extracellular polymers. These bio films affect not only the durability of the material, but also reduce the heat transfer. The present work studied the growth of aerobic and anaerobic heterotrophic microorganisms and sulfate reducing bacteria on aluminum brass (Uns C.a.), admiralty brass (Uns C.a.) and stainless steel Asi 316 in exposure experiments held in the Bay of Montevideo (Uruguay). The influence of the biofilm growth on the corrosion behavior was studied by electrochemical techniques: polarization curves and Electrochemical Impedance Spectroscopy (Ei). The selection of the most suitable material for the exposure conditions is discussed and hypotheses of the corrosion mechanism are presented. Although stainless steel Asi 316 presented the lowest corrosion rate it showed localized deterioration. (Author)

  3. Fatigue life of AISI 316L stainless steel welded joints, obtained by GMAW; Vida a la fatiga de juntas soldadas del acero inoxidable AISI 316L obtenidas mediante el proceso GMAW

    Energy Technology Data Exchange (ETDEWEB)

    Puchi-Cabrera, E. S.; Saya-Gamboa, R. A.; Barbera-Sosa, J. G. la; Staia, M. H.; Ignoto-Cardinale, V.; Berrios-Ortiz, J. A.; Mesmacque, G.

    2007-07-01

    An investigation has been conducted in order to determine the effect of both the metallic transfer mode (pulsed arc or short circuit) and the O{sub 2} content in the Ar/O{sub 2} gas mixture, of the gas-metal arc welding process (GMAW), on the fatigue life under uniaxial conditions of welded joints of 316L stainless. it has been concluded that the mixture of the protective gases employed in the process could have an important influence on the fatigue life of the welded joints of such steel in two different ways. firstly, through the modification of the radius of curvature at the joint between the welding tow and the base metal and, secondly, through a more pronounced degree of oxidation of the alloying elements induced by a higher O{sub 2} content in the mixture. As far as the metallic transfer mode is concerned, it has been determined that the welded joints obtained under a pulsed arc mode show a greater fatigue life in comparison with the joints obtained under short circuit for both gas mixtures. (Author) 25 refs.

  4. Deformation induced martensite in AISI 316 stainless steel

    Directory of Open Access Journals (Sweden)

    Solomon, N.

    2010-04-01

    Full Text Available The forming process leads to a considerable differentiation of the strain field within the billet, and finally causes the non-uniform distribution of the total strain, microstrusture and properties of the material over the product cross-section. This paper focus on the influence of stress states on the deformation-induced a’ martensitic transformation in AISI Type 316 austenitic stainless steel. The formation of deformation-induced martensite is related to the austenite (g instability at temperatures close or below room temperature. The structural transformation susceptibility is correlated to the stacking fault energy (SFE, which is a function not only of the chemical composition, but also of the testing temperature. Austenitic stainless steels possess high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Nevertheless, the deformation-induced martensite transformation may enhance the rate of work-hardening and it may or may not be in favour of further material processing. Due to their high corrosion resistance and versatile mechanical properties the austenitic stainless steels are used in pressing of heat exchanger plates. However, this corrosion resistance is influenced by the amount of martensite formed during processing. In order to establish the links between total plastic strain, and martensitic transformation, the experimental tests were followed by numerical simulation.

    El proceso de conformación da a lugar a una considerable diferenciación del campo de tensiones dentro de una barra de extrusión y, finalmente, causa una distribución no uniforme de la tensión total, la microestructura y propiedades del material sobre el corte transversal. En este trabajo se estudia la influencia de los estados de tensión sobre la transformación martensítica inducida por deformación en un acero inoxidable austenítico tipo AISI 316. La formación de martensita inducida por

  5. High temperature cyclic oxidation of AISI 310 steel in atmospheres with variable oxidation content; Oxidacion ciclica de un acero refractario AISI 310 a alta temperatura en atmosferas con centenidos de oxigeno variables

    Energy Technology Data Exchange (ETDEWEB)

    Higuera-Hidalgo, V.; Belzunce-Varela, F. J.; Riba-Lopez, J.

    2005-07-01

    High temperature oxidation test of an AISI 310 stainless steel was performed in two different environments: in an standard atmosphere (21% oxygen) at 704, 800, 884 and 1,000 degree centigree and in the typical environment of a gas turbine and vapor generator of a combined-cycle electric generation unit (10%oxygen) at 800 and 1,000 degree centigree. The oxidation kinetics was determined by means of the measurements of the weight gain per unit surface of the specimen and also determining the thickness of the oxide layer. Comparable results have been obtained using both methodologies and the effect of the oxygen content along with the other experimental differences were determined observing the oxidation kinetics in both environments. The cyclic oxidation of AISI 310 deteriorates at temperatures higher than 1,000 degree centigree. (Author) 9 refs.

  6. Estudio de la susceptibilidad de un acero inoxidable dúplex del tipo 22Cr5NiMoN al dañado por hidrógeno en condiciones estáticas (HIC y bajo carga (SSC

    Directory of Open Access Journals (Sweden)

    Gutiérrez de Saiz-Solabarría, S.

    1998-05-01

    Full Text Available The behavior to hydrogen damage caused by corrosion in a H2S medium is studied in a molded ferrite- austenite (52-48 % duplex stainless steel 22Cr5NiMoN type (UNS-J9.22.05 under both, static (damaging mechanism called Hydrogen Induced Cracking (HIC and sustained load (damaging mechanism called Sulfide Stress Cracking (SSC, conditions.

    Se estudia el comportamiento de un mismo acero moldeado inoxidable dúplex austeno-ferrítico (48-52 % del tipo 22Cr5NiMoN (UNS-J9.22.05 frente al dañado por hidrógeno generado por corrosión en medio H2S, tanto en condiciones estáticas, mecanismo de dañado conocido como HIC (Hydrogen Induced Cracking, como bajo carga de tracción, mecanismo de dañado conocido como SSC (Sulfide Stress Cracking.

  7. Dimensional characteristics of welds performed on AISI 1045 steel by means of the application of high power diode laser; Caracteristicas dimensionales de soldadura formadas sobre el acero AISI 1045 mediante la aplicacion del laser diodo de alta potencia

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Castillo, A.; Pou, J.; Lusquinos, F.; Quintero, F.; Soto, R.; Boutinguiza, M.; Saavedra, M.; Perez-Amor, M.

    2004-07-01

    The named High Power diode Laser (HPDL), emits a beam of optical energy generated by diode stimulation and offers the capability of supplying levels of power up to 6 kW. The objective of this research work was to study the main welding variables and their effects on dimensional characteristics of the beads performed by means of application of this novel laser. The results obtained, show that HPDL, is an energy source able to perform welds on AISI 1045 steel plates under conduction mode, without any kind of mechanized preparation, preheating or post-weld treatment and, without filler metal application. (Author) 16 refs.

  8. Influence of sintering atmosphere on the mechanical properties of steel P / M AISI 430L; Influencia de la atmosfera de sinterizacion en las propiedades mecanicas de los aceros P/M AISI 430L

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, F. J.; Martinez, C.; Costes, M. T.; Ruiz, J. M.; Garcia, L. E.; Corpas, F.

    2014-04-01

    It has studied the stainless steel powder metallurgy AISI 430L. It has compared the sintering in two different atmospheres; in vacuum, and in an atmosphere containing nitrogen. It has developed a heat treatment with the aim of improving the mechanical properties. This has been done through microstructural modification of complex nitrides of iron and chromium precipitates during the phase of sintering. Physical properties have been evaluated and are been performing a microstructural analysis for microstructure related to the increase in mechanical properties. (Author)

  9. Evaluación de Velocidades para la Deposición de FeSi y MoS2 por Triboadhesión en Aceros SAE 4140 y AISI 304 Evaluation of the Velocities Required for the Deposition of FeSi and MoS2 on SAE 4140 and AISI 304 Steels by Triboadhesion

    Directory of Open Access Journals (Sweden)

    J.M. Rodríguez

    2005-01-01

    Full Text Available En este trabajo se presenta la evaluación teórico-experimental de las velocidades y cargas requeridas para la deposición por triboadhesión de FeSi y MoS2 en los aceros SAE 4140 y AISI 304. Para ello se determinó el coeficiente de fricción entre la fresa y el material base. El proceso de deposición mediante la técnica de triboadhesión tiene lugar a causa del calor que se genera por fricción entre una fresa de algodón y un material base. Durante el proceso de fricción se provocan altas temperaturas instantáneas en la interfase de la fresa y el material base. En el estudio, se demuestra experimentalmente la deposición de material de aporte, utilizando las velocidades obtenidas de un análisis teórico.In this work a theoretical and experimental evaluation of the velocities required to deposit FeSi and MoS2 on SAE 4140 and AISI 304 steels is presented. To achieve this goal, the friction factor between the cotton mop and the base material was determined. The deposition process by triboadhesion is caused by the heat generated by friction between the cotton mop and the base material. During the friction, the contact between these two elements generates high instant temperatures. In the study, it was experimentally demonstrated the deposition of the material, using the tangential velocity obtained from a theoretical analysis.

  10. Comportamiento a la corrosión del acero 316L sinterizado con distinto grado de porosidad

    Directory of Open Access Journals (Sweden)

    Soria, L.

    1998-05-01

    Full Text Available AISI 316L sintered samples, with porosities ranging from 9 to 40 %, and without alloying losses at the surface, have been prepared. Those samples, along with conventional (rolled steel samples, have been subjected to electrochemical and immersion corrosion tests. According to porosity size quantitative measurements, before and after corrosion tests, two corrosion mechanisms, general and pitting, are proposed depending on the initial porosity.

    A partir de polvos de acero inoxidable AISI 316L, se han preparado muestras con distinto grado de porosidad, entre el 9 y el 40 %, asegurando que la superficie externa no resulta alterada durante el procesado pulvimetalúrgico. Junto a muestras de chapa laminada de la misma composición, han sido sometidas a ensayos de inmersión y a ensayos electroquímicos de corrosión. Estudios cuantitativos de la evolución de la porosidad superficial, antes y después de los ensayos, permiten plantear diversas hipótesis acerca de los mecanismos de corrosión actuantes en función de la porosidad de las piezas.

  11. Influence of the density of the microwave plasma in the nitridation of the AISI 4140 steel; Influencia de la densidad del plasma de microondas en la nitruracion de acero AISI 4140

    Energy Technology Data Exchange (ETDEWEB)

    Chirino O, S.; Camps C, E.; Escobar A, L.; Mejia H, J.A. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    A source of microwaves plasma type ECR was used to modify those mechanical properties of the surface of steel pieces AISI 4140. The experiments were carried out in a range of pressure among 4 X 10{sup -4} and 7 X 10{sup -4} Torr using one mixture of gases 60/40 hydrogen / nitrogen and an incident power of the microwaves of 400 W. Previous to the treatment of the samples, the plasma was studied using one Langmuir probe to determine the temperature of the electrons and the density of the plasma, the species excited in the plasma were determined by means of Optical emission spectroscopy. All the samples were treated during 50 min in a regime of low temperature (- 250 C), and the surface hardness it was increased up of 100% of their initial value, with a depth of penetration of the nitrogen of 4.5 {mu} m. The biggest hardness and depth of penetration of the nitrogen were obtained when the biggest density in the plasma was used to carry out the experiments. (Author)

  12. Flat friction tests applied to austenic stainless steels with several surface finish. Analysis of adhesion conditions in friction; Ensayos de rozamiento plano sobre aceros inoxidables austeniticos con diferente acabado superficial. Determinacion de las condiciones de adhesion en el rozamiento

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatatyd, A.; Martinez, A.

    2008-07-01

    The main purpose of this work is to evaluate the tribological behaviour of austenic stainless steels AISI 304 with bright surface finishing (B). The assays have been carried out in flat faced dies system with mineral oil of 200 cts viscosity, S{sub 2}Mo grease and in dry conditions. The relationship between friction coefficient and pressure and velocity has been established for the mineral oil as lubricant. In these conditions, a strong adhesive tendency has been found in boundary lubrication regime. The results obtained here, show us that S{sub 2}Mo grease leads to lowest values for the friction coefficient. A minor adhesive behaviour tendency for AISI 316 steel, harder than 304 grades, has been found. A relevant plowing phenomena has been observed for the more critical friction conditions tried out. A surface hardener is produced as a consequence of that. (Author) 19 refs.

  13. Desarrollo de un modelo matemático de diferencias finitas para el análisis del campo de temperaturas en la soldadura por arco de chapas finas de acero inoxidable

    OpenAIRE

    Miguel, V.; Estrems, M.; Martínez-Conesa, E. J.

    2010-01-01

    This work develops a finite difference method to evaluate the temperature field in the heat affected zone in butt welding applied to AISI 304 stainless steel thin sheet by GTAWprocess. A computer program has been developed and implemented by Visual Basic for Applications (VBA) in MS-Excel spreadsheet. The results that are obtained using the numerical application foresee the thermal behaviour of arc welding processes. An experimental methodology has been developed to validate the mathematical ...

  14. T.I.G. Welding of stainless steel. Numerical modelling for temperatures calculation in the Haz; Soldadura T.I.G. de acero inoxidable. Modelo numerico para el calculo de temperaturas en la ZAT

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Conesa, E. J.; Estrems-Amestoy, M.; Miguel-Eguia, V.; Garrido-Hernandez, A.; Guillen-Martinez, J. A.

    2010-07-01

    In this work, a numerical method for calculating the temperature field into the heat affected zone for butt welded joints is presented. The method has been developed for sheet welding and takes into account a bidimensional heat flow. It has built a computer program by MS-Excel books and Visual Basic for Applications (VBA). The model has been applied to the TIG process of AISI 304 stainless steel 2mm thickness sheet. The welding process has been considered without input materials. The numerical method may be used to help the designers to predict the temperature distribution in welded joints. (Author) 12 refs.

  15. Influencia del tiempo de nitruración en baño de sales en el comportamiento tribológico de un acero de herramientas AISI H13

    Directory of Open Access Journals (Sweden)

    Castro, G.

    2007-12-01

    Full Text Available Tribological high temperature characteristics of a H13 tool steel treated by salt bath have been studied. AISI H13 steel samples were nitrided by a sursulf bath, varying nitriding time from 1 to 24 h. Optical microscopy and micro-hardness deep profile through the nitrided layer were performed for each nitriding time. Standard pin-on-disk wear tests were conducted at high temperature. Sliding distance was varied from 150 m to 900 m. It has been observed that friction coefficient does not change with nitriding time and wear rate varies as a function of the sliding distance due to the presence of different wear mechanisms. For short sliding distances, the wear mechanisms that contribute to the total wear were plastic deformation and abrasion, whereas for greater sliding distances the mechanisms that control wear behaviour were oxidation and abrasion.

    Se han investigado las características tribológicas a alta temperatura de un acero de herramientas para trabajo en caliente nitrurado en baño de sales sursulf. Se ha variado el tiempo de nitruración desde 1 hasta 24 h, para analizar su influencia en la microestructura obtenida y en el comportamiento frente al desgaste. Se han realizado ensayos de desgaste a alta temperatura y se ha evaluado la ratio de desgaste y el coeficiente de fricción. Se ha observado que el coeficiente de fricción no varía con el tiempo de nitruración y que la ratio de desgaste varía con la distancia de deslizamiento debido a la presencia de distintos mecanismos de desgaste, pero es independiente del tiempo de nitruración. Así, para distancias de ensayo cortas, los mecanismos de desgaste que contribuyen al desgaste total son deformación plástica y abrasión, mientras que para mayores distancias de deslizamiento los mecanismos observados son oxidación y abrasión.

  16. Modificación de los aceros rápidos de herramientas AISI M2 por fusión superficial con láser bajo diferentes condiciones de operación

    Directory of Open Access Journals (Sweden)

    Arias, J.

    2010-06-01

    Full Text Available We applied a laser surface melting treatment to AISIM2 high-speed steel –hardened and tempered- and studied the resulting surface characteristics (microstructure and mechanical behavior (hardness and wear performance. The steel was treated using a Nd:YAG continuous-wave laser with different operation conditions. The influence of the laser processing parameters on the single tracks and on melted surface layer obtained by multipass system with 50% overlap were studied. The microstructure for all conditions is formed byMC- and M2C-type carbides, martensite and retained austenite; the quantities of this phase depends on the operations conditions. It has been determined that low levels of power density and high speed scanning of the beam leads to greater homogeneity in the microstructure with high hardness values and wear resistance.

    Se ha aplicado el tratamiento superficial de fusión con láser a un acero comercial rápido de herramientas AISI M2, templado y revenido, y se ha estudiado su microestructura superficial y comportamiento mecánico (dureza y resistencia al desgaste. Para ello, se ha empleado un láser continuo Nd:YAG, variando las condiciones de operación, analizando la influencia de los distintos parámetros sobre cordones individuales y sobre las características de la superficie fundida cuando se realiza el tratamiento en multipasada con un solape del 50 %. La caracterización microestructural realizada de la superficie fundida muestra que, en todos los casos, se encuentra constituida por carburos de pequeño tamaño,M2C yMC, martensita y austenita retenida, cuya cantidad depende de los parámetros de operación. Así mismo, se ha determinado que valores bajos de densidad de potencia y altas velocidades de barrido del haz conducen a mayor homogeneidad en la microestructura, con altos valores de dureza y resistencia al desgaste.

  17. Ionic implantation by plasma in titanium and stainless steels used in prosthesis and medical instruments; Implantacion ionica por plasma en titanio y aceros inoxidables usados en protesis e instrumental medico

    Energy Technology Data Exchange (ETDEWEB)

    Munoz C, A. E. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2008-07-01

    A study of a process known as plasma immersion ion implantation (PIII) of nitrogen at low voltages (< 4 kV) into three kind of samples: 1) austenitic stainless AISI 316-L steel plates, 2) ferritic stainless AISI 434 steel-based dentistry drills and 3) commercially pure titanium (CPTi) disks. On the case of CPTi the study was conducted in nitrogen- oxygen calibrated mixtures: 90% N-10% O, 80% N-20% O, 70% N-30% O and in 99.5% pure oxygen and 99.9% pure nitrogen. The PIII process was carried out by using a direct current plasma source controlled both in voltage and current, a negative voltage pulse modulator, a stainless AISI 304 steel vacuum chamber and a rod of the same material, horizontally located in the upper region of the chamber, which plays the role of anode in the plasma discharge. The purpose of the nitriding is forming a relatively thick layer on the surface of the steel specimens in order to enhance their both microhardness and general corrosion performances, desirable in medical applications. This layer contains interstitial nitrogen atoms ({approx}24% at.) which gives place to a deformed lattice (expanded phase) of the steel. Vickers microhardness and potentiodynamic tests (the latter in agreement to the norm ASTM G-61-89) confirm an increase of microhardness up to three times and a decrease of general corrosion rate in one order of magnitude. The nitriding of de dentistry drills is aimed at inhibiting the pitting corrosion produced by the asepsis process which results in pit nucleations, their propagation and consequent fractures when being under cyclic stress (fatigue). Scanning electron microscope micrographs reveal the risks involved in surpassing the critical treatment simple temperature of 450 C as the PIII process itself induces pitting. On its part, cyclic (ASTM G-61) potentiodynamic tests indicate an excellent pitting corrosion resistance of the samples treated under 450 C. In turn, the treatment of CPTi was meant to develop oxidized and

  18. A galvanic corrosion study of brass/stainless steel and brass/cast iron couples; Estudio de corrosion galvanica en pares laton/acero inoxidable y laton/fundicion de hierro

    Energy Technology Data Exchange (ETDEWEB)

    Ohanian, M.; Diaz, V.; Corengia, M.; Zinola, C. F.

    2011-07-01

    Corrosion attack in heat exchanger systems is a topic of main interest for the maintenance in each industrial plant. These are multi galvanic systems with particular geometric and fluidodynamic complexity. Corrosive damages include zinc selective dealeation in copper alloys. In order to explain zinc dealeation attack, this paper deals with laboratory scale testing, characterization and interactions between two copper and zinc alloys (Yellow brass UNS C268 and Admiralty brass UNS C443) compared to AISI 316 stainless steel and cast iron. The tests were performed at 20 degree centigrade in 1.5 % NaCl and 1.5 % Na{sub 2}SO{sub 4} solutions, pH 8 and each material was characterized by potentiodynamic sweeps. The couples are analyzed by studying transient galvanic currents. We conclude about the cause of the analyzed pathology, brass protection potential ranges and its coupling compatibility with other metals. (Author) 33 refs.

  19. Caracterizaci\\'on de austenita expandida generada por cementaci\\'on i\\'onica de aceros inoxidables. Estudio de la estabilidad frente a la irradiaci\\'on con haces de iones ligeros energ\\'eticos

    CERN Document Server

    Molleja, Javier García

    2014-01-01

    This thesis was focused on the surface modification with plasma discharge. Austenitic AISI 316L stainless steel sample was carburised under different experimental conditions and mechanical properties have been studied (thickness, lattice parameter, elemental composition, hardness, wear resistance and corrosion resistance). After that, steel substrates have been nitrided or carburised in order to analyse their stability under ion bombardment using a plasma focus device. Helium and deuterium were the gases used in 0, 1, 5, and 10 discharges. Optical and X-ray characterisations were used. Finally, using magnetron sputtering nitrided/carburised samples were coated with an AlN thin film in order to study their stability under long treatments at high temperatures.

  20. Influencia de los elementos residuales cobre, estaño, fósforo y arsénico en el agrietamiento de la superficie del acero inoxidable 18-8 durante la compresión a altas temperaturas

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1998-05-01

    Full Text Available The effect of certain different concentrations of Cu, Sn, P and As on the surface cracking of 18-8 austenitic stainless steel hot compressed specimens has been studied, at 1,123 and 1,273 K, in an oxidizing atmosphere (air. A procedure for determining surface cracking has been established, and the cracking factor obtained in this way is correlated with the chemical composition of the materials at both temperatures. The cracking factors obtained at 1,273 K have been compared with the reduction of area drops obtained by hot tension tests at the same temperature.

    Esta investigación aborda el estudio del efecto de concentraciones variables de cobre, estaño, fósforo y arsénico en el agrietamiento de la superficie de un acero 18-8, sometido a ensayos de compresión, a 1.123 y 1.273 K, en atmósfera oxidante (aire. Se desarrolla un procedimiento de cuantificación del grado de agrietamiento y se relaciona cada índice de agrietamiento así obtenido, a las distintas temperaturas, con la composición química" de los materiales. Los índices de agrietamiento correspondientes a los materiales comprimidos a 1.273 K se comparan con los valores de pérdida de reducción de área obtenidos mediante ensayos de tracción a la misma temperatura.

  1. Microestructura de una unión disímil AISI 321 y una aleación A 351 grado HK-40 obtenida mediante soldadura manual por arco eléctrico

    Directory of Open Access Journals (Sweden)

    Reilis Fuentes-Guilarte

    2016-05-01

    Full Text Available El objetivo fue establecer el comportamiento microestructural de una unión disímil de acero inoxidable austenítico AISI 321 y de la aleación A 351 grado HK 40 obtenida por fundición mediante soldadura manual por arco eléctrico y electrodos revestidos del tipo E 309 L-16. La estructura ferrita–austeníta que se forma en la unión del acero con la aleación es resultado del elevado contenido de carbono de la segunda. La baja velocidad de enfriamiento del cordón de soldadura revela ausencia de discontinuidades en el retículo cristalino de la zona afectada térmicamente y atenúa la formación de carburos de cromo del tipo Cr23C6, que puede formar la aleación A 351 grado HK 40 durante la difusión del volumen de fracción en masa del cromo.

  2. Comparative study in the induced corrosion by sulfate reducing microorganisms, in a stainless steel 304L sensitized and a carbon steel API X65; Estudio comparativo de la corrosion inducida por microorganismos sulfatorreductores, en un acero inoxidable 304L sensibilizado y un acero al carbono API X65

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.; Gonzalez F, E.; Arganis J, C.; Luna C, P.; Carapia M, L. [ININ, Carretera Mexico-Toluca Km. 36.5, 52045 Estado de Mexico (Mexico)]. e-mail: ads@nuclear.inin.mx

    2004-07-01

    In spite of the operational experience related with the presence of the phenomenon of microbiological corrosion (MIC) in industrial components, it was not but until the decade of the 80 s when the nuclear industry recognized its influence in some systems of Nuclear Generating Power plants. At the moment, diverse studies that have tried to explain the generation mechanism of this phenomenon exist; however, they are even important queries that to solve, especially those related with the particularities of the affected metallic substrates. Presently work, the electrochemical behavior of samples of stainless steel AISI 304L sensitized is evaluated and the carbon steel APIX65, before the action of sulfate reducing microorganisms low the same experimental conditions; found that for the APIX65 the presence of this type of bacteria promoted the formation of a stable biofilm that allowed the maintenance of the microorganisms that damaged the material in isolated places where stings were generated; while in the AISI 304L, it was not detected damage associated to the inoculated media. The techniques of Resistance to the Polarization and Tafel Extrapolation, allowed the calculation of the speed of uniform corrosion, parameter that doesn't seem to be influenced by the presence of the microorganisms; while that noise electrochemical it distinguished in real time, the effect of the sulfate reducing in the steel APIX65. (Author)

  3. Determinación de las modificaciones estructurales de la soldadura tipo SMAW en acero S355J2W

    OpenAIRE

    AIBAR MOSCOSO, ÁNGEL IVÁN

    2011-01-01

    La finalidad del presente proyecto es poder determinar las características de la soldadura por arco eléctrico tipo SMAW mediante tres diferentes electrodos, como son los básico con alma de acero al carbono, los de rutilo y los básico con alma de acero inoxidable sobre un acero st-52 así como los métodos destructivos y no destructivos para verificar el estado en el que se encuentra la soldadura. Estos objetivos se llevan a cabo mediante el seguimiento de una metodología de trabajo, así como...

  4. Algunas observaciones sobre la sinterización del acero austenítico 316L en atmósfera de argón

    Directory of Open Access Journals (Sweden)

    Gómez, F.

    1998-05-01

    Full Text Available PM high speed steels are prone to higher corrosion rates due to residual porosity as well as chromium depletion of the matrix during sintering AISI 316L powders have been cold compacted (100-1,000 MPa and sintered (1,000-1,250°C, 15-240 min under several argon containing or vacuum atmospheres. Better densification rates can be achieved as sintering time or temperature increase in the presence of argon. No surface oxidation has been observed with the use of low pressure argon atmospheres, as long as samples are protected in a stainless steel partially sealed container.

    La utilización de acero inoxidable pulvimetalúrgico está limitada, entre otras razones, por la presencia de porosidad que pueda favorecer procesos corrosivos, así como a posibles pérdidas de cromo en la matriz durante los procesos de sinterización. Se han realizado experiencias de procesado de polvos de acero 316L con distintas presiones de compactación (100-1.000 MPa, temperaturas de sinterización (1.100-1.250°C, tiempos de sinterización (15-240 min y en distintas atmósferas de sinterización, de argón y vacío. Se obtiene una mejor densificación con elevada temperatura y tiempos de sinterización en atmósferas de argón a baja presión. En dicha atmósfera, no se produce oxidación superficial aislando parcialmente las muestras del flujo directo del argón.

  5. Corrosión intergranular en aceros inoxidables

    Directory of Open Access Journals (Sweden)

    Álvaro Forero Mora

    2011-02-01

    Full Text Available Con alguna frecuencia llegan al IEI consultas acerca de la posibilidad de que se presente este problema en ciertas instalaciones industriales. El siguiente es un estudio sobre dicho fenómeno.

  6. Análisis de la fragilización por envejecimiento a baja temperatura de los aceros CF8M

    OpenAIRE

    Mazorra Incera, Luis; Gutiérrez-Solana Salcedo, Federico; González Martínez, Javier Jesús; Varona Ruiz, José María

    1989-01-01

    RESUMEN. En el marco de una investigación de carácter más general, en la que se analiza la fragilización térmica a 280º de los aceros inoxidables austenoferríticos moldeados, en el presente trabajo se estudia el comportamiento de los aceros CF8M frente a este problema como continuación a los resultados expuestos en un artículo anterior. Los modelos de comportamiento a que se llega, se basan en los efectos que ejercen los diferentes elementos que entran en la composición del acero y en la cant...

  7. Study on the types of craters produced in the impact of projectiles 5,56 SS109, over steel targets AISI-SAE 1045; Estudio de los tipos de crateres obtenidos en el impacto de proyectiles 5,56 SS109, sobre blancos de acero AISI-SAE 1045

    Energy Technology Data Exchange (ETDEWEB)

    Castro, A.; Espejo, E.; Martinez, L. [Universidad Nacional de Colombia. Santa Fe de Bogota (Colombia)

    2000-07-01

    The present work describes the morphology and formation of the types of craters obtained with the impact of projectiles 5,56 SS109 over seven steel plates AISI-SAE 1045 that received different cycles of heat treatment. A comparison between the type of deformation and fracture structures and the ones generated by the impact of this projectiles over one steel armor plate was made. Each one of the craters was characterized by visual and metallography observation. The influence of the plate microstructure on the efficiency for stopping the projectile and the mechanism of craters formation was evaluated. (Author) 10 refs.

  8. Comportamiento Tribológico y Microestructural en Recubrimientos Aplicados por GTAW y HVOF (Proceso Térmico de Espreado y Usado en Recuperación de Aceros Grado Herramienta AISI/SAE D2

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Guevara Chávez

    Full Text Available Resumen Las aleaciones de Fe-Cr-Mo se utilizan en recubrimientos para proteger componentes que están sometidos a condiciones de desgaste y corrosión. La alta velocidad de deposición del metalizado térmico (HVOF (High Velocity Oxi-Fuel aplicado en aleaciones de acero grado herramienta para trabajo en frío con la aplicación de sustratos Fe-Cr-Mo ha mostrado buenos resultados en los campos de proyección. El HOVF es un método atractivo para aplicar revestimientos y recuperar diámetros que fueron desgastados durante el proceso de operación. Nuevas superficies y materiales pueden ser provistos sin la distorsión causada por los procesos convencionales de soldadura. Para aquellos materiales que son susceptibles a agrietarse gracias a la formación de fases fuera de equilibrio duras con composiciones con altos contenidos de carbono y de cromo, debido a las condiciones del proceso que combinan una temperatura de la flama relativamente baja y con un tiempo de baja exposición. La microestructura las características del recubrimiento son determinadas por las propiedades físicas y químicas de las partículas impregnadas en el sustrato que a su vez dependen de una gran cantidad de parámetros como el diseño de pistola, la relación de oxígeno / combustible, método de inyección, tamaño de partícula y forma, entre otros La presente investigación estudia la influencia de los parámetros de procesamiento sobre las propiedades mecánicas y microestructurales del recubrimiento Diamalloy 1008 (aleación en mezcla de Fe-Cr-Mo revestimiento aplicado con Oxí-combustible de alta velocidad (HVOF y cinco diferentes tipos de electrodos aplicados por soldadura, TIG (GTAW en un acero grado herramienta para trabajo en frio. El objetivo de estos recubrimientos se utiliza habitualmente como una protección contra la corrosión y el desgaste, pero también tienen la capacidad de recuperar las zonas dañadas como es el caso de los dados de estampado de la

  9. Flank wear study of coating carbides and cermet inserts during the dry high speed turning of AISI 1045 steel; Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gonzalez, L. W.; Perez-Rodriguez, R.; Zambrano-Robledo, P.; Guerrero-Mata, M.; Dumitrescu, L.

    2011-07-01

    This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds. (Author) 19 refs.

  10. Stress corrosion (Astm G30-90 standard) in 08x18H10T stainless steel of nuclear fuel storage pool in WWER reactors; Corrosion bajo esfuerzo (Norma ASTM G30-90) en acero inoxidable 08x18H10T de piscinas de almacenamiento de combustible nuclear en reactores V.V.E.R

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, V.; Zamora R, L. [Centro de Estudios Aplicados al Desarrollo Nuclear (Cuba)

    1997-07-01

    At the water storage of the irradiated nuclear fuel has been an important factor in its management. The actual pools have its walls covered with inoxidable steel and heat exchangers to dissipate the residual heat from fuel. It is essential to control the water purity to eliminate those conditions which aid to the corrosion process in fuel and at related components. The steel used in this research was obtained from an austenitic inoxidizable steel standardized with titanium 08x18H10T (Type 321) similar to one of the two steel coatings used to cover walls and the pools floor. the test consisted in the specimen deformation through an U ply according to the Astm G30-90 standard. The exposition of the deformed specimen it was realized in simulated conditions to the chemical regime used in pools. (Author)

  11. Characterization of stainless steels submitted to P III in CD process and RF by corrosion, Sem and micro hardness mechanical tests; Caracterizacion de aceros inoxidables sometidos al proceso PIII en CD y RF por corrosion, MEB y pruebas mecanicas de micro dureza

    Energy Technology Data Exchange (ETDEWEB)

    Arellano C, J

    2004-07-01

    The modification of the surface of the austenitic stainless steel AISI 304 was carried out by immersed in plasma ion implantation (Plll), this process was carried out in a chamber of toroidal structure, in a nitrogen plasma created with one source of direct current (CD) and with a source of a radiofrequency current (RF) assisted with CD, that is to say (CD+RF); the main parameters of the plasma (density and temperature) with which the PIII process was carried out were monitored and determined by means of double electric probes. By means of scanning electronic microscopy, it was determined that the quantity of nitrogen implanted in the samples was of the order of 5% in weight and the implantation depth varies between 5-19 {mu}m. The results obtained by means of mechanical tests of Vickers micro hardness showed that the hardness of the steel was incremented of 200 HV up to 1400 HV, this according to different work conditions. The electrochemical behavior of the AISI 304 stainless steel was evaluated in a corrosive media one as it is the H{sub 2}SO{sub 4} making use of electrochemical techniques, the generated results showed variations in the velocities of corrosion, as well as in the potentials of corrosion of the samples subjected to the PIII process with regard to a sample without being subjected to this process. (Author)

  12. Aceros aluminotérmicos. Nuevas aplicaciones

    Directory of Open Access Journals (Sweden)

    Duart Blay, J. M.

    2004-02-01

    . Particular aplicación o interés presentan en la tecnología de los ferrocarriles para la obtención del carril continuo, prácticamente implantado en todo el mundo y en soldaduras cable de cobre-carril de acero empleadas en las señalizaciones para control de tráfico. En este trabajo se aportan las bases termodinámicas de la aluminotermia del hierro y su aplicación a la soldadura compleja de cruzamientos, juntas de dilatación y desvíos en FF.CC, que combinan aceros Hadfield, aceros inoxidables y aceros perlíticos de diferentes propiedades mecánicas. Las uniones deben ser compactas, resistentes y duras en los niveles que se citan en el trabajo, según requisitos exigidos por la circulación en líneas de alta velocidad (350 km/h., actualmente en construcción en España, pero que resultan generalizables a otro tipo de líneas menos exigentes y a ferrocarriles mineros.

  13. Oxidation behaviour at 1123 K of AISI 304-Ni/Al-Al2O3/TiO2 multilayer system deposited by flame spray

    Directory of Open Access Journals (Sweden)

    Cervera, I.

    2011-04-01

    Full Text Available The oxidation behaviour of alumina/titania (97/3, 87/13 and 60/40 ceramic coatings using a Ni-Al coupling layer was studied in a thermobalance. Both layers were deposited on an AISI 304 stainless steel base metal by the flame spray technique. The coated steel was heated from room temperature to 1,123 K at 40 K min –1, oxidized in air for 50 h, and then cooled to room temperature at 40 K min–1. The mass gain was mainly attributed to the oxidation of Ni-Al coupling layer. Kinetic laws, DW·S –1 (mg.mm–2 vs. time (hours were close to a parabolic plot for each sample. Surface composition of ceramic top layer and the cross section of multilayer system were analysed using a wide range of experimental techniques including Scanning Electron Microscopy (SEM, equipped with a link energy dispersive X-Ray spectroscopy (EDX and X-Ray diffraction (XRD before and after the oxidation process. Coatings 97/3 and 87/13 presented a stable structure after flame spray deposition and they did not evolve with the oxidation process, while most of the 60/40 coating changed to a metastable structure after deposition and to a more stable structure after oxidation with high micro-cracks content. SEM and EDX microanalysis of the cross-sections showed that significant oxidation and a weak intergranular precipitation had been produced in the coupling layer and on the stainless steel base metal, respectively.El comportamiento a oxidación de recubrimientos cerámicos alúmina/titania (97/3, 87/13, 60/40 usando una capa de anclaje Ni-Al se ha estudiado mediante una termobalanza. Ambas capas se han depositado sobre un acero inoxidable AISI 304 utilizando la técnica de proyección llama (FS. El acero recubierto se ha calentado desde la temperatura ambiente hasta 1.123 K a 40 K min–1, se ha oxidado al aire durante 50 h, y luego se ha enfriado hasta la temperatura ambiente a 40 K min–1. La ganancia en masa se atribuye a la oxidación de la capa de enganche Ni-Al. La cin

  14. A mathematical approach based on finite differences method for analyzing the temperature field in arc welding of stainless steel thin sheets; Desarrollo de un modelo matematico de diferencias finitas para el analisis del campo de temperaturas en la soldadura por arco de chapas finas de acero inoxidable

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Conesa, E.J.; Estrems, M.; Miguel, V.

    2010-07-01

    This work develops a finite difference method to evaluate the temperature field in the heat affected zone in butt welding applied to AISI 304 stainless steel thin sheet by GTAW process. A computer program has been developed and implemented by Visual Basic for Applications (VBA) in MS-Excel spreadsheet. The results that are obtained using the numerical application foresee the thermal behaviour of arc welding processes. An experimental methodology has been developed to validate the mathematical model that allows to measure the temperature in several points close to the weld bead. The methodology is applied to a stainless steel sheet with a thickness lower than 3 mm, although may be used for other steels and welding processes as MIG/MAG and SMAW. The data which has been obtained from the experimental procedure have been used to validate the results that have been calculated by the finite differences numerical method. The mathematical model adjustment has been carried out taking into account the experimental results. The differences found between the experimental and theoretical approaches are due to the convection and radiation heat losses, which have not been considered in the simulation model.With this simple model, the designer will be able to calculate the thermal cycles that take place in the process as well as to predict the temperature field in the proximity of the weld bead. (Author). 18 refs.

  15. Evaluación de diferentes aceros para la evolución de hidrógeno en KOH

    Directory of Open Access Journals (Sweden)

    Falk Michel Julke

    2014-05-01

    Full Text Available Se estudió el comportamiento electroquímico de los diferentes tipos de aceros comerciales de bajo costo (A36, 430 y 304 como electrodos para la obtención de hidrógeno. El propósito de este trabajo fue estudiar la evolución de hidrógeno, para lo cual se utilizaron técnicas electroquímicas como cronoamperometría y curvas voltamperométricas, en diferentes concentraciones de KOH (5% y 25% m/m. El acero inoxidable 304 en una concentración de 25%m/m tuvo el mejor desempeño, pues en estas condiciones el inicio de liberación de hidrógeno disminuyó y presentó el menor requerimiento de potencial para su uso como placa bipolar.

  16. Comportamiento del acero de baja aleación SA-508 y del acero al carbono A-410b en las condiciones de operación y parada del circuito primario de los reactores de agua ligera tipo PWR

    Directory of Open Access Journals (Sweden)

    García-Redondo, María del Sol

    2000-04-01

    Full Text Available The corrosion rate of low alloy steel SA-508 and carbon steel A-410b in simulated operation and shutdown conditions of pressurized water reactor has been determined. Moreover potentiodynamic polarization curves and galvanic effect through coupling of AISI-304 have been carried out under shutdown simulated condition.

    En este trabajo se ha determinado la cinética de corrosión del acero de baja aleación SA-508 y del acero al carbono A-410b en condiciones que simulan la operación y la parada de los reactores de agua ligera a presión. También se han realizado curvas de polarización potenciodinámica y se ha estudiado el acoplamiento galvánico con AISI-304 en condiciones de parada de los reactores de agua ligera a presión.

  17. Characterization of nitrides in an AISI 1010 steel; Caracterizacion de nitruros en un acero AISI 1010

    Energy Technology Data Exchange (ETDEWEB)

    Naquid G, C. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencia de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1998-07-01

    It was characterized the phase formation in the 1010 carbon steel nitrided in a plasma reactor nearby to eutectoid point. The microstructure and identification of these ones were evaluated by Optical microscopy (OM), Dilatometry and X-ray diffraction (XRD). (Author)

  18. Conformabilidad en caliente de aceros Twip

    OpenAIRE

    Pineda huitrón, Rosa M.

    2009-01-01

    En el presente proyecto de investigación, se trabajó con un acero de alto contenido en manganeso austenitico, TWIP, este acero se clasifica dentro de los aceros denominados: Aceros Avanzados de Alta Resistencia mecánica (AHSS). En este estudio se pretende estudiar las condiciones de trabajo en caliente óptimas para este acero, de modo que se pueda potenciar al máximo su resistencia sin penalizar su ductilidad. Para ello se efectuarán ensayos de compresión en caliente bajo difer...

  19. Diffusional Growth Kinetics Analisys of Fe2B Layers Applied During the Coating Powder-Pack Boriding Process on an AISI 1026 Steel

    OpenAIRE

    2015-01-01

    La exigencia de emplear materiales con propiedades avanzadas incluyen la necesidad de aplicar recubrimientos de alta resistencia que alarguen la vida de útil de aceros comerciales, de esta forma, el tratamiento termoquímico de borurización tiene el potencial para cumplir estos requerimientos. En este trabajo de investigación se formula un modelo matemático para analizar la cinética de crecimiento de las capas de 2 Fe B formadas sobre la superficie de un acero AISI 1026. El modelo matemático p...

  20. Efecto de las sales fundidas en la termofluencia del acero inoxidable tipo 304

    Directory of Open Access Journals (Sweden)

    González-Rodríguez, G.

    1995-06-01

    Full Text Available Problems caused by both hot corrosion and creep type-damage occurring on superheater and reheater tubes of power plants using heavy oil as fuel shorten their design lives. The acceleration of hot corrosion attack of boilers is caused by the presence of fuel ash deposits containing mainly vanadium, sodium and sulphur, in the form of Na2SO4 y V2O5 and V2O5 which form low melting point compounds. In addition to this, the tubes are exposed to the action of both high stresses and high temperatures, producing the so called creep damage. In this work, creep rupture tests were carried out in the temperature range of 620 to 660 °C in static air and in corrosive environments. The corrosive environments included 100 % Na2SO4, 100 % V2O5 and a 80 % V2O5 + 20 % Na2SO4 mixture.

    Los problemas causados tanto por la corrosión por sales fundidas, así como por la termofluencia en los tubos de los sobrecalentadores y recalentadores de una planta de potencia que usa combustibles fósiles, reducen su vida prevista en diseño. La aceleración de la corrosión por sales fundidas es causada por la presencia de cenizas que contienen principalmente vanadio, sodio y azufre en la forma de Na2SO4 y V2O5, los cuales forman mezclas con eutécticos de bajo punto de fusión. Adicionalmente, los tubos están expuestos a la acción de altos esfuerzos y altas temperaturas, lo cual propicia la termofluencia del material. En este trabajo, se han realizado ensayos de termofluencia hasta la rotura en aire y en ambientes corrosivos en el rango de temperaturas de 620 a 660 °C. Los ambientes corrosivos fueron 100 % Na2SO4, 100 % V2O5, y una mezcla 20 % Na2SO4-80 % V2O5.

  1. Comportamiento de armaduras de acero inoxidable en morteros con cenizas volantes

    OpenAIRE

    Paredes Cárdenas, Evelyn Carol

    2016-01-01

    Mención Internacional en el título de doctor Esta tesis contiene artículos de investigación en anexo. La sustitución parcial del cemento por adiciones de cenizas volantes (CV) tiene ventajas de tipo medioambiental (reduce la extracción en canteras, la emisión de CO₂ y reutiliza los residuos), económicas (reduce el gasto en cemento y evita costes de eliminación de residuos) y en algunos casos tecnológicas (dependiendo del tipo de cemento puede mejorar las propiedades mecánicas en hormigo...

  2. Phosphate coating on stainless steel 304 sensitized;Recubrimiento fosfatado sobre acero inoxidable 304 sensibilizado

    Energy Technology Data Exchange (ETDEWEB)

    Cruz V, J. P. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira, Km. 14.5 Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, Tamaulipas (Mexico); Vite T, J. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Castillo S, M.; Vite T, M., E-mail: jpcruz@ipn.m [IPN, Escuela Superior de Ingenieria Mecanica y Electrica, Seccion de Estudios de Posgrado e Investigacion, Unidad Profesional -Adolfo Lopez Mateos-, Zacatenco, 07738 Mexico, D. F. (Mexico)

    2009-07-01

    The stainless steel 304 can be sensitized when welding processes are applied, that causes the precipitation of chromium carbide in the grain limits, being promoted in this way the formation of galvanic cells and consequently the corrosion process. Using a phosphate coating is possible to retard the physiochemical damages that can to happen in the corrosion process. The stainless steel 304 substrate sensitized it is phosphate to base of Zn-Mn, in a immersion cell very hot. During the process was considered optimization values, for the characterization equipment of X-rays diffraction and scanning electron microscopy was used. The XRD technique confirmed the presence of the phases of manganese phosphate, zinc phosphate, as well as the phase of the stainless steel 304. When increasing the temperature from 60 to 90 C in the immersion process a homogeneous coating is obtained. (Author)

  3. un acero importado

    Directory of Open Access Journals (Sweden)

    Wilson A. Hormaza R.

    2007-01-01

    Full Text Available Este trabajo busca determinar las causas que llevaron al deterioro superficial de un conjunto de láminas y bobinas importadas de acero. Lo anterior implica precisar el tipo de deterioro de los componentes, es decir, si este se presentó durante el transporte marítimo o durante el almacenamiento. Los ensayos realizados fueron: análisis visual, análisis de espectrofotometría de infrarrojo y comparativo de los cristales de Cloruro de Sodio (NaCl, análisis de la morfología de la superficie deteriorada a través de microscopia óptica, análisis químico, metalografía y dureza. Los análisis determinaron la presencia de cristales de NaCl, los cuales, al disociarse, generan iones de Cl- (Cloruros y Na+ (Sodio, responsables del proceso de corrosión, indicándose, así la presencia de un ambiente marino

  4. Fuego y acero

    Directory of Open Access Journals (Sweden)

    Sfintesco, D.

    1965-03-01

    Full Text Available In a brief and appealing manner the author analysis the basic considerations which should be taken into account to deal effectively with the safety of steel structures in case of fire. He makes it clear that the safety measures must not be the result of a rather intuitive and hasty reaction to the possibility of a fire: for example, the costly covering of steel columns with fire resisting material, which in most cases is not necessary. A careful assessment of possible risks must be made, available means to reduce these must be adopted, and the potential losses in case of fire must be taken into account. The article is completed with a brief commentary on the new Italian Regulations, which are probably the most modern and advanced on this matter.El autor expone en este trabajo, en forma breve y llamativa, las bases en que conviene apoyarse para poder resolver racionalmente el problema de la seguridad de las estructuras de acero frente al fuego. Su lectura hace comprender claramente que no puede constituir esta base el temor irreflexivo, con sus secuelas de revestimientos y precauciones onerosos, e innecesarios la mayor parte de las veces, sino la ponderación prudente de los riesgos posibles, de los medios disponibles para combatir el peligro y de los daños probables que del incendio se puedan derivar. Termina el artículo con un rápido comentario del nuevo Reglamento italiano, probablemente el más moderno y avanzado de todos los existentes sobre esta materia de protección contra el fuego.

  5. Una herramienta para la selección automatizada de aceros en el contexto // A tool for the automated selection of steels in the Mechanical Engineering´s context

    Directory of Open Access Journals (Sweden)

    L. Dumitrescu

    2010-01-01

    Full Text Available ResumenEl diseno de Ingenieria de un producto o componente constituye una actividad dificil, compleja ymultidisciplinaria, enfocada a la resolucion de problemas. En el presente trabajo se muestra eldesarrollo de una herramienta automatizada para la seleccion de los aceros mas utilizados en laconstruccion de maquinarias. La herramienta constituye una ayuda para la seleccion de losmateriales desde la etapa conceptual del proceso de diseno, donde se identifican las diferentescategorias de materiales a utilizar. La herramienta comprende las caracteristicas y propiedades masrelevantes de los aceros de Ingenieria disponibles en seis normas internacionales: Japonesa (JIS,Alemana (DIN, Vbn, DIN-Vbn, Rusa (GOST, Americana (AISI, SAE, AISI-SAE, ASTM, Inglesa (BS, EN,GB, Francesa (AFNOR y la Norma Cubana (NC vigente.Palabras claves: materiales, automatizada, aceros, ingenieria.____________________________________________________________AbstractThe product or component design constitutes a difficult, complex and multidisciplinary activity,focused to the resolution of problems. Presently work show the development of an automated toolfor the selection of the more used steels in the construction of machineries. The tool constitute ahelp for the selection of the materials from the conceptual stage of the design process, where thedifferent categories of materials are identified to use. The tool analyze the characteristics and morecommon properties of the available steels in six international standards: JIS (Japan, DIN, Vbn, DINVbn(Germany, GOST (Russia, AISI, SAE, AISI-SAE, ASTM (USA, BS, IN, GB (England, AFNOR(France and NC (Cuba.Key words: materials, automated, steels, engineering.

  6. Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyección térmica por arco eléctrico

    Directory of Open Access Journals (Sweden)

    López-Covaleda, E. A.

    2013-10-01

    Full Text Available The commercial materials 140MXC (with iron, tungsten, chrome, niobium, 530AS (AISI 1015 steel and 560AS (AISI 420 steel on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1 homogeneous coatings and (2 coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical microscopy, Scanning electron microscopy and Laser confocal microscopy. The wear resistance was evaluated through dry sand rubber wheel test (DSRW. We found that the wear resistance depends on the quantity of defects and the mechanical properties like hardness. For example, the softer coatings have the biggest wear rates and the failure mode was characterized by plastic deformation caused by particles indentation, and the other hand the failure mode at the harder materials was grooving. The details and wear mechanism of the coatings produced are described in this investigation.Mediante proyección térmica de arco eléctrico fueron depositados tres materiales comercialmente conocidos como: 140MXC (a base de hierro, wolframio, cromo y niobio, 530AS (acero AISI 1020 y 560AS (acero AISI 420, sobre acero AISI 4340. Con el objetivo de evaluar la mejor estrategia para incrementar la resistencia al desgaste abrasivo, los recubrimientos fueron depositados de dos formas: (1 monocapas homogéneas de cada material y (2 recubrimientos depositando con alambres disimiles de 140MXC + 530AS y 140MXC + 560AS. Los recubrimientos fueron caracterizados microestructuralmente mediante Difracción de rayos X, Microscopía óptica, Microscopía láser confocal y Microscopía electrónica de barrido. La evaluación de la resistencia al desgaste abrasivo se realizó mediante ensayo con arena seca y rueda de caucho (DSRW. Se encontró que la resistencia al desgaste depende entre otras de las

  7. Procedimiento para endurecer el acero 45 mediante la deformación plástica con rodillo simple

    OpenAIRE

    Fernández Columbíe, Tomás; Rodríguez González, Isnel; Alcántara Borges, Dayanis; Fernández, Esther

    2010-01-01

    El trabajo muestra las técnicas empleadas en un diseño de experimento que permite evaluar el comportamiento de las variables independientes fuerza (P), desde 500 hasta 2500 N, número de revolución (n) mínimo 27, medio 54 y máximo 110 rev/min y avance (s), 0,075, 0, 125 y 0,25 mm/rev, para determinar el comportamiento de la variable dependiente dureza (H), cuando una probeta de acero AISI 1045 es sometida a tratamiento superficial por roda-dura para crear un estado compresivo que lo deforme e ...

  8. Estudio de la conformabilidad en aceros AHSS y aceros de embutición

    OpenAIRE

    Gutiérrez Castillo, Joan David

    2009-01-01

    El presente Proyecto de Final de Carrera tiene como objeto el estudio de la conformabilidad de chapas de acero TRIP(Transformation Induced Plasticity), acero que pertenece a La familia de aceros avanzados de alta resistencia mecánica AHSS (Advanced High Strength Steel), en comparación con un acero de embutición. Para ello se han utilizado los diagramas FLD (Forming Limit Diagram) los cuales indican las deformaciones existentes en diferentes condiciones de tensión y/o deformació...

  9. Desgaste por deslizamiento en seco de aceros perlíticos y bainíticos

    Directory of Open Access Journals (Sweden)

    Cristian Camilo Viáfara Arango

    2004-01-01

    Full Text Available El desgaste por deslizamiento tiene una gran influencia sobre el desempeño de los sistemas rueda-riel, en particular, por el deslizamiento de la pestaña de la rueda sobre la parte interna del riel en una pista curva. Dado que el deslizamiento entre la rueda y el riel involucra efectos de adhesión, altos porcentajes de deslizamiento/rodadura afectan fuertemente el desgaste por fatiga de contacto por rodadura, que actúa en las superficies de contacto. En una máquina Pin sobre Disco se llevaron a cabo ensayos de desgaste por deslizamiento para estudiar el comportamiento del acero perlítico AISI 1070 y el bainítico AISI 15B30. La velocidad de deslizamiento fue 1 ms-1 para todas las pruebas y se utilizaron cargas normales de 10, 30 y 50 N. La resistencia al desgaste fue relacionada con la pérdida de masa medida después de las pruebas y las superficies desgastadas, al igual que las partículas removidas, fueron analizadas por medio de los microscopios óptico y electrónico. Se realizaron perfiles de microdureza bajo las superficies de contacto para analizar el efecto del endurecimiento por deformación. El acero perlítico mostró mayor resistencia al desgaste que el acero bainítico, debido al excelente comportamiento de endurecimiento por deformación de la perlita comparado con el de la bainita. En el acero perlítico se observaron regímenes de desgaste oxidativo, mientras que en el bainítico el principal mecanismo de remoción de material fue el adhesivo, llevando a un daño mucho más fuerte en la superficie. De hecho, el régimen de desgaste para las probetas bainíticas fue siempre severo, aún con la menor carga normal aplicada.

  10. Caracterización de capas coloreadas sobre AISI 304

    Directory of Open Access Journals (Sweden)

    López, J.

    1998-05-01

    Full Text Available A common method for obtaining colour coatings on stainless steel surfaces is by dipping in strongly oxidizing solutions (H2SO4-CrO3 at 70°C. This work improves the knowledge of these coatings by means of techniques that were not available some years ago, such as ellipsometry, to determine the refraction index and the thickness, and atomic field microscopy (AFM, to observe the coloured surface. From these techniques, it is possible to state that films are formed by an aggregation of particle ranging in size from 5 to 15 nm, the interstices are pores of approximately 5 nm diameter.

    El método más usual de obtener en la superficie de los aceros inoxidables capas de colores variables es mediante su inmersión en soluciones fuertemente oxidantes (H2SO4-CrO3 a una temperatura en torno a 70°C. El trabajo mejora el conocimiento que de estas capas se tiene por medio de técnicas que no eran disponibles hace algunos años, tales como la elipsometría, para la obtención de parámetros ópticos y determinación de espesores, y la microscopía de campo atómico, para la observación de la superficie coloreada. El uso conjunto de estas técnicas permite observar que la película de color está formada por una agregación de partículas con un tamaño que oscila entre los 5 y los 15 nm, los intersticios que aparecen entre las partículas pueden identificarse como poros de unos 5 nm de tamaño.

  11. Surface fatigue and failure characteristics of hot-forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, Dennis P.

    1987-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground AISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  12. Una herramienta para la selección automatizada de aceros en el contexto de la Ingeniería Mecánica

    Directory of Open Access Journals (Sweden)

    L. Dumitrescu

    2010-01-01

    Full Text Available El diseño de Ingeniería de un producto o componente constituye una actividad difícil, compleja y multidisciplinaria, enfocada a la resolución de problemas. En el presente trabajo se muestra el desarrollo de una herramienta automatizada para la selección de los aceros más utilizados en la construcción de maquinarias. La herramienta constituye una ayuda para la selección de los materiales desde la etapa conceptual del proceso de diseño, donde se identifican las diferentes categorías de materiales a utilizar. La herramienta comprende las características y propiedades más relevantes de los aceros de Ingeniería disponibles en seis normas internacionales: Japonesa (JIS, Alemana (DIN, Vbn, DIN-Vbn, Rusa (GOST, Americana (AISI, SAE, AISI-SAE, ASTM, Inglesa (BS, EN, GB, Francesa (AFNOR y la Norma Cubana (NC vigente.The product or component design constitutes a difficult, complex and multidisciplinary activity, focused to the resolution of problems. Presently work show the development of an automated tool for the selection of the more used steels in the construction of machineries. The tool constitute a help for the selection of the materials from the conceptual stage of the design process, where the different categories of materials are identified to use. The tool analyze the characteristics and more common properties of the available steels in six international standards: JIS (Japan, DIN, Vbn, DIN-Vbn (Germany, GOST (Russia, AISI, SAE, AISI-SAE, ASTM (USA, BS, IN, GB (England, AFNOR (France and NC (Cuba.

  13. Surface fatigue and failure characteristics of hot forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, D. P.

    1986-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground SISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  14. Soldagem por Difusão de Aços Inoxidáveis para Fabricação de Trocadores de Calor Compactos

    Directory of Open Access Journals (Sweden)

    Marcus Vinícius Volponi Mortean

    2016-03-01

    Full Text Available Resumo A união de materiais diferentes ou componentes com geometrias complexas muitas vezes requer processos de uniões especiais, como por exemplo, uma fonte de energia de alta densidade como laser ou feixe de elétrons para soldagem por fusão ou mesmo um processo de soldagem no estado sólido. Em particular, este trabalho descreve os experimentos recentes da aplicação da soldagem por difusão no estado sólido (SDES para diferentes tipos de aços inoxidáveis: austenítico AISI 316L, duplex UNS 31803 e superduplex UNS 327250. A soldagem por difusão foi realizada sob alto vácuo a 1050 °C, durante 60 minutos, empregando uma pressão uniaxial de 18-35 MPa. A qualidade da união foi avaliada por microscopia óptica e testes mecânicos. Os resultados preliminares indicam a necessidade de otimização dos parâmetros de processo para os aços duplex e superduplex. Os resultados positivos alcançados no presente trabalho permitiram a fabricação de protótipos de trocadores de calor compacto em aço inoxidável, utilizando o novo método de fabricação, desenvolvido por LABTUCAL / UFSC, através do qual o processo de corte a jato de água é aplicado para confeccionar com precisão os canais do núcleo do permutador de calor.

  15. Mechanical properties of duple stainless steels laser joints; Propiedades mecanicas de las uniones por laser de aceros inoxidables duplex

    Energy Technology Data Exchange (ETDEWEB)

    Amigo, V.; Bonache, V.; Teruel, L.; Vicente, A.

    2005-07-01

    The welded joints of stainless steels always present problems for the microstructural modifications that occur in the heat affected zone. Particularly, duplex stainless steels present very important changes when the weld pool solidifies forming fundamentally ferritic structures with some austenite in grain boundaries. These microstructural modifications, and those which occur in the HAZ, justify the mechanical properties of the joint and mainly those of plasticity, being all of them influenced by the processing conditions. In this work the influence of the laser welding speed on the tensile behaviour od duplex stainless steel welded joints is presented. The microstructure of the obtained seams and of the heat affected zone will be evaluated by means of optic and scanning electron microscopy. Also, different microhardness profiles have been obtained to evaluate the modifications in the mechanical properties both in the seam and the zone of thermal affection. (Author) 23 refs.

  16. Formación de maclas durante el enfriamiento en aceros inoxidables superferríticos envejecidos

    OpenAIRE

    Salán, M. N.; Anglada, M. J.

    2005-01-01

    Superferritic stainless steels show a BCC structure free of austenite at any temperature. Intermediate ageing temperatures, close to 475 °C, induce a-chromium content modulation and only after long periods of time, it is possible to detect chromium rich α' phase, which is responsible for embrittlement (475 °C embrittlement). In this work, ageing thermal treatments at intermediate temperatures in the superferritic stainless steel DIN 1.4575, have allowed to relate the associated hardness incre...

  17. Modificación de las propiedades superficiales de aceros inoxidables Dúplex mediante recubrimientos por láser

    Directory of Open Access Journals (Sweden)

    Amigo, V.

    2004-12-01

    Full Text Available Laser cladding is one of the most promissing techniques to restore damaged surfaces and achieve properties similar to those of the base metal. In this work, duplex stainless steels have been cladded by a nickel alloy under different processing conditions. The influence of the beam speed and defocusing variables has been evaluated in the microstructure both of the cladding and heat affected zone, HAZ. These results have been correlated to mechanical properties by means of microhardness measurements from cladding area to base metal through the interface. This technique has shown to be very appropriate to obtain controlled mechanical properties as they are determined by the solidification microstructure, originated by the transfer of mass and heat in the system.

    La posibilidad de restaurar superficies y, con ello, las propiedades de las mismas mediante el recubrimiento por láser de polvos constituye uno de los mayores intereses en las investigaciones actuales. En este trabajo se ha obtenido un recubrimiento de una aleación base níquel, mediante el tratamiento láser de polvos elementales para diferentes condiciones de procesado. Se ha evaluado la influencia de las variables de proceso, velocidad del láser y desenfoque del haz láser en la microestructura de los recubrimientos y con ello en las propiedades finales de los mismos, así como en la transición de estas a través de la interfase y la zona afectada por el calor, ZAC, evaluada mediante perfiles de microdureza. La obtención de recubrimientos a partir de polvos resulta muy adecuada, en este caso, al obtener unas propiedades mecánicas que están determinadas por la microestructura de solidificación, originada por la transferencia de masa y calor en el sistema.

  18. Duplex stainless steel surface bay laser cladding; Modificacion de las propiedades superficiales de aceros inoxidables Duplex mediante recubrimientos por laser

    Energy Technology Data Exchange (ETDEWEB)

    Amigo, V.; Pineda, Y.; Segovia, F.; Vicente, A.

    2004-07-01

    Laser cladding is one of the most promising techniques to restore damaged surfaces and achieve properties similar to those of the base metal. In this work, duplex stainless steels have been cladded by a nickel alloy under different processing conditions. The influence of the beam speed and defocusing variables ha been evaluated in the microstructure both of the cladding and heat affected zone, HAZ. These results have been correlated to mechanical properties by means of microhardness measurements from cladding area to base metal through the interface. This technique has shown to be very appropriate to obtain controlled mechanical properties as they are determined by the solidification microstructure, originated by the transfer of mass and heat in the system. (Author) 21 refs.

  19. Estudio de la transformación martensítica, optimización de la microestructura y prevención de la rotura frágil en piezas coladas de acero X38CrMoV5-1 de alta resistencia

    OpenAIRE

    Pastor Muro, Ana

    2016-01-01

    La presente tesis trata sobre el "Estudio de la transformación martensítica, optimización de la microestructura y prevención de la rotura frágil en piezas coladas de acero X38CrMoV5-1 de alta resistencia”. El acero X38CrMoV5-1/AISI H11 es un acero martensítico al cromo-vanadio-molibdeno para trabajo en caliente fácilmente endurecible, que se fabrica generalmente por moldeo con la consiguiente presencia de porosidad interdendrítica. La primera parte de la tesis consiste en una introducción don...

  20. Experiencias en la selección de aceros asistida por computadoras en la carrera de ingeniería mecánica

    Directory of Open Access Journals (Sweden)

    Luminita Dumitrescu

    2010-01-01

    Full Text Available Se plantea que el diseño de Ingeniería de un producto o componente constituye una actividad difícil, compleja y multidisciplinaria, enfocada a la resolución de problemas. Se muestra el desarrollo de una herramienta automatizada para la selección de los aceros más utilizados en la construcción de maquinarias donde la herramienta constituye una ayuda para la selección de los materiales desde la etapa conceptual del proceso de diseño, donde se identifican las diferentes categorías de materiales a utilizar, la que comprende las características y propiedades más relevantes de los aceros de Ingeniería disponibles en seis normas internacionales: Japonesa (JIS, Alemana (DIN, Vbn, DIN-Vbn, Rusa (GOST, Americana (AISI, SAE, AISI-SAE, ASTM, Inglesa (BS, EN, GB, Francesa (AFNOR y la Norma Cubana (NC vigente.

  1. Comparing the Formability of AISI 304 and AISI 202 Stainless Steels

    Science.gov (United States)

    du Toit, M.; Steyn, H. G.

    2012-07-01

    The formability of AISI 202 austenitic stainless steel was compared with that of type AISI 304 stainless steel. Type 202 is a low-nickel austenitic stainless steel alloyed with manganese and nitrogen. In this study, the formability of the two grades was examined using Erichsen cupping tests and room temperature uniaxial tensile tests performed at various angles to the rolling direction. AISI 202 appears to work-harden at a slightly higher rate than AISI 304, even though the austenite in type 202 is more stable than that in 304 with respect to the formation of deformation-induced α' martensite. Although both grades are predicted to be susceptible to earing during deep drawing, AISI 202 displays a higher work-hardening exponent, higher average normal anisotropy, and a higher limiting drawing ratio than AISI 304. Similar cup heights were measured during Erichsen cupping tests, confirming that the two grades have very similar deep drawing properties. The results of this investigation therefore suggest that AISI 202 is a suitable alternative for AISI 304 in applications requiring good deep drawing properties.

  2. Comparative study of high temperature oxidation behaviour in AISI 304 and AISI 439 stainless steels

    Directory of Open Access Journals (Sweden)

    Antônio Claret Soares Sabioni

    2003-06-01

    Full Text Available This work deals with a comparison of high temperature oxidation behaviour in AISI 304 austenitic and AISI 439 ferritic stainless steels. The oxidation experiments were performed between 850 and 950 °C, in oxygen and Ar (100 vpm H2. In most cases, it was formed a Cr2O3 protective scale, whose growth kinetics follows a parabolic law. The exception was for the the AISI 304 steel, at 950 °C, in oxygen atmosphere, which forms an iron oxide external layer. The oxidation resistance of the AISI 439 does not depend on the atmosphere. The AISI 304 has the same oxidation resistance in both atmospheres, at 850 °C, but at higher temperatures, its oxidation rate strongly increases in oxygen atmosphere. Concerning the performance of these steels under oxidation, our results show that the AISI 439 steel has higher oxidation resistance in oxidizing atmosphere, above 850 °C, while, in low pO2 atmosphere, the AISI 304 steel has higher oxidation resistance than the AISI 439, in all the temperature range investigated.

  3. Diffusional Growth Kinetics Analisys of Fe2B Layers Applied During the Coating Powder-Pack Boriding Process on an AISI 1026 Steel

    Directory of Open Access Journals (Sweden)

    M. Elias-Espinosa

    2015-01-01

    Full Text Available La exigencia de emplear materiales con propiedades avanzadas incluyen la necesidad de aplicar recubrimientos de alta resistencia que alarguen la vida de útil de aceros comerciales, de esta forma, el tratamiento termoquímico de borurización tiene el potencial para cumplir estos requerimientos. En este trabajo de investigación se formula un modelo matemático para analizar la cinética de crecimiento de las capas de 2 Fe B formadas sobre la superficie de un acero AISI 1026. El modelo matemático propuesto se desarrolló en base a la solución de la ecuación de balance de masa de la interface de crecimiento 2 Fe B/Fe para evaluar el coeficiente de difusión del boro a través de las capas de Fe2B en un rango de temperaturas de 1123 a1273 K. En el modelo desarrollado se incluyó el tiempo de incubación del boruro para formar la fase Fe2B. El modelo matemático fue validado con datos experimentales realizados a una temperatura de 1253 K y tiempo de siete horas. Las capas de boruro fueron caracterizadas y analizadas por microscopia óptica y de barrido (se obtuvo un EDS, así como por Difracción de Rayos – X (XRD. Se utilizó la técnica de indentación Daimler-Benz Rockwell-C para evaluar cualitativamente la adherencia de la capa de Fe2B sobre el sustrato (acero AISI 1026. Para usos prácticos y para un espesor determinado, se propuso un diagrama a espesor constante (215 μm el cual es controlado con la variación de la temperatura y tiempo de exposición al recubrimiento. De los resultados obtenidos, se encontró que la energía de activación para el boro en el acero AISI 1026 es igual a 178 kJ mol-1.

  4. Proventricular nematodiasis in wrinkled hornbills (Aceros corrugatus).

    Science.gov (United States)

    Ferrell, Shannon T; Pope, Katherine A; Gardiner, Chris; Bradway, Daniel S; Ambrose, Dana L; MacLean, Robert A; Norton, Terry M; Stedman, Nancy L; Garner, Michael M

    2009-09-01

    Three immature Sunda wrinkled hornbills (Aceros corrugatus) were diagnosed postmortem with proventricular spirurid nematodiasis. Concurrent severe disseminated larval granulomatosis in other visceral organs was considered contributory to mortality in each case. Clinical signs of nematodiasis were vague but generally consisted of weight loss, anorexia, and lethargy. Frequent antemortem fecal examinations were negative for spirurid eggs. In these present cases, based on routine histopathology, both prophylactic and empirically based therapeutic anthelmintic treatments had no evident benefit in the elimination of the proventricular nematodes. Spirurid nematodiasis may be an important cause of mortality in young hornbills.

  5. Tensiones residuales en alambres de acero trefilados

    OpenAIRE

    Atienza Riera, José Miguel

    2001-01-01

    El alambre de acero eutectoide trefilado es un material de gran interés industrial. Se emplea masivamente en las obras de hormigón pretensado, en los cables de la minería y de la industria pesquera y en la industria del automóvil como hilos muy finos para refuerzo de neumáticos. El proceso de trefilado con el que se obtienen estos alambres es una de las más antiguas operaciones de conformado de metales. Consiste esencialmente en reducir las dimensiones de una barra haciéndola pasar a través d...

  6. Variación del módulo de Young en el acero C45E (norma EN 10083 tratado térmicamente

    Directory of Open Access Journals (Sweden)

    Fonseca, I.

    2002-08-01

    Full Text Available The parameters hardness, yield strength, ultimate tensile strength, toughness and Young's modulus of carbon steel C45E, EN 10083 (AISI 1045 annealed, quenched and tempered at various temperatures have been determined. Young's modulus has also been measured from ultrasonic techniques and also from the tension test; elastic deformation has been determined by the electric gaugue method. A metallographic study by scanning electron microscopy has also been carried out to confirm the results of the thermal treatment. Hardness, yield strength and ultimate tensile strength increases as it is with the thermal treatment. In addition Young=s modulus increases from 199-200 GPa (quenched state to 211-212 GPa (tempered 500 °C, 1 h.. The annealed steel presents a Young's modulus of 206-207 GPa. A good agreement between Young's modulus values obtained by ultrasonic measurements and by tension test has been observed. This behaviour has been correlated with the distribution of dislocations in the material under the various states.

    Se han determinado distintas propiedades mecánicas del acero C45E según norma EN10083 (AISI 1045 reconocido, templado y revenido a distintas temperaturas. Las propiedades mecánicas analizadas han sido: dureza, límite elástico convecional, resistencia a la tracción, resiliencia y módulo de Young. Esta última propiedad se determinó por ultrasonidos y a partir de curvas tensión-deformación midiendo ésta mediante extensometría eléctrica.En todos los casos se ha comprobado la bondad del tratamiento aplicado madiante observaciones metalográficas por microscopía eléctronica de barrido. Los valores de dureza, límite elástico convecional y resistencia a la tracción presentan las variaciones esperadas después de los distintos tratamientos térmicos aplicados. Sorprendentemente, el módulo de Young se incrementa desde valores de 199-200 GPa para el acero templado hasta 211-212 GPa para el acero templado y revenido a

  7. Deposición metálica de Stellite grado 6 sobre AISI 316 en superficies planas mediante soldadura por fricción. // Metallic deposition of Stellite degree 6 on AISI 316 in plane surfaces by means of friction welding.

    Directory of Open Access Journals (Sweden)

    J. Cabello Eras

    2003-01-01

    Full Text Available En el presente trabajo se realiza un estudio del proceso de deposición metálica de Stellite grado 6 sobre una superficie deacero inoxidable AISI 316 a través de la soldadura por fricción. Se estudiaron distintas combinaciones de parámetros desoldadura tales como, velocidad de rotación de la barra de material de aportación, velocidad transversal del sustrato, tiempode calentamiento, presión de apriete de la barra contra el sustrato y los depósitos obtenidos son sometidos a un análisismetalográfico en la zona de interfase y a una prueba de doblado para comprobar su adhesión al metal base.Palabras claves: Soldadura por fricción, depósitos metálicos._____________________________________________________________________________AbstractPresently work carried out a study of the process of metallic deposition of Stellite degree 6 on a surface of stainlesssteel AISI 316 through the welding by friction. Different combinations of welding parameters were studied as:rotation speed of the contribution material bar, sustain traverse speed, time of heating, pressure of the bar againstthe sustain. The obtained deposits are subject to metalografic analysis in the interface area and to bending test inorder to check their adhesion to the metal bases.Key words: Friction welding, metallic deposits.

  8. 76 FR 67253 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel ACERO AZUL; Invitation for...

    Science.gov (United States)

    2011-10-31

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel ACERO AZUL... the vessel ACERO AZUL is: INTENDED COMMERCIAL USE OF VESSEL: ``Passenger for hire.'' GEOGRAPHIC...

  9. An investigation on weldability of AISI 304 and AISI 1040 steels on friction welding; Untersuchung der Schweisseignung von AISI 304 und AISI 1040 mittels Reibschweissen

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Sare; Ay, Irfan [Balikesir Univ., Cagis Campus (Turkey). Mechanical Eng. Dept.; Dinc, Dincer [General Directorate of Highways, Canakkale (Turkey); Yaman, Ramazan [Balikesir Univ., Cagis Campus (Turkey). Industrial Eng. Dept.

    2010-04-15

    In welding technology, joining processes of different materials, which have dissimilar crystal structures are difficult. Welding of different materials becomes very important to reduce costs. Furthermore, the friction welding method is processed in lower temperature than the melting temperature. Especially, this is a big advantage to overcome difficulties that occur in the heat affected zone during usage of conventional methods. In this study, the weldability of AISI 304 stainless steel and AISI 1040 carbon steel by friction welding is studied. During the welding process, temperature variations in the welding zones were measured with an infrared temperature measurement device. After welding of the samples, tensile and hardness experiments were carried out. For metallographic investigations, optical microscope and scanning electron microscope (SEM) pictures were taken. Energy dispersive spectroscopy (EDS) analysis was carried out for composition investigations on welding and heat affected zones. As a result, these two steels could be joined by friction welding for industrial usage.

  10. State on AISI 304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    A. Fattah-alhosseini

    2011-01-01

    Full Text Available The passivity and protective nature of the passive films are essentially related to ionic and electronic transport processes, which are controlled by the optical and electronic properties of passive films. In this study, the electrochemical behavior of passive films anodically formed on AISI 304 stainless steel in sulfuric acid solution has been examined using electrochemical impedance spectroscopy. AISI 304 in sulphuric acid solution is characterized by high interfacial impedance, thereby illustrating its high corrosion resistance. Results showed that the interfacial impedance and the polarization resistance (pol initially increase with applied potential, within the low potential passive. However, at a sufficiently high potential passive (>0.4 V, the interfacial impedance and the polarization resistance decrease with increasing potential. An electrical equivalent circuit based on the impedance analysis, which describes the behavior of the passive film on stainless steel more satisfactorily than the proposed models, is presented.

  11. Characterization of AISI 4140 borided steels

    Energy Technology Data Exchange (ETDEWEB)

    Campos-Silva, I., E-mail: icampos@ipn.mx [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049 Cantoblanco, Madrid (Spain); Martinez-Trinidad, J. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico)

    2010-02-01

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe{sub 2}B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe{sub 2}B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 {mu}m from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form K{sub C}({pi}/2) > K{sub C} > K{sub C}(0) for the different applied loads and experimental parameters of the boriding process.

  12. Characterization of an AISI H-13 steel for work in hot; Caracterizacion del acero H-13 AISI para trabajado en caliente

    Energy Technology Data Exchange (ETDEWEB)

    Godinez, J.; Robles, E. [Instituto Nacional de Investigaciones Nucleares, Departamento de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1998-07-01

    Two materials were acquired which elaborated through secondary refining processes known as electroslag refusing (ESR) and electric arc in vacuum refusing (VAR) were acquired. These materials were thermically treated, for subsequently to determine their mechanical properties in longitudinal and transversal directions with respect to rolling direction, moreover they were characterized through scanning electron microscopy and X-ray diffraction determining microstructure, carbides and non-metallic inclusions. The results of the mechanical essays allowed to evaluate the fracture toughness to this steel by the Barsom and Rolfe method. (Author)

  13. Endurecimiento superficial de aceros y fundiciones mediante láser de Nd: YAG

    Directory of Open Access Journals (Sweden)

    Sagaró, R.

    2001-10-01

    Full Text Available This work relates with heat treatment by laser of metallic surfaces. The hardening of steels AISI 1045, W1, W112 and flake and nodular cast irons was carried out using a Nd: YAG laser. Operation parameters of laser like beam power (P and traverse speed of the laser Spot (V are closely related to the depth of hardening. The authors present some analyses on metallographic studies. In all cases Vickers microhardness valves of about 500-900 HV (three or four times higher than original substrates. Relations between microhardness and depth of hardening are presented for the processed materials. Experimental results showed that the scan speed increase produces a decrease on depth of hardening as reported by others researchers. On the other hand, the samples with higher carbon content show lower hardenining depth. In addition, tribological tests were carried out. These tests show wear resistance when compared with conventional heat treatment. The frictional coefficient decrease in the samples with laser surface treatment.

    En el trabajo se presentan los resultados del tratamiento térmico superficial, con técnica láser, de superficies metálicas. Con el empleo de un láser de Nd:YAG se procedió al endurecimiento superficial de los aceros AISI 1045, W1, W112 y fundiciones de tipo laminar y nodular. Se presentan los resultados del tratamiento térmico superficial atendiendo al parámetro velocidad de barrido del haz de láser (V. De igual forma se estudian las microestructuras metalográficas obtenidas. En todos los casos, se obtienen valores de microdureza Vickers que oscilan entre los 500-900 HV (incrementos de tres-cuatro veces respecto al material base. Los resultados obtenidos permiten afirmar que, en todos los casos estudiados, el incremento de la velocidad de barrido provocó una disminución de la profundidad de la capa endurecida, en correspondencia con otros resultados expuestos en la literatura especializada. Las experiencias del

  14. Hot hardness characteristics of ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C, and Super Nitralloy

    Science.gov (United States)

    Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

    1973-01-01

    Short-term hot hardness studies were performed with ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C (14-4-1) and case hardened Super Nitralloy. Hardness levels of each material were measured at elevated temperatures in an electric furnace with a low oxygen environment. Test temperatures ranged from 294 to 877 K. The hot hardness characteristics of the ausformed AISI-M-50, Matrix 2 WD-65, and modified AISI 440-C were the same as those determined for high-speed tool steels. Hot hardness for these steels can be predicted within one point Rockwell C. The hot hardness characteristics of both the case and core of Super Nitralloy were superior to AISI 52100 but inferior to the high-speed tool steels. The short-term Rockwell C hardness at temperature for the Super Nitralloy material between 294 and 769 K can be predicted within one point Rockwell C hardness.

  15. Comportamiento de las aleaciones termorresistentes AISI HH y HK-40 ante los procesos de carburización y nitruración

    Directory of Open Access Journals (Sweden)

    Eleno Alfonso-Brindis

    2001-03-01

    Full Text Available Se evalúa el comportamiento de los aceros austeníticos fundidos AISI HH y HK- 40 (de producción nacional ante los procesos de carburización y nitruración en los rangos de temperaturas desde 750 hasta 1 000 °C. Se estudia la cinética y la termodinámica de las posibles reacciones y los productos de las mismas se caracterizan mediante técnicas de Microscopía Óptica, Microscopía Electrónica de Barrido y Microanálisis (MEB-EDAX. En el análisis microscópico se observó la formación de carburos de cromo después de la carburización, mientras que la nitruración dio lugar a la formación de nitruros de cromo. Se concluye que la aleación AISI HK-40 posee una elevada resistencia intrínseca a la carburización y a la nitruración, que hace factible su empleo en componentes de hornos de soleras múltiples para la reducción de minerales lateríticos

  16. Obtención de un acero de calidad S355J2 partiendo de un acero microaleado

    OpenAIRE

    2014-01-01

    El acero ha sido, y sigue siendo, un material clave en el desarrollo de nuestra civilización. Es por ello, que la consecución de nuevas calidades es clave en los entornos industriales de este sector. Este proyecto se encamina a la consecución de una calidad de acero determinada, el tipo y grado S 355 J2 +AR, dentro de un entorno industrial concreto formado por una acería eléctrica seguida de un tren de laminación de perfiles estructurales. Esta calidad concreta plantea ventajas en cuanto a...

  17. Efeito da chuva ácida em aços inoxidáveis coloridos

    Directory of Open Access Journals (Sweden)

    Célia Regina de Oliveira Loureiro

    2007-03-01

    Full Text Available Em função da crescente demanda de utilização do aço inoxidável, na arquitetura, como material de revestimento externo e, considerando a preocupação dos órgãos de controle ambiental com a poluição no meio urbano, foram avaliados os efeitos da chuva ácida nas condições superficiais do aço inoxidável colorido e na lixiviação de cromo para o ambiente. Para esse estudo, foram realizados, em laboratório, ensaios de imersão de chapas de aço inoxidável colorido e natural em solução simulada de chuva ácida, sendo avaliados a liberação de cromo para a solução e a alteração da aparência superficial das amostras em tempos de exposição de 1, 3, 7, 14 e 28 dias. Nas amostras de aço inoxidável, com e sem coloração, foram medidos a cor e o brilho e, para soluções ácidas remanescentes, foram realizadas análises de cromo total e cromo hexavalente. Os resultados obtidos mostraram que, independente do tempo de contato do aço inoxidável colorido com a solução de chuva ácida, houve preservação da aparência do material, sem alteração das condições superficiais, e o teor de cromo hexavalente na solução se apresentou em níveis muito inferiores aos estabelecidos pelo Conselho de Política Ambiental de Minas Gerais - COPAM.Considering the increase of stainless steel application for exteriors in architecture and governmental environment protection policies, the effect of acid rain exposure on the surface appearance and chromium release of colored stainless steel and uncolored substrate was investigated. Laboratory experiments were conducted by immersing stainless steel samples in an artificial acid rain solution for 1, 3, 7, 14 and 28 days exposure. The surface appearance of the samples was evaluated by color and brightness measurements and chromium release by chemical analysis of total and hexavalent chromium. The obtained results have shown that the surface appearance of the stainless steel was preserved and the

  18. Mechanical and Microstructural Properties of Friction Welded AISI 304 Stainless Steel to AISI 1060 Steel AISI 1060

    Directory of Open Access Journals (Sweden)

    Ates H.

    2014-10-01

    Full Text Available Rotary Friction welding is one of the most popular methods of joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport and aerospace industrial component designs. This study investigates the influence of friction and upsetting pressures on the hardness, tensile properties and microstructure of the welds. The experimental results showed that as the friction and upsetting pressures increased, the hardness and tensile strength values increased, as well. The tensile fracture of welded joint occurred in the AISI 1060 side. The friction processed joints were evaluated for their integrity and quality aspects by optical and scanning electron microscopy. For the perfect interfacial bonding, sufficient upsetting and friction pressures are necessary to reach the optimal temperature and severe plastic deformation to bring these materials within the attraction range.

  19. Metallurgical and Mechanical Research on Dissimilar Electron Beam Welding of AISI 316L and AISI 4340

    Directory of Open Access Journals (Sweden)

    A. R. Sufizadeh

    2016-01-01

    Full Text Available Dissimilar electron beam welding of 316L austenitic stainless steel and AISI 4340 low alloy high strength steel has been studied. Studies are focused on effect of beam current on weld geometry, optical and scanning electron microscopy, X-ray diffraction of the weld microstructures, and heat affected zone. The results showed that the increase of beam current led to increasing depths and widths of the welds. The optimum beam current was 2.8 mA which shows full penetration with minimum width. The cooling rates were calculated for optimum sample by measuring secondary dendrite arm space and the results show that high cooling rates lead to austenitic microstructure. Moreover, the metallography result shows the columnar and equiaxed austenitic microstructures in weld zone. A comparison of HAZ widths depicts the wider HAZ in the 316L side. The tensile tests results showed that the optimum sample fractured from base metal in AISI 316L side with the UTS values is much greater than the other samples. Moreover, the fractography study presents the weld cross sections with dimples resembling ductile fracture. The hardness results showed that the increase of the beam current led to the formation of a wide softening zone as HAZ in AISI 4340 side.

  20. InfluÃncia da LaminaÃÃo a Frio na Microestrutura, Propriedades MecÃnicas e MagnÃticas, Textura e CorrosÃo por Pites de AÃos AISI 301LN e 316L

    OpenAIRE

    Paulo Maria de Oliveira Silva

    2005-01-01

    Os aÃos inoxidÃveis austenÃticos (AIAs) sÃo largamente aplicados nas indÃstrias de alimentos, transportes nuclear, petroquÃmica devido à adequada combinaÃÃo de resistÃncia mecÃnica, conformabilidade e resistÃncia à corrosÃo. Dentre estes tipos de aÃo, destaca-se o AISI 301 por sua resistÃncia mecÃnica superior. Entretanto, este tipo de aÃo apresenta um dos piores desempenhos em termos de corrosÃo. Toda a resistÃncia à corrosÃo dos AIAs se baseia em sua camada de filme passivo contendo Cr203 q...

  1. Comparação entre as técnicas de segmentação de imagens, difração de raios x e ferritoscopia na quantificação da martensita induzida por deformação no aço AISI 301L

    OpenAIRE

    Morais,N.W.S.; Viana,N.F.; Abreu, H. F. G.

    2011-01-01

    Este trabalho teve como intuito avaliar como as técnicas de segmentação de imagens, através de microscopia ótica, difração de raios x e ferritoscopia, seriam capazes de quantificar a martensita induzida por deformação em no aço inoxidável austenítico AISI 301L. Comparando qualitativamente as três técnicas, nota-se o mesmo comportamento para todas as amostras testadas, ou seja, que o percentual de martensita aumenta com o grau de deformação real medido em relação à redução de área, no entanto ...

  2. Internal microporosity formation in stainless steel powders: kinetics and mechanism; Formacion de microporosidad interna en polvos de acero inoxidable: cinetica y mecanismo

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.; Suwardijo, W.; Garcia, L.; Formoso, A.; Cores, A.

    2002-07-01

    The internal microporosity of stainless steel powders is obtained by a technology developed in the Metallurgical Research Center (CIME) in collaboration with ISPETP, which consists of carbon enrichment of alloy during the fusion process, and after powder atomization a subsequent decarburization annealing. The internal microporosity , which can reach up to 10 volume percent of the steel particle, reduces powder density and improves powder compressibility, while costs for technology installation are also reduced. In this paper the technology for obtaining the microporosity, the mathematical models of the process, and the structural transformations undergone by stainless steel powder are shown. It is concluded that for carbon contents lower than 0.05% internal microporosity tends to disappear. (Author) 17 refs.

  3. Waste water treatment of slaughterhouse through water treatment plants of stainless steel; Tratamiento de aguas residuales de mataderos mediante depuradoras compactas modulares de acero inoxidable

    Energy Technology Data Exchange (ETDEWEB)

    BaNales Sirvent, P.

    1997-06-01

    The object of this project was to develop an integral waste water treatment concept, based on compact module made of stainless steel, with a combination that allows to get performances according to given requirements stablished in the Community Directive 91/271/CEE (1991). The industrial pilot tests have been made in a slaughterhouse with a capacity of 20 tons per day. (Author)

  4. Sigma-phase formation in weldments of cast super duplex stainless steel; Formacion de fase sigma en uniones soldadas de acero inoxidable super duplex fundido

    Energy Technology Data Exchange (ETDEWEB)

    Garin, J. L.; Mannheim, R. L.; Camus, M. A.

    2011-07-01

    This paper describes the microstructural characteristics of weldments of cast super duplex stainless steel (J93404), being subjected to annealing processes to induce formation of sigma-phase at high temperatures. The influence of heating time at 1073 K, 1123 K and 1173 K upon precipitation of sigma in the heat affected zone, base metal and fusion zone of the weldments was analyzed. The experimental results revealed the formation of this intermetallic compound throughout decomposition of the ferritic phase into austenite and sigma. At earlier stages of the transformation the phase rapidly nucleates and growth along the ferrite-austenite grain boundaries, and then massively advances towards the bulk of the ferritic zone with greater effectiveness as temperature increases. The formation of sigma-phase in all weldments resembles the Johnson-Mehl-Avramis mechanism stated for nucleation and growth. (Author) 27 refs.

  5. Effect of boron on sintering of a ferritic stainless steel; Efecto del boro en la sinterizacion de un acero inoxidable ferritico

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Miramontes, J. A.; Barceinas-Sanchez, J. D. O.; Velez-Jacobo, L.; Martinez-Villafane, A.; Chacon-Nava, J. G.

    2008-07-01

    This work studies the effect of boron on the density of a 409Nb ferritic stainless steel obtained by powder metallurgy during the process of sintering. The purpose of adding boron is to promote the formation of a liquid phase during sintering at temperatures below 120 degree centigrade . The boron contents varied from 0.0 to 1.5%wt. Specimens were compacted at 700MPa, and sintering was made at 1075 and 1150 degree centigrade during 60 minutes under a hydrogen atmosphere, using a heating rate of 20 degree centigrade/min. Density values were determined by the Archimedes method, and the samples were analysed using scanning electron microscopy. This work shows the dependence of the steel density and morphology of the microstructure as a function of boron content and the temperature of sintering. (Author) 29 refs.

  6. Analysis of the passive layer developed on stainless steels implanted with chromium; Analisis de las peliculas pasivas generadas en aceros inoxidables implantados con cromo

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, C. M.; Cristobal, M. J.; Novoa, X. R.; Pena, G.; Perez, M. C.

    2004-07-01

    This work studies the effect of chromium implantation on the development of passive layers generated electrochemically in alkaline medium over two stainless steels. The XPS analyses show that the layers generated on the implanted steels present less thickness together with similar composition compared to the unimplanted steels layers. However, SEM micrographs show that the layers grown on implanted steels present more defects and less adherence that the films on unimplanted steels. These changes together with the results obtained by Cyclic Voltammetry suggest an oxide structure modification, lattice structure or crystallinity state. (Author) 6 refs.

  7. Influence of the heat treatment on the cold deformation od duplex stainless steels; Influencia de los tratamientos termicos en la deformacion en frio de los aceros inoxidables duplex

    Energy Technology Data Exchange (ETDEWEB)

    Fargas, G.; Manero, J. M.; Anglada, M.; Mateo, A.

    2004-07-01

    The purpose of this paper is to study the compression behavior of a duplex stainless steel after several annealing conditions, in order to simulate the response during cold rolling in the industrial process. For each studied condition, stress-strain curves present serrations in the flow zone due to austenite and ferrite twinning and the austenite phase transformation to martensite. At the same time, it is shown that sigma phase increases the strength and diminish the cold deformation capacity of the steel. (Author) 15 refs.

  8. Study of the neutronic activation of the stainless steel in a nuclear reactor; Estudios de la activacion neutronica del acero inoxidable en un reactor nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro Roche, I.; Rodenas Diago, J.; Marques, J. G.

    2013-07-01

    During operation of a nuclear reactor, various components can be activated by neutron reactions. The activity thus generated produces a dose that is a potential risk to workers and environment. Was simulated using the MCNP and CINDER'90 such activation codes on a piece of steel and the values obtained compared with experimental measurements. The equivalence of both methods is verified to calculate neutron activation and evolution of the dose rate with the cooling time.

  9. Corrosion behavior of powder metallurgical stainless steels in urban and marine environments

    Directory of Open Access Journals (Sweden)

    Bautista, A.

    2006-06-01

    Full Text Available This work studies the development of corrosive attack on sintered components manufactured from AISI 316L and AISI 304L powders. The stainless steels were sintered in vacuum and in nitrogen-base atmosphere at 1,120 and 1,250 ºC, and their corrosion resistance was then analyzed by electrochemical techniques and by atmospheric corrosion testing (two years at urban and marine test sites. Images are shown of the morphology of the attack on the surface of the stainless steels and the development of this attack in the interior of the material.

    Este trabajo estudia el desarrollo del proceso corrosivo en componentes sinterizados fabricados a partir de polvos de AISI 316L y AISI 304L. Los aceros inoxidables fueron sinterizados en vacío y en atmósfera base nitrógeno a 1.120 y 1.250 ºC y, su resistencia a corrosión se ha analizado mediante técnicas electroquímicas y mediante ensayos de corrosión atmosférica (dos años en ambientes urbano y marino. Se muestran imágenes de la morfología del ataque en la superficie de los aceros inoxidables y del desarrollo de este ataque en el interior del material.

  10. Estudio de la corrosión en caliente de la aleación aisi-sae 304h, mediante la técnica de espectroscopía de impedancia electroquímica (eis

    Directory of Open Access Journals (Sweden)

    JOSÉ TRISTANCHO

    2007-01-01

    Full Text Available La corrosión en caliente es uno de los mayores problemas que se presentan en la industria generadora de energía eléctrica, especialmente en los componentes que conforman los equipos generadores de vapor (calderas. El fenómeno corrosivo que presentan las sales fundidas, es por lo menos parcialmente, de naturaleza electroquímica y por lo tanto, puede ser estudiado empleando la técnica de impedancia electroquímica (EIS, adaptada a las condiciones especiales de temperatura y composición del medio corrosivo. En esta investigación se evalúo el comportamiento del acero AISI304H expuesto a un electrolito compuesto de 80%V2O5 – 20%Na2SO4 fundido, en un intervalo de temperatura comprendido entre 550ºC y 700ºC

  11. Austenización de aceros con microestructuras diferentes

    Directory of Open Access Journals (Sweden)

    García-Caballero, E.

    2004-06-01

    Full Text Available During the last years, physical-mathematical models concerning continuous cooling and isothermal phase transformations valid for wide range of steels have been attained. However, the modelling of continuous heating transformations has not undergone the same development than in cooling. This investigation concerns with the study and modélisation of continuous heating phase transformations to study the process which is generally referred to as austenitisation of the steel. Therefore, our main aim is to describe those processes which control the non-isothermal formation of austenite in steels with initial microstructures of ferrite and/or pearlite.

    Durante los últimos años se han desarrollado algunos modelos físico-matemáticos sobre las transformaciones de fase en enfriamiento continuo e isotérmicas, aplicables a un amplio rango de aceros. Sin embargo, la modelización de las transformaciones en calentamiento continuo no ha tenido un desarrollo paralelo a las de enfriamiento y su avance ha sido, apreciablemente, menor. En este trabajo se aborda el estudio y modelización de las transformaciones que se producen durante el calentamiento continuo a lo largo de lo que, genéricamente, se denomina la austenización del acero. El principal objetivo es, por consiguiente, describir los procesos que controlan la formación anisotérmica de la austenita en aceros con microestructuras iniciales de ferrita y/o perlita.

  12. Fretting fatigue in AISI 1015 steel

    Indian Academy of Sciences (India)

    R Gnanamoorthy; R Rosi Reddy

    2002-04-01

    A small osillatory movement between two contacting surfaces is termed as fretting and on many occasions it acts as the crack initiation site leading to catastrophic failure of the overall structure. The occurrence of fretting is observed in many engineering structures such as shaft flanges, gas turbines, steel ropes etc. An experimental facility, which can simulate the fretting fatigue in many engineering applications, is the primary requirement of the research program. A laboratory fretting fatigue test facility capable of varying many influencing parameters of fretting fatigue such as slip amplitutde, frequency, contact pressure, etc is designed and developed. Preliminary investigations on plain and fretting fatigue behaviour of AISI 1015 structural steel are reported in this paper. A strength reduction factor of about 1.30 was obtained due to fretting for the test material under the present experimental conditions. Influence of contact load on fretting was also studied. Increasing fretting contact load decreased the fatigue life in the range investigated. Failure analysis showed typical stage I oblique crack growth followed by stage II straight crack perpedicular to the fretting zone.

  13. Características dimensionales de soldaduras formadas sobre el acero AIS11045 mediante la aplicación del láser diodo de alta potencia

    Directory of Open Access Journals (Sweden)

    Sánchez-Castillo, A.

    2004-06-01

    Full Text Available The named High Power Diode Laser (HPDL, emits a beam of optical energy generated by diode stimulation and offers the capability of supplying levels of power up to 6 kW. The objetive of this research work was to study the main welding variables and their effects on dimensional characteristics of the beads performed by means of application of this novel laser. The results obtained, show that HPDL, is an energy source able to perform welds on AISI 1045 steel plates under conduction mode, without any kind of mechanized preparation, preheating or post-weld treatment and, without filler metal application.

    El denominado láser diodo de alta potencia (LDAP emite un haz de energía óptica generada mediante la estimulación de diodos y ofrece la capacidad de suministrar niveles de potencia hasta de 6 kW. El objetivo de este trabajo de investigación fue estudiar las principales variables de soldadura y sus efectos sobre las características dimensionales de los cordones formados mediante la aplicación de este novedoso láser. Los resultados obtenidos demuestran que el LDAP es una fuente de energía capaz de formar cordones de soldadura sobre placas de acero AISI 1045, en el modo de conducción, sin ningún tipo de preparación mecanizada, precalentamiento o tratamiento postsoldadura y sin la aplicación de metal de aporte.

  14. “CARACTERIZACIÓN Y SOLDABILIDAD DE UN ACERO AVANZADO DE ALTA RESISTENCIA MICROALEADO CON BORO.”

    OpenAIRE

    Alatorre Torres, Norma

    2012-01-01

    L os aceros micro-aleados, como es el caso de los Aceros Avanzados de Alta Resistencia (AHSS), presentan ventajas en relación a los aceros estructurales al carbón y de baja aleación, respecto al costo y a la mejora en propiedades mecánicas (límites elásticos hasta cuatro veces superiores a los aceros laminados tradicionales), que se obtienen mediante un tratamiento termo-mecánico controlado. Este hecho se ve reflejado en el aumento en la demanda de este acero (entre 10 y 15%...

  15. Optimization of tensile strength of friction welded AISI 1040 and AISI 304L steels according to statistics analysis (ANOVA)

    Energy Technology Data Exchange (ETDEWEB)

    Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi; Firat, Emrah Hanifi; Caligulu, Ugur [Firat Univ., Elazig (Turkey)

    2013-06-01

    Materials difficult to weld by fusion welding processes can be successfully welded by friction welding. The strength of the friction welded joints is extremely affected by process parameters (rotation speed, friction time, friction pressure, forging time, and forging pressure). In this study, statistical values of tensile strength were investigated in terms of rotation speed, friction time, and friction pressure on the strength behaviours of friction welded AISI 1040 and AISI 304L alloys. Then, the tensile test results were analyzed by analysis of variance (ANOVA) with a confidence level of 95 % to find out whether a statistically significant difference occurs. As a result of this study, the maximum tensile strength is very close, which that of AISI 1040 parent metal of 637 MPa to could be obtained for the joints fabricated under the welding conditions of rotation speed of 1700 rpm, friction pressure of 50 MPa, forging pressure of 100 MPa, friction time of 4 s, and forging time of 2 s. Rotation speed, friction time, and friction pressure on the friction welding of AISI 1040 and AISI 304L alloys were statistically significant regarding tensile strength test values. (orig.)

  16. The study on the properties of AISI 4140 and AISI 1040 steel rods welded by friction welding

    OpenAIRE

    Thanee Toomprasen; Chawalit Thinvongpituk; Sukangkana Talangkun

    2014-01-01

    This paper is aimed to investigate the properties of joint between AISI 4140 and AISI 1040 welded by friction welding. The specimens were prepared in round shape of 13 mm diameter and 100 mm long. They were welded by friction welding method under the following conditions; friction pressure of 183 MPa, friction time of 12 sec, upset pressure of 428 MPa, upset time of 7 sec. and rotational speed of 1400 rpm. The strength and hardness were tested on the welded area. The result showed finer grain...

  17. Modelación por Elementos Finitos como Método para la Sustitución de Piezas de Acero por Hierro Nodular.

    Directory of Open Access Journals (Sweden)

    Mario Jacas

    2005-09-01

    Full Text Available Dado el nivel de aplicación que ha tenido en los últimos años la sustitución de piezas de acero por hierrofundido nodular, en este trabajo se establece una vía de análisis con el empleo de un software deElementos Finitos que justifique desde el punto de vista de las propiedades mecánicas de los elementoslas posibilidades de sustitución.El objetivo del presente trabajo es la sustitución de un tope de maquina hormigonera originalmentefabricado de componentes soldados de material AISI 1020 por uno rediseñado con hierro nodularaustemplado (ADI, utilizando la modelación por elementos finitos, sobre la base de un análisis linealestático.Finalmente, al comparar las tensiones de Von Mises y los desplazamientos originados por la acción de lacarga, se pudo observar un mejor comportamiento mecánico en el modelo rediseñado del tope de hierronodular austemplado (ADI.

  18. Variacion del modulo de 'Young' con el tratamiento termico en aceros al carbono hipoeutectoides

    OpenAIRE

    Villuendas Latorre, Aránzazu; Jorba, Jordi; Roca, Antoni

    2005-01-01

    En trabajos anteriores se ha constatado que varios aceros al carbono hipoeutectoides, en estado de temple, presentan valores del módulo de Young inferiores a los correspondientes en estado de revenido. En todos los casos la determinación se ha realizado mediante ultrasonidos. En concreto, para el acero C22E (EN 10083), el módulo se incrementa ligeramente desde 209 GPa (material templado) hasta 211 GPa (revenido a 650 °C), para el acero C45E el módulo aumenta desde 199 GPa hasta 211 GPa (reven...

  19. The study on the properties of AISI 4140 and AISI 1040 steel rods welded by friction welding

    Directory of Open Access Journals (Sweden)

    Thanee Toomprasen

    2014-06-01

    Full Text Available This paper is aimed to investigate the properties of joint between AISI 4140 and AISI 1040 welded by friction welding. The specimens were prepared in round shape of 13 mm diameter and 100 mm long. They were welded by friction welding method under the following conditions; friction pressure of 183 MPa, friction time of 12 sec, upset pressure of 428 MPa, upset time of 7 sec. and rotational speed of 1400 rpm. The strength and hardness were tested on the welded area. The result showed finer grains. in the welded area. This is the result of friction pressure and upset pressure in the welding process. In addition, the observation result indicated some changes of Ferrite and Pearlite in welded zone. This phase change resulted in the increment of hardness in AISI 4140 at the contact area and adjacent. In part of AISI 1040, the portion of Pearlite and Ferrite are not significantly changed, therefore the value of hardness is almost constant.

  20. Influence of oil and water media on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel

    Institute of Scientific and Technical Information of China (English)

    REN Ping-di; CHEN Guang-xiong; ZHU Min-hao; ZHOU Zhong-rong

    2004-01-01

    A series of fretting test were carried out using a DELTA PLINT testing system to study the influence of hydraulic oil and water on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel. The test result shows that media hydraulic oil and water have a distinct influence on fretting behaviour of the tested materials. Medium water can lead to shifting of the partial slip regime in the fretting map from a larger displacement amplitude toward a smaller one and enlargement of the mixed slip regime, in comparison with that in ambient atmosphere. While medium hydraulic oil can result in shifting of the partial slip regime from a smaller displacement amplitude toward a larger one. In the gross slip regime, hydraulic oil and water play a positive role as lubrication media. They can clearly decrease the fretting friction coefficient between AISI 52100 and AISI 1045. The test result also demonstrates that this lubrication effect will get better with increasing displacement amplitude and that hydraulic oil is better than water for lubrication. SEM observation of the wear scars displays that the fretting wear mainly results from abrasive wear and delamination of the fretted materials when using these two kinds of substances as lubrication media.

  1. Control de calidad y mejoramiento de microsoldaduras de porta fuentes de Ir-192

    OpenAIRE

    López, Alcides; Medina, Max; Cavero, Luis

    2014-01-01

    Se muestran los resultados de la calidad de microsoldaduras de 5 porta fuentes usados para contener 30 discos de Ir-192 de 3 mm de diámetro y 0.5 mm de espesor fabricadas en acero inoxidable AISI 304, mediante tungsteno en gas inerte, que fueron parte de las pruebas de calificación al operador de soldadura de la Planta de Producción de Radioisótopos del IPEN para su uso en gammagrafía industrial. Se determinaron rangos y tolerancias apropiadas de los parámetros y posteriormente fueron probado...

  2. Solidificação da zona de fusão na soldagem do AISI 304 com inconel 600 por laser de Nd: YAG Microstructure development in Nd: YAG laser welding of AISI 304 and Inconel 600

    Directory of Open Access Journals (Sweden)

    Maurício David M. das Neves

    2009-06-01

    Full Text Available Neste trabalho estudou-se a morfologia de solidificação da zona de fusão, numa junta formada a partir de materiais dissimilares, composta por aço inoxidável austenítico AISI 304 e por liga de níquel Inconel 600, soldada com laser pulsado de Nd:YAG. Os parâmetros do feixe laser e do sistema óptico foram selecionados, visando obter uma solda com penetração total e bom acabamento superficial. A caracterização microestrutural foi realizada por microscopia ótica, onde se observou uma zona de fusão com penetração total do tipo keyhole, a presença de pequenos poros e a ausência de trincas. As juntas soldadas foram caracterizadas também, por meio de microscopia eletrônica de varredura (MEV. Medidas realizadas por espectrometria de raios X por dispersão de energia na zona de fusão indicaram uma distribuição levemente heterogênea de níquel e ferro. Observou-se que o início de solidificação da zona de fusão ocorreu por meio de crescimento epitaxial. A morfologia de solidificação da ZF foi basicamente dendrítica e celular sendo, influenciada pelo gradiente de temperatura, velocidade de solidificação e composição química. As variações de composição química e da morfologia de solidificação não alteraram significativamente os valores de microdureza Vickers na zona de fusão. Resultados obtidos nos ensaios de tração indicaram valores de eficiência de soldagem adequados.An autogenous laser welding of dissimilar materials involving AISI 304 austenitic stainless steels and Inconel 600 nickel alloy was investigated in this study. Hence, the aim of this investigation was to study the solidification and microstructure of fusion zone when using a pulsed Nd:YAG laser. The laser and optical beam parameters were chosen to achieve a good weld with total penetration. Optical microscopy pictures showed a typical keyhole weld with total penetration, small pores and free of cracks. The x-ray spectrometry by energy dispersion

  3. Tribological and corrosion behaviors of carburized AISI 4340 steel

    Science.gov (United States)

    Thong-on, Atcharawadi; Boonruang, Chatdanai

    2016-01-01

    AISI 4340 steel is widely used in automotive and aircraft industries as gear components. In such applications, surface hardening processes such as carburizing are required in order to improve the life time of the components. There are many studies showing the tribological behavior of the carburized steel, but the corrosion behavior has not yet been clarified. This paper reports on both tribological and corrosion behaviors of the carburized AISI 4340 steel. Factor associated with carburizing, such as the quantities of deposited carbon, dissolved carbon, and formed Cr23C6 and Fe3C, affect the tribological and corrosion behaviors of the steel by improving hardness, friction, lubrication, and wear resistance; but corrosion resistance is reduced. The dissolved carbon affects the formation of the oxide layer of the carburized steel, by obstructing the continuous oxide layer formation and by decreasing the chromium content of the steel, leading to the decrease in the corrosion resistance of the steel.

  4. Magnetic Barkhausen emission in lightly deformed AISI 1070 steel

    Energy Technology Data Exchange (ETDEWEB)

    Capo Sanchez, J., E-mail: jcapo@cnt.uo.edu.cu [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n, 90500 Santiago de Cuba (Cuba); Campos, M.F. de [EEIMVR-Universidade Federal Fluminense, Av. dos Trabalhadores 420, Vila Santa Cecilia, 27255-125 Volta Redonda, RJ (Brazil); Padovese, L.R. [Departamento de Engenharia Mecanica, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2231, 05508-900 Sao Paulo (Brazil)

    2012-01-15

    The Magnetic Barkhausen Noise (MBN) technique can evaluate both micro- and macro-residual stresses, and provides indication about the relevance of contribution of these different stress components. MBN measurements were performed in AISI 1070 steel sheet samples, where different strains were applied. The Barkhausen emission is also analyzed when two different sheets, deformed and non-deformed, are evaluated together. This study is useful to understand the effect of a deformed region near the surface on MBN. The low permeability of the deformed region affects MBN, and if the deformed region is below the surface the magnetic Barkhausen signal increases. - Highlights: > Evaluated residual stresses by the magnetic Barkhausen technique. > Indication about the relevance of micro-and macro-stress components. > Magnetic Barkhausen measurements were carried out in AISI 1070 steel sheet samples. > Two different sheets, deformed and non-deformed, are evaluated together. > Magnetic Barkhausen signal increases when deformed region is below the surface.

  5. Dense plasma focus-assisted nitriding of AISI-304

    Science.gov (United States)

    Shafiq, M.; Asghar, M.; Ahmad, S.; Sadiq, M.; Qayyum, A.; Zakaullah, M.

    Nitrogen ion implantation into AISI-304 stainless steel is carried out using a dense plasma focus device, operated at a charging voltage of 18 kV (discharge energyD1.45 kJ) with nitrogen filling at optimum pressure of 0.75 mbar. AISI-304 stainless steel samples placed axially above the anode tip are exposed to the ions for 10, 20 and 30 focus shots. X-ray diffraction (XRD), Vickers's micro hardness tester, scanning electron microscopy, and energy dispersive X-ray spectroscopy are used to explore the ion induced changes in the crystallographic structures, surface morphology, elemental composition and surface hardness of the ion irradiated samples. The XRD pattern confirms the formation of an expanded austenite phase, owing to nitrogen incorporated into the existing iron lattice. The results of micro hardness tester show that the hardness is increased about three times at an axial distance of 5 cm for 20 shots.

  6. Laser Welding Of Thin Sheet Of AISI 301 Stainless Steel

    Science.gov (United States)

    Vilar, R.; Miranda, R. M.

    1989-01-01

    Preliminary results of an investigation on laser welding of AISI 301 stainless steel thin sheet are presented. Welds were made with a CO2 continuous wave laser, varying power density and welding speed. The welds were studied by optical and electron scanning microscopy, X-ray diffraction and hardness tests. Experimental results show that under appropriate conditions, sound welds are obtained, with a negligeable heat affected zoneanda fine microstructure in the fusion zone. The fusion zone shows a cellular - dendritic microstructure, with austenite and ferrite as the major constituents. Ferrite, whose content is 5 to 7%, is predominantly intradendritic with both vermicular and acicular morphologies. However some interdendritic ferrite may also be present. The characteristics of the structure suggest that the solidification mode of AISI 301 stainless steel is essentially ferritic.

  7. Weldability of AISI 304 to copper by friction welding

    Energy Technology Data Exchange (ETDEWEB)

    Kirik, Ihsan [Batman Univ. (Turkey); Balalan, Zulkuf [Firat Univ., Elazig (Turkey)

    2013-06-01

    Friction welding is a solid-state welding method, which can join different materials smoothly and is excessively used in manufacturing industry. Friction welding method is commonly used in welding applications of especially cylindrical components, pipes and materials with different properties, for which other welding methods remain incapable. AISI 304 stainless steel and a copper alloy of 99.6 % purity were used in this study. This couple was welded in the friction welding machine. After the welding process, samples were analyzed macroscopically and microscopically, and their microhardness was measured. Tensile test was used to determine the bond strength of materials that were joined using the friction welding method. At the end of the study, it was observed that AISI 304 stainless steel and copper could be welded smoothly using the friction welding method and the bond strength is close to the tensile strength of copper. (orig.)

  8. Laser surface hardening of AISI H13 tool steel

    Institute of Scientific and Technical Information of China (English)

    Jae-Ho LEE; Jeong-Hwan JANG; Byeong-Don JOO; Young-Myung SON; Young-Hoon MOON

    2009-01-01

    An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating source. The hardness of laser melted zone was investigated. In order to identify the effect of heat input on the laser melting zone, scanning conditions were controlled. The results show that, the hardness of as-received AISI H13 tool steel is approximately Hv 240, and the hardness after laser surface heat treatment is around Hv 480-510. The hardening depth and width are increased with the increase in the heat input applied. Application of experimental results will be considered in tooling industry.

  9. The aluminizing in powder technology of AISI 304 steel

    Science.gov (United States)

    Băitanu, D. B.; Găluşcă, D. G.; Achiţei, D. C.; Minciună, M. G.; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    The paper presents a study about the aluminizing treatments applied to AISI 304 stainless steel, with the purpose to improve the corrosion resistance. The aluminizing is realized in a powder medium, composed by aluminium powder (with 99.95% purity), aluminium oxide Al2O3 and ammonium chloride NH4Cl. The structural characterization was made by scanning electronic microscopy to highlight the structure of layer after aluminizing, at different magnitudes.

  10. Cutting Forces Analysis in Additive Manufactured AISI H13 Alloy

    OpenAIRE

    Montevecchi, Filippo; Grossi, Niccolò; Takagi, Hisataka; Scippa, Antonio; Sasahara, Hiroyuki; Campatelli, Gianni

    2016-01-01

    Combining Additive Manufacturing (AM) and traditional machining processes is essential to meet components functional requirements. However significant differences arise in machining AM and wrought parts. Previous works highlighted the increasing of tool wear and worse surface finish. In this paper cutting forces are investigated as an indicator of material machinability. Milling cutting force coefficients are identified using mechanistic approach, comparing AISI-H13 wrought and AM specimen. C...

  11. Ecuaciones constitutivas de la fluencia en caliente de aceros microaleados

    Directory of Open Access Journals (Sweden)

    Cabrera, J. M.

    1998-05-01

    Full Text Available Over centuries, the hot forming has been employed to provide shape to metáis. Nowadays, the deformation at high temperatures gives also the required final mechanical properties. From this point of view, the obtention of a constitutive equation describing the hot flow behaviour of microalloyed steels in particular is a very important task. The main difficulty in modelling the high temperature flow arises from the simultaneity of two opposite phenomena, namely, work hardening and dynamic softening due to recovery and recrystallization. In this is work a review of constitutive equations (including the effect of the chemical composition describing the flow behaviour of microalloyed steels deformed under high temperature conditions.

    Durante siglos el conformado en caliente se ha utilizado para proporcionar a los metales la forma deseada. Hoy en día la deformación en caliente no sólo genera la geometría deseada sino las características mecánicas requeridas. Así, la obtención de una ecuación constitutiva para la fluencia en caliente de un acero en particular, es una tarea ineludible para efectuar simulaciones por ordenador de procesos industriales. La complicación de la modelización de la fluencia a alta temperatura proviene de la simultaneidad de dos fenómenos contrapuestos durante la deformación, a saber, endurecimiento por deformación y ablandamiento por recuperación de la estructura. Este último a su vez puede constar de restauración y recristalización dinámicas. En este trabajo se revisan y plantean las ecuaciones constitutivas que describen las curvas de fluencia bajo condiciones de deformación en caliente, y se presenta una aplicación de las mismas a aceros microaleados.

  12. Determining nitrogen requirements of Aceros and Buceros hornbills.

    Science.gov (United States)

    Foeken, Sijmen G; de Vries, Max; Hudson, Elisabeth; Sheppard, Christine D; Dierenfeld, Ellen S

    2008-07-01

    Over 2 months, seven feeding trials were conducted at St. Catherines Island, GA, to quantify protein intake and utilization in captive mature nonreproducing Aceros (n=3 spp.) and Buceros (n=2 spp.) Hornbills were fed homogeneous isocaloric diets. A mixture of Bird of Paradise pellets, grapes, and raisins was offered to the birds as grape-sized balls, supplemented with diced cantaloupe melon to maintain hydration. To vary the protein level (range 10.8-22.6%) within the diets, different amounts of a powdered soy protein supplement were added to the mixture. Test diets were fed for 3 consecutive days. Birds were weighed to test for differences among diets. All excreta and diet samples were collected for nitrogen (N) analysis. Feeding trials were separated by a 4-day period, in which the bird's regular diet was fed. Data were analyzed for N balance, N equilibrium (regression of N intake vs. N excretion) and body mass. Regression analysis of N balances of the nine birds showed that the N equilibriums ranged from 0.081 to 0.595 g N/kg(0.75)/d with an average of 0.387+/-0.298. No differences in N balances were found between Aceros and Buceros hornbills. The methodology of this study suggested a dietary crude protein (CP) requirement of 7.3+/-3.0% dry matter (DM) in a diet containing 4.0 kcal. However, this value was determined by extrapolation and has not been experimentally determined to be adequate. In this study, the hornbills maintained body mass on a diet containing 10.8% CP (with energy at 4.0 kcal/g DM). Zoo Biol 27:282-293, 2008. (c) 2008 Wiley-Liss, Inc.

  13. Análisis de falla en cable de acero Análisis de falla en cable de acero

    Directory of Open Access Journals (Sweden)

    E. A. Ossa

    2005-12-01

    Full Text Available Este artículo describe el análisis de falla realizado en dos muestras de cables de acero que sufrieron falla súbita bajo condiciones de carga de trabajo normales. La falla fue causada por una carga menor a la capacidad nominal. Luego de inspección óptica se evidenció que la falla fue ocasionada por fatiga del material de uno de los cables.This paper describes the failure analysis of two wire ropes fractured during normal working conditions. The failure was caused by a load well below the nominal maximum resistance of the ropes. Optical microscopy indicated fatigue failure of one of the cables.

  14. Viabilidad de nuevos materiales frente a materiales convencionales en la construcción de pantalanes

    OpenAIRE

    Marín Gallego, Enric

    2012-01-01

    Este proyecto estudia la viabilidad de nuevos materiales estructurales, tales como los materiales compuestos, comparándolos con materiales convencionales como el acero, el acero inoxidable o el hormigón.

  15. Mössbauer studies on an AISI 1137 type steel

    Indian Academy of Sciences (India)

    E Güler; H Akta

    2006-06-01

    An AISI 1137 type medium carbon steel was studied by means of scanning electron microscopy and Mössbauer spectroscopy. This steel in as received state at room temperature was ferritic. Different heat treatments on related steel exhibited different microstructures such as pearlite and bainite. Also magnetism of these product phases was determined as 32.7 T and 32.6 T relatively where ferromagnetism of ferritic phase in as received state was 33.05 T. Mössbauer parameters such as isomer shifts and % volumes were also determined before and after transformations.

  16. A study of cumulative fatigue damage in AISI 4130 steel

    Science.gov (United States)

    Jeelani, S.; Musial, M.

    1986-01-01

    Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.

  17. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A.QAYYUM; M.A.NAVEED; S.ZEB; G.MURTAZA; M.ZAKAULLAH

    2007-01-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis.The treated samples were analysed by X-ray diffraction(XRD)to explore the changes induced in the crystallographic structure.The XRD pattern confirmed the formation of an expanded austenite phase(γN)owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice.A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth(μm).The results showed clear evidence of surface changes with substantial increase in surface hardness.

  18. Formação de biofilme por Pseudomonas aeruginosa sobre aço inoxidável em contato com leite e seu controle por óleos essenciais

    Directory of Open Access Journals (Sweden)

    Nádia Nara BATISTA

    2014-01-01

    Full Text Available Objetivo: Avaliar a ação bacteriostática e bactericida de diferentes óleos essenciais sobre células planctônicas de Pseudomonas aeruginosa ATCC 27853, bem como verificar a ação sanitizante, dos óleos essenciais que apresentarem a menor Concentração Mínima Inibitória (CMI, sobre o biofilme formado por esta espécie, Material e Métodos: A ação bacteriostática foi realizada por meio da determinação das CMIs dos óleos de Zingiber officinale, Eugenia caryophyllus, Elettaria cardamomum, Citrus limon e Citrus reticulata v, tangerine, O tempo de morte bacteriana foi determinado utilizando-se as CMIs de cada óleo essencial submetidos a diferentes tempos de contato, O biofilme de P, aeruginosa foi desenvolvido em cupons de aço inoxidável AISI 304 dispostos em placa de Petri contendo leite tratado por Ultra Alta Temperatura (UAT, sendo incubado sob agitação de 70 rpm, a 37 °C/96 horas, Células aderidas foram removidas através de swabs e enumeradas por contagem em placas após submissão a diferentes tratamentos, Resultados: Todos os óleos essenciais apresentaram efeito bacteriostático, se destacando Z, officinale, E, caryophyllus e E, cardamomum, por apresentarem menor CMI, O tempo de morte de P, aeruginosa foi de 10 minutos quando utilizadas soluções a base de E, cardamomum e E, caryophyllus, No entanto, quando testados em biofilme, apenas E, caryophyllus eliminou as células bacterianas viáveis de P, aeruginosa, Conclusão: E, caryophyllus é uma nova alternativa para o controle do biofilme de P, aeruginosa na indústria de alimentos, pois, além de sua alta atividade antimicrobiana, é um composto natural, o que atende as exigências do mercado consumidor.

  19. ESTUDIO DEL DESGASTE EROSIVO POR CAVITACIÓN DE UN ACERO AUSTENÍTICO DE ALTO NITRÓGENO APOYADO EN EL USO DE LA DIFRACCIÓN DE ELECTRONES RETROPROYECTADOS-EBSD ASSESSMENT OF CAVITATION-EROSION WEAR OF A HIGH NITROGEN AUSTENITIC STAINLESS STEEL FROM ELECTRON BACKSCATTERING DIFFRACTION-EBSD

    Directory of Open Access Journals (Sweden)

    Dairo Hernán Mesa Grajales

    2010-08-01

    Full Text Available Muestras de acero inoxidable con estructura austenítica y contenido aproximado de nitrógeno de 0,9% en peso en solución sólida fueron sometidas a ensayos de cavitación vibratoria en agua destilada, con el fin de estudiar la evolución del desgaste erosivo por cavitación (EC a escala del tamaño de grano (mesoescala. Las muestras fueron obtenidas por medio de nitruración gaseosa a alta temperatura (HTGN del acero inoxidable dúplex UNS S31803, las cuales fueron caracterizadas por difracción de electrones retroproyectados (EBSD, a fin de obtener información de la orientación cristalina de los granos en la superficie a ser cavitada. La técnica de microscopía electrónica de barrido (SEM, fue usada para acompañar el proceso de desgaste para diferentes tiempos de ensayo. Como resultados de los ensayos de cavitación se determinó la pérdida de masa y se hizo un estudio secuencial de la apariencia superficial de las muestras para determinar los mecanismos de desgaste operantes en cada etapa. Los resultados fueron analizados a la luz de la caracterización cristalográfica previa. Para propósitos de comparación, fue usado el acero austenítico convencional UNS S30403. A partir de los resultados se observó que tanto la nucleación del daño como su evolución se dan de forma heterogénea a escala del tamaño de grano, resultado atribuido a la anisotropía en la deformación plástica. El carácter heterogéneo del daño por cavitación fue atribuido principalmente a las características de los límites de grano y a la microtextura dentro de los granos.Stainless steel samples with 100% austenitic microstructure and alloyed with 0.9 wt-% of nitrogen in solid solution were tested under vibratory cavitation experiments in distilled water to study the cavitation-erosion wear (EC at grain size level (mesoscale. Fully austenitic samples were obtained by high temperature gas nitriding (HTGN a commercially available dúplex stainless steel, UNS

  20. Analisis no-lineal de estructuras de acero expuestas al fuego

    OpenAIRE

    Ortega Blanco, Josep LLuís

    2015-01-01

    La presente Tesis de Máster plantea las bases del problema numérico del cálculo no-lineal de un modelo de barras tridimensional de estructuras de acero expuestas al fuego. La Tesis se articula en dos partes. La primera parte corresponde al estado del arte o del conocimiento donde se expone el análisis del fenómeno de incendio, del comportamiento del material acero y su planteamiento normativo. Gran parte de este volumen es dedicado al reducido número de ensayos realizados a esc...

  1. The effect of nitrogen in sintered atmosphere of the ferritic stainless steels AISI 430L P/M; Efecto del nitrogeno en la atmosfera de sinterizacion del acero inoxiable ferritico AISI 430L P/M

    Energy Technology Data Exchange (ETDEWEB)

    Corpas, F. A.; Ruiz-Roman, J. M.; Codina, S.; Iglesias, F. J.

    2005-07-01

    In this paper, we have studied the nitrogen effects different sintering atmospheres (nitrogen-hydrogen, and dissociate ammonia) on ferritic stainless steels (430L), fabricated by powder metallurgy process. We have carried out a study of the physical (density, porosity and dimensional variation) and mechanical properties (hardness, tensile strength, and lengthening) of the ferritic stainless steels sintered in the afore-mentioned atmospheres, as well as of their behaviour in pitting corrosion. We have studied, also the microstructure of the steels, which depends on the atmosphere used for sintering. (Author) 13 refs.

  2. Modification of AISI M2 high speed tool steels after laser surface melting under different operation conditions; Modificacion de los aceros rapidos de herramientas AISI M2 por fusion superficial con laser bajo diferentes condiciones de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Arias, J.; Cabeza, M.; Castro, G.; Feijoo, I.; Merino, P.; Pena, G.

    2010-07-01

    We applied a laser surface melting treatment to AISIM2 high-speed steel hardened and tempered- and studied the resulting surface characteristics (microstructure) and mechanical behavior (hardness and wear performance). The steel was treated using a Nd:YAG continuous-wave laser with different operation conditions. The influence of the laser processing parameters on the single tracks and on melted surface layer obtained by multipass system with 50% overlap were studied. The microstructure for all conditions is formed by MC- and M{sub 2}C-type carbides, martensite and retained austenite; the quantities of this phase depends on the operations conditions. It has been determined that low levels of power density and high speed scanning of the beam leads to greater homogeneity in the microstructure with high hardness values and wear resistance. (Author) 26 refs.

  3. Tropical hornbills (Aceros cassidix, Aceros undulatus, and Buceros hydrocorax) use ballistic transport to feed with their large beaks.

    Science.gov (United States)

    Baussart, Sabine; Bels, Vincent

    2011-02-01

    The most common and plesiomorphic mechanism of food transport in tetrapods is lingual-based. Neognathous birds use this mechanism for exploiting a large diversity of food resources, whereas paleognathous birds use cranioinertial mechanism with or without tongue involvement. Food transport in three hornbills' species (Aceros cassidix, A. undulatus, and Buceros hydrocorax) is defined by a ballistic transport mechanism. Only one transport cycle is used for moving the food from the tip of the beak to the pharynx. The tongue never makes contact with the food nor is it used to expand the buccal cavity. In hornbills, filmed through high-speed video, time to food release occurred between 0.11 and 0.16 sec before time to maximum gape. The ballistic curves show similar patterns. Maximum gape angle is significantly different between the three species. Each species show a different kinematic and motor pattern of head movements associated with ballistic transport. In A. undulatus, head rotation follows a continuous pattern similar to that reported earlier in toucans. A. cassidix rotates head downward at the time of maximum gape to permit food to reach the pharynx without touching the mandible. B. hydrocorax elevates the head along the transport cycle to avoid contact with the food to the cavity of the upper beak. Selection of large food items in the diet may explain the evolutionary trend of using ballistic transport in the feeding behavior of hornbills, which play a key role in tropical forest ecology by dispersing seeds.

  4. PERFORMANCE STUDY ON AISI316 AND AISI410 USING DIFFERENT LAYERED COATED CUTTING TOOLS IN CNC TURNING

    Directory of Open Access Journals (Sweden)

    K. RAJA

    2015-01-01

    Full Text Available Stainless steel (SS is used for many commercial and industrial applications owing to its high resistance to corrosion. It is too hard to machine due to its high strength and high work hardening property. A surface property such as surface roughness (SR is critical to the function-ability of machined components. SS is generally regarded as more difficult to machine material and poor SR is obtained during machining. In this paper an attempt has been made to investigate the SR produced by CNC turning on austenitic stainless steel (AISI316 and martensitic stainless steel (AISI410 by different cases of coated cutting tool used at dry conditions. Multilayered coated with TiCN/Al2O3, multilayered coated with Ti(C, N, B and single layered coated with TiAlN coated cutting tools are used. Experiments were carried out by using Taguchi’s L27 orthogonal array. The effect of cutting parameters on SR is evaluated and optimum cutting conditions for minimizing the SR are determined. Analysis of variance (ANOVA is used for identifying the significant parameters affecting the responses. Confirmation experiments are conducted to validate the results obtained from optimization.

  5. Influência da velocidade de circulação do leite na adesão de Pseudomonas aeruginosa sobre aço inoxidável The speed of milk circulation influences the adhesion of Pseudomonas aeruginosa on stainless steel

    Directory of Open Access Journals (Sweden)

    Hamilton Mendes de Figueiredo

    2009-09-01

    Full Text Available A influência da velocidade de circulação do leite na adesão bacteriana de Pseudomonas aeruginosa foi avaliada em teste de uso simulado por meio de um modelo de circuito de processamento de leite. O circuito é composto por uma tubulação de aço inoxidável AISI 304, com 1,9 cm de diâmetro e 5,8 m de comprimento, além de um tanque de 25 L, utilizado como reservatório do produto e das soluções sanitizantes. O reservatório foi acoplado a uma bomba centrífuga de ½ HP, para impulsionar o alimento ou soluções de higienização pelo sistema equipado com cupons de prova em aço inoxidável nas formas cilíndrica, cotovelo 90º e T. As velocidades de circulação foram de 0,5, 1,0 e 1,5 m.s-1, correspondentes a fluxo turbulento com número de Reynolds de 14.000, 28.000 e 42.000, respectivamente. Quando se utilizou velocidade de 0,5 m.s-1, permaneceram aderidas à superfície 10,7% das células. Já nas velocidades e 1,0 e 1,5 m.s-1 as porcentagens de adesão foram de 5,36 e 4,9%, respectivamente, o que demonstra uma menor remoção de células aderidas à medida que o fluxo diminui, permitindo assim que mais células permaneçam aderidas na linha de produção, o que pode favorecer a formação de biofilmes.The influence of the flow milk circulation in the bacterial adhesion of Pseudomonas aeruginosa was evaluated by simulation tests through a circuit model of milk processing. The circuit is composed of a tubulation of stainless steel AISI 304, with 1.9 cm of diameter, 5.8 m of length and a tank of 25 L used as the reservoir of the product and sanitizer solutions. The reservoir was coupled to a centrifugal bomb of ½ HP to impel the food or sanitizer solutions for the system equipped with 90º and T cylindrical stainless steel specimens. The speed of circulation values were 0.5, 1.0 and 1.5 m.s-1, corresponding to turbulent flow with number of Reynolds 14.000, 28.000 and 42.000, respectively. When flow of 0.5 m.s-1 was used 10.7% the

  6. Propiedades mecánicas del acero de refuerzo utilizado en Colombia Propiedades mecánicas del acero de refuerzo utilizado en Colombia

    Directory of Open Access Journals (Sweden)

    Victoria González Quintana

    2005-04-01

    Full Text Available Se presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materialA statistical analysis applied to a experimental study that determines the mechanical properties of steels produced in Colombia subjected to monotonic loads of tension is presented. Typical stress-strain diagram that allow to characterize these steels making emphasis in the variables that determine the change of behaviour of the materia are presented.

  7. Resistência à erosão por cavitação de aços inoxidáveis austeníticos CrMnSiN depositados por PTA Cavitation erosion resistance of CrMnSiN austenitic stainless steels deposited by PTA

    Directory of Open Access Journals (Sweden)

    Hélio Ormeu Ribeiro

    2010-06-01

    Full Text Available A erosão por cavitação deteriora componentes em serviço, tais como partes metálicas de bombas de água, válvulas e, em especial, pás de turbinas hidráulicas, sendo nesse último caso responsável por elevados prejuízos ligados tanto aos custos da manutenção direta, como sobretudo às perdas por interrupção na geração de energia elétrica. Dentre os materiais aplicados no reparo por soldagem de danos por cavitação incluem-se aços inoxidáveis tradicionais tipo AISI 308 e 309, aços inoxidáveis ao Co e ligas à base de Co (stellites, caracterizando-se essas últimas pela maior sensibilidade a trincas, dificuldade de esmerilhamento e pelo mais alto custo. Nesse contexto este trabalho buscou formular, depositar e analisar o desempenho de aços inoxidáveis austeníticos CrMnSiN, soldados pelo processo PTA. A resistência à erosão por cavitação foi avaliada segundo a norma ASTM G 32-92. A microestrutura foi caracterizada por microscopia ótica e microscopia eletrônica de varredura e a formação de martensitas α' e ε, induzida pela cavitação, foi avaliada por difração de raios-X. A integridade da superfície dos depósitos foi controlada por END, além disso a dureza e a facilidade de acabamaneto por esmerilhamento serviram como critérios para avaliar os revestimentos soldados. Verificou-se que os revestimentos aplicados por PTA eram livres de trincas de solidificação, com baixa porosidade, boa molhabilidade e adequado acabamento superficial. A melhor liga inoxidável austenítica elaborada (0,03%C; 0,35% N; 13,2%Cr; 11,8% Mn; 2,8%Si; bal %Fe mostrou uma resistência à erosão por cavitação próxima aquela das principais ligas comerciais.Cavitation erosion deteriorates components like metallic parts of water pumps, valves and blades of hydraulic turbines, in this last case being responsible for high economical losses, associated to direct maintenance costs, but above all due to the interruption of the electric

  8. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface Sanificantes químicos no controle de biofilmes formados por duas espécies de Pseudomonas em superfície de aço inoxidável

    Directory of Open Access Journals (Sweden)

    Danila Soares Caixeta

    2012-03-01

    Full Text Available The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1 when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.A capacidade de adesão e formação de biofilme por Pseudomonas aeruginosa e Pseudomonas fluorescens em aço inoxidável AISI 304, na presença de leite desnatado resconstituído sobre diferentes temperaturas foi conduzido e o potencial de três sanificantes químicos na remoção de biofilmes monoespécies foi comparado. Pseudomonas aeruginosa cultivada em leite desnatado a 28 °C apresentou melhor crescimento (10,4 log UFC.mL-1 quando comparado com 3,7 and 4,2 log UFC.mL-1 para P. aeruginosa e P. fluorescens cultivadas a 7 °C, respectivamente. Pseudomonas aeruginosa formou biofilme quando cultivada a 28 °C. Contudo foi observado somente adesão de P. aeruginosa e P. fluorescens quando incubada a 7 °C. O dicloroisocianurato de sódio foi o sanificante mais eficiente na redução de células aderidas e em biofilme de P. aeruginosa a 7 e 28 °C, respectivamente. O peróxido de hidrogênio foi o mais eficiente na redução de células aderidas de P. fluorescens a 7 °C.

  9. COMPARACION TECNICO-FINANCIERA DEL ACERO ESTRUCTURAL Y EL HORMIGON ARMADO

    Directory of Open Access Journals (Sweden)

    MIGUEL DAVID ROJAS LOPEZ

    2008-01-01

    Full Text Available Este trabajo presenta un análisis comparativo de las propiedades operativas, estéticas, mecánicas, económicas y financieras de los sistemas constructivos en acero estructural y hormigón armado, con el fin de establecer criterios de escogencia para la construcción en Colombia.

  10. Tratamiento isotérmico de los aceros aleados al silicio Tipo SAE 92XX

    Directory of Open Access Journals (Sweden)

    Páez, J. L.

    1996-02-01

    Full Text Available SAE 9260 type steels have silicon and carbon contents similar to those of the ductile iron matrix, and present a bainitic transformation with the same characteristics as ADI (Austempered Ductile Iron. The hypothesis is that excellent mechanical properties can be obtained by means of austempering (in times so short as to be accessible from the industrial point of view, the same as in ADI and even better because it is a rolling material instead of a cast material. It will be compared with the mechanical properties obtained by quenching and tempering at different temperatures.

    La composición química de los aceros SAE 92XX es similar a la de la matriz metálica de una fundición esferoidal, por lo que se pensó en someter a un acero de ese tipo a tratamientos de austempering similares a los que se aplican para lograr una ADI (Austempered Ductile Iron, y verificar si se alcanzaban valores aceptables de plasticidad con elevados valores de resistencia a la tracción para el mismo acero, tal y como sucede con aquellas fundiciones, y comparar dichos resultados con los obtenidos en el mismo acero con tratamientos convencionales de temple y revenido. Se alcanzaron valores que demostraron que, por austempering, se logran excelentes valores de plasticidad, muy superiores a los alcanzados por temple y revenido para durezas del mismo orden.

  11. Plasma nitriding of AISI 304L and AISI 316L stainless steels: effect of time in the formation of S phase and the chromium nitrides; Nitretacao a plasma dos acos inoxidaveis AISI 304L e AISI 316L: efeito do tempo na formacao da fase S e dos nitretos de cromo

    Energy Technology Data Exchange (ETDEWEB)

    Souza, D.A. de; Barbosa, G.C.; Pinto, F.A.M.; Gontijo, L.C. [Instituto Federal de Educacao, Ciencia e Tecnologia do Espirito Santo - IFES, Vitoria, ES (Brazil); Canal, G.P.; Cunha, A.G., E-mail: disouzam@yahoo.com.br [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Dept. de Fisica

    2009-07-01

    Plasma nitriding can improve hardness and wear resistance of austenitic stainless steels without losses in corrosion resistance. This fact relies on a nitrided layer constituted only by S phase, without chromium nitrides precipitation. In this work, the effect of nitriding time on phases formed on nitrided layer was investigated in two austenitic stainless steels: AISI 304L e AISI 316L. The samples were nitrided at 420 deg C, using a mixture of 60 % N{sub 2} and 40% H{sub 2}, during 5, 7 and 9 hours. It was noted that chromium nitrides were formed on samples of AISI 304L, nitrided for 7 e 9 hours, while all nitrided samples of AISI 316L showed only formation of S phase. The nitrided layers were characterized using optical microscope and x-ray diffraction. (author)

  12. Caracterização microestrutural de soldas dissimilares dos aços ASTM A-508 e AISI 316L Characterization of dissimilar metal weld between low alloy steel ASTM A-508 and 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Luciana Iglésias Lourenço Lima

    2010-06-01

    Full Text Available As soldas dissimilares (dissimilar metal welds - DMWs são utilizadas em diversos segmentos da indústria. No caso específico de usinas nucleares, tais soldas são necessárias para conectar tubulações de aço inoxidável com componentes fabricados em aços baixa liga. Os materiais de adição mais utilizados neste tipo de solda são as ligas de níquel 82 e 182. Este trabalho consistiu na soldagem de uma junta dissimilar de aço baixa liga ASTM A-508 G3 e aço inoxidável austenítico AISI 316L utilizando as ligas de níquel 82 e 182 como metais de adição. A soldagem foi realizada manualmente empregando os processos de soldagem ao arco SMAW (Shielded Metal Arc Welding e GTAW (Gas Tungsten Arc Welding. Os corpos de prova foram caracterizados microestruturalmente utilizando-se microscópio óptico e microscópio eletrônico de varredura com microanálise por dispersão de energia de raios X (EDS e ensaios de microdureza Vickers. Observou-se uma microestrutura constituída de dendritas de austenita com a presença de precipitados com formas e dimensões definidas pelo aporte térmico e pela direção de soldagem. Não houve variação significativa da dureza ao longo da junta soldada, demonstrando a adequação dos parâmetros de soldagem utilizados.The dissimilar metal welds (DMWs are used in several areas of the industries. In the nuclear power plant, this weld using nickel alloy welding wires is used to connect stainless steel pipes to low alloy steel components on the reactor pressured vessels. The filler materials commonly used in this type of weld are nickel alloys 82 and 182.. In this study, dissimilar metal welds composed of low alloy steel ASTM A-508 G3, nickel alloys 82 e 182 as weld metals, and austenitic stainless steel AISI 316L were prepared by manual shielded metal arc welding (SMAW and gas tungsten arc welding techniques (GTAW. Samples were microstructural characterized by optical microscopy and scanning electron microscopy

  13. Investigation of Machinability Characteristics of AISI 316Ti Stainless Steel

    Directory of Open Access Journals (Sweden)

    Yunus Kayır

    2012-01-01

    Full Text Available In this study, many experiments of machinability were carried out on universal turning lathe. The cutting forces that occur during machining of workpieces were measured. A standard dynamometer was used to measure cutting forces. The Dynamometer were assembled on the lathe efficiently. An apart were designed and machined to assembly the dynamometer. Moreover, AISI 316Ti stainless steel parts were turned by carbide cutting tools coated with TiAlN components. Effects of cutting tools with different radius on cutting forces and surface roughness were investigated by using different cutting parameters. Moreover, machined parts' surface roughness was controlled. The experimental results showed that cutting forces increased with the increasing federate, but the surface roughness decreased with increasing the radius of cutting edge.

  14. COLD ROLLING ORTHODONTIC WIRES OF AUSTENITIC STAINLESS STEEL AISI 304

    Directory of Open Access Journals (Sweden)

    Rodrigo Santos Messner

    2013-03-01

    Full Text Available Austenitic stainless steels wires are widely used in the final stages of orthodontic treatment. The objective of this paper is to study the process of conformation of rectangular wires from round wires commercial austenitic stainless steel AISI 304 by the process of cold rolling. The wire quality is evaluated by means of dimensional analysis, microhardness measurements, tensile strength and fractographic analysis of the wires subjected to tensile tests. Also a study on the application of finite element method to simulate the process, comparing the force and rolling stress obtained in the rolling is done. The simulation results are consistent with those obtained in the actual process and the rolled wires show ductile fracture, tensile strength and dimensional variations appropriate to orthodontic standards. The fracture morphology shows the model cup-cone type besides the high deformation and hardness inherent in the cold rolling process.

  15. Fretting of AISI 9310 and selected fretting resistant surface treatments

    Science.gov (United States)

    Bill, R. C.

    1977-01-01

    Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, aluminum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a selflubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

  16. The Study of Plasma Nitriding of AISI304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Liang; JI Shi-jun; GAO Yu-zhou; SUN Jun-cai

    2004-01-01

    This paper presents results on the plasma nitriding of AISI 304 stainless steel at different temperatures in NH 3 gas. The working pressure was 100~200 Pa and the discharge voltage was 700~800V. The phase of nitrided layer formed on the surface was confirmed by X-ray diffraction. The hardness of the samples was measured by using a Vickers microhardness tester with the load of 50g. After nitriding at about 400 ℃ for two hours a nitrided layer consisting of single γN phase with thickness of 5μm was obtained. Microhardness measurements showed significant increase in the hardness from 240 HV (for untreated samples) up to 950 HV (for nitrided samples at temperature of 420℃). The phase composition, the thickness, the microstructure and the surface topography of the nitrided layer as well as its properties depend essentially on the process parameters.

  17. Experimental survey on the behaviour of AISI 304 steel sheets subjected to perforation

    OpenAIRE

    2010-01-01

    This paper presents and analyzes the behaviour of AISI 304 steel sheets subjected to perforation under a wide range of impact velocities. The relevance of this steel resides in the potential transformation of austenite into martensite during mechanical loading. This process leads to an increase in strength and ductility of the material. It makes the AISI 304 attractive for many engineering applications, especially for building structural elements responsible for absorbing energy under fast lo...

  18. Linear friction welding of AISI 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Bhamji, Imran, E-mail: imran.bhamji@postgrad.manchester.ac.uk [Manchester Materials Science Centre, University of Manchester, Grosvenor Street, M1 7HS (United Kingdom); Preuss, Michael [Manchester Materials Science Centre, University of Manchester, Grosvenor Street, M1 7HS (United Kingdom); Threadgill, Philip L. [Formerly with TWI Ltd., Cambridge, UK (now retired) (United Kingdom); Moat, Richard J. [Manchester Materials Science Centre, University of Manchester, Grosvenor Street, M1 7HS (United Kingdom); Addison, Adrian C. [TWI Ltd., Cambridge (United Kingdom); Peel, Matthew J. [University of Bristol, Queens Building, University Walk, Bristol BS8 1TR (United Kingdom)

    2010-12-15

    Research highlights: {yields} Linear friction welding is a feasible process for joining AISI316L. {yields} Most welds had tensile strengths superior to the parent material. {yields} Welding parameters had a significant impact on weld microstructure. {yields} Control of microstructure by controlling welding parameters is a process benefit. - Abstract: Linear friction welding is a solid state joining process established as a niche technology for the joining of aeroengine bladed disks. However, the process is not limited to this application, and therefore the feasibility of joining a common engineering austenitic steel, AISI 316L, has been explored. It was found that mechanically sound linear friction welds could be produced in 316L, with tensile properties in most welds exceeding those of the parent material. The mechanical properties of the welds were also found to be insensitive to relatively large changes in welding parameters. Texture was investigated in one weld using high energy synchrotron X-ray diffraction. Results showed a strong {l_brace}1 1 1{r_brace}< 1 1 2 > type texture at the centre of the weld, which is a typical shear texture in face centre cubic materials. Variations in welding parameters were seen to have a significant impact on the microstructures of welds. This was particularly evident in the variation of the fraction of delta ferrite, in the thermo-mechanically affected zone of the welds, with different process parameters. Analysis of the variation in delta ferrite, with different welding parameters, has produced some interesting insights into heat generation and dissipation during the process. It is hoped that a greater understanding of the process could help to make the parameter optimisation process, when welding 316L as well as other materials, more efficient.

  19. Austenitic Stainless Steel AISI 316L Corrosion Test Research%奥氏体不锈钢AISI 316L腐蚀试验研究

    Institute of Scientific and Technical Information of China (English)

    王金刚; 刘江涛; 程珊珊

    2014-01-01

    在精对苯二甲酸(PTA)生产中,选取干燥机BM302壳体常用材料奥氏体不锈钢AISI 316L为研究对象,在醋酸环境中,对AISI 316L 受Br-及Cl-作用的电化学极化试验和电化学阻抗试验进行腐蚀性试验研究。试验结果表明,Br-或Cl-浓度的增加都会导致AISI 316L不锈钢腐蚀速率增加、击穿电位降低、腐蚀反应电阻减小,导致其耐腐蚀性能下降,腐蚀加剧。为PTA设备腐蚀的现场监测和设备维护提供参考依据。%In purified terephthalic acid (PTA) production, selected the drying machine BM302 shell commonly use material austenitic stainless steel AISI 316L as the research object. In the acetic acid environment, for corrosive test research of AISI 316L, through Br-and Cl-the role of electrochemical polarization test and electrochemical impedance test. The test results show that Br-or Cl-will lead to the increasing of the concentration of seawater AISI 316L stainless steel corrosion rate increase, breakdown voltage is reduced, and the corrosion reaction resistance decreases, and lead to its corrosion resistance drop, corrosion intensifies. That will provide reference for PTA equipment corrosion field monitoring and equipment maintenance.

  20. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment

    Directory of Open Access Journals (Sweden)

    A. Ruiz

    2016-06-01

    Full Text Available This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  1. Physical properties of the AISI 348 L{sup *} austenitic stainless steel; Propriedades fisicas do aco inoxidavel austenitico AISI 348 L{sup *}

    Energy Technology Data Exchange (ETDEWEB)

    Teodoro, Celso Antonio; Lucki, Georgi; Silva, Jose Eduardo Rosa da; Terremoto, Luis Antanio Albiac; Castanheira, Myrthes; Damy, Margaret de Almeida [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: cteodoro@ipen.br

    2005-07-01

    The study of radiation damage in metals and alloys, used as structural materials of nuclear reactors has a strategic meaning in nuclear technology, because it allows the performance evaluation of these materials in working conditions of PWR. For this sake it is necessary to know the detrimental structural changes that occur during fast neutron irradiation. The aim of the present work is to show some strain-stress results of the AISI 348 L{sup *} stainless steel utilized as a structural material of the fuel elements of PWR, in comparison with the AISI 304. (author)

  2. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment.

    Science.gov (United States)

    Ruiz, A; Timke, T; van de Sande, A; Heftrich, T; Novotny, R; Austin, T

    2016-06-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  3. Effects of X-rays Radiation on AISI 304 Stainless Steel Weldings with AISI 316L Filler Material: A Study of Resistance and Pitting Corrosion Behavior

    Directory of Open Access Journals (Sweden)

    Francisco Javier Cárcel-Carrasco

    2016-04-01

    Full Text Available This article investigates the effect of low-level ionizing radiation, namely X-rays, on the micro structural characteristics, resistance, and corrosion resistance of TIG-welded joints of AISI 304 austenitic stainless steel made using AISI 316L filler rods. The welds were made in two different environments: natural atmospheric conditions and a closed chamber filled with inert argon gas. The influence of different doses of radiation on the resistance and corrosion characteristics of the welds is analyzed. Welded material from inert Ar gas chamber TIG showed better characteristics and lesser irradiation damage effects.

  4. Study of residual stresses generated in machining of AISI 4340 steel; Estudo das tensoes residuais geradas na usinagem de aco AISI 4340

    Energy Technology Data Exchange (ETDEWEB)

    Reis, W.P. dos; Fonseca, M.P. Cindra; Serrao, L.F.; Chuvas, T.C.; Oliveira, L.C., E-mail: mcindra@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    Among the mechanical construction steels, AISI 4340 has good harden ability, while combining high strength with toughness and good fatigue strength, making it excellent for application in the metalworking industry, where it can work at different levels and types of requests. Residual stresses are generated in almost all processes of mechanical manufacturing. In this study, the residual stresses generated in different machining processes and heat treatment hardening of AISI 4340 were analyzed by X-ray diffraction, by the sen{sup 2} {psi} method, using Cr{kappa}{beta} radiation and compared. All samples, except for turned and cut by EDM, presented compressive residual stresses in the surface with various magnitudes. (author)

  5. El refuerzo de las estructuras de concreto armado con aceros de grado 75 en el Perú

    OpenAIRE

    Lovera Martínez, Luis Guillermo

    2016-01-01

    Muchos investigadores han estudiado el comportamiento de las estructuras de concreto armado cuando son reforzadas con aceros de alta resistencia. Algunas normas extranjeras han evaluado los resultados de estas investigaciones y procedido a actualizar sus estándares en ese sentido. En Perú no se ha investigado el comportamiento de estructuras reforzadas con aceros de alta resistencia, en ese sentido en la presente Tesis se estableció como objetivo estudiar el comportamiento d...

  6. Comparative study of pulsed Nd:YAG laser welding of AISI 304 and AISI 316 stainless steels

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-02-01

    Laser welding is a potentially useful technique for joining two pieces of similar or dissimilar materials with high precision. In the present work, comparative studies on laser welding of similar metal of AISI 304SS and AISI 316SS have been conducted forming butt joints. A robotic control 600 W pulsed Nd:YAG laser source has been used for welding purpose. The effects of laser power, scanning speed and pulse width on the ultimate tensile strength and weld width have been investigated using the empirical models developed by RSM. The results of ANOVA indicate that the developed models predict the responses adequately within the limits of input parameters. 3-D response surface and contour plots have been developed to find out the combined effects of input parameters on responses. Furthermore, microstructural analysis as well as hardness and tensile behavior of the selected weld of 304SS and 316SS have been carried out to understand the metallurgical and mechanical behavior of the weld. The selection criteria are based on the maximum and minimum strength achieved by the respective weld. It has been observed that the current pulsation, base metal composition and variation in heat input have significant influence on controlling the microstructural constituents (i.e. phase fraction, grain size etc.). The result suggests that the low energy input pulsation generally produce fine grain structure and improved mechanical properties than the high energy input pulsation irrespective of base material composition. However, among the base materials, 304SS depict better microstructural and mechanical properties than the 316SS for a given parametric condition. Finally, desirability function analysis has been applied for multi-objective optimization for maximization of ultimate tensile strength and minimization of weld width simultaneously. Confirmatory tests have been conducted at optimum parametric conditions to validate the optimization techniques.

  7. Aceros de baja aleación y alto rendimiento

    Directory of Open Access Journals (Sweden)

    Campos, M.

    2008-02-01

    Full Text Available A highly demanding automobile market requires an intensification of the efforts on increasing the performance and reducing costs of sintered steels, in order to stay in such a competitive market. Final properties of sintered parts and their cost depend on two main factors, density and the alloying system. The growing interest for Cr and Mn as alloying elements is due to both price, more suitable than Mo, and the excellent level of properties which are achieved in assintered parts as well as after the heat treatments. In this work, the possible techniques which lead to an enhancement of density are discussed, such as warm and high velocity compaction, or high temperature sintering; moreover it is important to study the synergy between the proposed techniques which may be compatible.

    Las nuevas demandas en el sector del automóvil están haciendo que se intensifiquen los esfuerzos en aumentar las prestaciones y reducir los costes de los aceros sinterizados, para poder mantenerse en este mercado tan competitivo. Las propiedades finales de los componentes sinterizados y su coste dependen de dos factores principales, la densidad y el sistema de aleación. El creciente interés por el cromo y el manganeso como elementos de aleación se debe tanto al precio, más ventajoso que, por ejemplo, el molibdeno, como al nivel excelente de propiedades que se pueden conseguir tanto en estado sinterizado como después de los tratamientos térmicos. En este trabajo, se discuten además las posibles técnicas que conducen a una mejora de la densidad del componente, como la compactación de polvos precalentados, la compactación por propagación de ondas de impacto, o la sinterización a alta temperatura; además, es importante estudiar los efectos sinérgicos entre las técnicas propuestas que sean compatibles.

  8. Study on tempering behaviour of AISI 410 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Gopa, E-mail: gopa_mjs@igcar.gov.in [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V. [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Panneerselvam, G. [Chemistry Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Dasgupta, Arup [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India)

    2015-02-15

    Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M{sub 23}C{sub 6}) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe{sub 2}C and M{sub 23}C{sub 6} types of carbides coexisting in the material. The nucleation of Fe{sub 2}C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M{sub 23}C{sub 6} carbides, instead of Fe{sub 2}C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of

  9. Reflexión sobre la industria del acero en el mercado globalizado

    Directory of Open Access Journals (Sweden)

    Luis Felipe Camacho Carvajal

    2011-06-01

    Full Text Available El propósito de este ensayo es hacer un seguimiento a la evolución de la producción de acero en elmundo. Se evidencia que el resultado de la estrategia de adquisiciones y fusiones de poderosas empresas del sector siderúrgico a nivelmundial, llevó a que China pasara de ser un país netamente importador a ser exportador de materia prima de la cadena siderúrgica, alimentando una nueva etapa de crecimiento y desarrollo de esta cadena. El análisis de las cifras de acero en Suramérica referidas a producción, flujos de comercio y consumo aparente sugiere que la región no demanda lo que produce.

  10. Influence of the filler material on the pitting corrosion in welded duplex stainless; Influencia del material de aporte en la resistencia a corrosion por picadura en uniones soldadas de un acero inoxidable duplex

    Energy Technology Data Exchange (ETDEWEB)

    Munez, C. J.; Utrilla, M. V.; Urena, A.; Otero, E.

    2007-07-01

    In this work, it has been studied the pitting corrosion resistance of welding duplex stainless steel 2205. Unions were made by GMAW process with different fillers: duplex ER 2209 and two austenitic (ER 316LSi and ER 308LSi). the microstructure obtained with the duplex ER 2209 filler is similar to the duplex 2205 base material, but the unions produced with the austenitic fillers cause a decrease of the phases relation{alpha}/{gamma}. To evaluate the influence of the filler on the weld, the pitting corrosion resistance was determined by electrochemical critical pitting temperature test (TCP) and the mechanical properties by the hardness. The phases imbalance produced for the dissimilar fillers bring out a variation of the pitting corrosion resistance and the mechanical properties. (Author)

  11. Characterization of stainless steel through Scanning Electron Microscopy, nitrided in the process of implantation of immersed ions in plasma; Caracterizacion de acero inoxidable mediante Microscopia Electronica de Barrido nitrurado en el proceso de implantacion de iones inmersos en plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Moreno S, H

    2003-07-01

    The present project carries out the investigation of the nitridation of the austenitic stainless steel schedule 304, applying the novel technology of installation of nitrogen ions in immersed materials in plasma (Plll), by means of which they modify those properties of the surface of the steel. The obtained results by means of tests of Vickers microhardness, shows that the hardness was increment from 266 to 740 HV (microhardness units). It was determined by means of scanning electron microscopy, the one semiquantitative chemical analysis of the elements that constitute the austenitic stainless steel schedule 304; the obtained results, show to the nitrogen like an element of their composition in the pieces where carried out to end the PIII technology. The parameters of the plasma with which carried out the technology Plll, were monitored and determined by means of electric probes, and with which it was determined that the density of particles is stable in the interval of 1x10{sup -1} at 3x10{sup -1}Torr, and it is where better results of hardness were obtained. That reported in this work, they are the first results obtained when applying the technology Plll in Mexico, and with base in these, it is even necessary to investigate and to deepen until to dominate the process and to be in possibilities of proposing it to be carried out and exploited in an industrial way. (Author)

  12. Microstructure influence on fatigue behaviour of austenitic stainless steels with high molybdenum content; Influencia de la microestructura en el comportamiento a fatiga de aceros inoxidables austeniticos con alto contenido en molibdeno

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J.; Gamboa, R.; Ranninger, C.

    2006-07-01

    Austenitic stainless steels with molybdenum present high mechanical properties and corrosion resistance to aggressive environments. These steels have been used to tank and vessel components for high liquids as phosphoric, nitric and sulphuric acids. These materials with low carbon and nitrogen addition have been proposed candidates as structural materials for the international thermonuclear experimental reactor (ITER) in-vessel components. Molybdenum addition in austenitic stainless steel improves mechanical and corrosion properties, but with it can produce the presence of nitrogen microstructure modifications by presence or precipitation of second phases. This paper summarises the fatigue and corrosion fatigue behaviour of two 317LN stainless steels with different microstructure. Fully austenitic steel microstructure show better fatigue, corrosion fatigue resistance and better ductility than austenitic steel with delta ferrite microstructure, mainly at low stresses. (Author)

  13. Influence of the chemical composition, heat and surface treatment in the biofouling of austenitic stainless steels; Influencia de la composicion quimica, del tratamiento termico y del acabado supreficial en el bioensuciamiento de aceros inoxidables austeniticos

    Energy Technology Data Exchange (ETDEWEB)

    Sarro, M. I.; Aleman, O.; Moreno, D. A.; Roso, M.; Ranninger, C.

    2004-07-01

    The main objective of this study was to analyse the biofouling processes in the kinds of stainless steels used normally in industry (UNS S30400, UNS S30403 and UNS S31600), with different surface treatments after grinding and polishing. The study was developed using two microscopy techniques. Scanning Electron Microscopy (SEM) was used to evaluate the microorganisms distribution in the materials, and Epi fluorescence Microscopy was used to evaluate the viability of cells in the biofilm. The results revealed the influence of the material, heat treatment, surface treatment and roughness in the biofouling processes in the stainless steel assays. (Author) 33 refs.

  14. Caracterización de la Pasividad del Acero Inoxidable uns N08031 en Ácido Fosfórico Contaminado mediante Técnicas Electroquímicas.

    OpenAIRE

    ESCRIVÁ CERDÁN, CLARA

    2013-01-01

    La obtención de ácido fosfórico a partir del proceso húmedo constituye aproximadamente un 95% de su producción. Entre las etapas principales de este proceso productivo, hay que mencionar el ataque de la roca fosfórica con ácido sulfúrico concentrado, la filtración y posterior concentración del ácido producido. Esta técnica genera severos problemas de corrosión en los equipos e instalaciones, debido principalmente a la presencia de impurezas en el ácido fosfórico, como son cloruros, fluoruros ...

  15. Effect of biofilm in the corrosion of austenitic stainless steels in wastewater treatment plants; Efecto de la biopelicula en la corrosion de aceros inoxidables austeniticos en estaciones depuradoras de aguas residuales

    Energy Technology Data Exchange (ETDEWEB)

    Bethencourt, M.; Garcia de Lomas, J.; Corzo, A.; Villahermosa, D.; Matres, V.

    2010-07-01

    In this work, the influence of the biofilm in the corrosion process of different alloys of stainless steel was studied in two sampling points in a wastewater treatment plant during 4 years. The physicochemical microenvironment within the biofilm was characterized through O{sub 2}, H{sub 2}S and pH microelectrodes. Corrosion rates were quantified from the number, diameter and depth of pits. The results show a remarkable development of the biofilm and a significantly greater number of pits in the grit removal channel than in the sludge recirculation channel. Based on the characteristics of the water phase and microelectrode measurements, our results suggest that biofilm induced corrosion throughout 3 mechanisms: creation of differential aeration cells, areas with different pH and areas having high sulphide production which may react with metal ions. (Author) 54 refs.

  16. Wear properties of niobium carbide coatings performed by pack method on AISI 1040 steel

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Ugur [Sakarya University, Technical Education Faculty, Department of Metal Education, 54187 Sakarya (Turkey)]. E-mail: ugursen@sakarya.edu.tr

    2005-07-01

    A series of experiments was performed to evaluate tribological properties of niobium carbide coated AISI 1040 steel. In coating process, thermo-reactive diffusion treatment by pack method was performed at the temperatures of 800, 900 and 1000 deg. C for 1-4 h, respectively. Depending on coating process time and temperature, the thickness of niobium carbide layer formed on substrate ranged from 3.4{+-}0.5 to 12{+-}2 {mu}m. The hardness of niobium carbide layers on the steel sample is 1792 HV. The presence of carbides (e.g. NbC, Nb{sub 2}C) formed on the surface of coated AISI 1040 steel was confirmed by X-ray diffraction analysis. Dry wear tests for uncoated and coated AISI 1040 steel against AISI D2 steel were carried out on pin-on-disk configuration and at sliding speed range of 0.5, 1, 2 and 5 m/s, and under 15 N and 30 N loads. The results showed that the average coefficient of friction for coated and uncoated AISI 1040 steel were 0.3 and 0.5, respectively. The specific wear rates for uncoated and coated steel are 4.47x10{sup -5} mm{sup 3}/N.m to 4.29x10{sup -4} and 4.37x10{sup -7} to 3.55x10{sup -5} mm{sup 3}/N.m.

  17. Nitriding Process Characterization of Cold Worked AISI 304 and 316 Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Waldemar Alfredo Monteiro

    2017-01-01

    Full Text Available The nitriding behavior of austenitic stainless steels (AISI 304 and 316 was studied by different cold work degree (0% (after heat treated, 10%, 20%, 30%, and 40% before nitride processing. The microstructure, layer thickness, hardness, and chemical microcomposition were evaluated employing optical microscopy, Vickers hardness, and scanning electron microscopy techniques (WDS microanalysis. The initial cold work (previous plastic deformations in both AISI 304 and 306 austenitic stainless steels does not show special influence in all applied nitriding kinetics (in layer thicknesses. The nitriding processes have formed two layers, one external layer formed by expanded austenite with high nitrogen content, followed by another thinner layer just below formed by expanded austenite with a high presence of carbon (back diffusion. An enhanced diffusion can be observed on AISI 304 steel comparing with AISI 316 steel (a nitrided layer thicker can be noticed in the AISI 304 steel. The mechanical strength of both steels after nitriding processes reveals significant hardness values, almost 1100 HV, on the nitrided layers.

  18. Plasma post oxidation of nitrocarburized AISI 4140 steel

    Institute of Scientific and Technical Information of China (English)

    LEE Insup

    2006-01-01

    Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of AISI 4140 steel.Plasma nitrocarburizing was conducted for 3 h at 570 ℃ in the nitrogen, hydrogen and methane atmosphere to produce the ε-Fe2-3(N,C) phase.It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of ε-phase, with a small proportion of γ'-Fe4(N,C) phase.The thickness of the compound layer was about 10 μm and the diffusion layer was about 300 μm in thickness, respectively.Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at a constant temperature of 500 ℃ for 1 h.The very thin magnetite (Fe3O4) layer 1-2 μm in thickness on top of the compound layer was obtained by plasma post oxidation.It was confirmed that the corrosion characteristics of the nitrocarburized compound layer can be further improved by the application of the superficial magnetite layer.

  19. AISI waste oxide recycling program. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Aukrust, E.; Downing, K.B.; Sarma, B.

    1995-08-01

    In March 1995 AISI completed a five-year, $60 million collaborative development program on Direct Steelmaking cost-shared by DOE under the Metals Initiative. This program defined an energy-efficient and environmentally-friendly technology to produce hot metal for steelmaking directly from coal and iron ore pellets without incurring the high capital costs and environmental problems associated with traditional coke oven and blast furnace technology. As it becomes necessary to replace present capacity, this new technology will be favored because of reduced capital costs, higher energy efficiency, and lower operating costs. In April 1994, having failed to move forward with a demonstration plant for direct ironmaking, despite substantial efforts by both Stelco and Geneva Steel, an alternative opportunity was sought to commercialize this new technology without waiting until existing ironmaking capacity needed to be replaced. Recycling and resource recovery of steel plant waste oxides was considered an attractive possibility. This led to approval of a ten-month, $8.3 million joint program with DOE on recycling steel plant waste oxides utilizing this new smelting technology. This highly successful trial program was completed in December 1994. The results of the pilot plant work and a feasibility study for a recycling demonstration plant are presented in this final technical report.

  20. Ferromagnetic properties of cold rolled AISI 304L steel

    Science.gov (United States)

    Tavares, S. S. M.; da Silva, M. R.; Neto, J. M.; Miraglia, S.; Fruchart, D.

    2002-04-01

    The ferromagnetic properties (coercive force, residual and saturation magnetisation) of a cold rolled AISI 304L stainless steel were measured as function of the applied deformation, using a vibrating sample magnetometer. The martensite volume fraction produced by deformation was calculated through the magnetisation saturation ( σs) value. A maximum amount of martensite (81%) was obtained by applying a true deformation ɛ=2.41 and a heat treatment at 400°C after rolling. The residual induction ( Br) and the squareness (=ratio between residual ( Br) and saturation ( Bs) inductions) increased, while the coercive field ( Hc) decreased with the amount of deformation. The heat treatment at 400°C promotes as well the increase of both Br and Br/ Bs and the decrease of Hc. The magnetic properties obtained in the most severely deformed samples ( Hc=23.08-23.63 kJ/m 3, Br=1.01-1.20 T and Bs=1.12-1.28 T) are comparable to that of some hard and semi-hard alloys used as magnets. The stability of the ferromagnetic martensite ( α') was investigated by thermomagnetic analysis. The starting ( As) and final ( Af) temperatures of the martensite phase ( α') transformation into austenite during heating were determined to As=430-440°C and Af=610-616°C.

  1. Ductility in a new low nickel stainless steel for reinforced concrete

    Directory of Open Access Journals (Sweden)

    Cobo, A.

    2011-12-01

    Full Text Available This paper discusses the stress-strain curves for a new low nickel stainless steel, a conventional AISI 304 stainless steel and a carbon steel commonly used in reinforced concrete structures. Ductility was studied in terms of ultimate tensile strength (fmax, elastic limit (fy and total elongation at maximum force [ultimate strain; uniform elongation] (εmax. The three materials were assessed with internationally accepted criteria, such as plastic rotational capacity, necking region and the toughness index (total energy absorbed at uniform elongation. The findings were compared to the properties of three types of conventional reinforcing steel: 500SD, 500N and 500H (EC-2.

    En este trabajo se presentan los diagramas tensióndeformación de un nuevo acero inoxidable con bajo contenido en níquel, un inoxidable convencional AISI 304 y un acero al carbono de uso común en estructuras de hormigón armado. Dicha ductilidad se ha estudiado determinando la tensión máxima (fmax, la tensión en el límite elástico (fy y la deformación bajo carga máxima (εmax. Los tres materiales se han evaluado utilizando criterios aceptados internacionalmente, como son el índice p (capacidad de rotación plástica, el índice A* (área plástica de endurecimiento y el índice de tenacidad Id (energía total absorbida en el punto de alargamiento bajo carga máxima, los resultados obtenidos se han comparado con los aceros convencionales de armaduras 500SD, 500N y 500H (EC-2.

  2. DIAGRAMAS DE FLUJO PARA EL DISEÑO DE ESTRUCTURAS DE ACERO

    OpenAIRE

    Romanjek Blimel, MARIJA

    2011-01-01

    Se desarrollan los "diagramas de flujo" que representan el proceso o los procedimientos para diseñar componentes estructurales de acero bajo la acción de fuerzas axiales de comprensión y flexión, siguiendo las condiciones exigidas por las normas americanas  AISC(1) y por el CSCR(2).Se presentan diagramas de flujo para distintas secciones transversales y condicones de carga. 

  3. Fabricación del acero de Damasco: estudio metalográfico

    Directory of Open Access Journals (Sweden)

    Criado, A. J.

    1997-02-01

    Full Text Available Damascus Steel is the denomination that the Europeans gave to the material with which the musulman swords were manufactured during the Era of the Crusades. This hypereutectoid steel presents a high content in carbon, more than 0.8 %, and in some cases up to 2 % in weight. The secret of its good mechanical characteristics is based in the hot forging process in the temperatures interval between 650 and 850 °C. The final quenching in water, brine or other aqueous solutions, confers to the swords manufactured with this steel a good resistance to its cutting edge and a high toughness. In the present investigation, the manufacture processes of this type of steel are studied. Electronic scanning microscopy has been applied to the study of materials manufactured by the authors following the ancient craftsmen methods of forging and quenching.

    Acero de Damasco es la denominación que los europeos dieron al material del que estaban hechas las espadas musulmanas durante la época de las Cruzadas. Este acero hipereutectoide, presenta un alto contenido de carbono que supera en todos los casos el 0,8 %, llegando en algunos casos al 2,1 % en masa. El secreto de sus buenas características mecánicas radica en los procesos de forja en caliente, en un intervalo de temperaturas entre 650 y 850 °C, a los que se puede someter. El temple final en agua, salmuera u otras soluciones acuosas, confiere a las armas fabricadas con este acero una buena resistencia en su filo cortante y una tenacidad elevada. En la presente investigación se estudian los procesos de fabricación de este tipo de acero. Se ha aplicado la microscopía electrónica de barrido al estudio de materiales fabricados por los autores siguiendo los métodos artesanos antiguos de forja y temple.

  4. AUMENTO EN LA RESISTENCIA A LA CORROSIÓN DE UN ACERO T91 ALUMINIZADO

    Directory of Open Access Journals (Sweden)

    LUZ S. QUINTERO

    2011-01-01

    Full Text Available El acero ferrítico T91 ha sido ampliamente utilizado en plantas de generación de energía eléctrica, calderas y plantas nucleares. Sin embargo, su resistencia a la oxidación se ve gravemente afectada a temperaturas superiores a los 600ºC. En esta investigación se empleó la técnica de cementación empacada para aluminizar un acero T91 y se encontraron las condiciones óptimas para la formación de un recubrimiento libre de porosidad y con espesor uniforme (300 micras. Se evaluó la capa de óxido formada luego de una exposición a 800ºC en atmósfera de aire. La caracterización del recubrimiento y de la capa de óxido (Al2O3 se llevó a cabo empleando un microscopio electrónico de barrido (SEM, Espectroscopia de Rayos X (EDX y mapping. Se comprobó una buena resistencia a la oxidación del acero T91 aluminizado, debido a la formación de una fina capa continua de óxido de aluminio de aproximadamente 6 micras de espesor luego de una exposición de 7 días.

  5. Tratamiento térmico de acero cubano // Thermal treatment of cuban steel

    Directory of Open Access Journals (Sweden)

    N. Caballero Stevens

    2001-01-01

    Full Text Available En este trabajo se muestran algunos de los resultados obtenidos durante la investigación de un nuevo acero cubano que sepretende destinar a la fabricación de elementos de corte para máquinas combinadas cortadoras de caña de azúcar,herramientas de mano y otras piezas de gran responsabilidad que requieren elevada dureza para su trabajo. En el trabajo sepresentan los aspectos principales que relacionan la composición química, microestructura y dureza de este acero. Seestablecen experimentalmente las temperaturas de los puntos críticos para definir los regímenes de tratamiento térmico. Seincluye el comportamiento de las propiedades de dureza ante diferentes regímenes de tratamiento térmico.Palabras claves: Acero, recocido, temple, revenido, martensita, dureza________________________________________________________________________________AbstractIn this article are shown some of the results obtained during the investigation of a new cuban steel that it is going to beused in the manufacture of blades for cane cutting machines, hand tools and other part of great responsibility that requirehigh hardness for the job.In the article are presented the principles aspects of quimical composition, microstructure and hardness of this steel. Thereare stablished experimentally the temperature of the critic points in order to determine the regimes of the thermal treatment.The behavior of the properties of hardness is included at different regimes of thermal treatment.Key words: Steel, thermal treatment, quenching, tempering, hardness.

  6. Influencia sobre los tratamientos térmicos del contenido de aluminio de aceros no aleados

    Directory of Open Access Journals (Sweden)

    Carreras, L.

    1999-08-01

    Full Text Available The main purpose of this article is to determine the optimal level of aluminum content in plain steels to have the optimal mechanical properties by means of surface heat treatments. Various plain steels with different aluminium content have been studied. The importance of treatment temperature is analyzed. The influence of other factors, like nitrogen content or the homogenous distribution of particles, is evaluated. It is concluded that the aluminum composition of plain steels that are subjected to heat treatments should not exceed 0.02 %.

    El objetivo de este trabajo es determinar el intervalo óptimo de contenidos de aluminio en aceros no aleados para los que se consiguen las propiedades mecánicas óptimas mediante tratamientos térmicos de superficie. Se estudian diferentes coladas de acero en las que varía el contenido de aluminio y las temperaturas de tratamiento. Se evalúa la importancia de otros factores tales como el contenido de nitrógeno y la homogeneidad en la distribución de partículas endurecedoras. Se llega a la conclusión de que los aceros no aleados destinados a tratamientos térmicos no deben tener un contenido de aluminio superior al 0,02 %.

  7. ESTUDIO DE LA CORROSIÓN DEL ACERO EMBEBIDO EN CONCRETO AAS SOMETIDO A CLORUROS

    Directory of Open Access Journals (Sweden)

    ROBINSON TORRES GÓMEZ

    2010-01-01

    Full Text Available Se presenta un estudio sobre el comportamiento frente a la corrosión de barras de acero de refuerzo de un concreto de escoria activado alcalinamente. La escoria de alto horno fue activada mediante el uso de silicato sódico al 5% obteniéndose un material con buenas propiedades cementantes. Las probetas de concreto fueron fabricadas a partir de este cemento, después de mezclar con los agregados fueron reforzadas con barras de acero sismoresistente ASTMA706. Las probetas de concreto reforzado estuvieron sometidas en ambientes contaminados con iones cloruro para simular condiciones marinas. La evaluación electroquímica se realizo aplicando las técnicas de resistencia a la polarización lineal (LPR y espectroscopia de impedancia electroquímica (EIS. Se logra determinar el comportamiento de la capa pasiva del acero y electroquímico del metal cuando está inmerso en estos materiales cerámicos novedosos.

  8. Efecto de la Nitruración a Plasma en el Endurecimiento por Precipitación del Acero 15-5 PH Plasma Nitriding Effect on Precipitation Hardening of 15-5 PH Steel

    Directory of Open Access Journals (Sweden)

    A. Moreno

    2005-01-01

    Full Text Available Acero inoxidable endurecible por precipitación, 15-5 PH, fue sometido a un ciclo térmico de tratamiento combinando el envejecimiento y la nitruración por plasma en un mismo ciclo. Se aplicaron diversos ciclos térmicos cuyo principal objetivo fue verificar la evolución de la dureza del núcleo del material y de la superficie conforme la condición de tratamiento. En todos los ciclos térmicos ocurrió el endurecimiento del núcleo por precipitación y de la superficie por la formación de una capa nitrurada. La variable tiempo fue mantenida en 2 horas y la atmósfera utilizada fue 25% de Nitrógeno, 75% Hidrógeno. La dureza superficial y del núcleo fueron evaluadas a través de ensayos Vickers HV 10. El perfil de dureza de la capa nitrurada fue evaluado a través de ensayos de microdureza Vickers con carga 50g. Se concluyó en este trabajo que el tratamiento de endurecimiento por precipitación y el endurecimiento superficial por nitruración a plasma pueden ser realizados de forma conjunta.Stainless steel precipitation hardening was evaluated by the thermal treatment for precipitation combined with plasma nitriting surface hardening treatment of 15-5 PH steel. Several thermal treatments were applied to study the core and surface hardness evolution during the treatment process. The core hardness was improved by the precipitation and the surface as well as by the nitrided layer for all the conditions used. For all the samples the same time (2 hours was used and the same nitriding gas mixture (25% Nitrogen and 75% Hydrogen was employed. Metalographic analysis, Vickers HV10, and microVickers test 50g were used to study the behavior of the steel. The results show that the precipitation hardening and plasma nitriding can be done using the same cycle to improve core and surface hardening.

  9. Surface fatigue life of CBN and vitreous ground carburized and hardened AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Patel, P. R.

    1988-01-01

    Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9310 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temeprature of 320 K (116 F), an outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

  10. EFFECTS OF COPPER ION IMPLANTATION ON ANTIBACTERIAL ACTIVITY OF AISI420 STAINLESS STEEL

    Institute of Scientific and Technical Information of China (English)

    Z.G. Dan; H.W. Ni; B.F. Xu; J. Xiong; P. Y. Xiong

    2005-01-01

    Antibacterial activity of AISI420 stainless steel (SS) implanted by copper was investigated. Ions extracted from a metal vapor vacuum arc (MEVVA) are sourced with 100keV energy and a dose range from 0.2×1017 to 2.0×1017ions .cm-2. The saturation dose of Cu implantation in AISI420 SS and Cu surface concentration were calculated at the energy of 100keV. The effect of dose on the antibacterial activity was analyzed. Results of antibacterial test show that the saturation dose is the optimum implantation dose for best antibacterial activity, which is above 99% against both Escherichia coli and Staphylococcus aureus. Novel phases such as Fe4Cu3 and Cu9.9Fe0.1 were found in the implanted layer by glancing angle X-ray diffraction (GXRD). The antibacterial activity of AISI420 SS attributes to Cu-contained phase.

  11. Diseño de nuevos aceros bainíticos.

    Directory of Open Access Journals (Sweden)

    Caballero, F. G.

    2002-02-01

    Full Text Available Mixed microstructures consisting of fine plates of upper bainitic ferrite separated by thin films of stable retained austenite have seen many applications in recent years because of their impressive combination of strength and toughness. There may also be some martensite present in the microstructure, but its formation can be controlled increasing the stability of the retained austenite. On the other hand, carbides are avoided by the judicious use of silicon as an alloying element. The aim of the present work was to see how far these concepts can be extended in order to achieve the highest ever combination of strength and toughness in bulk-samples subjected to continuous cooling transformation. Three alloys were proposed and manufactured, and the results of metallographic characterisation and mechanical tests have shown that the designed steels have the highest ever combination of strength and toughness for bainitic microstructures, matching even the maraging steels which are at least thirty times more expensive. The experimental results confirm the alloy design procedures.

    En los últimos años se han diseñado aceros con microestmcturas formadas por placas de ferrita bainítica superior y finas regiones de austenita retenida que, por su excelente combinación de propiedades de resistencia y tenacidad, han sido empleados para numerosas aplicaciones. Aunque en estas microestructuras puede haber algo de martensita, su formación puede controlarse aumentando la estabilidad de la austenita retenida. Por otra parte, la presencia de carburos en la bainita, causa de importantes disminuciones de tenacidad en los aceros bainíticos convencionales, se evita gracias al uso del silicio como elemento de aleación. El objetivo de este trabajo es estudiar la posibilidad de optimizar la citada combinación de propiedades, generalmente antagónicas, en muestras masivas para aplicación industrial sujetas a transformaciones por enfriamiento continuo. Para

  12. Modificación superficial de aceros y hierros fundidos mediante láser de Nd: YAG. // Steels and cast irons superficial modification by means of laser Nd: YAG.

    Directory of Open Access Journals (Sweden)

    R. Sagaró Z.

    2001-10-01

    Full Text Available Se presentan los resultados de los autores en el tratamiento térmico superficial con técnica láser (TTSL. Con el empleo deun láser de Nd: YAG se procedió al endurecimiento superficial de los aceros AISI 1045, W1, W112 y hierros fundidos detipo laminar y nodular. Los autores prestan atención a las rutas de endurecimiento superficial atendiendo a los parámetrosoperacionales del láser: potencia incidente en la zona de interacción (P y la velocidad de barrido del haz de láser (V. Deigual forma se establecen valoraciones acerca de las estructuras metalográficas obtenidas. En todos los casos se reportanvalores de microdureza Vickers que oscilan entre los 500-900 HV (incrementos de 3-4 veces respecto al substratooriginal. Los resultados obtenidos permiten establecer en todos los casos experimentados que el incremento de lavelocidad de barrido provocó una disminución de la profundidad de la capa endurecida. Las experiencias del TTSL en losaceros ensayados muestran una tendencia a la disminución de la profundidad del endurecimiento con el incremento delcontenido de carbono.Palabras claves: Endurecimiento superficial, parámetros de operación de láser., microdureza, profundidadde capa endurecida, de fallo, vibraciones.____________________________________________________________________________AbstractThis paper expose the experiences of researchers on the laser surface heat treatment. The hardening of AISI 1045, W1,W112 steels and cast irons flake and nodular was carried out by using a Nd: YAG laser. Operation parameters of laser, likebeam power (P and traverse speed of the laser spot (V are closely with hardening depth . Authors present some analysesabout metallographic studies. In all cases are reported Vickers microhardness about 500-900 HV (three or four times higherthan original substrates. Relations between microhardness and depth of hardening are presented for the processedmaterials. Experimental results showed that the increased

  13. FLOW STRESS MODEL FOR HARD MACHINING OF AISI H13 WORK TOOL STEEL

    Institute of Scientific and Technical Information of China (English)

    H. Yan; J. Hua; R. Shivpuri

    2005-01-01

    An approach is presented to characterize the stress response of workpiece in hard machining,accounted for the effect of the initial workpiece hardness, temperature, strain and strain rate on flow stress. AISI H13 work tool steel was chosen to verify this methodology. The proposed flow stress model demonstrates a good agreement with data collected from published experiments.Therefore, the proposed model can be used to predict the corresponding flow stress-strain response of AISI H13 work tool steel with variation of the initial workpiece hardness in hard machining.

  14. Activated flux tungsten inert gas welding of 8 mm-thick AISI 304 austenitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    刘观辉; 刘美华; 易耀勇; 张宇鹏; 罗子艺; 许磊

    2015-01-01

    AISI 304 stainless steel plates were welded with activated flux tungsten inert gas (A-TIG) method by utilizing self-developed activated flux. It is indicated from the experimental results that for 8 mm-thick AISI 304 stainless steel plate, weld joint of full penetration and one-side welding with good weld appearance can be obtained in a single pass without groove preparation by utilizing A-TIG welding. Moreover, activated flux powders do not cause significant effect on the microstructure of TIG weld and the mechanical properties of A-TIG weld joints are also superior to those of C-TIG (conventional TIG) welding.

  15. Development of Flow Stress of AISI H13 Die Steel in Hard Machining

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; QIAN Guohua; HU Qiang

    2007-01-01

    An approach was presented to characterize the stress response of workpiece in hard machining, accounting for the effect of the initial workpiece hardness in addition to temperature, strain and strain rate on flow stress in this paper. AISI H13 die steel was chosen to verify this methodology. The proposed flow stress model demonstrates a good agreement with experimental data. Therefore, the proposed model can be used to predict the corresponding flow stress-strain response of AISI H13 die steel with variation of the initial workpiece hardness in hard machining.

  16. Ductilidad en caliente y mecanismos de fractura de un acero de construcción

    Directory of Open Access Journals (Sweden)

    Calvo, J.

    2006-02-01

    Full Text Available The hot ductility of a structural steel produced from scrap recycling has been studied to determine the origin of the transverse cracks in the corners that appeared in some billets. Samples extracted both from a billet with transverse cracks and from a billet with no external damage were tested. To evaluate the influence of residual elements and inclusions, the steel was compared to another one impurity free. Reduction in area of the samples tensile tested to the fracture was taken as a measure of the hot ductility The tests were carried out at temperatures ranging from 1000ºC to 650ºC and at a strain rate of 1·10- 3 s-1. The fracture surfaces of the tested samples were observed by scanning electron microscopy in order to determine the embrittling mechanisms that could be acting. The steel with residuals and impurities exhibited lower ductility values for a wider temperature range than the clean steel. The embrittling mechanisms also changed as compared to the impurity free steel.

    Se evaluó la ductilidad en caliente de un acero de construcción procedente del reciclaje de chatarra con el fin de determinar el origen de las grietas transversales que aparecen en las esquinas de algunas palanquillas. Para ello, se extrajeron probetas de dos palanquillas de una misma calidad de acero. Una de las palanquillas había presentado agrietamiento transversal al ser colada y, la otra, no. Para conocer la influencia de los elementos residuales e inclusiones en la ductilidad en caliente, otro acero, con la misma composición pero sin impurezas, se fabricó en laboratorio y fue sometido al mismo análisis que los aceros comerciales. La ductilidad en caliente se midió como la reducción del área de las probetas ensayadas a tracción hasta la rotura. Las condiciones a las que se realizaron los ensayos fueron temperaturas de 1.000 a 650 ºC y a una velocidad de deformación de 1·10-3 s-1. Las superficies de fractura de las probetas ensayadas se

  17. Biomaterial Studies on AISI 316L Stainless Steel after Magnetoelectropolishing

    Directory of Open Access Journals (Sweden)

    Massimiliano Filippi

    2009-03-01

    Full Text Available The polarisation characteristics of the electropolishing process in a magnetic field (MEP – magnetoelectropolishing, in comparison with those obtained under standard/conventional process (EP conditions, have been obtained. The occurrence of an EP plateau has been observed in view of the optimization of MEP process. Up-to-date stainless steel surface studies always indicated some amount of free-metal atoms apart from the detected oxides and hydroxides. Such a morphology of the surface film usually affects the thermodynamic stability and corrosion resistance of surface oxide layer and is one of the most important features of stainless steels. With this new MEP process we can improve metal surface properties by making the stainless steel more resistant to halides encountered in a variety of environments. Furthermore, in this paper the stainless steel surface film study results have been presented. The results of the corrosion research carried out by the authors on the behaviour of the most commonly used material - medical grade AISI 316L stainless steel both in Ringer’s body fluid and in aqueous 3% NaCl solution have been investigated and presented earlier elsewhere, though some of these results, concerning the EIS Nyquist plots and polarization curves are also revealed herein. In this paper an attempt to explain this peculiar performance of 316L stainless steel has been undertaken. The SEM studies, Auger electron spectroscopy (AES and X-ray photoelectron spectroscopy (XPS were performed on 316L samples after three treatments: MP – abrasive polishing (800 grit size, EP – conventional electrolytic polishing, and MEP – magnetoelectropolishing. It has been found that the proposed magnetoelectropolishing (MEP process considerably modifies the morphology and the composition of the surface film, thus leading to improved corrosion resistance of the studied 316L SS.

  18. TEMPERATURE AND HEAT FLOW WHEN TAPPING OF THE HARDENED STEEL USING DIFFERENT COOLING SYSTEMS TEMPERATURA Y FLUJO DE CALOR AL ROSCAR CON MACHOS ACERO ENDURECIDO UTILIZANDO DIVERSOS SISTEMAS DE LUBRICACIÓN

    Directory of Open Access Journals (Sweden)

    Lincoln Cardoso Brandão

    2009-08-01

    Full Text Available Machining hardened steels has always been a great challenge in metal cutting, particularly for tapping operations. In the present paper, temperature was assessed when tapping hardened AISI H13. Dry machining and two cooling/lubrication systems were used: flooded and minimum quantity of fluid (MQF with 20ml/h, both using mineral oil. The tapping operation was performed on 100 x 40 mm, 14 mm thick workpieces with 55 HRc. An implanted thermocouple technique was used for temperature measurement at distances very close to the highest thread diameter (at 0.1, 2.5 and 5.0 mm. Three thermocouples were used for each distance along the workpiece diameter at 3.0, 7.0 and 11.0 mm from the tap entrance. Measurements were replicated twice for each condition tested. An analytical theoretical heat conduction model was used to evaluate the temperature at the tool-workpiece interface and determine the heat flow and convection coefficient. The smallest temperature increase and heat flow were observed when using the flooded system, followed by the MQF, compared to the dry condition. The effect was directly proportional to the amount of lubricant applied, as well as with the MQF system, when compared to dry cutting.Trabajar los aceros endurecidos siempre ha sido un desafío para el corte de metales, particularmente en las operaciones de roscado. En el presente trabajo se mide la temperatura del acero AISI H13 endurecido, realizándose ensayos sin lubricación (seco y dos sistemas con lubricación: aceite lubricante en grandes cantidades y mínima cantidad de líquido (minimum quantity of fluid MQF a 20 ml/h, en ambos casos se utilizó aceite integral mineral. El roscado se realiza sobre probetas de prueba de 100 x 40 mm con 14mm de espesor y dureza de 55 HRc. Para medir la temperatura se utiliza la técnica de termocuplas situadas muy próximas al diámetro mayor del hilo de rosca (a 0.1, 2.5 y 5 mm de distancia. Se utiliza tres termocuplas a lo largo del espesor de

  19. Formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo Biofilm formation by Aeromonas hydrophila and Staphylococcus aureus on stainless steel using milk and different conditions of cultivation

    Directory of Open Access Journals (Sweden)

    Cleube Andrade Boari

    2009-12-01

    Full Text Available O objetivo desta pesquisa consistiu em avaliar a formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo. As variáveis em estudo consistem no cultivo monoespécie e combinado, dos referidos microrganismos e nas temperaturas de 4, 7 e 18 °C. Recipientes contendo 1000 mL de leite, densidade populacional de 10(5 UFC.mL-1 de cada microrganismo e 10 cupons de aço inoxidável (10 × 20 mm foram lacrados e armazenados, sob agitação de 60 rpm, por um período de 10 dias. As análises ocorreram a cada 48 horas. Células sésseis de A.hydrophila e S. aureus foram enumeradas através do plaqueamento seletivo em ágar m-Aeromonas selective e Baird-Parker, respectivamente. Estudos sobre o tempo de geração, enumeração de células planctônicas e observação dos cupons através da microscopia eletrônica de varredura foram conduzidos. S. aureus, em monocultivo, formou biofilme a 18 °C e a 7 °C. Para 4 °C, foi observado um processo de adesão. A presença de A. hydrophila reduziu o desempenho de S. aureus. Nesta condição de cultivo multiespécie houve formação de biofilme a 18 °C. A. hydrophila, tanto em monocultivo quanto em presença de S. aureus, formou biofilme em todas as condições pesquisadas.The aim of this research was to verify the capability of biofilm formation on stainless steel by Aeromonas hydrophila and Staphylococcus aureus using milk and different conditions of cultivation. The variables consisted in mono and multi-species cultivation of these microorganisms and in the temperatures of 4, 7 and 18 °C. Containers containing 1000 mL of milk, population density of 10(5 CFU.mL-1 of each microorganism, and ten suspended chips of stainless steel AISI 304 (10 × 20 mm were used to seal up and storage, under 60 rpm of agitation for 10 days. The analyses were conducted every 48 hours. Sessile cells of A. hydrophila and S. aureus and were enumerated

  20. CARACTERIZACIÓN NO DESTRUCTIVA DEL ENDURECIMIENTO POR PRECIPITACIÓN DE UN ACERO 17-4PH

    OpenAIRE

    García Pérez, Ivan Xicotencatl

    2012-01-01

    El acero endurecible por precipitación 17-4 PH ha sido usado ampliamente, debido a que presenta una combinación balanceada de propiedades mecánicas y una buena resistencia a la corrosión. La temperatura de trabajo de este acero está por debajo de los 390 ̊C. Existe una gran preocupación en la industria ya que después de una exposición prolongada a esta temperatura, presentan degradación de sus propiedades, causada por envejecimiento. Los ensayos no destructivos ofrecen gran ...

  1. The adhesion of hot-filament CVD diamond films on AISI type 316 austenitic stainless steel

    NARCIS (Netherlands)

    Buijnsters, J.G.; Shankar, P.; Enckevort, W.J.P. van; Schermer, J.J.; Meulen, J.J. ter

    2004-01-01

    Steel ball indentation and scratch adhesion testing of hot filament chemical vapour deposited diamond films onto AISI type 316 austenitic stainless steel substrates using two different interlayer systems, namely chromium nitride and borided steel, have been investigated. In order to compare the adhe

  2. Micro-structural strengthening mechanism of multiple laser shock processing impacts on AISI 8620 steel

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Zhong, J.W., E-mail: zjw1033@126.com [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Luo, K.Y.; Zhang, L.; Dai, F.Z. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China); Chen, K.M. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Q.W.; Zhong, J.S.; Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Xuefu Road 301, Jingkou District, Zhenjiang 212013 (China)

    2011-07-25

    Highlights: {yields} LSP can clearly refine coarse grains in the shocked region by dislocation movement. {yields} Micro-structural evolution of AISI 8620 steel after LSP impacts is revealed. {yields} LSP on AISI 8620 steel have grain refinement and dispersion strengthening of carbon. {yields} The results can provide some insights on surface modification of low carbon steel. - Abstract: Micro-structural evolution in the near-surface region of AISI 8620 steel subjected to multiple laser shock processing (LSP) impacts were investigated by means of cross-sectional optical microscopy (OM) and transmission electron microscopy (TEM) observations. Micro-structural evolution process subjected to multiple LSP impacts can be described as follows: (i) the parallel lamellar pearlites are broken into bitty pearlites, and dislocation activities simultaneously led to the formation of dislocation lines (DLs) and dislocation pile-ups in original grains; (ii) bitty pearlites were all broken into Fe{sub 3}C granules, and dislocation movement made Fe{sub 3}C granules disperse near subgrain boundaries and led to subgrain boundaries separating individual cells, and (iii) subgrain boundaries were refined to grain boundaries. Multiple LSP impacts on AISI 8620 steel had dual-function: the refinement of coarse grains in the near-surface region by dislocation movement and dispersion strengthening of C atoms which cut cementite and diffused into the ferrite by moving dislocations.

  3. Influence of temperature on AISI 316L corrosion in phosphoric acid solutions under hydrodynamic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Tovar, R.; Montanes, M.T.; Garcia-Anton, J. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain); Ben Bachir, A.; Abdelkebir, B.; Elmandoubi, N. [University Mohammed V-Agdal, Lab. Corrosion-Electrochimie, Faculty of Sciences, Rabat (Morocco)

    2009-07-01

    AISI 316L stainless steel, due to its good mechanical properties and corrosion resistance, is widely used in the phosphoric acid industry, including piping lines. However, phosphoric acid (H{sub 3}PO{sub 4}) is a medium-strong acid, and corrosion problems could occur, especially working with concentrated solutions and increasing temperature. Furthermore, fluid flow can increase corrosion rates. The objective of this work is to study the dynamic corrosion of AISI 316L stainless steel in a range of temperature from 25 C to 60 C by means of cyclic potentiodynamic curves. A hydrodynamic circuit was used in order to study dynamic corrosion. The experiments were carried out in an oxygen-free environment at different Reynolds numbers: 1,456, 3,166 and 5,066. The results show that uniform corrosion mechanisms can be expected for AISI 316L stainless steel in 5.5 M H{sub 3}PO{sub 4} solutions, since no hysteresis loop was observed. Moreover, temperature affects the corrosion parameters obtained from the polarization curves. Temperature shifts corrosion potential to nobler values, reduces the passivity region and enhances passivation current density. On the other hand, little influence of Reynolds number was observed on AISI 316L stainless steel corrosion. (authors)

  4. Formation of abrasion-resistant coatings of the AlSiFexMny intermetallic compound type on the AISI 304L alloy

    Directory of Open Access Journals (Sweden)

    Martínez-Perales, Laura G.

    2016-03-01

    Full Text Available The α-Al9FeMnSi and β-Al9FeMn2Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 °C, pressure (5, 10 y 20 MPa and holding time (3600, 5400 y 7200 seconds. Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 °C, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of α-Al9FeMnSi and β-Al9FeMn2Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface.Los intermetálicos α-Al9FeMnSi y β-Al9FeMn2Si formados por sinterización reactiva de polvos Al, Si, Mn, Fe, Cr, Ni se han utilizado en aceros AISI 304L para mejorar la microdureza. Las variables de procesamiento de sinterización reactiva fueron temperatura (600, 650, 700, 750, y 800 °C, presión (5, 10 y 20 MPa y el tiempo de retención (3600, 5400 7200 segundos. Los resultados experimentales muestran que la temperatura es la variable más importante que afecta a la formación del sustrato/recubrimiento, mientras que la presión no parece tener un efecto significativo una influencia significativa. Los resultados muestran las condiciones óptimas de la sinterización reactiva que favorecen la formación del sustrato/recubrimiento a 800 °C, 20 MPa y 7200 segundos. En estas condiciones, la zona de reacción entre el sustrato y el recubrimiento es más compacta y bien

  5. Variación de la rugosidad y de la dureza en el maquinado de formas complejas en aceros endurecidos utilizando altas velocidades de corte. // Variation of roughness and of the hardness in machining of complex forms in hardness steel using high speed cuttin

    Directory of Open Access Journals (Sweden)

    L. Cardoso Brandão

    2008-05-01

    Full Text Available Este trabajo evalúa la influencia de la variación de la velocidad de corte en el corte con altas velocidades en superficies conformas complejas. Fueron maquinados cuerpos de prueba con 1/4 de circunferencia en acero AISI D2 y H13 con dureza de53 y 50 HRC, respectivamente. Los experimentos fueron realizados utilizando la estrategia “raster” con herramientasesféricas (Ball Nose en un centro de maquinado de tres ejes. Los valores de rugosidad y dureza HRC fueron medidosperpendiculares a la dirección de corte en cuatro regiones diferentes. Los resultados demuestran que las regiones dediámetro mínimo, próximas a la línea central de la herramienta y en el punto de contacto del diámetro máximo, presentanlos menores valores de rugosidad. No ocurren modificaciones significativas en los valores de HRC y no hubo formación decapa blanca en ninguno de los dos materiales. Considerándose los valores de microdureza medidas radialmente en loscuerpos de prueba no se observa ninguna variación de la microdureza.Palabras claves: Rugosidad Ra; altas velocidades de corte; moldes y matrices; dureza HRC._____________________________________________________________________________Abstract.This work evaluated the influences of cutting speed variation in machining with High Speed Cutting on complex surface forms.Work pieces of AISI D 2 e AISI H13 with hardness of 53 and 50 HRC, respectively with a quarter of circumference was milled.Tests were carried out in a vertical machining centre using the raster strategy and Ball-Nose tool. The roughness values andhardness HRC were measured perpendicular the cutting direction in six different regions. The results show that the regions whereoccur the contact of minimum tool diameter, nearest to tool centre line and the maximum diameter contact point show the lowervalues of roughness. During the tests, it did not occur significantly modifications in the values of HRC hardness and the whitelayer not was formed

  6. Desarrollo de aceros reforzados con carburos primarios vía metalurgia líquida

    Directory of Open Access Journals (Sweden)

    Agote, I.

    2005-12-01

    Full Text Available The steel reinforcement by means of the addition of primary carbides via liquid metallurgy needs to fulfill two essential requirements to be technically viable: the development of a solid reinforcing product which is appropriate to be mixed with the steel and the optimization of the metallurgic addition of these reinforcing particles into the liquid steel. Besides, the improvement of the reinforced alloy characteristics is directly related to the particles' nature of reinforcing particles, their homogeneous and uniform distribution in the matrix and their size and morphology. The manufacture of these carbides by SHS ('Self propagating High temperature Synthesis' and their addition before steel is poured into moulds allows achieving the above-mentioned conditions.

    Para que el reforzamiento de los aceros con carburos primarios vía metalurgia líquida sea técnicamente viable se requiere del desarrollo de un tipo de producto reforzante sólido, adecuado para su incorporación al acero, así como de la optimización de dicha vía metalúrgica de adición del producto reforzante al material base en estado líquido. Además, la mejora de características de la aleación reforzada es función directa de la naturaleza de las partículas, de su homogénea y uniforme distribución en la matriz y del tamaño y morfología regular de las mismas. Estas condiciones se consiguen cuando las partículas de carburo se elaboran previamente mediante la técnica SHS (selfpropagating high temperature synthesis y se añaden al baño de acero líquido previo a su colada en moldes o lingoteras.

  7. Efecto del boro en la deformación en caliente de un acero al carbono

    OpenAIRE

    2005-01-01

    En el presente estudio se evalúa el comportamiento a fluencia de tres aceros al carbono con distinto contenido en boro. Las curvas de fluencia se han obtenido a partir de ensayos de compresión uniaxial en caliente, realizada sobre probetas cilíndricas en una máquina de ensayos INSTRON que disponía de un horno de calentamiento por radiación adaptado al sistema. Los ensayos se realizaron a velocidad de deformación constante de 0,1s-1, 0,01s-1 y 0,001s-1, y las temperaturas de ens...

  8. Efecto del contenido de silicio en el comportamiento a fluencia de un acero al carbono

    OpenAIRE

    2004-01-01

    En el presente estudio se evalúa el comportamiento a fluencia de tres aceros al carbono con distinto contenido en silicio. Las curvas experimentales de fluencia se han obtenido a partir de ensayos de compresión en caliente, realizados sobre probetas cilíndricas en una máquina universal de ensayos, que disponía de un horno de calentamiento por radiación adaptado al sistema. Los ensayos se realizaron a velocidades de deformación constante sobre un intervalo de 3·10-4 s-1 a 0,1 s-1, y a las temp...

  9. CAPACIDAD estructural DE JUNTAS T de perfilES de acero LAMINADO EN FRÍO

    OpenAIRE

    2011-01-01

    Este estudio es consecuencia del uso extendido de tubo estructural y cajones formados con dos secciones tipo C(ambas de acero laminado en frío) en las estructuras principales de diferentes tipos de edificaciones. Dichas prácticashan puesto en evidencia la necesidad de cuantificar la resistencia de la unión viga y columna elaboradas con estematerial. Se investigaron cuatro diferentes tipos de uniones, con el propósito de determinar la capacidad máximacorrespondiente. Esta evaluación se realizó...

  10. Plan exportación de cocinas a gas de la empresa Fibro Acero a Colombia

    OpenAIRE

    2010-01-01

    El presente trabajo consiste en desarrollar un plan de exportación a Colombia para la empresa Fibro Acero, mercado en el cual aún no ha logrado comercializar sus cocinas, cocinetas y encimeras. Tiene como objetivo analizar la capacidad de la empresa y realizar una investigación mas detallada del mercado meta; es decir, identificar los perfiles geográficos, culturales y socio - políticos del país. A su vez, sugerir un plan de marketing cuyas estrategias permitan un posicionamiento de la empres...

  11. Comportamiento de hormigones de alta resistencia con fibras de acero frente al impacto de proyectiles

    OpenAIRE

    Cánovas, M. F.; Gaitán Rodríguez, Vidal Hernando

    2012-01-01

    Este trabajo presenta los resultados de la investigación llevada a cabo por los autores sobre el comportamiento de hormigón de 80 MPa de resistencia característica a compresión reforzado con diferentes cuantías de fibras de acero de alto contenido en carbono sometido al impacto de proyectiles de distintos calibres, determinando el espesor de muros de este tipo de hormigón que sería preciso disponer para impedir su perforación por dichos proyectiles, así como los valores máximos de penetración...

  12. El acero que nunca se fundió. Una reseña sobre Stalin

    Directory of Open Access Journals (Sweden)

    Iñaki Oneca Agurruza

    2004-02-01

    Full Text Available Era el 5 de marzo de 1953 cuando murió el fetiche, el gurú, el símbolo. Stalin significa “acero”, y precisamente una de las cosas que se reprochó al joven revolucionario, tras la adopción de este apodo, era que el acero era duro pero también frío. Así iniciamos esta breve nota sobre la figura de uno de los personajes clave del siglo XX.

  13. Aceros de alto límite elástico para conformación en frío: daño estructural

    OpenAIRE

    Riba López, Julio Antonio

    1985-01-01

    El trabajo de tesis analiza experimentalmente las propiedades mecánicas y parámetros racionales derivados del ensayo de tracción, la textura, conformabilidad y daño estructural de cuatro aceros de alto límite elástico en forma de chapas laminadas en frío para su empleo en la industria del automóvil, dos microaleados con niobio, otro refosforado y un acero de fase dual ferrito-martensítico. Se ha comprobado la buena embutibilidad por expansión del acero de fase dual ; la buena embutibilidad...

  14. Effect of heat treatment on an AISI 304 austenitic stainless steel evaluated by the ultrasonic attenuation coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Moghanizadeh, Abbas; Farzi, Abolfazl [Islamic Azad Univ., Esfarayen (Iran, Islamic Republic of). Dept. of Civil Engineering

    2016-07-01

    The properties of metals can be substantially changed by various methods, one of them is using heat treatment processes. Moreover, ultrasonic testing is the most preferred and effective, nondestructive testing technique for characterization of mechanical material properties. Austenitic stainless steel AISI 304 serves in many applications due to high strength and corrosion resistance. In certain applications, it is important to evaluate the mechanical properties of AISI 304 stainless steel. In this study, the ultrasonic method (attenuation measurement technique) is used to evaluate the hardness of AISI 304 stainless steel samples which were heat treated at different levels. Due to the heat treatment process, each sample has its specific microstructure and hardness which attenuate ultrasonic waves appropriately. The ultrasonic and hardness test show that it is possible to evaluate the hardness of AISI 304 stainless steel by ultrasonic attenuation coefficient. In addition, the relationship between ultrasonic attenuation coefficients and time of heat treatment is investigated.

  15. Análisis comparativo de la calidad del acero de refuerzo distribuido en Boyacá

    Directory of Open Access Journals (Sweden)

    Jimmy Vergara Silva, Óscar Javier Gutiérrez Junco

    2011-05-01

    Full Text Available Presenta  los  resultados  del  análisis  comparativo  de barras de acero de refuerzo, según las exigencias de la Norma Técnica Colombiana NTC 2289 [1], realizado a cinco marcas diferentes distribuidas para la industria de  la  construcción  en  Boyacá.  Inicialmente  se caracterizaron  las barras de  acero mediante  ensayos, para  determinar  su  composición  química  y  sus propiedades físicas y mecánicas; las características de la fractura del acero de refuerzo se observaron con el microscopio  electrónico  de  barrido  (MEB. Adicionalmente,  se  analizaron  muestras  conmicroscopio óptico, con  técnicas de espectrometría paraobservar y determinar las características del metal base de  las probetas. Los resultados  indican que la calidad del acero de refuerzo distribuido en Boyacá cumple en un alto  porcentaje con las exigencias sismo-resistentes para construcción; sin embargo, es importante que los constructores realicen control de calidad.

  16. Coeficiente de fricción y mecanismos de degradación superficial en materiales usados para la construcción de implantes de juntas articulares

    Directory of Open Access Journals (Sweden)

    Juan Alejandro Uribe A.

    2004-01-01

    Full Text Available El presente estudio evaluó los materiales más usados en nuestro medio para la fabricación de implantes de juntas articulares, evidenciando los mecanismos de deterioro superficial presentes en tres tribosistemas: a pin de acero AISI 316LVM contra un disco de acero AISI 316L, b pin de acero inoxidable AISI 316LVM contra disco de polietileno de ultra alto peso molecular (UHMWPE y c pin de una aleación Ti6Al4V contra disco de polietileno de ultra alto peso molecular (UHMWPE, con velocidad de deslizamiento de 0.58 m/s y diferentes cargas normales. Se adaptó una máquina de ensayos de desgaste normalizada del tipo pin – disco (norma ASTM G 99, de tal forma que permitiera sumergir el sistema en una solución de suero de sangre de bovino con una concentración de proteínas de 0.03 g/ml, la cual simula el ataque corrosivo al que se ven sometidos los materiales en las juntas implantadas dentro del cuerpo humano. Se midieron la variación de la fuerza y el coeficiente de fricción en el tiempo para estudiar el comportamiento del tribosistema, caracterizando las superficies desgastadas macro y microscópicamente con el fin de identificar los fenómenos de deterioro superficial. La adhesión fue el mecanismo predominante en el deslizamiento de los pares metal – polímero, mientras que la combinación de adhesión y abrasión fue responsable por un daño mucho mayor en el sistema metal-metal.

  17. Fundamentos microestructurales de la anisotropía resistente en aceros fuertemente trefilados

    Directory of Open Access Journals (Sweden)

    Toribio, J.

    1998-05-01

    Full Text Available An explanation of the anisotropic fracture behaviour of heavily drawn steels is proposed on the basis of micromechanical considerations: the change in crack propagation direction can be explained by the oriented pearlitic microstructure of the steels. Apart from the standard pearlitic colonies (more or less oriented, sometimes an exceptional pearlitic pseudocolony can be observed, extremely slender and aligned in the drawing direction, which makes it a preferential fracture path with minimum local resistance.

    Se propone una explicación del comportamiento anisótropo en fractura que exhiben los aceros fuertemente trefilados sobre la base de consideraciones micromecánicas: el cambio de dirección de fisuración puede explicarse por la microestructura perlítica orientada de estos aceros. Aparte de las colonias perlíticas tipo (más o menos orientadas, a veces puede observarse una pseudocolonia perlítica excepcional, extremadamente esbelta y alineada en la dirección del trefilado, lo que hace de ella un camino preferente de fractura con resistencia local mínima.

  18. Transferencia de calor en la colada continua de aceros. I parte. El molde

    Directory of Open Access Journals (Sweden)

    Cicutti, C.

    1997-10-01

    Full Text Available The continuous casting mold plays the important role of receiving the liquid steel and allowing an uniform and defect free solidified skin to be developed. In this work, the different heat transfer mechanisms which are present from the liquid steel to the mold cooling water are reviewed. The effect of operating variables on heat extraction and the relationship between global and distributed heat flux are also analyzed.

    El molde de colada continua cumple la importante función de recibir el acero líquido y permitir que se desarrolle una capa solidificada uniforme y libre de defectos. En este trabajo se revisan los distintos mecanismos implicados en el proceso de transferencia de calor, desde el acero líquido hasta el agua de refrigeración del molde. Se analiza también el efecto de las distintas variables de funcionamiento en la extracción calórica producida y la relación entre el flujo global de calor y su distribución a lo largo del molde.

  19. Mejora de la calidad del acero obtenido por colada continua mediante influencias electrofísicas

    Directory of Open Access Journals (Sweden)

    Shklyar, V.

    1998-12-01

    Full Text Available Laboratory tests with tin smelted in a crucible and industrial tests with crude steel poured in moulds had been carried out. These metals were subjected to electrophysical influences. As a result of the applied electric field, it is observed in tin that during the solidification, the crystalization temperature and the solidification time are changed. Crystal growth in the electric field direction and an increase of the fracture limit in the steel ingot are observed.

    Se han realizado ensayos de laboratorio con estaño fundido en crisol y a escala industrial con acero líquido vertidos en moldes, sometiendo estos metales a influencias electrofísicas. Como resultado del campo aplicado, en el estaño se observa que durante la solidificación varía la temperatura de cristalización y el tiempo de solidificación. En el lingote de acero se observa un crecimiento de los cristales en dirección del campo eléctrico y un aumento del límite de rotura.

  20. Corrosión bajo tensión en aceros para pretensado

    Directory of Open Access Journals (Sweden)

    del Pozo, Florencio

    1969-12-01

    Full Text Available This paper summarises the first results of a testing program to investigate behaviour of prestressing steels in corrosion. This work is being done at the Central Laboratory for Testing Construction Materials, of the Centre of Research and Experiments of Public Works. The tests confirm the belief that patented drawn steels are very suitable for prestressing, and that the phenomenon of corrosion under stress must be infrequent in practice, if the work is well done. The most aggressive agents are those which provoke fragilization through hydrogen, the most frequent being SH2. Nitrates, which are often cited as typical corrosion agents associated to stress, are less dangerous than SH2. Tempered and case hardened steels are more susceptible to these attacks than cold drawn steels. Chlorates have turned out to be less dangerous than nitrates. After prolonged tests no failure has been recorded due to corrosion under stress. The purpose of this investigation is to develop a simple and representative test for the phenomenon of corrosion under stress and fragilization due to hydrogen, so that this test may complement the normal ones that are applied to classify steel.En este trabajo se resumen los primeros resultados de un plan de ensayos, para investigar el comportamiento frente a la corrosión de los aceros para pretensado, que está realizando el Laboratorio Central de Ensayo de Materiales de Construcción del Centro de Estudios y Experimentación de Obras Públicas. Los ensayos confirman el criterio de que los aceros patentados y trefilados reúnen buenas condiciones para su uso en pretensado y que el fenómeno de corrosión bajo tensión debe ser poco frecuente en la práctica, si la obra está bien realizada. Los agentes más agresivos son los que provocan fragilización por hidrógeno; el más frecuente es el SH2. Los nitratos, citados frecuentemente como agentes típicos de corrosión bajo tensión, son menos peligrosos que el SH2. Los aceros

  1. uniaxial

    Directory of Open Access Journals (Sweden)

    HADER VLADIMIR MARTÍNEZ T.

    2007-01-01

    Full Text Available Se reporta un estudio sobre el contacto deslizante entre una aleación de aluminio 2117-T4 y un acero inoxidable X19CrNi17.2 (AISI 431, el mismo es relevante en el caso de operaciones de deformación plástica. Teniendo en cuenta la geometría inicial de algunas de las probetas de ensayo, v.g. 7.14mm de longitud y 4.76mm de diámetro, fue seleccionado un ensayo de compresión uniaxial para la determinación de las condiciones tribológicas. El coeficiente de fricción de Coulomb existente en la interfase probeta-plato de compresión, para las condiciones experimentales que fueron consideradas, se halla entre 0.02 y 0.03.

  2. Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100. Part 1. Experimental Results (Preprint)

    Science.gov (United States)

    2009-10-01

    factors to the L-P life model are currently used as standard practice to account for improvements in bearing material cleanliness and processing...eleven 12.7 mm diameter ABMA Grade 10 silicon nitride (Si3N4) balls, Ra finish of 6.4 nm and one piece machined silver plated AISI 4340 steel cages...piloted on both sides of the outer ring. The outer ring cage- land shoulders of the M50NiL bearings were titanium nitride (TiN) coated per aerospace

  3. Caracterización de aceros API-5L por medio de la medición de ruido magnético Barkhausen

    OpenAIRE

    P. Martínez-Ortiz; J. H Espina-Hernández; Hallen, J. M.; R. Linares y Miranda

    2010-01-01

    En este trabajo se presenta la caracterización de aceros API- 5L (grado X52, X56, X60) a través de ruido magnético Barkhausen. Un campo magnético sinusoidal de 10 Hz de frecuencia e intensidad de 5.2 kA/m se aplicó a las muestras de acero API-5L. Se demostró que cada acero genera un señal de ruido magnético Barkhausen propia que depende de su composición química y microestructura. Se comprobó la anisotropía magnética de los aceros a través de la señal de ruido magnético Barkhausen. Se proces...

  4. Oxidation behavior of 26Cr-16Ni and AISI 309 austenitic stainless steels in air flow at 1,173 K

    Energy Technology Data Exchange (ETDEWEB)

    Pipatnukun, Peeraya; Wangyao, Panyawat; Lothongkum, Gobboon [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgical Engineering

    2015-11-01

    This work investigates the isothermal oxidation behavior of as cast 26Cr-16Ni, as cold-rolled AISI 309 and as cast AISI 309 at 1,173 K in air flow rate of 40 cm{sup 3} x min{sup -1} using thermogravimetric analysis (TGA). In 33 hours, the oxidation resistance declines from high to low are as cast 26Cr-16Ni, as cold-rolled AISI 309 and as cast AISI 309, respectively. The oxidation kinetic results show that the exponential rate constant of the as cast 26Cr-16Ni, as cold-rolled AISI 309 and as cast AISI 309 are 8.79 x 10{sup -6}, 4.02 x 10{sup -5} and 4.35 x 10{sup -5} g x cm{sup -2} x s{sup -n}, respectively. The exponential growth rates of as cast 26Cr-16Ni, as cold-rolled AISI 309 and as cast AISI 309 are 0.42, 0.29 and 0.32, respectively. It indicates that the oxidation kinetic of as cast 26Cr-16Ni approaches a parabolic rate law, but those of as cold-rolled and as cast AISI 309 approach the cubic rate law. The sequence of oxide scale formations on the tested samples is also discussed.

  5. Finite Element Simulation and Experimental Verification of Internal Stress of Quenched AISI 4140 Cylinders

    Science.gov (United States)

    Liu, Yu; Qin, Shengwei; Hao, Qingguo; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2017-03-01

    The study of internal stress in quenched AISI 4140 medium carbon steel is of importance in engineering. In this work, the finite element simulation (FES) was employed to predict the distribution of internal stress in quenched AISI 4140 cylinders with two sizes of diameter based on exponent-modified (Ex-Modified) normalized function. The results indicate that the FES based on Ex-Modified normalized function proposed is better consistent with X-ray diffraction measurements of the stress distribution than FES based on normalized function proposed by Abrassart, Desalos and Leblond, respectively, which is attributed that Ex-Modified normalized function better describes transformation plasticity. Effect of temperature distribution on the phase formation, the origin of residual stress distribution and effect of transformation plasticity function on the residual stress distribution were further discussed.

  6. Finite Element Simulation and Experimental Verification of Internal Stress of Quenched AISI 4140 Cylinders

    Science.gov (United States)

    Liu, Yu; Qin, Shengwei; Hao, Qingguo; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2017-01-01

    The study of internal stress in quenched AISI 4140 medium carbon steel is of importance in engineering. In this work, the finite element simulation (FES) was employed to predict the distribution of internal stress in quenched AISI 4140 cylinders with two sizes of diameter based on exponent-modified (Ex-Modified) normalized function. The results indicate that the FES based on Ex-Modified normalized function proposed is better consistent with X-ray diffraction measurements of the stress distribution than FES based on normalized function proposed by Abrassart, Desalos and Leblond, respectively, which is attributed that Ex-Modified normalized function better describes transformation plasticity. Effect of temperature distribution on the phase formation, the origin of residual stress distribution and effect of transformation plasticity function on the residual stress distribution were further discussed.

  7. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    Sub-surface fatigue crack growth at non metallic inclusions is studied in AISI 52100 bearing steel under typical rolling contact loads. A first 2D plane strain finite element analysis is carried out to compute the stress history in the innner race at a characteristic depth, where the Dang Van...... damage factor is highest. Subsequently the stress history is imposed as boundary conditions in a periodic unit cell model, where an alumina inclusion is embedded in a AISI 52100 matrix. Cracks are assumed to grow radially from the inclusion under cyclic loading. The growth is predicted by means...... of irreversible fatigue cohesive elements. Different orientations of the cracks and different matrix-inclusion bonding conditions are analyzed and compared....

  8. Behavior of AISI SAE 1020 Steel Implanted by Titanium and Exposed to Bacteria Sulphate Deoxidizer

    Science.gov (United States)

    Niño, Ely Dannier V.; Garnica, Hernán; Dugar-Zhabon, Veleriy; Castillo, Genis

    2014-05-01

    A hybrid technology to treat solid surfaces with the pulse high voltage and electric arc discharges of low pressure with a three-dimensional ion implantation technique (3DII) is applied. This technology is used to protect AISI SAE 1020 steel against a microbiological corrosion. The titanium ion implanted steel samples (coupons) are subjected to a medium of bacteria sulphate deoxidizer (BSD) which are very typical of the hydrocarbon industry and are potentially harmful for structures when are in contact with petroleum and some of its derivatives. The used technology aims to find an effective hybrid procedure to minimize the harmful effects of bacteria on AISI SAE 1020 steel. The hybrid technology efficiency of superficial titanium implantation is estimated through the measurements of the point corrosion characteristics obtained after testing both the treated and non-treated coupons. The three-dimensional surface structures of the samples are reconstructed with help of a confocal microscope.

  9. Study of carbonitriding thermochemical treatment by plasma screen in active with pressures main austenitic stainless steels AISI 409 and AISI 316L; Estudo do tratamento termoquimico de carbonitretacao por plasma em tela ativa com pressoes variaveis nos acos inoxidaveis austenitico AISI 316L e ferririco AISI 409

    Energy Technology Data Exchange (ETDEWEB)

    Melo, M.S.; Oliveira, A.M.; Leal, V.S.; Sousa, R.R.M. de; Alves Junior, C. [Centro Federal de Educacao Tecnologica do Maranhao (CEFET/MA), Sao Luis, MA (Brazil); Centro Federal de Educacao Tecnologica do Piaui (CEFET/PI), Teresina, PI (Brazil); Universidade Federal do Rio Grande do Norte (DF/UFRN), Natal, RN (Brazil). Dept. de Fisica. Labplasma

    2010-07-01

    The technique called Active Screen Plasma Nitriding (ASPN) is being used as an alternative once it offers several advantages with respect to conventional DC plasma. In this method, the plasma does not form directly in the sample's surface but on a screen, in such a way that undesired effects such as the edge effect is minimized. Stainless steels present not very satisfactory wearing characteristics. However, plasma carbonitriding has been used as to improve its resistance to wearing due to the formation of a fine surface layer with good properties. In this work, samples of stainless steel AISI 316L and AISI 409 were treated at pressures of 2.5 and 5 mbar. After the treatments they were characterized by microhardness, microscopy and Xray diffraction. Microscopy and hardness analysis showed satisfactory layers and toughness in those steels. (author)

  10. Corrosion resistance of the welded AISI 316L after various surface treatments

    Directory of Open Access Journals (Sweden)

    Tatiana Liptáková

    2014-01-01

    Full Text Available The main aim of this work is to monitor the surface treatment impact on the corrosion resistance of the welded stainless steel AISI 316L to local corrosion forms. The excellent corrosion resistance of austenitic stainless steel is caused by the existence of stable, thin and well adhering passive layer which quality is strongly influenced by welding. Therefore surface treatment of stainless steel is very important with regard to its local corrosion susceptibility Surfaces of welded stainless steel were treated by various mechanical methods (grinding, garnet blasting. Surface properties were studied by SEM, corrosion resistance was evaluated after exposition tests in chlorides environment using weight and metalographic analysis. The experimental outcomes confirmed that the mechanical finishing has a significant effect on the corrosion behavior of welded stainless steel AISI 316L.

  11. Experimental study of mechanical properties of friction welded AISI 1021 steels

    Indian Academy of Sciences (India)

    Amit Handa; Vikas Chawla

    2013-12-01

    Friction welding is widely used as a mass production method in various industries. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed AISI 1021 steels. In this study, low alloy steel (AISI 1021) was welded under different welding parameters and afterwards the mechanical properties such as tensile strength, impact strength and hardness were experimentally determined. On the basis of the results obtained from the experimentation, the graphs were plotted. It is the strength of welded joints, which is fundamental property to the service reliability of the weldments and hence present work was undertaken to study the influence of axial pressure and rotational speed in friction welded joints. Axial pressure and rotational speed are the two major parameters which can influence the strength and hence the mechanical properties of the friction welded joints. Thus the axial pressure and rotational speed were taken as welding parameters, which reflect the mechanical properties.

  12. In Situ Observation of Solidification Process of AISI 304 Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    HUANG Fu-xiang; WANG Xin-hua; ZHANG Jiong-ming; JI Chen-xi; FANG Yuan; YU Yan

    2008-01-01

    The solidification process of AISI 304 stainless steel during cooling at a rate of 0.05 K/s has been observed in situ using a confocal scanning laser microscope(CSLM).The results show that the δ phase appeared first in liquid steel,as the temperature decreased,the γ phase precipitated prior at δ-grain boundary at 1452.2℃,the liquid steel disappeared at 1431.3℃,and then theγphase precipitated on the δ ferrite.Based on the Scheil-GulliVer solidification model,the solidification processes of AISI 304 stainless steel are simulated using the Scheil model in Thermo-Calc.and the simulation results agree well with the results observed in the experiment.

  13. Modelización de las transformaciones de fase en calentamiento continuo de aceros con microestructura inicial de ferrita, perlita y ferrita-perlita

    OpenAIRE

    Garcia Caballero, Francisca

    2011-01-01

    En este trabajo se han efectuado modelos te?ricos que describen los diferentes procesos de nucleaci?n y crecimiento que caracterizan las transformaciones de fases producidas durante el calentamiento continuo de aceros con diferentes composiciones y microestructuras iniciales. Dichos modelos se han aplicado con ?xito al c?lculo de la fracci?n de volumen de austenita que se forma, en funci?n de la temperatura, durante el calentamiento continuo de aceros con contenido de carbono u...

  14. Martensitic Transformation in Ultrafine-Grained Stainless Steel AISI 304L Under Monotonic and Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Heinz Werner Höppel

    2012-02-01

    Full Text Available The monotonic and cyclic deformation behavior of ultrafine-grained metastable austenitic steel AISI 304L, produced by severe plastic deformation, was investigated. Under monotonic loading, the martensitic phase transformation in the ultrafine-grained state is strongly favored. Under cyclic loading, the martensitic transformation behavior is similar to the coarse-grained condition, but the cyclic stress response is three times larger for the ultrafine-grained condition.

  15. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    OpenAIRE

    Chen Ying An; Francisco Piorino Neto; Eder Paduan Alves

    2010-01-01

    The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW), which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The results we...

  16. Martensitic transformation during fatigue testing of an AISI 301LN steel

    OpenAIRE

    Mateo García, Antonio Manuel; Fargas Ribas, Gemma

    2012-01-01

    The plastic deformation accumulated during fatigue testing can induce the transformation of austenite to martensite in metastable austenitic stainless steels. To analyze this issue, a metastable austenitic stainless steel grade AISI 301 LN was studied in two different conditions, i.e. annealed and cold rolled. In the first case, the steel was fully austenitic, whereas cold rolled material had almost 30% of martensite. High cycle fatigue tests at a stress ratio of 0.8 were carried out on flat ...

  17. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    Directory of Open Access Journals (Sweden)

    Rômulo Ribeiro Magalhães de Sousa

    2012-04-01

    Full Text Available AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN, with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

  18. Friction welding of AA6061 to AISI 4340 using silver interlayer

    OpenAIRE

    Suresh D. Meshram; G. Madhusudhan Reddy

    2015-01-01

    The present work pertains to the study on joining of AA6061 and AISI 4340 through continuous drive friction welding. The welds were evaluated by metallographic examination, X-ray diffraction, electron probe microanalysis, tensile test and microhardness. The study reveals that the presence of an intermetallic compound layer at the bonded interface exhibits poor tensile strength and elongation. Mg in AA6061 near to the interface is found to be favourable for the formation and growth of Fe2Al5 i...

  19. Inhibidores de escaso impacto medioambiental. Sistemas basados en tierras raras

    Directory of Open Access Journals (Sweden)

    Aballe, A.

    1997-12-01

    Full Text Available Lanthanum, Cerium and Samarium chlorides have been investigated as uniform and pitting corrosion inhibitors of AISI 434 and AISI 304 stainless steels and AA 5083 Al-Mg alloy in 3.5 % NaCl aerated aqueous solutions. Their inhibitor power was evaluated by using electrochemical techniques such as Linear and Cyclic Polarisation. In each case, the highest protection degree was found in the solution dopped with 500 ppm of CeCl3. Similar results were obtained for additions of 500 ppm of LaCl3. Scanning Electron Microscopy and Energy Dispersive Spectroscopy allowed us to confirm the cathodic nature of the inhibition process.

    Se estudia el comportamiento de los cloruros de lantano, cerio y samario como inhibidores de los procesos de corrosión uniforme y por picaduras de los aceros inoxidables AISI 434 y AISI 304 y de la aleación de aluminio AA 5083 en disoluciones aireadas de NaCl al 3,5 %. Utilizando técnicas electroquímicas como polarización lineal y cíclica, se ha podido evaluar el poder inhibidor de estas sustancias. El mejor comportamiento inhibidor se ha obtenido para una concentración de 500 ppm de CeCl3, si bien para los aceros se obtienen resultados del mismo orden para 500 ppm de LaCl3. Con la ayuda de microscopía electrónica de barrido y espectroscopia de dispersión de energía se ha podido confirmar el carácter catódico del mecanismo de inhibición que tiene lugar en el proceso.

  20. Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

    Science.gov (United States)

    Hartwig, A.; Decker, M.; Klein, O.; Karl, H.

    2015-12-01

    The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO2 implanted AISI 304 - examined for different implantation and annealing parameters - is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 1016 cm-2 (Ti+) and 1 × 1017 cm-2 (O+) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 1015 cm-2 (Ti+) and 1 × 1016 cm-2 (O+). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO2 inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

  1. Application of direct laser metal tooling for AISI H13 tool steel

    Institute of Scientific and Technical Information of China (English)

    Jae-Ho LEE; Jeong-Hwan JANG; Byeong-Don JOO; Hong-Sup YIM; Young-Hoon MOON

    2009-01-01

    In the die industry, it is commonly agreed that residual tool life can be successfully extended by timely repair of damaged surfaces. Traditionally, the main repair process is tungsten inert gas (TIG) welding, but a new process called direct laser metal tooling (DLMT) emerges. DLMT is a manual process, of which results depend on the materials of the powders and tools, the laser process and parameters. This technology is a direct-metal freeform fabrication technique in which a 200 W fiber laser is used. AISI H13 tool steel is a suitable material for die casting tools because of the high resistance to thermal fatigue and dimensional stability. In this research, AISI HI3 tool steel was melted with metal powder by fiber laser. Before melting AISI H13, the powders were analyzed with XRF equipment. Then, hardness distribution of laser melted zone was investigated. The microstructure in laser melted zone was discussed. In order to identify the effect of particle size of powder on the melted zone, two types of particle sizes of powders were used. Experimental results show that the mold repair process using DLMT can be applied in the mold repair industry.

  2. Nanoscale precipitates and comprehensive strengthening mechanism in AISI H13 steel

    Science.gov (United States)

    Mao, Wen-wen; Ning, An-gang; Guo, Han-jie

    2016-09-01

    The effects of heat treatment on the precipitates and strengthening mechanism in AISI H13 steel were investigated. The results showed that the presence of nanoscale precipitates favorably affected grain refinement and improved the yield strength. The volume fraction of precipitates increased from 1.05% to 2.85% during tempering, whereas the average precipitate size first decreased then increased during tempering. Contributions to the yield strength arising from the various mechanisms were calculated quantificationally, and the results demonstrated that grain refinement and dislocation density most strongly influenced the yield strength. In addition, under the interaction of average size and volume fraction, precipitates' contribution to the yield strength ranged from 247.9 to 378.5 MPa. Finally, a root-mean-square summation law of σ = σg + σs + (σd 2 + σp 2)1/2, where σg, σs, σd, and σp represent the contributions of fine-grain strengthening, solid-solution strengthening, dislocation strengthening, and precipitation strengthening, respectively, was confirmed as the most applicable for AISI H13 steel, which indicates a strong link between precipitates and dislocations in AISI H13 steel.

  3. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Sylvia Dundeková

    2015-05-01

    Full Text Available Stainless steels from 316 group are very often and successfully uses for medical applications where the good mechanical and chemical properties in combination with non-toxicity of the material assure its safe and long term usage. Corrosion properties of AISI 361L stainless steel are strongly influenced by surface roughness and treatment of the engineering parts (specimens and testing temperature. Electrochemical characteristics of ground, mechanically polished and passivated AISI 316L stainless steel specimens were examined with the aim to identify the polarization resistance evolution due to the surface roughness decrease. Results obtained on mechanically prepared specimens where only natural oxide layer created due to the exposure of the material to the corrosion environment was protecting the materials were compared to the passivated specimens with artificial oxide layer. Also the influence of temperature and stabilization time before measurement were taken into account when discussing the obtained results. Positive influence of decreasing surface roughness was obtained as well as increase of polarization resistance due to the chemical passivation of the surface. Increase of the testing temperature and short stabilization time of the specimen in the corrosion environment were observed negatively influencing corrosion resistance of AISI 316L stainless steel.

  4. Experimental investigation of wear characteristics on TiCN-coated AISI 410 steel

    Science.gov (United States)

    Prabakaran, Vijayasarathi; Sivakumaran, Ilaiyavel; Palimar, Suresh Prabhu

    2016-04-01

    In this work, the dry sliding wear test of uncoated and multilayer TiCN-coated AISI 410 steel against high carbon steel disc recognized at 2.30267 ms-1 sliding speeds and under a three series load of 5, 10 and 20 N at room temperature. On account of the more coherent interface between TiCN and C probably found, there are high hardness and superior wear resistance. Compared to AISI 410 uncoated steel, the presence of C in the multilayer TiCN coatings leads to reduced coefficient of friction and wear loss. The multilayer TiCN coating is characterized by X-ray diffraction analysis, scanning electron microscopy, micro-hardness and pin-on-disc tribometer tests. The more grooving region, pits and ploughing ridge were examined on the worn surface of the AISI 410 uncoated steel. The result shows hard multilayer TiCN-coated particles viewing on the worn surface of the high carbon steel disc.

  5. Comportamiento en frío y en caliente de aceros con bajo contenido de carbono obtenidos a través de procesos de laminación controlada

    OpenAIRE

    Quintana Hernández, María José

    2013-01-01

    Los aceros con bajo contenido de carbono microaleados con Ti y Nb fabricados en la planta de Arcelor Mittal en Asturias, España usando el método avanzado de control termomecánico para laminación (ATMCRP) de aceros se pueden dividir en dos rubros: aceros de fase dual (enfriados con agua) y aceros HSLA (cuando el enfriamiento se realiza más lentamente). Dentro de las ventajas de este proceso se encuentran las propiedades mecánicas que permiten su aplicación industrial y el bajo costo en compara...

  6. Estudio de la oxidación a elevada temperatura de ocho aleaciones en atmósferas de combustión de biomasa

    Directory of Open Access Journals (Sweden)

    Berlanga-Labari, C.

    2008-08-01

    resultados indican un buen comportamiento de los aceros inoxidables austeníticos y de las aleaciones de Inconel, mientras que el del acero martensítico no ha sido aceptable. Se ha propuesto el mecanismo conocido como “oxidación activa” para interpretar el comportamiento a la corrosión de estos materiales en estos medios.

  7. Mecanismos de fractura a alta temperatura en aceros eléctricos no-orientados

    Directory of Open Access Journals (Sweden)

    García-Sánchez, E. O.

    2007-08-01

    Full Text Available In this research work the effect of deformation temperature on the hot ductility of non-oriented electrical steels (0.6 % Si-0.3 Al % was studied using high temperature tensile tests. The specimens were machined from two thin slabs (50 mm thickness produced by CSP process (Compact Strip Process, one of them using 100 % sponge iron and the other using 67 % scrap and 33 % sponge iron. The tensile tests were carried out at constant strain rate (5×1010–4 s–1, and a temperature range from 850 to 1,200 °C. The results showed that the ductility decreased with the increment in the temperature until approximately 1,000 °C. At higher temperatures, a ductility recovery was observed only in the steel fabricated without scrap. Scanning Electron Microscopy on fracture surfaces showed that the loss of ductility is associated with intergranular cracking promoted by the austenitic transformation and AlN grain boundaries precipitation.

    Se investigó el efecto de la temperatura de deformación sobre la ductilidad de aceros eléctricos de grano no-orientado (0,6 % Si-0,3 % Al mediante ensayos de tracción uniaxial. Las probetas se obtuvieron de planchones delgados (50 mm de espesor tipo CSP (Continuous Strip Processing fabricados a partir de 100 % hierro esponja y una mezcla de 67 % chatarra y 33 % de hierro esponja. El rango de temperatura de estudio fue de 850 a 1.200 °C y los ensayos se llevaron a cabo a una velocidad de deformación constante de 5×10–4 s–1. Los resultados experimentales demostraron que la ductilidad (% RA disminuye con el aumento en la temperatura hasta un mínimo a ~1.000 °C. A temperaturas mayores, la ductilidad del acero fabricado a partir de 100 % hierro esponja se recupera. Este efecto no fue observado en el acero fabricado a partir de chatarra. La caracterización de las superficies de fractura mediante microscopía electrónica de barrido demostró que la pérdida de

  8. Corrosión bajo tensión de aceros eutectoides con trefilado progresivo

    Directory of Open Access Journals (Sweden)

    Ovejero, E.

    1998-05-01

    Full Text Available The consequences of the microstructural evolution in an eutectoid steel that has undergone a cold drawing process are studied. This manufacturing technique produces changes in the steel microstructure: a progressive orientation and slenderising of the pearlite colonies and an orientation and packing of the pearlite lamellae, thus reducing the interlamellar spacing. In addition, the experimental results of the stress corrosion cracking tests show that cold drawing produces resistant anisotropy in the steel and thus the stress corrosion cracking resistance is a directional property which seems to depend on the orientation of the microstructure in relation to the cold drawing direction. As a consequence, a transversal crack tends to change its propagation direction approaching the wire axis and a crack growth in mode I evolves to a mixed mode propagation.

    Se estudian las consecuencias de la evolución microestructural en un acero eutectoide que ha sufrido un proceso de trefilado progresivo. Esta técnica de fabricación origina una serie de cambios en la microestructura del acero: una orientación progresiva y un estiramiento de las colonias de perlita y una orientación y densificación de las láminas de perlita, reduciendo así el espaciado interlaminar. Por otra parte, los resultados experimentales de los ensayos de corrosión bajo tensión demuestran que el trefilado produce anisotropía resistente en el acero, y así la resistencia a la corrosión bajo tensión es una propiedad direccional que parece depender de la orientación de la microestuctura con respecto a la dirección del trefilado. Como consecuencia, una fisura transversal tiende a cambiar su dirección de propagación para aproximarse a la del eje del alambre, y un crecimiento en modo I evoluciona hacia una propagación en modo mixto.

  9. Soldagem por Atrito com Pino Não Consumível de Aços Inoxidáveis Duplex

    Directory of Open Access Journals (Sweden)

    Tiago Felipe de Abreu Santos

    2016-03-01

    Full Text Available Resumo Os aços inoxidáveis duplex são bem sucedidos em uma variedade de aplicações como a indústria alimentícia, petroquímica e para plantas de dessalinização da água do mar, onde alta a resistência à corrosão e alta resistência mecânica são exigidas. Contudo, durante operações de soldagem por fusão pode haver alteração da microestrutura favorável destes materiais comprometendo seu desempenho. O processo de soldagem por atrito com pino não consumível pode gerar juntas no estado sólido evitando os típicos problemas da solidificação da poça fundida como segregação de elementos de liga, formação de trincas de solidificação e liquação; para o caso de aços inoxidáveis superduplex, pode-se evitar proporções desbalanceadas de ferrita e austenita, formação de fases secundárias deletérias e crescimento de grão ferrítico na zona termicamente afetada. Juntas consolidadas com penetração completa foram obtidas usando chapas de 6 mm de espessura para os aços inoxidáveis duplex UNS S32101 e S32205 e superduplex S32750 e S32760. As amostras foram submetidas a ensaios de tração indicando uma melhoria do desempenho mecânica das juntas soldadas com o aumento da tensão de escoamento e do limite de resistência à tração para todos os casos. Em relação à caracterização microestrutural, um pronunciado refinamento da ordem de 1 μm foi observado na junta soldada. Este refinamento foi associado à combinação de mecanismos de restauração na microestrutura bifásica promovida pela deformação severa junto com a alta temperatura durante o processo de soldagem.

  10. Efecto del vanadio en la forja en tibio de un acero con contenido medio de carbono

    Directory of Open Access Journals (Sweden)

    García-Mateo, C.

    1998-05-01

    Full Text Available In the present work the influence of vanadium on the microstructure and mechanical properties of a medium carbon steel forged below 900°C is analysed. Undisolved V(CN refines the microstructure and together with reprecipitated particles during cooling contribute to strengthening. Both effects maintain mechanical strength levels without decreasing toughness values.

    En el presente trabajo se analiza la influencia del vanadio en la microestructura y en la resistencia mecánica de un acero con contenido medio de carbono, tras ser deformado por compresión plana a temperaturas inferiores a 900°C. Los carbonitruros de vanadio no disueltos afinan la microestructura y junto a los reprecipitados durante el enfriamiento contribuyen al endurecimiento por precipitación, manteniendo la resistencia mecánica y logrando una tenacidad aceptable al bajar la temperatura de deformación.

  11. Recomendaciones europeas para el empleo de tornillos de alta resistencia en las estructuras de acero

    Directory of Open Access Journals (Sweden)

    Batanero, J.

    1962-10-01

    Full Text Available Con el enlace de los perfiles de acero por medio de tornillos de alta resistencia, pretensados, se ha introducido en la construcción metálica un nuevo tipo de uniones, que resisten por rozamiento. Los tomillos de alta resistencia (exceptuados los calibrados deberán quedar en el agujero con una cierta holgura; y, mediante apretadura de la tuerca o de la cabeza, tensarse en forma que las superficies de contacto de las piezas unidas quedan fuertemente presionadas, una contra otra, muy especialmente en las proximidades del agujero. Con ello el esfuerzo que actúa perpendicularmente al eje del tomillo es resistido por el rozamiento estático entre las superficies unidas; en tanto que, como consecuencia, la espiga del tomillo queda sometida a una tracción axil y a una torsión.

  12. Selección automatizada de electrodos para la soldadura manual de los aceros al carbono

    Directory of Open Access Journals (Sweden)

    Alexander Velázquez Font

    2008-01-01

    Full Text Available Se aborda lo relativo a un sistema para la selección automatizada de electrodos en la soldadura de los aceros al carbono. Se inicia con una breve revisión de los problemas que presentan estos en su soldabilidad y los factores concernientes a la selección correcta del electrodo en los mismos. En el mismo se expone el fundamento teórico sobre el diseño del sistema el cual da solución a lo anteriormente expuesto. En la elaboración del software se tiene en cuenta los siguientes principios: propiedades mecánicas de la unión soldada, tipo de revestimiento, posición de la soldadura, etc. Se tienen en cuenta en el trabajo diferentes firmas y normas de fabricantes de electrodos y países que mas se utilizan en la industria mecánica en Cuba. El software tiene la ventaja de ser sencillo, rápido y seguro, garantizando la selección correcta de los electrodos para cada caso y situación. El software supone que el usuario no tenga que tener conocimientos profundos de soldadura, debido a que el sistema se encarga de la mayor parte de las decisiones para la selección del electrodo, procedimiento que con métodos convencionales, exigen del usuario una determinada experiencia en la selección de estos materiales para la soldadura de los aceros al carbono.

  13. Agitación electromagnética en la colada continua de acero

    Directory of Open Access Journals (Sweden)

    Álvarez de Toledo, G.

    1995-02-01

    Full Text Available The electromagnetic stirring of steel in the machines for the continuous casting process has improved the internal quality of the cast product. Experimental work with stirrers situated at different positions of continuous casting machines of billets has been carried out. The in-mould stirrer is the one that produces a major modification of the billet internal structure, and also the biggest decrease of the central segregation. An in-mould electromagnetic coil has been developed which allows the use of high stirring power without producing an undesirable movement of the liquid steel in the meniscus zone, therefore no mould powders entrapments are produced. It has been developed a method for determining the optimum electric frequency of the stirrer.

    La instalación de agitadores electromagnéticos en las máquinas de colada continua del acero ha mejorado notablemente la calidad interna del producto colado. En este trabajo se describen los ensayos efectuados con bobinas agitadoras situadas en diferentes lugares en máquinas de colada continua de palanquilla. Se ha puesto de manifiesto que la bobina situada en el molde, al comienzo del proceso de solidificación, es la que produce una mayor modificación de la estructura de solidificación junto con una disminución de la segregación central de la palanquilla. Se ha diseñado una bobina para el molde que permite utilizar altas potencias de agitación sin que el movimiento del acero líquido, a la altura del menisco, produzca atrapes de los polvos de colada. Por otro lado, se ha encontrado un método por el que se puede calcular la frecuencia eléctrica óptima de trabajo de la bobina situada en el molde.

  14. Caracterização química e metalográfica dos aços inoxidáveis de implantes removidos de pacientes

    OpenAIRE

    Silva,Elison da Fonseca e; Oliveira,Luiz Fernando Cappa de

    2011-01-01

    OBJETIVO: Este trabalho estudou a composição química e metalográfica (microestrutura, tamanho de grão, teor de inclusões) de aços inoxidáveis austeníticos, desenvolvidos para aplicações como biomateriais, utilizados na fabricação de implantes ortopédicos. MÉTODO: Foram analisados doze implantes removidos de pacientes afetados por quadro inflamatório. As análises químicas foram desenvolvidas pelas técnicas Espectrometria de Emissão Ótica e Microanálise por Dispersão de Energia (EDS) e o tamanh...

  15. Mejora de la tenacidad de un acero de ultraalto contenido en carbono nnediante unión por laminación con un acero al cromo y molibdeno

    Directory of Open Access Journals (Sweden)

    Pozuelo, M.

    2005-12-01

    Full Text Available Laminated composite materials containing five layers of ultrahigh carbon steel, 1.35%C, and five layers of a Cr-Mo steel were processed by roll bonding. The rolling procedure improves the bonding of layers and refines the microstructure, diminishing grain size and removing the pearlitic zones. Charpy impact tests were carried out to evaluate the impact properties. Toughness of the laminated composite was highly improved respect to the ultrahigh carbon steel. Moreover, it was double than that of the Cr-Mo steel in the arrester orientation. These results reveal the important role of the interfaces in the mechanical properties of the composite materials.

    Se procesaron mediante unión por laminación, dos materiales compuestos laminados de 10 capas: cinco capas de un acero de ultraalto contenido en carbono con 1,35 % C, alternadas con otras cinco de un acero al cromo y molibdeno. La laminación en caliente consolida la unión entre las capas y afina la microestructura, reduciendo el tamaño de grano y eliminando las zonas de perlita presentes inicialmente. Se realizaron ensayos de impacto Charpy para evaluar su resistencia al impacto. El material compuesto laminado mejoró sustancialmente la tenacidad del acero de ultraalto carbono, además de duplicar la resiliencia del acero al cromo y molibdeno en la orientación "en serie". Estos resultados ponen de manifiesto la importancia de las intercaras en las propiedades mecánicas de los materiales compuestos.

  16. Modelización de las transformaciones de fase en el proceso de endurecimiento de aceros con láser de CO2

    Directory of Open Access Journals (Sweden)

    Amado, J. M.

    2004-10-01

    Full Text Available Hardening processes of steel are very dependent on the heating and cooling rates, in both cases high rates are needed. In the laser hardening the power density of the laser beam is responsible of the fast heating of the material; fast cooling is achieved due to the heat conduction from the region being treated to the bulk of the workpiece. Within this work thermal cycles are determined with a Finite Element Model which computes the temperature of the material during the laser treatment. For the prediction of the hardening IT diagrams are applied, isothermal steps are connected with constant volume fraction steps; the content of each phase is computed in the framework of the Johnson-Mehl and Avrami law. During the cooling process, a similar procedure is applied but now using TTT diagrams. Model validation is done comparing, on a local basis, microhardness measurement on a treated workpiece with the martensite concentration extracted from the model.

    Los procesos de endurecimiento superficial de aceros dependen de los ritmos de calentamiento y enfriamiento del material, que han de ser rápidos. En el endurecimiento por láser, el rápido calentamiento viene asegurado por la elevada densidad de potencia del haz láser incidiendo sobre un pequeño volumen de la pieza, mientras que el flujo de calor por conducción hacia el resto del material ayuda a producir un rápido ritmo de enfriamiento. En este artículo, los ciclos térmicos se determinan con la ayuda de un modelo de elementos finitos que calcula la evolución de la temperatura en los diferentes puntos del material durante el proceso de tratamiento con láser. Para la predicción del endurecimiento son necesarios los diagramas de calentamiento isotermo (IT para su aplicación durante el calentamiento; la cuantificación de las transformaciones se realiza en una serie de pasos isotermos conectados con otros de fracción de volumen constante; el porcentaje de cada fase se calcula

  17. Comportamiento Frente a la Corrosión en Ambiente Marino de Acero Galvanizado y Acero Galvanizado Pintado (Duplex Corrosion Behaviour of Galvanized and Coated Galvanized Steel (Duplex in Marine Environment

    Directory of Open Access Journals (Sweden)

    R.M. Vera

    2005-01-01

    Full Text Available En este estudio se evaluó el comportamiento frente a la corrosión en medio marino de acero galvanizado y acero galvanizado pintado (Duplex haciendo uso de ensayos electroquímicos y acelerados de laboratorio. Las medidas electroquímicas consideraron potencial de corrosión a circuito abierto, curvas de polarización y polarización potenciostática en cloruro de sodio 0.1M. Los ensayos acelerados se realizaron en cámara de niebla salina y con el método Cebelcor. El grado de ataque del material se observó por microscopia electrónica de barrido. Los resultados muestran que el sistema Duplex presenta un mejor comportamiento frente la corrosión en medio de cloruros que el acero galvanizado, aumentando su durabilidad en el tiempo.This study evaluated the resistence to corrosion of galvanized and painted galvanized (Duplex steel in a marine environment using electrochemical and accelerated laboratory essays. The electrochemical measurements included open circuit potential, polarization curves, and potentiostatic polarization in 0.1M sodium chloride. The accelerated essays were carried out in a saline fog chamber and also using the Cebelcor method. The degree of corrosion attack of the material was observed by scanning electronic microscopy. The results show that the Duplex system presents a better behaviour against corrosion in chloride media than galvanized steel, increasing its useful life.

  18. Evaluation of performance of AISI 444 steel for application in distillation towers; Avaliacao do desempenho do aco AISI 444 para aplicacao como 'lining' em torres de destilacao

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, R.F.; Miranda, H.C. de; Farias, J.P. [Universidade Federal do Ceara (DEMM/UFC), Fortaleza, CE (Brazil). Dept. de Engenharia Metalurgica e de Materiais. Lab. de Caracterizacao de Materiais], e-mail: rf.guimaraes@yahoo.com.br

    2008-07-01

    In this work, the behavior of the AISI 444 ferritic stainless steel submitted to thermal fatigue test and their corrosion resistance in heavy crude oil was evaluated. The AWS E309MoL-16 and E316L-17 weld metal was employed as filler metal. Plates of the AISI 444 were welded on ASTM A-516 Gr. 60 plates and submitted to fatigue thermal cycle. Samples were extracted from plates welded and heat treated immersed in heavy crude oil at 300 deg C. Optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive of X-ray analysis (EDX) were used to characterize the microstructure and the corroded surface. The results show that the AISI 444 stainless steels did not present cracks after the thermal fatigue cycle and the heat treated immerse in heavy crude oil. The electrode AWS E309MoL-16 show better corrosion resistance than the AWS E316L-17. (author)

  19. Wear Evaluation of AISI 4140 Alloy Steel with WC/C Lamellar Coatings Sliding Against EN 8 Using Taguchi Method

    Science.gov (United States)

    Kadam, Nikhil Rajendra; Karthikeyan, Ganesarethinam

    2016-10-01

    The purpose of the experiments in this paper is to use the Taguchi methods to investigate the wear of WC/C coated nitrided AISI 4140 alloy steel. A study of lamellar WC/C coating which were deposited by a physical vapor deposition on nitrided AISI 4140 alloy steel. The investigation includes wear evaluation using Pin-on-disk configuration. When WC/C coated AISI 4140 alloy steel slides against EN 8 steel, it was found that carbon-rich coatings show much lower wear of the countersurface than nitrogen-rich coatings. The results were correlated with the properties determined from tribological and mechanical characterization, therefore by probably selecting the proper processing parameters the deposition of WC/C coating results in decreasing the wear rate of the substrate which shows a potential for tribological application.

  20. Preparation of high-performance ultrafine-grained AISI 304L stainless steel under high temperature and pressure

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2016-08-01

    Full Text Available Bulk ultra-fine grained (UFG AISI 304L stainless steel with excellent mechanical properties was prepared by a high-temperature and high-pressure (HTHP method using nanocrystalline AISI 304L stainless steel powders obtained from ball milling. Samples were sintered in high-pressure conditions using the highest martensite content of AISI 304L stainless steel powders milled for 25 h. Analyses of phase composition and grain size were accomplished by X-ray diffraction and Rietveld refinement. By comparing the reverse martensite transformation under vacuum and HTHP treat, we consider that pressure can effectively promote the change in the process of transformation. Compared with the solid-solution-treated 304L, the hardness and yield strength of the samples sintered under HTHP are considerably higher. This method of preparation of UFG bulk stainless steel may be widely popularised and used to obtain UFG metallic materials with good comprehensive performance.

  1. Corrosion Inhibition of AISI 316L and Modified-AISI 630 Stainless Steel by the New Organic Inhibitor [(CH32N]3PSe in Chloride Media:Electrochemical and Physical Study

    Directory of Open Access Journals (Sweden)

    Yafa ZARGOUNI

    2015-04-01

    Full Text Available We evaluate the effect of the Tris-dimethylaminoselenophosphoramide (SeAPon the corrosion inhibition of modified-AISI 630 and AISI 316L stainless steel (SS in 3 wt. % NaCl. The electrochemical behaviors of tested SS samples are investigated before and after adding the Seep into the chloride media by potentiodynamic polarization technique. The adsorption of SeAP onto both SS surfaces is verified by global discharge optical emission spectroscopy (GDOES.  SeAP is found to be a good inhibitor for SS corrosion, especially when added at a concentration of 0.5 wt. %.

  2. Modification and characterization of the AISI 410 martensitic stainless steels surface; Modificacao e caracterizacao da superficie do aco inoxidavel martensitico AISI 410

    Energy Technology Data Exchange (ETDEWEB)

    Bincoleto, A.V.L. [Universidade Federal de Sao Carlos (PPG-CEM/UFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Nascente, P.A.P. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    Steam turbines are used in the generation of more than half the electric energy produced in the world nowadays. It is important the study which aims to improve the efficiency by means of the optimization of leaks and of the aerodynamic profiles, as well as to maintain the integrity of the components. The martensitic stainless steels are widely employed due to the combination of their good mechanical properties with higher corrosion resistance. However, their lower wear resistance and their poor tribological behavior limit their use, since they decrease the component life time. In order to evaluate the improvement in the performance of the AISI 410 stainless steel, several process of surface modification were employed. Five samples were produced: the first one was not treated, the second one received liquid nitriding, the third, gas nitriding, the forth, thermal aspersion of tungsten carbide, and the fifth, boronizing. The samples were characterized by optical microscopy, surface microhardness, and X-ray diffractometry. (author)

  3. Numerical-experimental analysis of a rin AISI{sub 7}Mg Alloy; Analisis numerico experimental de un rin de aleacion AISi{sub 7}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Sauceda Mesa, Israel; Mata Lucero, Omar; Tirado Delgado, Luis; Ocampo Diaz, Juan de Dios [Universidad Autonoma de Baja California, Mexicali, Baja California (Mexico)

    2005-10-15

    The present work shows the results obtained from an investigation mode on the behaviour of a rin of alloy AISi{sub 7}Mg, which is used in compact Volkswagen's cars. Due to two kind of analysis were realized, firstly an experimental and numerical analysis was done, using a special machine for test the flexionante torque and material fatigue, besides was used an equipment of laser to scanner zone with strength concentrations and the maximum displacement amplitudes. The second analysis was done with the finite element technique, using the software ANSYS and CATIA. The difference between life fatigue cycles obtained from the two analyses was 0.6%. While the time optimize by MEF, was of 85% less than experimental analysis. [Spanish] En el presente trabajo se hicieron investigaciones del comportamiento de un rin de aleacion AISi{sub 7}Mg, el cual es usado en automoviles compactos de volkswagen (VW). Para esto, se realizo analisis experimental y numerico. En el primero se utilizo una maquina para prueba de fatiga de momento flexionante, un equipo de medicion de laser escaner donde se detectaron las zonas de concentraciones de esfuerzos y la maxima amplitud de desplazamiento en el rin. Mientras que en el segundo se obtuvieron los esfuerzos que ocasionaban la fatiga por el elemento finito, utilizando los paquetes de computo Ansys y Catia. La diferencia de los ciclos de vida de fatiga obtenidos entre ambos analisis fue del 0.6%. Mientras que el tiempo que se optimizo por el MEF, fue de un 85% menos que el analisis experimental.

  4. Characterization Of Oxide Layers Produced On The AISI 321 Stainless Steel After Annealing

    Directory of Open Access Journals (Sweden)

    Bochnowski W.

    2015-09-01

    Full Text Available In this study, the structure, chemical composition and topography of oxide layers produced on the surface of the AISI 321 austenitic steel in the annealing process were analyzed. Heat treatment was done at 980°C temperature for 1 hour time in different conditions. The annealing was done in a ceramic furnace in oxidation atmosphere and in vacuum furnaces with cylindrical molybdenum and graphite chambers. The analysis was carried out using the following methods: a scanning electron microscope (SEM equipped with an energy-dispersive X-ray spectrometer (EDX, a transmission electron microscope (TEM equipped with an energy-dispersive X-ray spectrometer (EDX, an X-ray diffractometer (XRD, a secondary ion mass spectrometer with time-of-flight mass analyzer (TOF SIMS and an atomic force microscope (AFM. The oxide layer formed during annealing of the AISI 321 steel at 980°C consisted of sub-layers, diversified in the chemical composition. The thickness of the oxidized layer is depended on the annealing conditions. In a ceramic furnace in oxidation atmosphere, the thickness of the oxide layer was of 300-500 nm, in a vacuum furnace with molybdenum and graphite heating chambers, it ranged from 40 to 300 nm and from a few to 50 nm, respectively. TOF SIMS method allows to get average (for the surface of 100 μm × 100 μm depth profiles of concentration of particular elements and elements combined with oxygen. In oxide layers formed in vacuum furnaces there are no iron oxides. Titanium, apart from being bounded with carbon in carbides, is a component of the oxide layer formed on the surface of the AISI 321 steel.

  5. Electrochemical and pitting corrosion resistance of AISI 4145 steel subjected to massive laser shock peening treatment with different coverage layers

    Science.gov (United States)

    Lu, J. Z.; Han, B.; Cui, C. Y.; Li, C. J.; Luo, K. Y.

    2017-02-01

    The effects of massive laser shock peening (LSP) treatment with different coverage layers on residual stress, pitting morphologies in a standard corrosive solution and electrochemical corrosion resistance of AISI 4145 steel were investigated by pitting corrosion test, potentiodynamic polarisation test, and SEM observations. Results showed massive LSP treatment can effectively cause an obvious improvement of pitting corrosion resistance of AISI 4145 steel, and increased coverage layer can also gradually improve its corrosion resistance. Massive LSP treatment with multiple layers was shown to influence pitting corrosion behaviour in a standard corrosive solution.

  6. An Electrochemical Impedance Study of AISI 321 Stainless Steel in 0.5 M H2SO4

    Directory of Open Access Journals (Sweden)

    A. Fattah-Alhosseini

    2011-01-01

    Full Text Available The electrochemical behavior of passive films formed on AISI 321 has been examined using electrochemical impedance spectroscopy. AISI 321 is characterized by high interfacial impedance, thereby illustrating its high corrosion resistance. Results showed that the interfacial impedance and the polarization resistance initially increase with applied potential, within the low potential. However, at a sufficiently high potential (>0.6 V, the interfacial impedance and the polarization resistance decrease with increasing potential. The impedance data were adequately represented by an equivalent electrical circuit model based on point defect model, which described the behavior of the passive film on stainless steel more satisfactorily than the proposed models.

  7. Estimation of embrittlement during aging of AISI 316 stainless steel TIG welds

    Indian Academy of Sciences (India)

    J Nayak; K R Udupa; K R Hebbar; H V S Nayak

    2004-12-01

    Weldments of AISI grade 316 stainless steel, having a ferrite content of 4–6% and a variety of nitrogen concentrations were prepared using a modified element implant technique. Charpy impact specimens prepared from these weldments were subjected to a variety of aging treatments. Impact toughness decreases with aging time at all aging temperatures. Nitrogen is found to be beneficial to toughness. An empirical relation connecting the aging temperature, aging time and nitrogen content with toughness has been developed which can be used to estimate the time for embrittlement.

  8. Biaxial fatigue tests of notched specimens for AISI 304L stainless steel

    Directory of Open Access Journals (Sweden)

    G. Beretta

    2016-07-01

    Full Text Available High cycle fatigue tests were conducted for stainless steel AISI 304L. The geometry was a thin walled tube with a passing through hole. The tests were axial, torsional and in-phase axial-torsional, all of them under load control with R = −1. The S-N curves were constructed following the ASTM E739 standard and the fatigues limits were calculated following the method of maximum likelihood proposed by Bettinelli. The crack direction along the surface was analysed, with especial attention to the crack initiation zones. The notch fatigue limits for different hole diameters were compared with the predictions done with a microstructural fracture mechanics model.

  9. HTS SQUID application for measuring the magnetic properties of AISI type 316L(N) steel

    Energy Technology Data Exchange (ETDEWEB)

    Park, D.G. E-mail: dgpark@nanum.kaeri.re.kr; Kim, D.W.; Hong, J.H.; Timofeev, V.P.; Kim, C.G

    2000-06-02

    A portable RF HTS SQUID-based susceptometer was used for small-size magnetized sample testing in weak DC (up to 200 A/m) and AC (up to 4 A/m) magnetic fields. The system resolution for the magnetic moment is of the order of 1.6x10{sup -10} A m{sup 2}. The measured DC susceptibility of a tested sample of Gd{sub 88}La{sub 12} agrees well with the value obtained by using a commercial liquid helium susceptometer. The measured volume susceptibility of AISI type 316L(N) steel increases after fatigue due to the microcrack induced by cyclic stress.

  10. Microstructural changes due to laser surface melting of an AISI 304 stainless steel

    Directory of Open Access Journals (Sweden)

    d?Oliveira A.S.C.M.

    2001-01-01

    Full Text Available Several techniques can be used to improve surface properties. These can involve changes on the surface chemical composition (such as alloying and surface welding processes or on the surface microstructure, such as hardening and melting. In the present work surface melting with a 3kW CO2 cw laser was done to alter surface features of an AISI 304 stainless steel. Microstructure characterisation was done by optical and scanning electron microscopy. Vickers and Knoop microhardness tests evaluated mechanical features after surface melting. Phase transformation during rapid solidification is analysed and discussed.

  11. PITTING CORROSION OF AISI 316Ti STAINLESS STEEL WITH POLISHED SURFACE

    Directory of Open Access Journals (Sweden)

    Viera Zatkalíková

    2010-05-01

    Full Text Available AISI 316Ti is Cr–Ni–Mo austenitic stainless steel with the high Pitting Resistance Equivalent Number (PREN. The effect of the surface finishing by polishing on the pitting corrosion resistance was tested in aggressive 5% FeCl3 solution. The immersion tests were curried out at the temperature 30, 50, 80 °C. The electrochemical cyclic potentiodynamic tests were carried out in the same solution at temperature 30 and 50 °C. The evaluation of the corrosion resistance arose from the comparison of the results of the immersion and the cyclic potentiodynamic tests.

  12. 1020 AISI-SAE steel Austenitic Nitrocarburising with alcohol and triethanolamine

    Directory of Open Access Journals (Sweden)

    Álvaro Castro P

    2010-04-01

    Full Text Available The present work shows AISI-SAE 1020 steel's nitrocarbide layer's microstructure and micro-hardness profile following 4 hours at 700ºC using methanol, isopropanol and triethanolamine. The steel was then hardened by quenching it in water and then tempered at 350ºC for 1 hour. Its surface had been partially oxidised by heating it at 400ºC for 1 hour. An example is given of other researchers analysing microstructure and propierties in steel having 0,5% C, using endothermic gas and different amounts of ammoniac.

  13. The structural characterization of some biomaterials, type AISI 310, used in medicine

    Science.gov (United States)

    Minciuna, M. G.; Vizureanu, P.; Hanganu, C.; Achitei, D. C.; Popescu, D. C.; Focsaneanu, S. C.

    2016-06-01

    Orthopedics biomaterials are intended for implantation in the human body and substituted or help to repair of bones, cartilage or organ transplant, and tendons. At the end of the 20th century, the availability of materials for the manufacture implants used in medicine has been the same as for other industrial applications. The most used metals for manufacturing the orthopedics implants are: stainless steels, cobalt-chrome-molybdenum alloys, titanium and his alloys. The structural researches which are made in this paper, offer a complete analysis of AISI310 stainless steels, using: optical spectrometry, X-ray diffraction and scanning electronic microscopy.

  14. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  15. Mechanical Properties of Stellite-6 coated AISI 316L Stainless Steel

    Directory of Open Access Journals (Sweden)

    Pushpinderjit Singh

    2016-01-01

    Full Text Available Present paper describes the mechanical properties of Stellite-6 coated AISI 316 L stainless steel. Specimens were coated using Detonation Gun thermal spray process, with different coating thicknesses of Stellite-6 ranging from 50 µm to 150 µm. Afterwards their properties like tensile strength, impact strength and micro hardness were evaluated on the basis of the results obtained from the experimentation. For comparison of substrate and coated material the graphs were plotted. The coated specimens exhibited superior impact strength and microhardness than that of the bare specimens, whereas the tensile strength of coated specimens decreased marginally with the increase in coating thickness.

  16. Investigating early stages of biocorrosion with XPS: AISI 304 stainless steel exposed to Burkholderia species

    Science.gov (United States)

    Johansson, Leena-Sisko; Saastamoinen, Tuomas

    1999-04-01

    We have investigated the interactions of an exopolymer-producing bacteria, Burkholderia sp. with polished AISI 304 stainless steel substrates using X-ray photoelectron spectroscopy (XPS). Steel coupons were exposed to the pure bacteria culture in a specially designed flowcell for 6 h during which the experiment was monitored in situ with an optical microscope. XPS results verified the formation of biofilm containing extracellular polymer on all the samples exposed to bacteria. Sputter results indicated that some ions needed for metabolic processes were trapped within the biofilm. Changes in the relative Fe concentration and Fe 2p peak shape indicated that also iron had accumulated into the biofilm.

  17. Tratamiento térmico con láser de cuchillas de acero para uso agrícola

    Directory of Open Access Journals (Sweden)

    Muñiz, G.

    2003-12-01

    Full Text Available The present paper focuses on the laser surface treatment of mild steels with different %wt of carbon to be used as cutting blades in agricultural applications. The results are discussed in function of the metallographic study, hardness profiles, wear resistance and corrosion testing. Special attention is paid to the results of the results obtained with the experimental steel with carbon 0.33 %wt because it is a new promising material specifically developed to be applied in such agricultural uses. Metallographic studies showed three well defined regions: the laser treated zone, where solid state phase transformation occurs, the heat affected zone (HAZ with partial transformations and finally the bulk metal with the original microstructure. Surface hardness was in all cases higher than the base steel in a depth range 600 μm. Wear resistance is notably improved with laser heat treatment while no detrimental effects were induced in their specific corrosion resistance.

    En el presente trabajo se muestran los resultados obtenidos en el temple superficial mediante láser, sobre aceros con distintos contenidos en carbono susceptibles de empleo en la producción de cuchillas de corte para aplicaciones agrícolas. Se comparan los resultados de los distintos aceros en función de su estudio metalográfico, perfiles de dureza y ensayos de resistencia al desgaste y a la corrosión. Destacan los resultados obtenidos con el acero de 0,33 % de carbono, por tratarse de un acero experimental de producción reciente para su empleo en cuchillas de uso agrícola. Tras el estudio metalográfico, se aprecia, en la capa superficial del metal tratado, la existencia de tres zonas bien definidas: la zona tratada en la que ocurren las transformaciones de fase típicas del temple, una zona de transición, que podemos considerar como la zona afectada térmicamente (ZAT, con transformaciones parciales y, por último, el metal base con su microestructura de origen. Las

  18. Técnicas para revelar el borde de grano austenítico en aceros microaleados

    Directory of Open Access Journals (Sweden)

    García de Andrés, Carlos

    2001-08-01

    Full Text Available The prior austenite grain size (PAGS exerts an important influence on the microstructures forged by continuous cooling in the steel and on their mechanical properties. Since microalloyed steels have received considerable attention in the last years and enormous difficulties have been repetitively to reveal the austenite grain boundaries in these steels, this work analyzes the different techniques effective in that sense, which enable thus an accurate determination of the PAGS. This paper presents results obtained applying different conventional techniques such us chemical etching of quenched microstructures, the application of thermal cycles that enable the formation of phases around the prior austenite grain boundaries or oxidation etching which reveals the austenite grain boundaries by the preferential accumulation of oxides. Finally, an innovative and effective technique to reveal the prior austenite grain boundaries is presented. This technique is based on the preferential transfer of matter from the grain boundaries to the surrounding austenite by complicated mechanisms such as evaporation-condensation and volume and surface diffusion of atoms.

    El tamaño de grano austenítico (TGA tiene una gran influencia sobre la microestructura final y sobre las propiedades mecánicas de los productos obtenidos por transformación anisotérmica del acero. Debido a la considerable atención que se está prestando a los aceros microaleados en los últimos años y a las dificultades que se encuentran en muchos casos para poder revelar los bordes de grano austenítico de estos aceros, en este trabajo se han analizado las técnicas que lo hacen posible, permitiendo así la determinación fiable del TGA. En este sentido, se presentan los resultados obtenidos al aplicar aislada y combinadamente distintas técnicas tradicionales, como el ataque químico de microestructuras obtenidas directamente por temple, la aplicación de diferentes tipos de ciclos t

  19. Aceros para embutido profundo: fabricación, caracterización, microestructura y texturas

    Directory of Open Access Journals (Sweden)

    Sipos, K.

    2005-12-01

    Full Text Available The knowledge of the characteristics of formability of steel sheets is of high technological interest in the deep drawing industry. In this paper we show how steel sheets are evaluated for their formability through various parameters of their mechanical properties, and how they are related to their manufacture at the steel plant. During this process the knowledge of the different metallurgical phenomena in the various steps allow the correct control of the cristalographical textures, which finally permit the development of good normal and planar anisotropy indexes. Industrial examples show the relationship between the operative parameters and the obtained results, illustrated not only through the values of the anisotropy indexes but also through the obtained textures. The characterization of the product through the forming limit curves permits to evaluate different product designs and the use of different types of steels for their manufacture. An example of a polishing machine cover is shown.

    El conocimiento de las características de formabilidad de las chapas metálicas es de gran interés tecnológico para la industria del conformado de planchas de acero. En el presente trabajo se muestra cómo se evalúan las chapas en su aptitud a la embutición a través de variados parámetros de propiedades mecánicas, y cómo éstas se relacionan con su fabricación en la industria siderúrgica. Durante este proceso, el conocimiento de los fenómenos metalúrgicos en las distintas etapas permiten el correcto control de las texturas cristalográficas, las cuales, finalmente, permiten el desarrollo de buenos índices de anisotropía normal y planar. Se muestra, a través de ejemplos industriales, la relación entre los parámetros operativos y los resultados obtenidos, ilustrándose éstos no solo a través de valores de los índices de anisotropía sino que también a través de las texturas obtenidas. La caracterización del producto a través de

  20. Reciclado de los residuos siderúrgicos de fabricación de acero. Nueva alternativa

    Directory of Open Access Journals (Sweden)

    Fernández López, Miguel

    2001-08-01

    Full Text Available A brief description of a new process for recycling hot electric steelmaking wastes of high iron oxides content, from ministeel mills that produce common and special steels is made. The new process is designed to get the best treatment cost for the residues recycling. It is based in the application of the principles of technologies experienced in ministeel industries. This is possible because the following improvements are obtained: a obtention of a commercial product of high zinc oxide content; b avoidance of new toxic wastes; c use of low cost process energy; d increase of metallic yield in the residues; and e treatment of residues in the mill ("in situ", or from other ministeel mill ("off site". Previous technologies precedents of the new process, are given and a comparative study between the new recycling process and the same recycling process without heating pretreatment using the same furnace is made. Electric steel making wasts. Recycling

    Se presenta una breve descripción de un nuevo procedimiento de reciclado de residuos, de alto contenido en óxidos de hierro, generados en miniacerías fabricantes de acero por hornos eléctricos de arco (común y especial, dentro y/o fuera de las instalaciones del generador (“in situ” y ''off site''. El procedimiento pretende, la reducción de los costes de reciclado de dichos residuos, respecto a procedimientos actuales, al incluir las siguientes mejoras: a obtención de un producto comercializable rico en ZnO; b ausencia de residuos tóxicos necesitados de tratamiento; c utilización de energía de proceso de bajo coste, en sustitución parcial de energía eléctrica; d aumento de la recuperación de metales en los residuos; y e versatilidad para poder reciclar los residuos ”in situ'' u ''off site", según procedan de una o de varias miniacerías, respectivamente. Se describen los fundamentos y sus precedentes tecnológicos, así como un breve an

  1. Dynamic strain ageing of deformed nitrogen-alloyed AISI 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Ehrnsten, U.; Toivonen, A. [Materials and Structural Integrity, VTT Technical Research Centre of Finland, Kemistintie 3, P.O. Box 1704, FIN-02044 VTT (Finland); Ivanchenko, M.; Nevdacha, V.; Yagozinskyy, Y.; Haenninen, H. [Department of Mechanical Engineering, Helsinki University of Technology Puumiehenkuja 3, P.O. Box 4200, FIN-02015 HUT (Finland)

    2004-07-01

    Intergranular stress corrosion cracking has occurred in BWR environment in non-sensitized, deformed austenitic stainless steel materials. The affecting parameters are so far not fully known, but deformation mechanisms may be decisive. The effect of deformation and nitrogen content on the behaviour of austenitic stainless steels was investigated. The materials were austenitic stainless steels of AISI 316L type with different amounts of nitrogen (0.03 - 0.18%) and they were mechanically deformed 0, 5 and 20%. The investigations are focused on the dynamic strain ageing (DSA) behaviour. A few crack growth rate measurements are performed on nuclear grade AISI 316NG material with different degrees of deformation (0, 5 and 20%). The effects of DSA on mechanical properties of these materials are evaluated based on peaks in ultimate tensile strength and strain hardening coefficient and minimum in ductility in the DSA temperature range. Additionally, internal friction measurements have been performed in the temperature range of -100 to 600 deg. C for determining nitrogen interactions with other alloying elements and dislocations (cold-worked samples). The results show an effect of nitrogen on the stainless steel behaviour, e.g. clear indications of dynamic strain ageing and changes in the internal friction peaks as a function of nitrogen content and amount of deformation. (authors)

  2. Improving by postoxidation of corrosion resistance of plasma nitrocarburized AISI 316 stainless steels

    Science.gov (United States)

    Yenilmez, A.; Karakan, M.; Çelik, İ.

    2017-01-01

    Austenitic stainless steels are widely used in several industries such as chemistry, food, health and space due to their perfect corrosion resistance. However, in addition to corrosion resistance, the mechanic and tribological features such as wear resistance and friction are required to be good in the production and engineering of this type of machines, equipment and mechanic parts. In this study, ferritic (FNC) and austenitic (ANC) nitrocarburizing were applied on AISI 316 stainless steel specimens with perfect corrosion resistance in the plasma environment at the definite time (4 h) and constant gas mixture atmosphere. In order to recover corrosion resistance which was deteriorated after nitrocarburizing again, plasma postoxidation process (45 min) was applied. After the duplex treatment, the specimens' structural analyses with XRD and SEM methods, corrosion analysis with polarization method and surface hardness with microhardness method were examined. At the end of the studies, AISI 316 surface hardness of stainless steel increased with nitrocarburizing process, but the corrosion resistance was deteriorated with FNC (570 °C) and ANC (670 °C) nitrocarburizing. With the following of the postoxidation treatment, it was detected that the corrosion resistance became better and it approached its value before the process.

  3. Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel

    Science.gov (United States)

    Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

    2014-04-01

    High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

  4. PARAMETRIC STUDY OF ELECTRICAL DISCHARGE MACHINING OF AISI 304 STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    P. SRINIVASA RAO,

    2010-08-01

    Full Text Available Electrical discharge machining (EDM is widely used process in the production of mould / dies, aerospace, automobile and electronics industries where intricate complex shapes need to be machined in very hard materials. The selection of the AISI 304 stainless steel was made taking into account its use in almost all industrial applicationsfor approximately 50% of the world’s stainless steel production and consumption. In this work, a study has been carried out on the influence of four design factors: current, open-circuit voltage, servo and dutycycle over material removal rate, tool wear rate, surface roughness and hardness on the die-sinking electrical discharge machining of AISI 304 stainless steel. This has been done using design of experiments (DOE, which allows us to carry out theabove-mentioned analysis performing a relatively small number of experiments. In this case, a 3*24-1 mixed level factorial design, whose resolution is V, has been selected due to the number of factors considered in the study. The resolution of this mixed factorial design allows us to estimate all the main effects, two-factor interactions and pure quadratic effects of the four design factors selected to perform this study.

  5. Improving electrochemical properties of AISI 1045 steels by duplex surface treatment of plasma nitriding and aluminizing

    Energy Technology Data Exchange (ETDEWEB)

    Haftlang, Farahnaz, E-mail: f.haftlang@students.semnan.ac.ir [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Habibolahzadeh, Ali [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Sohi, Mahmoud Heydarzadeh [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-02-28

    Highlights: • AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing. • Plasma nitriding and post-aluminizing result in AlN single phase layer on the steel. • PN–Al coated steel had better corrosion resistance than Al–PN one. • Formation of oxide layer provided protection of PN–Al coated steel against corrosion. • Pitting and surface defects was the dominant corrosion mechanism in Al–PN coated steel. - Abstract: Improvement in electrochemical behavior of AISI 1045 steel after applying aluminum nitride coating was investigated in 3.5% NaCl solution, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. Aluminum nitride coating was applied on the steel surface by duplex treatment of pack aluminizing and plasma nitriding. Some specimens were plasma nitrided followed by aluminizing (PN–Al), while the others were pack aluminized followed by plasma nitriding (Al–PN). Topological and structural studies of the modified surfaces were conducted using scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscope (EDS), and X-ray diffractometer (XRD). The electrochemical measurements showed that the highest corrosion and polarization (R{sub p}) resistances were obtained in PN–Al specimens, having single phase superficial layer of AlN. Pitting mechanism was dominant reason of lower corrosion resistance in the Al–PN specimens.

  6. Structural and Microhardness Changes After Turning of the AISI 1045 Steel for Minimum Quantity Cooling Lubrication

    Science.gov (United States)

    Maruda, Radoslaw W.; Krolczyk, Grzegorz M.; Michalski, Mariusz; Nieslony, Piotr; Wojciechowski, Szymon

    2017-01-01

    This work presents the cooling effect under minimum quantity cooling lubrication and dry cutting on structural changes and microhardness of the ferritic-pearlitic AISI 1045 steel after turning. Due to the fact that the AISI 1045 steel has a two-phase structure, microhardness tests using the Vickers method were conducted with a load of 0.05 HV separately for ferrite and pearlite grains. The tests showed that cooling of the cutting zone under minimum quantity cooling lubrication (MQCL) condition decreased the depth of the hardened layer compared to dry cutting by approximately 40% for both pearlite and ferrite. Scanning electron microscopy analysis revealed that applying MQCL limits the formation of plastic deformations, among others, by reducing the surface crumple zone by approximately 50% compared to dry cutting. As a result of cooling being applied to the cutting zone using the MQCL method, the average diameter of ferrite grains has been decreased in the entire surface area compared to dry cutting. When using dry cutting, clear structural changes of the surface layer were also observed. This may be the result of sulfide inclusions which have formed, causing microcracks on the edge of the hardened layer and surface deformation visible as notches.

  7. Improvement in cavitation erosion resistance of AISI 316L stainless steel by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Hajian, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Abdollah-zadeh, A., E-mail: zadeh@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Rezaei-Nejad, S.S.; Assadi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [Department of Materials Science and Engineering, MA University of Technology, Tehran (Iran, Islamic Republic of); Chung, K. [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Engineering Research Institute, Seoul National University, Seoul (Korea, Republic of); Shokouhimehr, M. [Department of Chemical Engineering, College of Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-07-01

    Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3–6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

  8. Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

    Directory of Open Access Journals (Sweden)

    Yang Shicai

    2016-01-01

    Full Text Available AISI 316 austenitic stainless steel balls (diameters 5.0 and 12.0 mm, typical hardness 250 HV0.3 and flat samples (20×20×2.0 mm were nitrided by a pulsed glow discharge Ar/N2 plasma. Hardness of the ball surfaces was analysed using Vickers indentation. Thermal stability of the nitrided balls (diameter 12.0 mm was studied using a furnace to heat them in air for 8 hours at temperatures up to 700.0°C and then, after cooling to room temperature, the surface hardness of the heated balls was re-measured. Scanning electron microscopy and X-ray diffraction were used to study the microstructures, composition and phase formation of the nitrided sublayers. Unlubricated pin-on-disc wear testing was used to evaluate the wear resistance of nitrided stainless steel balls (5.0 mm diameter and the results were compared with similar testing on hardened Cr-Steel balls (5 mm diameter with hardness of about 650 HV0.3. All the test results indicated that the nitrided AISI 316 austenitic stainless steel balls have advantages over the hardened Cr-Steel balls in terms of retaining high hardness after heat treatment and high resistance to sliding wear at room temperature under higher counterpart stress. These properties are expected to be beneficial for wide range of bearing applications.

  9. Friction welding of AA6061 to AISI 4340 using silver interlayer

    Directory of Open Access Journals (Sweden)

    Suresh D. Meshram

    2015-09-01

    Full Text Available The present work pertains to the study on joining of AA6061 and AISI 4340 through continuous drive friction welding. The welds were evaluated by metallographic examination, X-ray diffraction, electron probe microanalysis, tensile test and microhardness. The study reveals that the presence of an intermetallic compound layer at the bonded interface exhibits poor tensile strength and elongation. Mg in AA6061 near to the interface is found to be favourable for the formation and growth of Fe2Al5 intermetallics. Introduction of silver as an interlayer through electroplating on AISI 4340 resulted in accumulation of Si at weld interface, replacing Mg at AA6061 side, thereby reducing the width of intermetallic compound layer and correspondingly increasing the tensile strength. Presence of silver at the interface results in partial replacement of Fe–Al based intermetallic compounds with Ag–Al based compounds. The presence of these intermetallics was confirmed by X-ray diffraction technique. Since Ag–Al phases are ductile in nature, tensile strength is not deteriorated and the silicon segregation at weld interface on AA6061 in the joints with silver interlayer acts as diffusion barrier for Fe and further avoids formation of Fe–Al based intermetallics. A maximum tensile strength of 240 MPa along with 4.9% elongation was obtained for the silver interlayer dissimilar metal welds. The observed trends in tensile properties and hardness were explained in relation to the microstructure.

  10. Microstructure and Properties of Plasma Source Nitrided AISI 316 Austenitic Stainless Steel

    Science.gov (United States)

    Li, G. Y.; Lei, M. K.

    2016-11-01

    Plasma source nitriding is a relatively new nitriding technology which can overcome those inherent shortcomings associated with conventional direct current plasma nitriding technology such as the arcing surface damage, the edging effect and the hollow cathode effect. There is considerable study on the properties of nitrided samples for laboratorial scale plasma source nitriding system; however, little information has been reported on the industrial-scale plasma source nitriding system. In this work, AISI 316 austenitic stainless steel samples were nitrided by an industrial-scale plasma source nitriding system at various nitriding temperatures (350, 400, 450 and 500 °C) with a floating potential. A high-nitrogen face-centered-cubic phase (γN) formed on the surface of nitrided sample surface. As the nitriding temperature was increased, the γN phase layer thickness increased, varying from 1.5 μm for the lowest nitriding temperature of 350 °C, to 30 μm for the highest nitriding temperature of 500 °C. The maximum Vickers microhardness of the γN phase layer with a peak nitrogen concentration of 20 at.% is about HV 0.1 N 15.1 GPa at the nitriding temperature of 450 °C. The wear and corrosion experimental results demonstrated that the γN phase was formed on the surface of AISI 316 austenitic stainless steel by plasma source nitriding, which exhibits not only high wear resistance, but also good pitting corrosion resistance.

  11. Statistical regression modeling and machinability study of hardened AISI 52100 steel using cemented carbide insert

    Directory of Open Access Journals (Sweden)

    Amlana Panda

    2017-01-01

    Full Text Available The present study investigates performance and feasibility of application of low cost cemented carbide insert in dry machining of AISI 52100 steel hardened to (55 ± 1 HRC which is rarely researched as far as machining of bearing steel is concerned. Machinability studies i.e. flank wear, surface roughness and morphology analysis of chip has been investigated and statistical regression modeling has been developed. The test has been conducted based on Taguchi L16 OA taking machining parameters like cutting speed, feed and depth of cut. It is observed that uncoated cemented carbide insert performs well at some selected runs (Run 1, 5 and 9 which show its feasibility for hard turning applications. The developed serrated saw tooth chip of burnt blue colour adversely affects the surface quality. Adequacy of the developed statistical regression model has been checked using ANOVA analysis (depending on F value, P value and R2 value and normal probability plot at 95% confidence level. The results of optimal parametric combinations may be adopted while turning hardened AISI 52100 steel under dry environment with uncoated cemented carbide insert.

  12. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    Science.gov (United States)

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

    2007-04-01

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

  13. Pitting and Intergranular Corrosion Resistance of AISI Type 301LN Stainless Steels

    Science.gov (United States)

    Ningshen, S.; Kamachi Mudali, U.

    2010-03-01

    The pitting and intergranular corrosion (IGC) resistance of AISI type 301LN stainless steels were evaluated using ASTM methods, anodic polarization, and electrochemical impedance techniques. The IGC results indicated that the microstructure of the samples after sensitization heat treatment at 675 °C for 1 h shows step or dual structure for both imported and indigenous materials indicating insignificant Cr23C6 precipitation. The results of immersion tests in boiling 6% copper sulfate + 16% sulfuric acid + copper solution for 24 h followed by the bend test (ASTM A262 Practice-E method) indicated no crack formation in any of the tested specimens. Pitting corrosion resistance carried out in 6% FeCl3 solution at different temperatures of 22 ± 2 and 50 ± 2 °C (ASTM G 48) up to the period of 72 h revealed pitting corrosion attack in all the investigated alloys. The potentiodynamic anodic polarization results in 0.5 M NaCl revealed variation in passive current density and pitting potential depending on the alloy chemistry and metallurgical condition. The passive film properties studied by electrochemical impedance spectroscopy (EIS) correlated well with the polarization results. The x-ray diffraction (XRD) results revealed the presence of austenite (γ) and martensite (α') phases depending on the material condition. The suitability of three indigenously developed AISI type 301LN stainless steels were compared with imported type 301LN stainless steel and the results are highlighted in this article.

  14. Estudio de la degradación de elementos refractarios de alúmina en la sinterización de aceros modificados con Mn

    OpenAIRE

    Peña, P; Sicre-Artalejo, J.; Campos, M; Torralba Castelló, José Manuel; Zbiral, J.; Danniger, H.

    2008-01-01

    [ES] En este trabajo se estudia la degradación de los refractarios de un horno de sinterización, cuando están involucrados en el proceso aceros de baja aleación con adición de manganeso. Dada la elevada Pvapor del manganeso y las atmósferas habituales de sinterización para este tipo de aceros, se produce su sublimación durante el ciclo térmico. Se proporciona así, una fase gaseosa, que pudiendo ser beneficiosa para la difusión en las muestras de acero, puede alterar la composición de los refr...

  15. EFECTO DEL PRECALENTAMIENTO Y LA SEVERIDAD DE TEMPLE SOBRE LA RESISTENCIA AL DESGASTE ADHESIVO DEL ACERO AUSTENÍTICO AL MANGANESO

    Directory of Open Access Journals (Sweden)

    OSCAR FABIÁN HIGUERA COBOS

    2010-01-01

    Full Text Available En este trabajo de investigación se estudió el efecto del precalentamiento y la severidad de temple sobre la resistencia al desgaste adhesivo del acero austenítico al manganeso ASTM A 128 grado C. El material se sometió a ciclos térmicos de temple y revenido con y sin precalentamiento con el fin de evaluar su influencia sobre la resistencia al desgaste. Posteriormente el material fue sometido a prueba según norma ASTM G83 y se determinó que el acero Austenítico al manganeso, es un material que presenta una microestructura metaestable en condiciones estables y no debe ser sometido a tratamiento térmico de revenido a altas temperaturas debido que favorece la descomposición de esta a ferrita (fase blanda de los acero y por ende disminuye su resistencia al desgaste.

  16. The effect of cladding speed on phase constitution and properties of AISI 431 stainless steel laser deposited coatings

    NARCIS (Netherlands)

    Hemmati, I.; Ocelik, V.; De Hosson, J. Th. M.

    2011-01-01

    Shorter processing time has given impetus to laser cladding technology and therefore in this research the AISI 431 martensitic stainless steel coatings are laser deposited at high cladding speeds, i.e. up to 117 mm/s. The analysis of phase constitution and functional properties of the coatings are p

  17. Effects of Ultrasonic Nanocrystal Surface Modification (UNSM) on Residual Stress State and Fatigue Strength of AISI 304

    Science.gov (United States)

    Cherif, A.; Pyoun, Y.; Scholtes, B.

    2010-03-01

    The effects of a new mechanical surface treatment method, called ultrasonic nanocrystal surface modification (UNSM), on near-surface microstructures and residual stress states as well as on the fatigue behavior of an austenitic steel AISI 304 are investigated and discussed. The results are compared with consequences of other mechanical surface treatment methods such as deep rolling or shot peening.

  18. Extended X-Ray Absorption Fine Structure Investigation of Carbon Stabilized Expanded Austenite and Carbides in Stainless Steel AISI 316

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny;

    2011-01-01

    Low temperature carburized AISI 316 stainless steel - carbon expanded austenite - was investigated with EXAFS and synchrotron diffraction together with synthesized carbides of the type M3C2, M7C3 and M23C6. It was found that the chemical environment of carbon expanded austenite is not associated ...

  19. Aplicabilidad de un concreto de escoria activada alcalinamente como material protector del acero de refuerzo

    Directory of Open Access Journals (Sweden)

    Robinson de Jesús Torres Gómez, William A. Aperador Ch., Enrique Vera López,Rubi Mejía de Gutiérrez

    2011-05-01

    Full Text Available Se presentan los resultados del análisis electroquímico de las  barras  de  acero  embebidas  en  un  concreto  no convencional usado internacionalmente para reparación de estructuras. Este concreto utiliza materiales de desecho de otros procesos; en este caso específico se empleó escoria siderúrgica de  la empresa Acerías Paz del Río S.A. Se estudio el comportamiento frente a la corrosión generada por  los iones cloruro, con el uso de la técnica de resistencia lineal a la polarización LPR y pulso galvanostático GPT. Simultáneamente, se compararon los resultados con otras probetas  fabricadas  con  cemento  Portland  tipo  I.  Se realizaron mediciones con  intervalos de veinte días durante nueve  meses  y  finalmente  se  establecieron  las características protectoras del concreto.

  20. Transferencia de calor en la colada continua de aceros. II parte. Enfriamiento secundario

    Directory of Open Access Journals (Sweden)

    Cicutti, C.

    1997-12-01

    Full Text Available Once the strand leaves the mold, the solidification of steel progresses due to the heat extracted in the secondary cooling zone of the continuous casting machine. In this zone, heat is extracted mainly by: the incidence of water from sprays, radiation to surroundings contact with rolls and run out water accumulated between rolls and strand. In this work, all these mechanisms are evaluated and, when it is possible, they are quantified. Methods which are usually employed to measure solidification profiles in the continuous casting machine are also reviewed. Finally, the incidence of secondary cooling on the quality of cast products is discussed.

    La solidificación del acero iniciada en el molde continúa en la zona de enfriamiento secundario de la máquina donde el calor es extraído, principalmente por la incidencia del agua de los rociadores, la radiación al medio ambiente, el contacto con los rodillos y el agua acumulada en ellos. En este trabajo se revisa cada uno de estos mecanismos determinando, en los casos en que es posible, valores cuantitativos de los mismos. Además, se analizan los distintos métodos empleados para medir el avance del espesor solidificado en la máquina de colada continua. Por último, se discute la incidencia del enfriamiento secundario en la calidad final de los productos colados.

  1. Implicaciones industriales del endurecimiento por explosivos de piezas de acero Hadfield

    Directory of Open Access Journals (Sweden)

    Miguel A. Caraballo-Núñez

    2004-03-01

    Full Text Available El desgaste prematuro que sufren las piezas fabricadas de acero Hadfield en los equipos de laboreo minero de la industria cubana del níquel, limita la capacidad de trabajo de estos equipos. El trabajo expone los resultados alcanzados en el desarrollo y aplicación de un procedimiento tecnológico de endurecimiento, empleando las cargas de impacto generadas por la energía de detonación de una sustancia explosiva. Este procedimiento ha sido empleado en los dientes de la pala excavadora ESH-5/45 M utilizados en la extracción del mineral laterítico de la mina de la Empresa Comandante Ernesto Che Guevara en Moa, provincia Holguín, y en los martillos de las trituradoras de sínter M - 8 - 6B de la Planta de Calcinación y Sínter de la propia empresa. La utilización de tal procedimiento reportó un alargamiento equivalente a 1,5 y 2 veces de la vida útil de las piezas con su correspondiente efecto económico, social y ambiental.

  2. Diseño de una unidad de proceso para el tratamiento superficial (cromado y niquelado) de piezas de acero para automoción

    OpenAIRE

    2012-01-01

    El proyecto se centra en la desmineralización continua de aguas residuales de lavado para su posterior reutilización en baños de tratamiento superficial de piezas de acero para automoción. Concretamente se centra en tratar un número máximo de 300000 piezas anuales, 75 piezas diarias. Tratando un volumen máximo de 16 m3/h de agua residual procedente de los baños de tratamiento superficial de piezas de acero.

  3. Proceso de formación de inclusiones de Cr2 O3 en el vidrio a partir de aceros refractarios

    OpenAIRE

    Montes López, C.

    1985-01-01

    Tras pasar revista a las causas de inclusiones de óxido de cromo en el vidrio que figuran en la bibliografía, se describe el proceso de formación de defectos de la misma naturaleza a partir de un instrumento fabricado con acero conteniendo Cr-Ni y colocado en la superestructura de un horno de llama. Los productos originados en el ataque sufrido por dicho acero se analizan química y radiocristalográ-ficamente y se someten en el laboratorio a ensayos en contacto con vidrio fundido, hasta obt...

  4. Diseño y programación de un sistema de control para el proceso de corte longitudinal de bobinas de acero

    OpenAIRE

    2016-01-01

    El proceso objeto de estudio se ubica en una empresa metalmecánica del sector, que se dedica a la producción de perfiles, tuberías y cañerías en diferentes calidades de acero laminados en caliente, laminados en frío y galvanizados y en una gran variedad de dimensiones y espesores. Este tipo de producción diversificada genera a la empresa la necesidad de producir flejes o cortes de diversos tamaños a las bobinas de acero y estos flejes a su vez, constituyen la materia prima, para los siguiente...

  5. Investigación del traslape de acero con el efecto de la espiral para estructuras con concreto armado de grandes luces

    OpenAIRE

    Hadi Mohamed, Mohamed Mhedí

    2009-01-01

    El progreso de elaboración (diseño) de las construcciones de concreto armado esta ligado con las soluciones de uniones de los elementos. En las construcciones de concreto armado, y especialmente en las construcciones de grandes luces surgen problemas de empalmes o traslape de acero. El objetivo del perfeccionamiento de las uniones (empalmes o traslapes) de los aceros, es aseguras su solidez y el mínimo consumo de materiales con tecnología simple. El empleo de los métodos tradicional...

  6. Influência da temperatura interpasse nas propriedades do aço inoxidável duplex durante a soldagem pelo processo a arco submerso

    Directory of Open Access Journals (Sweden)

    Tatiana Resende Alvarez

    2014-06-01

    Full Text Available Os aços inoxidáveis duplex (AID são materiais que apresentam elevada resistência à corrosão com altos valores de resistência mecânica motivando sua utilização em diversos componentes de processo na indústria offshore. No entanto, existem grandes desafios na soldagem destes materiais em termos de produtividade e qualidade da junta produzida, tendo em vista sua ampla utilização desde componentes de pequenas espessuras, tais como umbilicais, até de grandes espessuras, como tubulações de linhas de injeção de água salgada. No que concerne a tubulações de espessuras pequenas é empregado satisfatoriamente o processo de soldagem Gas Tungsten Arc Welding (GTAW conhecido como TIG. No que diz a respeito a tubulações de paredes espessas foi implementado, recentemente, o processo automático de soldagem por arco submerso (SAW na linha de pré-montagem de tubulações, aumentando consideravelmente a produtividade das juntas produzidas. No entanto, existe uma grande demanda de tempo para a realização de um novo passe de solda, em virtude da máxima temperatura interpasse exigida ser inferior a 150ºC. Portanto, o presente trabalho apresenta os resultados da caracterização e avaliação da resistência à corrosão de uma junta soldada correspondente a uma tubulação de aço inoxidável duplex (AID UNS S31803 de 21,4 mm de espessura de parede soldada pelos processos de soldagem MIG (GMAW na raiz e arco submerso (SAW no enchimento e acabamento, empregando-se temperaturas interpasses entre 150 e 290ºC. Os resultados da caracterização das propriedades mecânicas, composição química e resistência à corrosão em diversas regiões da junta soldada foram comparadas com os obtidos para o metal de base (MB da tubulação, assim como com os valores mínimos exigidos pelas normas de projeto. Deste modo, o presente trabalho permite avaliar a influência da temperatura interpasse nas propriedades da junta em decorrência de um poss

  7. Evaluación del trabajo esencial de fractura en chapa de un acero de alta resistencia de fase dual

    Directory of Open Access Journals (Sweden)

    Gutiérrez, D.

    2013-02-01

    Full Text Available Fracture toughness of advanced high strength steels (AHSS, can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets.

    La tenacidad de fractura de aceros de alta resistencia (AHSS, es una propiedad interesante para optimizar el comportamiento a impacto, pero su caracterización experimental en chapas metálicas es compleja debido a su espesor. En este trabajo se plantea el método del Trabajo Esencial de Fractura (TEF, como alternativa al cálculo de la tenacidad. Este método ya ha sido utilizado con éxito en polímeros y aceros dúctiles, aunque la información sobre su aplicación en AHSS es escasa. Se ha evaluado la tenacidad en un acero de fase dual de 800 MPa de resistencia y se ha comparado con la de un acero de embutición. Los resultados muestran que se cumplen los requisitos del método y ponen en evidencia la influencia del radio de entalla en el valor obtenido de TEF, especialmente para AHSS. Con todo ello, el método TEF se puede usar para caracterizar la tenacidad de AHSS en formato chapa.

  8. ESTUDIO DEL LIBRO ARMAS, GÉRMENES Y ACERO. UNA INVESTIGACIÓN TRANSDISCIPLINAR EN ACCIÓN

    Directory of Open Access Journals (Sweden)

    Carlos Arturo Alvarez Urrego

    2012-01-01

    Full Text Available El propósito de este trabajo es explorar el concepto de transdisciplinariedad en la obra Armas, Gérmenes y Acero escrita por Jared Diamond. Es posible observar que los más importantes elementos epistemológicos, tales como el enfoque por objetos y el tratamiento de problemas a partir de diversas disciplinas que expone Diamond, hacen de esta una investigación transdisciplinar. Además, se analiza el concepto de transdisciplinariedad y sus implicaciones epistemológicas.

  9. ESTUDIO DEL LIBRO ARMAS, GÉRMENES Y ACERO. UNA INVESTIGACIÓN TRANSDISCIPLINAR EN ACCIÓN

    OpenAIRE

    Carlos Arturo Alvarez Urrego

    2012-01-01

    El propósito de este trabajo es explorar el concepto de transdisciplinariedad en la obra Armas, Gérmenes y Acero escrita por Jared Diamond. Es posible observar que los más importantes elementos epistemológicos, tales como el enfoque por objetos y el tratamiento de problemas a partir de diversas disciplinas que expone Diamond, hacen de esta una investigación transdisciplinar. Además, se analiza el concepto de transdisciplinariedad y sus implicaciones epistemológicas.

  10. Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guenen, Ali [Mustafa Kemal Univ., Hatay (Turkey). Dept. of Metallurgy and Material Engineering; Kuecuek, Yilmaz; Oege, Mecit; Goek, M. Sabri [Bartin Univ. (Turkey). Dept. of Mechanical Engineering; Er, Yusuf [Firat Univ., Elazig (Turkey); Cay, V. Veli [Dicle Univ., Diyarbakir (Turkey). Civil Aviation Higher School

    2015-06-01

    In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10 50 nm and commercial Ekabor 3 powders (<1400 μm) at 950 C to 1000 C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.

  11. Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel

    Indian Academy of Sciences (India)

    M Ghorannevis; A Shokouhy; M M Larijani; S H Haji Hosseini; M Yari; A Anvari; M Gholipur Shahraki; A H Sari; M R Hantehzadeh

    2007-01-01

    This work presents the results of a low-energy nitrogen ion implantation of AISI 304 type stainless steel (SS) at a moderate temperature of about 500° C. The nitrogen ions are extracted from a Kauffman-type ion source at an energy of 30 keV, and ion current density of 100 A cm-2. Nitrogen ion concentration of 6 × 1017, 8 × 1017 and 1018 ions cm-2, were selected for our study. The X-ray diffraction results show the formation of CrN polycrystalline phase after nitrogen bombardment and a change of crystallinity due to the change in nitrogen ion concentration. The secondary ion mass spectrometry (SIMS) results show the formation of CrN phases too. Corrosion test has shown that corrosion resistance is enhanced by increasing nitrogen ion concentration.

  12. The Investigation of Surface Roughness on AISI 1040 Steel with Dry Turning

    Directory of Open Access Journals (Sweden)

    Nergizhan Kavak

    2012-12-01

    Full Text Available In this study, the effect of cutting speed and feed rate on the surface roughness was investigated experimentaly in the machining of AISI 1040 steel being mostly used in industry. Experiments was done by dry turning with uncoated cementite carbite cutting tools at different speeds (46. 91 ve 128 m/dk and feed rates (0.16, 0.22 ve 0.28 mm/dev while cutting depth stays stable at 2 mm. It was observed that workpiece surface quality get worse with the increase of feed rate or decrease of cutting speed. As a result of this work, it was seen that 128 m/min cutting speed and 0.16 mm/rev feed rate for the 2 mm cutting depth are the optimum cutting conditions from the point of surface quality.

  13. Tensile and Impact Properties of Shielded Metal Arc Welded AISI 409M Ferritic Stainless Steel Joints

    Institute of Scientific and Technical Information of China (English)

    K.Shanmugam; A.K.Lakshminarayanan; V.Balasubramanian

    2009-01-01

    The present study is concerned with the effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the joints fabricated by austenitic stainless steel, ferritic stainless steel and duplex stainless steel filler metals were evaluated and the results were reported. From this investigation, it is found that the joints fabricated by duplex stainless steel filler metal showed higher tensile strength and hardness compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Joints fabricated by austenitic stainless steel filler metal exhibited higher ductility and impact toughness compared with the joints fabricated by ferritic stainless steel and duplex stainless steel filler metals.

  14. Stress corrosion cracking of AISI 321 stainless steel in acidic chloride solution

    Indian Academy of Sciences (India)

    Yanliang Huang

    2002-02-01

    The stress corrosion cracking (SCC) of AISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) technique and fracture mechanics method. The fractured surface was characterized by cleavage fracture. In order to clarify the SCC mechanism, the effects of inhibitor KI on SCC behaviour were also included in this paper. A study showed that the inhibition effects of KI on SCC were mainly attributed to the anodic reaction of the corrosion process. The results of strain distribution in front of the crack tip of the fatigue pre-cracked plate specimens in air, in the blank solution (acidic chloride solution without inhibitor KI) and in the solution added with KI measured by speckle interferometry (SPI) support the unified mechanism of SCC and corrosion fatigue cracking (CFC).

  15. Effect of Plasma Nitriding Temperatures on Characteristics of Aisi 201 Austenitic Stainless Steel

    Science.gov (United States)

    Gao, Yuxin; Zheng, Shaomei

    2016-10-01

    Samples of AISI 201 austenitic stainless steel were produced by plasma nitriding at 350∘C, 390∘C, 420∘C, 450∘C and 480∘C for 5h. Systematic characterization of the nitrided layer was carried out in terms of micrograph observations, phase identification, chemical composition depth profiling, surface microhardness measurements and electrochemical corrosion tests. The results show that the surface hardness and the layer thickness increased with increasing temperature. XRD indicated that a single S-phase layer was formed during low temperature (≤420∘C), while Cr2N or CrN phase was formed besides S-phase when nitrided at 450∘C and 480∘C. The specimen treated at 390∘C presents a much enhanced corrosion resistance compared to the untreated substrate. The corrosion resistance deteriorated for samples treated above 450∘C due to the formation of chromium nitrides.

  16. Influence of nitrogen alloying on hydrogen embrittlement in AISI 304-type stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Hannula, S.-P.; Hanninen, H.; Tahtinen, S.

    1984-12-01

    Hydrogen embrittlement of AISI 304-type austenitic stainless steels has been studied with special emphasis on the effects of the nitrogen content of the steels. Hydrogen charging was found to degrade the mechanical properties of all the steels studied, as measured by a tensile test. The fracture surfaces of hydrogen charged specimens were brittle cleavage-like whereas the uncharged specimens showed ductile, dimpled fracture. In sensitized materials transgranular cleavage mode of fracture was replaced by an intergranular mode of fracture and the losses of mechanical properties were higher. Nitrogen alloying decreased the hydrogen-induced losses of mechanical properties by increasing the stabilit of austenite. In sensitized steels the stability of austenite and nitrogen content were found to have only a minor effect on hydrogen embrittlement, except when sensitization had caused ..cap alpha..'-martensite transformation at the grain boundaries.

  17. Influence of nitrogen alloying on hydrogen embrittlement in AISI 304-type stainless steels

    Science.gov (United States)

    Hannula, Simo-Pekka; Hänninen, Hannu; Tähtinen, Seppo

    1984-12-01

    Hydrogen embrittlement of AISI 304-type austenitic stainless steels has been studied with special emphasis on the effects of the nitrogen content of the steels. Hydrogen charging was found to degrade the mechanical properties of all the steels studied, as measured by a tensile test. The fracture surfaces of hydrogen charged specimens were brittle cleavage-like whereas the uncharged specimens showed ductile, dimpled fracture. In sensitized materials transgranular cleavage mode of fracture was replaced by an intergranular mode of fracture and the losses of mechanical properties were higher. Nitrogen alloying decreased the hydrogen-induced losses of mechanical properties by increasing the stability of austenite. In sensitized steels the stability of austenite and nitrogen content were found to have only a minor effect on hydrogen embrittlement, except when sensitization had caused α'-martensite transformation at the grain boundaries.

  18. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  19. Surface characteristics analysis of dry EDMed AISI D2 steel using modified tool design

    Energy Technology Data Exchange (ETDEWEB)

    Pragadish, N.; Kumar, M. Pradeep [Anna University, Chennai (China)

    2015-04-15

    A modified tool design is proposed which helps in drilling holes without any central core, and also enables the effective removal of the debris particles. Experiments were conducted on AISI D2 Steel using copper electrode as tool in both conventional EDM and dry EDM processes and the performance of both processes is compared. Experiments were designed using Taguchi's L27 orthogonal array. Discharge current (I), gap voltage (V), pulse on time (T{sub ON}), gas pressure (P) and tool rotational speed (N) were chosen as the various input parameters, and their effect on the material removal rate (MRR), surface roughness (SR), surface morphology, microstructure and elemental composition of the machined surface is analyzed. The experimental results show better surface characteristics in the surface machined under dry EDM process.

  20. ANALYSIS OF CUTTING FORCE AND CHIP MORPHOLOGY DURING HARD TURNING OF AISI D2 STEEL

    Directory of Open Access Journals (Sweden)

    X. M. ANTHONY

    2015-03-01

    Full Text Available In this research work AISI D2 tool steel at a hardness of 55 HRC is being used for experimental investigation. Cutting speed, feed rate and depth of cut are the cutting parameters considered for the experimentation along with tool geometry namely, nose radius, clearance angle and rake angle. Three different cutting tool materials are used for experimentation namely multicoated carbide, cermet and ceramic inserts. The cutting force generated during the machining process is being measured using Kistler dynamometer and recorded for further evaluation. The chips produced during the machining process for every experimental trail is also collected for understanding the chip morphology. Based on the experimental data collected Analysis of Variance (ANOVA was conducted to understand the influence of all cutting parameters and tool geometry on cutting force.

  1. Determining Ms temperature on a AISI D2 cold work tool steel using magnetic Barkhausen noise

    Energy Technology Data Exchange (ETDEWEB)

    Huallpa, Edgar Apaza, E-mail: gared1@gmail.com [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Sánchez, J. Capó, E-mail: jcapo@usp.br [Departamento de Física, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n 90500, Santiago de Cuba (Cuba); Padovese, L.R., E-mail: lrpadove@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Goldenstein, Hélio, E-mail: hgoldens@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil)

    2013-11-15

    Highlights: ► MBN was used to follow the martensite transformation in a tool steel. ► The results were compared with resistivity experiments. ► The Ms was estimated with Andrews equation coupled to ThermoCalc calculations. The experimental results showed good agreement. -- Abstract: The use of Magnetic Barkhausen Noise (MBN) as a experimental method for measuring the martensite start (Ms) temperature was explored, using as model system a cold-work tool steel (AISI D2) austenitized at a very high temperature (1473 K), so as to transform in sub-zero temperatures. The progress of the transformation was also followed with electrical resistance measurements, optical microscopy and scanning electron microscopy. Both MBN and resistivity measurements showed a change near 230 K during cooling, corresponding to the Ms temperature, as compared with 245 K, estimated with Andrews empirical equation applied to the austenite composition calculated using ThermoCalc.

  2. Evaluation of the corrosion resistance of AISI 316 stainless steel filters

    Directory of Open Access Journals (Sweden)

    Luzinete Pereira Barbosa

    2005-06-01

    Full Text Available In this investigation, the corrosion resistance of AISI 316 SS filters prepared with powders in the size ranges 74-44 µm and 210-105 µm and compacted with pressures of 300 MPa and 400 MPa has been evaluated in naturally aerated 0.5 M H2SO4 solution at 25 °C. Weight loss of filters manufactured with compacting pressure of 400 MPa were significantly higher than that of filters compacted at 300 MPa. The filter compacted at 400 MPa had higher carbon and nitrogen contents compared to those compacted at 300 MPa. The former also had chromium rich precipitates and oxides in the grain boundaries. The pores in filters compacted at 400 MPa were smaller than in filters compacted at 300 MPa. Smaller pores favor the formation of concentration cells and consequently, increased crevice corrosion.

  3. Dynamic fracture toughness and Charpy impact properties of an AISI 403 martensitic stainless steel

    Science.gov (United States)

    Sreenivasan, P. R.; Ray, S. K.; Mannan, S. L.; Rodriguez, P.

    1996-04-01

    Dynamic fracture toughness and Charpy impact properties of a normalised and tempered AISI 403 martensitic stainless steel obtained from instrumented impact tests are presented. Procedures for estimating dynamic fracture toughness ( KId) from the load-time traces obtained in instrumented tests of unprecracked Charpy V-notch (CVN) specimens are considered. The estimated KId values show reasonable agreement with those obtained from instrumented drop-weight and precracked Charpy tests. Also, except in the upper transition and uppershelf regions, the ASME KIR curve is generally conservative (i.e. gives lower KId values) when compared to the above KId estimates. The conservatism of the ASME KIR at the upper transition and uppershelf temperatures needs verification/validation. The lowest KId values estimated at the lower shelf temperatures for the above steel, namely, 33-42 MPa√m are in good agreement with the reported values of 35-50 MPa√m for the same steel in the literature.

  4. Martensitic Transformation during Fatigue Testing of an AISI 301LN Stainless Steel

    Science.gov (United States)

    Mateo, A.; Fargas, G.; Zapata, A.

    2012-02-01

    The plastic deformation accumulated during fatigue testing can induce the transformation of austenite to martensite in metastable austenitic stainless steels. To analyze this issue, a metastable austenitic stainless steel grade AISI 301 LN was studied in two different conditions, i.e. annealed and cold rolled. In the first case, the steel was fully austenitic, whereas cold rolled material had almost 30% of martensite. High cycle fatigue tests at a stress ratio of 0.8 were carried out on flat specimens from both steel conditions. Several characterization techniques, including optical microscopy, X-ray diffraction (XRD) and electron back scattered diffraction (EBSD), were used to detect and quantify the martensite induced by the cyclic deformation.

  5. Microstructure and Texture Evolutions in AISI 1050 Steel by Flow Forming

    Energy Technology Data Exchange (ETDEWEB)

    Bedekar, Vikram [Timken Technology Center, Canton, OH; Pauskar, Praveen [Ohio State University, Columbus; Shivpuri, Rajiv [Ohio State University, Columbus; Howe, Jane Y [ORNL

    2014-01-01

    Hot rolled and annealed AISI 1050 steel cylindrical coupons were flow formed at different levels of deformation (66% and 90% wall thickness reduction). TEM studies revealed development of ultra fine (sub) grain cell structure due to severe plastic deformation. The transverse subgrain size changed from 10 m (beginning) to 300nm (66% deformation) to 40nm (90% deformation). EBSD study revealed decreased recrystallization fraction at 90% deformation compared with 66% deformation due to orientation pinning from preferred orientation along {002} planes. No evidence of dislocation pinning or cracking was observed on any samples. The aim of the present work is to study the deformation behaviour and microstructural evolution during conventional flow forming process. The study also sheds light on the strengthening behaviour and structural changes during severe straining.

  6. Optimization of Process Parameters in Turning of AISI 8620 Steel Using Taguchi and Grey Taguchi Analysis

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Sharma

    2014-03-01

    Full Text Available The aim of this research is to investigate the optimization of cutting parameters (cutting speed, feed rate and depth of cut for surface roughness and metal removal rate in turning of AISI 8620 steel using coated carbide insert. Experiments have been carried out based on Taguchi L9 standard orthogonal array design with three process parameters namely cutting speed, feed rate and depth of cut for surface roughness and metal removal rate. The objective function has been chosen in relation to surface roughness and metal removal rate for quality target. Optimal parameters contribution of the CNC turning operation was obtained via grey relational analysis. The analysis of variance is applied to identify the most significant factor. Experiment with the optimized parameter setting, which has been obtained from the analysis, are giving to validate the results.

  7. Nitrocarburizing of AISI-304 stainless steel using high-voltage plasma immersion ion implantation

    Science.gov (United States)

    Abd El-Rahman, A. M.; Mohamed, S. H.; Ahmed, M. R.; Richter, E.; Prokert, F.

    2009-05-01

    AISI-304 austenitic stainless steel has been nitrocarburized in N 2 and C 2H 2 ambient using high-voltage plasma immersion ion implantation (PIII) technology. The use of different PIII treatment times revealed important hints with respect to the microstructural, mechanical and corrosion properties of the nitrocarburized layer. Grazing incidence X-ray diffraction (GIXRD) shows the presence of nitride ( γN and CrN) and carbide ( γC and Fe 3C) phases. Glow discharge optical spectroscopy (GDOS) has been used to characterize the elemental depth profiles in which the thickness of the modified layers is derived. Dynamic microindentation method is used for the study of mechanical performance of the nitrocarburized layer as well as the untreated material. The microhardness has been increased to a maximum value of more than nine times compared to that of the untreated one. The corrosion performance is characterized by potentiodynamic polarization technique and was found to be treatment time dependent.

  8. Fatigue assessment by energy approach during tensile tests on AISI 304 steel

    Directory of Open Access Journals (Sweden)

    A. Risitano

    2017-01-01

    Full Text Available Estimation of the fatigue limit for steel ductile materials using non-destructive methods is a topic of great interest to researchers today. In recent years, the method adopted has implemented infrared sensors to detect the surface temperature and correlate it with the fatigue limit. In previous paper, a new energy approach was proposed to investigate the fatigue limit during tensile test. The numerical procedure proposed by Chrysochoos is adopted to clean infrared images and applied to analyse the surface heat sources during tensile test. AISI 304 specimens with rectangular cross-sections are tested. Moreover fatigue tests at increasing loads were carried out on steel by a stepwise succession, applied to the same specimen, for applying the thermographic method. The predictions of the fatigue limit, obtained by the analysis of the energy evolution during the static tests, were compared with the predictions obtained applying the thermographic method during fatigue tests.

  9. Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Sang Hwan Bak

    2016-07-01

    Full Text Available Plastic deformation and strain-induced martensite (SIM, α′ transformation in metastable austenitic AISI 304 stainless steel were investigated through room temperature tensile tests at strain rates ranging from 2 × 10−6 to 2 × 10−2/s. The amount of SIM was measured on the fractured tensile specimens using a feritscope and magnetic force microscope. Elongation to fracture, tensile strength, hardness, and the amount of SIM increased with decreasing the strain rate. The strain-rate dependence of RT tensile properties was observed to be related to the amount of SIM. Specifically, SIM formed during tensile tests was beneficial in increasing the elongation to fracture, hardness, and tensile strength. Hydrogen suppressed the SIM formation, leading to hydrogen softening and localized brittle fracture.

  10. Effect of Carbon and Nitrogen Content on Deformation and Fracture of AISI 304 Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    C. Menapace

    2008-04-01

    Full Text Available The effect of small differences in the content of carbon and nitrogen on the room temperature tensile deformation and fracture behaviour of an AISI 304 stainless steel was studied. In the steel containing the lower amount of carbon and nitrogen, a higher amount of strain induced alfa’ martensite is formed, which increases strain hardening rate and both uniform and total elongation at fracture. The presence of large martensitic areas in the cross section causes strain localization at the austenite/martensite interface, which promotes the nucleation of cracks and their propagation along the interface. This results in a decrease of Ultimate Tensile Strength. Strain induced transformation slightly reduces strain rate sensitivity, as well.

  11. Surface Modification by Nitrogen Plasma Immersion Ion Implantation on Austenitic AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    Miguel CASTRO-COLIN; William DURRER; Jorge ALPEZ; Enrique RAMIREZ-HOMS

    2016-01-01

    Surfaces of AISI 304 austenitic stainless steel plates nitrided by plasma immersion ion implantation (PIII) technology were studied by means of Auger electron spectroscopy (AES)and X-ray photoelectron spectroscopy (XPS)to determine the effect of the nitriding process on the surface and subjacent layers.Elemental compositions obtained by AES and XPS at varying depths indicate that the saturation of N is relatively constant as a function of depth,indicating the reliability of PIII technology for subsurface saturation.It is concluded that the concentrations of both Cr and O increase with depth,the subjacent oxide is driven by the Ar+ sputtering process used to access the lower layers,and then N is bound to Cr.

  12. Adhesion of composite carbon/hydroxyapatite coatings on AISI 316L medical steel

    Directory of Open Access Journals (Sweden)

    J. Gawroński

    2009-07-01

    Full Text Available In this paper are contains the results of studies concerning the problems associated with increased of hydroxyapatite (HAp adhesion, manufactured by using Pulse Laser Deposition (PLD method, to the austenitic steel (AISI 316L through the coating of carbon interlayer on it. Carbon coating was deposited by Radio Frequency Plasma Assisted Chemical Vapour Deposition (RF PACVD method.Test results unequivocally showed that the intermediate carbon layer in a determined manner increase the adhesion of hydroxyapatite to the metallic substrate. Obtained results give rise to deal with issues of manufacturing composite bilayer – carbon film/HAp – on ready implants, casted from austenitic cast steel by lost-wax process method as well as in gypsum forms.

  13. Analysis of deformation induced martensite in AISI 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jagarinec, Darko; Kirbis, Peter; Predan, Jozef; Vuherer, Tomaz; Gubeljak, Nenad [Maribor Univ. (Slovenia). Faculty of Mechanical Engineering

    2016-08-01

    Metastable austenite stainless steel AISI 316L is sensitive to cold deformation, where transformation from austenite to martensite occurred. The bending deformation as the formation process leads to tensile and compression throughout the thickness of the billet. Tensile testing of the specimen causes differences in the true stress-strain along the contraction neck prior to fracture as well. The aim of the paper is to find correlation between microhardness as brief inspection parameters and extension of martensitic transformation. The total equivalent plastic strain extend diagram obtained by numerical simulation of bending was compared with tensile true stress-strain diagram. Results show very good correlation between hardness, true strain and martesite content. Therefore, one can conclude that by hardness measurement, it is possible to measure the level of equivalent plastic strain until ultimate tensile stress as a linear correlation between hardness, true strain and martesite content.

  14. An investigation of the aseptic loosening of an AISI 316L stainless steel hip prosthesis.

    Science.gov (United States)

    Godec, Matjaz; Kocijan, Aleksandra; Dolinar, Drago; Mandrino, Djordje; Jenko, Monika; Antolic, Vane

    2010-08-01

    The total replacement of joints by the implantation of permanently indwelling prosthetic components has been one of the major successes of modern surgery in terms of relieving pain and correcting deformity. However, the aseptic loosening of a prosthetic-joint component is the most common reason for joint-revision surgery. Furthermore, it is thought that wear particles are one of the major contributors to the development and perpetuation of aseptic loosening. The aim of the present study was to identify the factors related to the aseptic loosening of an AISI 316L stainless steel total hip prosthesis. The stem was evaluated by x-ray photoelectron spectroscopy, with polished and rough regions being analyzed in order to establish the differences in the chemical compositions of both regions. Specific areas were examined using scanning electron microscopy with energy dispersive x-ray spectroscopy and light microscopy.

  15. Active flux tungsten inert gas welding of austenitic stainless steel AISI 304

    Directory of Open Access Journals (Sweden)

    D. Klobčar

    2016-10-01

    Full Text Available The paper presents the effects of flux assisted tungsten inert gas (A-TIG welding of 4 (10 mm thick austenitic stainless steel EN X5CrNi1810 (AISI 304 in the butt joint. The sample dimensions were 300 ´ 50 mm, and commercially available active flux QuickTIG was used for testing. In the planned study the influence of welding position and weld groove shape was analysed based on the penetration depth. A comparison of microstructure formation, grain size and ferrit number between TIG welding and A-TIG welding was done. The A-TIG welds were subjected to bending test. A comparative study of TIG and A-TIG welding shows that A-TIG welding increases the weld penetration depth.

  16. Electrochemical behaviour of iron and AISI 304 stainless steel in simulated acid rain solution

    Energy Technology Data Exchange (ETDEWEB)

    Pilic, Zora; Martinovic, Ivana [Mostar Univ. (Bosnia and Herzegovina). Dept. of Chemistry

    2016-10-15

    The growth mechanism and properties of the oxide films on iron and AISI 304 stainless steel were studied in simulated acid rain (pH 4.5) by means of electrochemical techniques and atomic absorption spectrometry. The layer-pore resistance model was applied to explain a potentiodynamic formation of surface oxides. It was found that the growth of the oxide film on iron takes place by the low-field migration mechanism, while that on the stainless steel takes place by the high-field mechanism. Kinetic parameters were determined. Impedance measurements revealed that Fe surface film has no protective properties at the open circuit potential, while the resistance of stainless steel oxide film is very high. The concentration of the metallic ions released into solution and measured by atomic absorption spectroscopy was in accordance with the results obtained from the electrochemical techniques.

  17. Influence of Laser Peening on Phase Transformation and Corrosion Resistance of AISI 321 steel

    Science.gov (United States)

    Karthik, D.; Swaroop, S.

    2016-07-01

    The objective of this study is to investigate the influence of laser peening without coating (LPwC) on austenitic to martensitic (γ → α') phase transformation and corrosion behavior of austenitic stainless steel AISI 321 in 3.5% NaCl environment. Results indicate that LPwC induces a large compressive residual stresses of nearly -854 MPa and γ → α' phase transformation of about 18% (volume fraction). Microstructures of peened surface confirmed the γ → α' phase transformation and showed no grain refinement. Hardness increased slightly with a case depth of 900 μm. Despite the smaller surface roughness introduced, corrosion resistance improved after peening due to compressive residual stresses.

  18. Microstructure and Hardness of High Temperature Gas Nitrided AISI 420 Martensitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Ibrahim Nor Nurulhuda Md.

    2014-07-01

    Full Text Available This study examined the microstructure and hardness of as-received and nitrided AISI 420 martensitic stainless steels. High temperature gas nitriding was employed to treat the steels at 1200°C for one hour and four hours using nitrogen gas, followed by furnace cooled. Chromium nitride and iron nitride were formed and concentrated at the outmost surface area of the steels since this region contained the highest concentration of nitrogen. The grain size enlarged at the interior region of the nitrided steels due to nitriding at temperature above the recrystallization temperature of the steel and followed by slow cooling. The nitrided steels produced higher surface hardness compared to as-received steel due to the presence of nitrogen and the precipitation of nitrides. Harder steel was produced when nitriding at four hours compared to one hour since more nitrogen permeated into the steel.

  19. Acoustic Emission Methodology to Evaluate the Fracture Toughness in Heat Treated AISI D2 Tool Steel

    Science.gov (United States)

    Mostafavi, Sajad; Fotouhi, Mohamad; Motasemi, Abed; Ahmadi, Mehdi; Sindi, Cevat Teymuri

    2012-10-01

    In this article, fracture toughness behavior of tool steel was investigated using Acoustic Emission (AE) monitoring. Fracture toughness ( K IC) values of a specific tool steel was determined by applying various approaches based on conventional AE parameters, such as Acoustic Emission Cumulative Count (AECC), Acoustic Emission Energy Rate (AEER), and the combination of mechanical characteristics and AE information called sentry function. The critical fracture toughness values during crack propagation were achieved by means of relationship between the integral of the sentry function and cumulative fracture toughness (KICUM). Specimens were selected from AISI D2 cold-work tool steel and were heat treated at four different tempering conditions (300, 450, 525, and 575 °C). The results achieved through AE approaches were then compared with a methodology proposed by compact specimen testing according to ASTM standard E399. It was concluded that AE information was an efficient method to investigate fracture characteristics.

  20. On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

    Institute of Scientific and Technical Information of China (English)

    V.Soundararajan; N.Alagurmurthi; K.Palaniradja

    2004-01-01

    Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates.Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching.Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load,speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified(Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -Ⅱ hardening was followed by quenching was carried out as said in Part- I and the hardened specimen were quenched in liquid Nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, Mn0.4% and the rest Iron)

  1. Effect of the purging gas on properties of Ti stabilized AISI 321 stainless steel TIG welds

    Energy Technology Data Exchange (ETDEWEB)

    Taban, Emel; Kaluc, Erdinc; Aykan, T. Serkan [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering

    2014-07-01

    Gas purging is necessary to provide a high quality of stainless steel pipe welding in order to prevent oxidation of the weld zone inside the pipe. AISI 321 stabilized austenitic stainless steel pipes commonly preferred in refinery applications have been welded by the TIG welding process both with and without the use of purging gas. As purging gases, Ar, N{sub 2}, Ar + N{sub 2} and N{sub 2} + 10% H{sub 2} were used, respectively. The aim of this investigation is to detect the effect of purging gas on the weld joint properties such as microstructure, corrosion, strength and impact toughness. Macro sections and microstructures of the welds were investigated. Chemical composition analysis to obtain the nitrogen, oxygen and hydrogen content of the weld root was done by Leco analysis. Ferrite content of the beads including root and cap passes were measured by a ferritscope. Vickers hardness (HV10) values were obtained. Intergranular and pitting corrosion tests were applied to determine the corrosion resistance of all welds. Type of the purging gas affected pitting corrosion properties as well as the ferrite content and nitrogen, oxygen and hydrogen contents at the roots of the welds. Any hot cracking problems are not predicted as the weld still solidifies with ferrite in the primary phase as confirmed by microstructural and ferrite content analysis. Mechanical testing showed no significant change according to the purge gas. AISI 321 steel and 347 consumable compositions would permit use of nitrogen rich gases for root shielding without a risk of hot cracking.

  2. Investigating the correlation between some of the properties of plasma nitrided AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    M. Olzon-Dionysio

    2013-01-01

    Full Text Available When AISI 316L stainless steels are submitted to the nitriding process at temperatures lower than 450 °C, a high nitrogen content expanded austenite phase is formed, which shows higher hardness and higher pitting corrosion resistance compared to the untreated material. As a result, this material becomes adequate for biomedical application. The conditions of the nitriding technique, such as gas mixture, pressure, time and temperature, play an important role in some properties of the modified layer, including: thickness, hardness and N concentration along the layer. This paper explores a set of six samples of AISI 316L, nitrided at different times and temperatures, whose properties show important differences. The aim of this research is to investigate the correlation between the nitrided layer thickness (in the range of 0.77 to 11 µm with both X-ray patterns characteristics and hardness measurements, which used two distinct loads. The results of this study show that: whereas the 3.6 gf load was suitable to measure the real hardness for four of the nitrided layers showing thickness ≥ 2.9 µm, the 50 gf load measured a substrate contribution, probably even for the highest thickness, 11 µm. Moreover, analyzing different reflections of the X-ray patterns showed evidence of the clear consistency between the X-Ray depths and the nitrided layer thicknesses: if the layer thickness is lower than the penetration depth of X-rays, two phases (austenite and expanded substrate are present. If the layer thickness is higher, only the austenite is observed. Finally, concerning the citotoxicity property, all the samples, nitrided or not, were approved in the test for biocompatibility, indicating their potential use for biomedical applications.

  3. Tribological Properties of Nanometric Atomic Layer Depositions Applied on AISI 420 Stainless Steel

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    E. Marin

    2013-09-01

    Full Text Available Atomic Layer Deposition ( ALD is a modern technique that Allows to deposit nanometric, conformal coatings on almost any kind of substrates, from plastics to ceramic, metals or even composites. ALD coatings are not dependent on the morphology of the substrate and are only regulated by the composition of the precursors, the chamber temperature and the number of cycles. In this work, mono- and bi -layer nanometric, protective low-temperature ALD Coatings, based on Al2O3 and TiO2 were applied on AISI 420 Stainless Steel in orderto enhance its relatively low corrosion resistance in chloride containing environments. Tribological testing were also performed on the ALD coated AISI 420 in order to evaluate the wear and scratch resistance of these nanometric layers and thus evaluate their durability. Scratch tests were performed using a standard Rockwell C indenter, under a variable load condition, in order to evaluate the critical loading condition for each coating. Wear testing were performed using a stainless steel counterpart, in ball-on-discconfiguration, in order to measure the friction coefficient and wear to confront the resistance. All scratch tests scars and wear tracks were then observed by means of Scanning Electron Microscopy (SEM in order to understand the wear mechanisms that occurred on the sample surfaces. Corrosion testing, performed under immersion in 0.2 M NaCl solutions, clearly showed that the ALD coatings have a strong effect in protecting the Stainless Steel Substrate against corrosion, reducing the corrosion current density by two orders of magnitude.Tribological The preliminary results showed that ALD depositions obtained at low Temperatures have a brittle behavior caused by the amorphous nature of their structure, and thus undergo delamination phenomena during Scratch Testing at relatively low applied loads. During ball-on-disc testing, the coatings were removed from the substrate, in particular for monolayer ALD configurations

  4. Influencia del nitruro de aluminio en el crecimiento anormal de grano de aceros microaleados

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    Cabrera, J. M.

    1995-02-01

    Full Text Available After a brief review about concepts and theories involved in control of grain growth by second phase particles, an experimental study of a medium carbon microalloyed steel with two levels of AIN is carried out. A system to study the grain size distributions in order to detect the abnormal grain growth is proposed. Results permit to plot a map of abnormal grain growth-time-temperature. The abnormal grain growth is derived to be due to the AIN dissolution by correlating the above maps with the theoretical volume fraction of precipitates. The importance and effect of the heating rate is also shown: high heating rates can produce a transient oversaturation that can lead to abnormal growing during the dissolution.

    Tras una breve revisión de los conceptos y teorías involucradas en el control del crecimiento de grano por partículas de segunda fase, se efectúa un estudio del mismo en un acero microaleado con contenido medio de carbono con dos niveles de nitruro de aluminio. Se propone un sistema de estudio de las distribuciones de tamaño de grano tendente a poder detectar la presencia de crecimiento anormal de grano. De este modo, se construyen mapas de crecimiento anormal-tiempo-temperatura que, correlacionados con las teóricas fracciones de volumen de los precipitados presentes, permiten comprobar que la disolución del nitruro de aluminio es la responsable fundamental de la aparición del crecimiento anormal de grano. También se muestra el efecto e importancia de la velocidad de calentamiento, ya que altas velocidades pueden producir una sobresaturación transitoria de precipitados que, al disolverse, pueden dar lugar a crecimiento de grano anormal.

  5. Microbiological corrosion in low carbon steels; Corrosion microbiologica en aceros de bajo carbono

    Energy Technology Data Exchange (ETDEWEB)

    Medina-Custodio, O; Ortiz-Prado, A; Jacobo-Armendariz, V. H; Schouwenaars-Franssens, R [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: medina_1979@yahoo.com; armandoo@servidor.unam.mx; vjacobo@dgapa.unam.mx; raf_schouweenaars@yahoo.com

    2009-01-15

    The Microbiologically Induced Corrosion affects several industries, such as oil industry where it is estimated that 20% to 30% pipes failures are related with microorganism. The chemical reactions generate ions transfer, this validate the use of electrochemical technique for its analysis. Coupons submerged in a nutritional medium with presence and absence of three different microorganisms during two periods, 48 hours and 28 days were studied. Polarization resistance (Rp) and Electrochemical Impedance Spectroscopy (EIS) techniques were applied to determine the corrosively of the systems. The results show a greater corrosive effect of abiotic systems, this indicates a microorganisms protection effect to the metal, opposite to the first hypothesis. This result was ratified observing surface coupons by using Scanning Electron Microscopy (SEM) technique. A possible mechanism based on Evans - Tafel graph is proposed to explain inhibitor microorganism effect. [Spanish] La corrosion microbiologica es un tipo comun de deterioro que afecta diversas industrias, una de ellas es la petrolera en la que se estiman que el 20% o 30% de fallas en las tuberias de trasporte de hidrocarburos es favorecida por microorganismos. Las reacciones quimicas que sustentan estos, generan transferencia de iones, lo que justifica el empleo de tecnicas electroquimicas para su analisis. En este trabajo, se estudiaron probetas de acero de bajo carbono SAE 1018, sumergidas en un medio nutritivo rico en cloruros en presencia y ausencia de tres diferentes cargas microbianas, en tiempos de exposicion de 48 horas y 28 dias. Se realizaron ensayos de resistencia a la polarizacion (Rp) y espectroscopia de impedancia electroquimica (EIS) para determinar el efecto corrosivo de los diferentes sistemas. Los resultados muestran que el medio abiotico causa el mayor efecto corrosivo, lo que indica un efecto protector de los microorganismos al metal contradiciendo la hipotesis inicialmente propuesta. La observacion

  6. Precisiones sobre la corrosión del acero en contacto con hormigón

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    Andrade, C.

    1982-09-01

    Full Text Available In this paper, we emphasize that now it is possible to use some electrochemical non-destructive techniques for measuring the corrosion rate of the metals. Also, it is possible to use the gravimetric determinations if the appropriate instrumentation is not available. The simple visual observation is a good complementary technique but it must not be used alone because of its subjectivity. Also, we stress some aspects, such as the influence of the alkalinity and the humidity, about the corrosion, that the bare and galvanized steel, can suffer in contact with construction materials. We analyze mainly, the influence of the type of cement on the risk of corrosion of both kinds of metals.

    En los presentes comentarios se insiste en que, para evaluar la velocidad de corrosión de los metales, en la actualidad se pueden utilizar técnicas electroquímicas no destructivas que permiten seguir la evolución del proceso diariamente, o bien, en el caso de no contar con los aparatos apropiados, se puede acudir a una determinación gravimétrica de la pérdida de metal. La simple observación visual es una valiosa indicación complementaria de las técnicas antes mencionadas, pero no debe utilizarse como técnica de medida única por la subjetividad que conlleva. También se precisan algunos aspectos sobre la corrosión que el acero desnudo y el galvanizado pueden sufrir por estar en contacto con materiales de construcción, como son la influencia de la alcalinidad y de la humedad del medio y, fundamentalmente, se analiza la influencia que puede ejercer el tipo de cemento en el riesgo de corrosión de ambas clases de metales.

  7. Taladrado por fricción en aceros de doble fase

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    Nardi, D.

    2012-02-01

    Full Text Available This work describes the experimental study of the friction drilling process in dual phase (DP steels, with yield strengths from 600 to 800 Mpa. The optimal machining conditions with different thicknesses was assessed through controlled tests at different rotation speeds and feed rates. On one hand, the torque and the thrust force were computed and monitorized. On the other hand, the dimensional tolerances of the holes were evaluated. Another topic of interest inherent to this special technique is the temperature level reached during the friction process which is crucial when it comes to development of microstructural transformations. This thermal condition can transform the mechanical properties of material near the hole and the burr.

    En este trabajo se expone un estudio del proceso de taladrado por fricción en chapas de diferentes aceros de doble fase (DP, con límites elásticos variables desde 600 hasta 800 MPa. Se realiza una evaluación de las condiciones óptimas de mecanizado en función del material y el espesor empleado, variando las velocidades de giro y los avances de penetración. Al mismo tiempo se monitoriza el par y la fuerza axial resultante, analizando además el espesor de la rebaba en distintas profundidades, es decir, las tolerancias dimensionales generadas por el proceso. Otro punto de interés es la medición de la temperatura alcanzada durante el proceso como consecuencia de la fricción, ya que la cantidad de calor absorbido por la pieza puede influir en las transformaciones microestructurales que el material experimenta. Esta afectación térmica puede transformar las propiedades mecánicas del material en las cercanías del agujero y en la rebaba.

  8. GEL DE ALOE-VERA COMO POTENCIAL INHIBIDOR DE LA CORROSIÓN DEL ACERO DE REFUERZO ESTRUCTURAL

    Directory of Open Access Journals (Sweden)

    Héctor Herrera-Hernández

    2015-01-01

    Full Text Available En el presente trabajo se estudiaelectroquímicamente un GELextracto de las hojas de ALOE VERAcomo un posible inhibidor de la corrosión del acero de refuerzo estructuraldel concreto.Los estudiosde corrosiónse llevaron a cabo en 1M de HCl y utilizando la técnica de espectroscopia de impedancia electroquímica (EISse evaluó la resistencia a la corrosión en presencia y ausencia del GEL.Los diagramas de impedancia mostraronque la adición en diferentes proporcionesdel GELinhibe notablemente el proceso de la corrosión del acero inmerso en la solución ácida. También se determinó que las moléculas del GEL obedecena un mecanismo de fisisorciónsobre la superficie del metal de acuerdo con el modelo de isoterma de Langmuircon unG°adsde alrededor de 14.17 kJ/mol. El GEL se clasificócomo un inhibidor orgánico del tipo mixto.

  9. Caracterización de los aceros sinterizados obtenidos a partir de polvos prealeados Fe-1,5% Mo

    Directory of Open Access Journals (Sweden)

    Torralba, J. M.

    1995-02-01

    Full Text Available Sintered molybdenum-, copper-, nickel- alloyed steels, have been studied through the influence of the Chemical composition on different mechanical and physical properties. In all the studied steels, a constant percentage of carbon has been used, as well Fe-Mo prealloyed powders, with a 1,5% Mo content. Selected sintering conditions were close to those used in the P/M industry, potential consumer of the studied steels.

    Se estudian los aceros aleados sinterizados con molibdeno, cobre, níquel y grafito, a partir de la influencia de su composición sobre distintas propiedades mecánicas y físicas. En todos los aceros, se utilizó una composición de carbono constante, así como polvos prealeados de Fe-Mo, con 1,5% Mo. Las condiciones de sinterización elegidas han sido las más próximas a las utilizadas en la industria pulvimetalúrgica, que es el usuario potencial de los materiales estudiados.

  10. COMPORTAMIENTO DEL CONCRETO REFORZADO CON FIBRAS DE ACERO ZP-306 SOMETIDO A ESFUERZOS DE COMPRESIÓN

    Directory of Open Access Journals (Sweden)

    Lina P. Gallo-Arciniegas

    2013-01-01

    Full Text Available En Colombia, el uso del concreto reforzado con fibras de acero (CRFA es muy limitado, debido a que en el país no existe suficiente evidencia experimental y requisitos reglamentarios al respecto. En el artículo se presentan los resultados de una investigación experimental y analítica sobre el comportamiento del CRFA elaborado con fibras ZP-306, sometidas a esfuerzos de compresión. El estudio involucra la revisión y discusión de los modelos disponibles en la literatura, así como un programa experimental que incluye el ensayo de 48 especímenes. A partir de un análisis de regresión de los datos medidos, se proponen ecuaciones para estimar las principales propiedades mecánicas del CRFA, tales como resistencia a compresión, módulo de elasticidad y relación de Poisson. Las ecuaciones correlacionan las propiedades mecánicas con las principales características de las fibras de acero, tales como dosificación y relación de aspecto.

  11. Procesos de conversión de acero y efecto de variables en convertidores tipo L.B.E.

    Directory of Open Access Journals (Sweden)

    Blanco, C.

    1995-10-01

    Full Text Available In order to determine control equations based on qualitative and quantitative changes of the raw materials, an analysis of the efficiency of the steel production process was carried out in converters under specified operation conditions. Empirical equations to obtain the final composition of the steel as a function of the additives, the initial concentrations of the hot metal and the blowing oxygen patterns are established. The resulting relationships depend on the considered variables and therefore could be used to determine operational strategies in order to obtain steels of a certain quality.

    Se analiza la eficacia de los procesos de transformación en convertidores en condiciones de trabajo determinadas, para deducir relaciones aplicables al control basadas en la modificación de cantidades y composiciones de las materias primas. Se plantean ecuaciones empíricas para determinar la composición final del acero como función de los aditivos y de las concentraciones iniciales del arrabio tratado, así como el patrón de soplado de oxígeno. Las relaciones obtenidas establecen las dependencias entre cada una de las variables consideradas y, por tanto, permiten determinar estrategias de operación para obtener aceros con unas calidades finales dadas.

  12. Study of corrosion resistance of AISI 444 ferritic stainless steel for application as a biomaterial; Estudo da resistencia a corrosao do aco inoxidavel ferritico AISI 444 para aplicacao como biomaterial

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Rogerio Albuquerque

    2014-09-01

    Ferritic stainless steels are ferromagnetic materials. This property does not allow their use in orthopedic prosthesis. Nevertheless, in some specific applications, this characteristic is very useful, such as, for fixing dental and facial prostheses by using magnetic attachments. In this study, the corrosion resistance and cytotoxicity of the AISI 444 ferritic stainless steel, with low nickel content, extra-low interstitial levels (C and N) and Ti and Nb stabilizers, were investigated for magnetic dental attachments application. The ISO 5832-1 (ASTM F-139) austenitic stainless steel and a commercial universal keeper for dental attachment (Neo-magnet System) were evaluated for comparison reasons. The first stainless steel is the most used metallic material for prostheses, and the second one, is a ferromagnetic keeper for dental prostheses (NeoM). In vitro cytotoxicity analysis was performed by the red neutral incorporation method. The results showed that the AISI 444 stainless steel is non cytotoxic. The corrosion resistance was studied by anodic polarization methods and electrochemical impedance spectroscopy (EIS), in a saline phosphate buffered solution (PBS) at 37 °C. The electronic properties of the passive film formed on AISI 444 SS were evaluated by the Mott-Schottky approach. All tested materials showed passivity in the PBS medium and the passive oxide film presented a duplex nature. The highest susceptibility to pitting corrosion was associated to the NeoM SS. This steel was also associated to the highest dopant concentration. The comparatively low levels of chromium (nearly 12.5%) and molybdenum (0.3%) of NeoM relatively to the other studied stainless steels are the probable cause of its lower corrosion resistance. The NeoM chemical composition does not match that of the SUS444 standards. The AISI 444 SS pitting resistance was equivalent to the ISO 5832-1 pointing out that it is a potential candidate for replacement of commercial ferromagnetic alloys used

  13. "Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

    Science.gov (United States)

    Martinez Mateo, Isidoro Jose

    fabricacion del molde, tienen una gran influencia sobre su comportamiento en servicio a lo largo de la vida util del molde. En la primera parte del presente estudio, a partir de ensayos punzon sobre disco, se ha determinado la relacion entre la resistencia al desgaste y la dureza de aceros para moldes obtenidos a partir de bloques de gran espesor, estudiando los principales mecanismos de desgaste que tienen lugar. A continuacion, con el fin de determinar el dano superficial que sufren los aceros para moldes en condiciones reales de inyeccion, se han estudiado distintos tipos de aceros utilizados comercialmente en moldes de inyeccion de polimeros y materiales compuestos, seleccionando las condiciones de operacion para determinar la variacion de la rugosidad superficial del acero en funcion del material inyectado, del numero de operaciones sucesivas de inyeccion y de la orientacion del flujo de inyeccion, mediante tecnicas de perfilometria optica y microscopia electronica de barrido. Ademas del dano superficial sufrido por el acero con el numero de piezas inyectadas, tambien se ha determinado la evolucion de la rugosidad superficial de los materiales inyectados, polibutilentereftalato (PBT) puro y materiales compuestos derivados de PBT por adicion de un 20 o un 50% en peso de fibra de vidrio. En el caso de las piezas inyectadas, se ha caracterizado su microestructura en funcion del flujo de inyeccion y de la densidad de fibra, se han determinado sus propiedades termicas y dinamico-mecanicas, asi como la variacion de la rugosidad superficial de las piezas inyectadas con el numero de operaciones de inyeccion y con la geometria de las distintas secciones de las piezas. Finalmente, se ha evaluado la resistencia a la abrasion de PBT reforzado con un 50% de fibra, en funcion del numero de piezas inyectadas y de la direccion de rayado con respecto a la orientacion del flujo de inyeccion.

  14. Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

    Directory of Open Access Journals (Sweden)

    Richárd Székely

    2010-10-01

    Full Text Available This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potential (Epit and repassivation potential (Erepass. Seawater is an electrochemically aggressive medium, which can initiate localised corrosion in welded stainless steels. Different electrochemical and testing methods were used, including cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy (EIS, pH measuring and penetration tests.

  15. EFFECTS OF CARBURIZING AND NITRIDING PROCESSES ON THE COST AND QUALITY OF GEARS PRODUCED WITH AISI 4140 AND 8620 STEELS

    Directory of Open Access Journals (Sweden)

    Claudio José Leitão

    2012-09-01

    Full Text Available This study compares the effects of nitriding and carburizing processes applied to gears subjected to contact stresses below 1300 MPa. The manufacturing cost, as well the depth of hardened layer and the distortion produced by two processes are analyzed. AISI 4140 gears quenched, tempered, liquid and gas nitriding and AISI 8620 gears after liquid carburizing, quenching and tempering are analyzed. The dimensional control of the gears was carried out before and after heat and thermochemical treatments. It is concluded that liquid or gas nitriding processes are about 30% more economical than liquid carburizing an also they reduce the dimensional changes. By the other hand liquid carburizing achieves greater case depth. Liquid nitriding process presents the lowest cost, dimensional changes and case depth.

  16. OPTIMIZATION OF SURFACE ROUGHNESS AND TOOL FLANK WEAR IN TURNING OF AISI 304 AUSTENITIC STAINLESS STEEL WITH CVD COATED TOOL

    Directory of Open Access Journals (Sweden)

    M. KALADHAR

    2013-04-01

    Full Text Available AISI 304 austenitic stainless steel is a popularly used grade in the various fields of manufacturing because of its high ductility, high durability and excellent corrosion resistance. High work hardening, low heat conductivity and high built up edge (BUE formation made this as difficult-to- machine material. Poor surface quality and rapid tool wear are the common problems encountered while machining it. In the present work, an attempt has been made to explore the influence of machining parameters on the performance measures, surface roughness and flank wear in turning of AISI 304 austenitic stainless steel with a two layer Chemical vapour deposition(CVD coated tool. In order to achieve this, Taguchi approach has been employed. The results revealed that the cutting speed most significantly, influences both surface roughness and flank wear. In addition to this the optimal setting of process parameters and optimal ranges of performance measures are predicted.

  17. OPTIMIZATION OF SURFACE ROUGHNESS OF AISI 304 AUSTENITIC STAINLESS STEEL IN DRY TURNING OPERATION USING TAGUCHI DESIGN METHOD

    Directory of Open Access Journals (Sweden)

    D. PHILIP SELVARAJ

    2010-09-01

    Full Text Available The present work is concentrated with the dry turning of AISI 304 Austenitic Stainless Steel (ASS. This paper presents the influence of cutting parameters like cutting speed, feed rate and depth of cut on the surface roughness of austenitic stainless steel during dry turning. A plan of experiments based on Taguchi’s technique has been used to acquire the data. An orthogonal array, the signal to noise (S/N ratio and the analysis of variance (ANOVA are employed to investigate the cutting characteristics of AISI 304 austenitic stainless steel bars using TiC and TiCN coated tungsten carbide cutting tool. Finally the confirmation tests that have been carried out to compare the predicted values with the experimental values confirm its effectiveness in the analysis of surface roughness.

  18. LaCrO3 composite coatings for AISI 444 stainless steel solid oxide fuel cell interconnects

    Directory of Open Access Journals (Sweden)

    Wilson Acchar

    2012-12-01

    Full Text Available Doped lanthanum chromite-based ceramics are the most widely used interconnector material in solid fuel cells (SOFC since they exhibit significant electrical and thermal conductivity, substantial corrosion resistance and adequate mechanical strength at ambient and high temperatures. The disadvantage of this material is its high cost and poor ductility. The aim of this study is to determine the mechanical and oxidation behavior of a stainless steel (AISI 444 with a LaCrO3 deposition on its surface obtained through spray pyrolisis. Coated and pure AISI 444 materials were characterized by mechanical properties, oxidation behavior, X-ray diffraction and scanning electronic microscopy. Results indicated that the coated material displays better oxidation behavior in comparison to pure stainless steel, but no improvement in mechanical strength. Both materials indicate that deformation behavior depends on testing temperatures.

  19. Design of Quenching Process for Large-sized AISI P20 Steel Block Used as Plastic Die

    Institute of Scientific and Technical Information of China (English)

    Dongli SONG; Jianfeng GU; Jiansheng PAN; Xin YAO

    2006-01-01

    For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.

  20. Texture analysis of deformation induced martensite in an AISI 301L stainless steel: microtexture and macrotexture aspects

    OpenAIRE

    Hamilton Ferreira Gomes de Abreu; Marcelo José Gomes da Silva; Luís Flávio Gaspar Herculano; Harry Bhadeshia

    2009-01-01

    Experiments have been conducted to study the strain induced transformation from austenite to martensite in a metastable AISI 301LN austenitic stainless steel, deformed by uniaxial tension applied along rolling direction. Samples deformed 10 and 20% have shown the presence of α´ martensite phase. Measured pole figures of martensite phase were compared to calculated ones, assuming no variant selection and selection of variants where interaction between stress and the plate of martensite ad...