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Sample records for al carbono aisi

  1. 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.

  2. 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

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    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.

  3. 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.

  4. Consideraciones teórico prácticas acerca de la soldadura de los aceros al carbono

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    Osmundo Héctor Rodríguez Pérez

    2006-01-01

    Full Text Available Se analizan los tres tipos de aceros al carbono y su clasificación desde el punto de vista de su soldabilidad. Se pueden observar los aspectos físico - químicos en la zona fundida, zona de transición y zona afectada por el calor. Existen varios aspectos en la tecnología de la soldadura de los aceros al carbono, tales como: preparación de los bordes, limpieza superficial, posición relativa de las piezas, precalentamiento, selección del material de aporte, deposición de los cordones, postcalentamiento, tratamiento térmico posterior y el control de la calidad de las uniones soldadas a tomar en cuenta para realizar la soldadura.

  5. Wear and Adhesive Failure of Al2O3 Powder Coating Sprayed onto AISI H13 Tool Steel Substrate

    Science.gov (United States)

    Amanov, Auezhan; Pyun, Young-Sik

    2016-07-01

    In this study, an alumina (Al2O3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the adhesive failure of the Al2O3 coating and on the hardness of the substrate was investigated. The adhesive failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to adhesive failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the adhesive failure of the Al2O3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the adhesive failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.

  6. Alótropos del carbono: experimentos de laboratorio que se hacen famosos años después

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    F. Rodríguez Reinoso

    2011-03-01

    Full Text Available Es destacable que el “descubrimiento” de los tres últimos alótropos del elemento carbono se haya producido en un intervalo de pocos años: fullerenos en 1985, nanotubos en 1991 y grafeno en 2004.

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

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    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

  8. Joining of Dissimilar alloy Sheets (Al 6063&AISI 304 during Resistance Spot Welding Process: A Feasibility Study for Automotive industry

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    Reddy Sreenivasulu

    2014-12-01

    Full Text Available Present design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to achieve higher fuel efficiency and to bring down vehicle emission. Although some other joining techniques are more and more being used, spot welding still remains the primary joining method in automobile manufacturing so far. Spot welds for automotive applications should have a sufficiently large diameter, so that nugget pullout mode is the dominant failure mode. Interfacial mode is unacceptable due to its low load carrying and energy absorption capability. Strength tests with different static loading were performed in, to reveal the failure mechanisms for the lap-shear geometry and the cross-tension geometry. Based on the literature survey performed, venture into this work was amply motivated by the fact that a little research work has been conducted to joining of dissimilar materials like non ferrous to ferrous. Most of the research works concentrated on joining of different materials like steel to steel or aluminium alloy to aluminium alloy by resistance spot welding. In this work, an experimental study on the resistance spot weldability of aluminium alloy (Al 6063 and austenitic stainless steel (AISI304 sheets, which are lap joined by using a pedestal type resistance spot welding machine. Welding was conducted using a 45-deg truncated cone copper electrode with 10-mm face diameter. The weld nugget diameter, force estimation under lap shear test and T – peel test were investigated using digital type tensometer attached with capacitive displacement transducer (Mikrotech, Bangalore, Model: METM2000ER1. The results shows that joining of Al 6063 and AISI 304 thin sheets by RSW method are feasible for automotive structural joints where the loads are below 1000N act on them, it is observed that by increasing the spots per unit length, then the joint with standing strength to oppose failure is also increased linearly incase of

  9. 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.

  10. EXPOSICIÓN AL MONÓXIDO DE CARBONO DEL PERSONAL ESPECIALISTA EN EXTINCIÓN DE INCENDIOS FORESTALES

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    Belén Carballo Leyenda

    2010-01-01

    Full Text Available Fundamento: Se ha descrito que la salud y el rendimiento laboral del personal dedicado a la extinción de los incendios forestales se ven perjudicados principalmente por el monóxido de carbono (CO. El objetivo de este trabajo ha sido analizar la exposición al CO a la que se ve sometido el personal especialista en la extinción de los incendios. Métodos: Durante 58 incendios reales se monitorizó en 44 sujetos la exposición al CO a la que se vieron sometidos. También se analizó la concentración ponderada para una jornada de 8h (VA-ED. Todos los incendios fueron divididos en función del tipo de trabajo realizado (ataque directo, indirecto y combinado y del combustible presente (pasto, matorral, bajo arbolado y mixto. Las variables analizadas fueron estudiadas mediante la prueba de Kruskal-Wallis, se usó el test de Mann-Whitney para establecer las diferencias entre medias. Resultados: La concentración media de CO en los incendios fue de 18,4±1,7 ppm, lo que supuso una VA-ED de 7,0±1,0 ppm. Las mayores exposiciones al CO se analizaron en los ataques combinados (20,4±2,3 ppm seguidas de las obtenidas en los ataques directos (17,5±2,7 ppm e indirectos (10,6±5,4 ppm. Únicamente se obtuvieron diferencias significativas (p<0,05 al comparar las exposiciones al CO generadas por la combustión del matorral (19,8±2,2 y bajo arbolado (17,2±3,9 y pasto (12,0±5,6. Conclusiones: Las exposiciones de CO analizadas se vieron influidas por el tipo de combustible y trabajo desempeñado. Los valores medios obtenidos se situaron dentro de los límites establecidos como seguros por diferentes organismos nacionales (INSHT e internacionales (NIOSH, OSHA.

  11. Carbono, matéria orgânica leve e frações oxidáveis do carbono orgânico sob sistemas de aléias

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    Roni Fernandes Guareschi

    2013-06-01

    Full Text Available O objetivo deste estudo foi avaliar os teores de carbono orgânico (COT do solo, matéria orgânica leve (MOL em água e as frações oxidáveis do COT em uma área de cultivo de milho em aléias de Flemingia macrophylla submetida a diferentes manejos de sua parte aérea. A área de estudo está localizada na “Fazendinha Agroecológica”, no município de Seropédica, Rio de Janeiro, Brasil. O desenho experimental foi em blocos ao acaso, com 3 tratamentos e 8 repetições, consistindo dos seguintes tratamentos: testemunha (cultivo de milho com ausência de aléias; cultivo de milho em sistema de aléias com poda de 0,6 m de altura e cultivo de milho em sistema de aléias sem poda. Em cada uma das áreas foram coletadas amostras compostas nas profundidades de 0-5 cm. A presença de aléias, bem como, as podas realizadas em Flemingia macrophylla na área que essa encontrava-se associada ao cultivo de milho não alterou o teor de COT do solo. No entanto, a utilização dos caules e das folhas como adubo verde oriunda do tratamento onde se realizou a poda da parte aérea das aléias de Flemingia macrophylla, proporcionou ao solo aumento dos teores de MOL, Conteúdo de C da MOL e da fração F1.

  12. Empleo de la cáscara de arroz en la fundición de piezas de acero al carbono//Using of rice husk in the carbon steel casting parts process

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    Juan Carlos Cruz-Pérez; Jesús Eduardo González-Ruiz; Lorenzo Perdomo-González; Pantaleón Rodríguez-González

    2012-01-01

    Los materiales auxiliares desempeñan un papel importante en el aumento de la eficiencia tecnológica del proceso de fundición de piezas de acero al carbono. En este artículo se exponen los primeros resultados del empleo de la cáscara de arroz como material termoaislante en la obtención de piezas fundidas de acero al carbono. En los experimentos se evaluó la influencia  de seis combinaciones de las variables espesor de pared del casquillo y capa de cobertura. En la confección de los casquillos ...

  13. The Effect of NiAl Coatings on Oxidation Behavior of AISI 403 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    M. Ebrahimian; F. Ashrafizadeh

    2004-01-01

    This paper reports the oxidation behavior of stainless steel type 403 as a substrate material with and without NiAl coating. Evaluation of oxidation resistance was performed on uncoated and coated specimens at 850 and 1050℃. A commercial diffusion process was used for the formation of NiAl intermetallic coatings on the specimens. Before aluminizing, a layer of nickel, about 40 μm, was deposited on specimens by electroplating. Various techniques including SEM, EDAX, optical microscopy and micro-hardness testing were employed to investigate the coatings before and after oxidation tests. Nickel-aluminides produced by two stage; plating-aluminizing, treatment with NiAl on the surface increased the performance of stainless steel samples significantly.

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

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    López-Covaleda, E. A.; Mercado-Velandia, J. L.; Olaya-Flórez, J. J.

    2013-01-01

    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 micros...

  15. Tribological and mechanical properties of Ti/TiAlN/TiAlCN nanoscale multilayer PVD coatings deposited on AISI H11 hot work tool steel

    Energy Technology Data Exchange (ETDEWEB)

    AL-Bukhaiti, M.A., E-mail: m.albukhaiti@gmail.com [Mechanical Engineering Department, Faculty of Engineering, Sana’a University, Sana’a 12544 (Yemen); Al-hatab, K.A. [Mechanical Engineering Department, Faculty of Engineering, Sana’a University, Sana’a 12544 (Yemen); Tillmann, W.; Hoffmann, F.; Sprute, T. [Institute of Materials Engineering, Technische Universitat Dortmund, Leonhard-Euler-Str.2, 44227 Dortmund (Germany)

    2014-11-01

    Highlights: • New Ti/TiAlN/TiAlCN multilayer coating was developed. • It showed low wear rates (10{sup −16} m{sup 3}/N m), low friction coefficients (μ ∼ 0.25), and good hardness (17–20 GPa). • Friction coefficients and wear rates decrease and increase, respectively, with the increase in normal load and sliding velocity. • The coating/Al{sub 2}O{sub 3} pair showed superior wear resistance and low friction coefficient in comparison to coating/100Cr6 pair. - Abstract: A new [Ti/TiAlN/TiAlCN]{sub 5} multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al{sub 2}O{sub 3} balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10 N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10{sup −15} m{sup 3}/N m, low friction coefficients against 100Cr6 and Al{sub 2}O{sub 3} balls in the range of 0.25–0.37, and good hardness in the range of 17–20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al{sub 2}O{sub 3} and coating/100Cr6 sliding system. Compared with the uncoated-H11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al{sub 2}O{sub 3} pair, while

  16. Comparación de la corrosividad atmosférica del acero al carbono en Colombia y Cuba

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    Delgado Lastra, Juan

    2001-06-01

    Full Text Available Samples of structural carbon steel were exposed to the atmosphere in a number of sites in Colombia and Cuba for periods of 2, 3, 6, 12 and 24 months. Corrosion rate was determined by mass loss measurements, and cause-effect relationship to exposure time and pollutants (deposited chloride and sulfur oxides were calculated. Analysis let to adjust models by the multiple regression method. Also, comparison of atmospheric corrosion rates between Colombia and Cuba were done using covariance analysis.

    Se expusieron a la atmósfera probetas de aceros estructurales de bajo contenido de carbono, en varios sitios de Colombia y Cuba, que se retiraron a intervalos de 2, 3, 6, 12, 18 y 24 meses. Se determinó la corrosión por pérdida de masa y se buscaron relaciones de causalidad con el tiempo de exposición y las cantidades de cloruro y óxidos de azufre depositados. El análisis permitió ajustar modelos de regresión múltiple y también, a través de variables dicótomas, realizar la comparación de la corrosión atmosférica entre Colombia y Cuba, mediante análisis de covarianza.

  17. Formation of abrasion-resistant coatings of the AlSiFe{sub x}Mny intermetallic compound type on the AISI 304L alloy

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    Martinez-Peralez, L. G.; Flores-Valdes, A.; Salinas-Rodriguez, A.; Ochoa-Palacios, R. M.; Toscano-giles, J. A.; Torres-Torres, J.

    2016-05-01

    The α-Al{sub 9}FeMnSi and α-Al{sub 9}FeMn{sub 2}Si 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 degree centigrade), 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 degree centigrade, 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 β-Al{sub 9}FeMnSi and β-Al{sub 9}FeMn{sub 2}Si 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. (Author)

  18. Nature in corrosion-erosion surface for [TiN/TiAlN]n nanometric multilayers growth on AISI 1045 steel

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: jcaicedoangulo@gmail.com [Thin Films Group Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360, Cali (Colombia); Advanced Materials for Micro and NanoTechnology Research Group Universidad Autonoma de Occidente (Colombia); Cabrera, G. [Thin Films Group Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360, Cali (Colombia); Caicedo, H.H. [Department of Bioengineering, University of Illinois at Chicago, IL 60612 (United States); Department of Anatomy and Cell Biology, University of Illinois at Chicago, IL 60612 (United States); Amaya, C. [Thin Films Group Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360, Cali (Colombia); Hard Coating Laboratory CDT-ASTIN SENA, Cali (Colombia); Aperador, W. [Ingenieria Mecatronica, Universidad Militar Nueva Granada, Bogota (Colombia)

    2012-04-30

    The aim of this work is to characterize the electrochemical behavior of [TiN/TiAlN]n multilayer coatings under corrosion-erosion condition. The multilayers with bilayer numbers (n) of 2, 6, 12, and 24 and/or bilayer period ({Lambda}) of 1500 nm, 500 nm, 250 nm, 150 nm and 125 nm were deposited by magnetron sputtering technique on Si (100) and AISI 1045 steel substrates. Both, the TiN and the TiAlN structures for multilayer coatings were evaluated via X-ray diffraction analysis. Mechanical and tribological properties were evaluated via nanoindentation measurements and scratch test respectively. Silica particles were used as abrasive material on corrosion-erosion test in 0.5 M of H{sub 2}SO{sub 4} solution at impact angles of 30 Degree-Sign and 90 Degree-Sign over surface. The electrochemical characterization was carried out using polarization resistance technique (Tafel), in order to observe changes in corrosion rate as a function of the bilayer number (n) or the bilayer period ({Lambda}) and the impact angle. Corrosion rate values of 9115 {mu}m y for uncoated steel substrate and 2615 {mu}m y for substrate coated with n = 24 ({Lambda} = 125 nm) under an impact angle of 30 Degree-Sign were found. On the other hand, for an impact angle of 90 Degree-Sign the corrosion rate exhibited 16401 {mu}m y for uncoated steel substrate and 5331 {mu}m y for substrate coated with n = 24 ({Lambda} = 125 nm). This behavior was correlated with the curves of mass loss for both coated samples and the surface damage was analyzed via scanning electron microscopy images for the two different impact angles. These results indicate that TiN/TiAlN multilayer coatings deposited on AISI 1045 steel represent a practical solution for applications in corrosive-erosive environments. - Highlights: Black-Right-Pointing-Pointer Determination of superficial phenomenon that occurs in surface of multilayer films. Black-Right-Pointing-Pointer Innovative multilayer system [TiN/TiAlN]n electrochemical

  19. Formation of abrasion-resistant coatings of the AlSiFexMny intermetallic compound type on the AISI 304L alloy

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    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

  20. Variación del módulo de Young con el tratamiento térmico en aceros al carbono hipoeutectoides

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    Roca, A.

    2005-12-01

    Full Text Available In previous papers, several hipoeutectoide carbon steels in quenched condition showed values of Young's modulus inferior to values corresponding to tempered condition. In all cases, Young's modulus was measured by ultrasound techniques. In fact, modulus of C22E steel (EN 10083 increases from 209 GPa (quenched condition up to 211 GPa (tempered to 650 °C; for C45E steel, modulus increases from 199 GPa to 211 GPa (tempered to 500 °C, and for C55E steel Young's modulus varies from 202 GPa to 209 GPa for tempered steel to 650 °C. The present work focuses on the microstructural characterization of these steels at different heat conditions using reflection optical microscopy and also scanning electronic microscopy and the authors propose an explanation of the modulus variation using the behaviour of the dislocations array and their interaction with solute atoms and other dislocations present in steel.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 (revenido a 500 °C y para el acero C55E el módulo varía desde 202 GPa hasta 209 GPa para el acero revenido a 650 °C. El presente trabajo se centra en la caracterización estructural de los tres aceros mencionados a los distintos estados de tratamiento térmico, utilizando las técnicas de microscopía óptica de reflexión y microscopía electrónica de barrido, y se propone una explicación de la variación del módulo a partir del comportamiento de las dislocaciones y su interacción con átomos de soluto y con otras dislocaciones.

  1. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Tomashchuk, I., E-mail: iryna.tomashchuk@u-bourgogne.fr; Grevey, D.; Sallamand, P.

    2015-01-12

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution.

  2. 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.

  3. 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.

  4. Corrosion resistance of Al2O3 biomedical nanometer coatings on AISI 304 austenitic stainless steel%用于奥氏体不锈钢AISI 304上的生物医学纳米涂层Al2O3的耐腐蚀性

    Institute of Scientific and Technical Information of China (English)

    雷明凯; 曹保胜; 王兴军; 杨涛

    2004-01-01

    奥氏体不锈钢、钴-铬合金、钛及其合金经常被用作医用植入材料.在这些金属材料中,奥氏体不锈钢是最常用的材料.然而,它在侵蚀性生物效应的长期作用下容易受到局部侵蚀.为了改进奥氏体不锈钢的抗磨损和耐腐蚀的效应,已经研究了几种不同的表面改性技术[1,2].本文的研究是采用具有耐腐蚀性的生物医学纳米涂层Al2O3涂复在奥氏体不锈钢AISI 304的表面上,工艺中是采用溶胶-凝胶方法和浸入技术,并使用电化学极化进行测量.

  5. Application of digital image processing to determine the causes of failures in SAE 1018 carbon steel; Aplicacion del procesamiento digital de imagenes para la determinacion de las causas que provocan fallas en el acero al carbono SAE 1018

    Energy Technology Data Exchange (ETDEWEB)

    Bolanos-Rodriguez, E [Escuela Superior de Tizayuca, Universidad Autonoma del Estado de Hidalgo, Tizayuca, Hidalgo (Mexico)]. E-mail: bola7112@yahoo.com.mx; Gonzalez-Islas, J.C. [Universidad Tecnologica de Tulancingo, Tulancingo, Hidalgo (Mexico)]. E-mail: juanc.gonzalez@utec-tgo.edu.mx; Felipe-Riveron, E.M. [Centro de Investigacion en Computacion, Instituto Politecnico Nacional, Mexico, D.F. (Mexico)]. E-mail: edgardo@cic.ipn.mx

    2013-03-15

    The research is focused on determining the causes of failures in the SAE 1018 carbon steel that is used in pipes carrying drinking water. Digital processing of images captured by photomicrographs by scanning electron microscopy coupled with the technique of X-ray microanalysis. The results demonstrate that the low quality of the raw materials and the manufacturing process of steel are the reasons for the occurrence of cracks observed in the material. [Spanish] La investigacion se centra en determinar las causas que provocan fallas en el acero al carbono SAE 1018 que es utilizado en tuberias que transportan agua potable. Se emplea el procesamiento digital de imagenes de las microfotografias captadas por medio de microscopia electronica de barrido, unido a la tecnica de microanalisis de rayos X. Los resultados obtenidos demuestran que la baja calidad de las materias primas y el proceso de manufactura del acero son las razones de la ocurrencia de fisuras observadas en el material.

  6. Low temperature plasma carburizing of AISI 316L austenitic stainless steel and AISI F51 duplex stainless steel Cementação sob plasma à baixa temperatura do aço inoxidável austenítico AISI 316L e do aço inoxidável duplex AISI F51

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Pinedo

    2013-06-01

    Full Text Available In this work an austenitic AISI 316L and a duplex AISI F51 (EN 1.4462 stainless steel were DC-Plasma carburized at 480ºC, using CH4 as carbon carrier gas. For the austenitic AISI 316L stainless steel, low temperature plasma carburizing induced a strong carbon supersaturation in the austenitic lattice and the formation of carbon expanded austenite (γC without any precipitation of carbides. The hardness of the carburized AISI 316L steel reached a maximum of 1000 HV due to ∼13 at% carbon supersaturation and expansion of the FCC lattice. For the duplex stainless steel AISI F51, the austenitic grains transformed to carbon expanded austenite (γC, the ferritic grains transformed to carbon expanded ferrite (αC and M23C6 type carbides precipitated in the nitrided case. Hardness of the carburized case of the F51 duplex steel reached 1600 HV due to the combined effects of austenite and ferrite lattice expansion with a fine and dispersed precipitation of M23C6 carbides.O aço inoxidável austenítico AISI 316L e o aço inoxidável duplex AISI F51 (EN 1.4462 foram cementados sob plasma-DC na temperatura de 480ºC, utilizando-se CH4 como gás de arraste. A cementação sob plasma à baixa temperatura conduziu a uma elevada supersaturação do reticulado cristalino em carbono com a formação de austenita expandida(γC, sem a precipitação de carbonetos. A dureza do aço 316L, após a cementação, atingiu um valor máximo de 1000 HV, devido à supersaturação de ∼ 13 at% de carbono e à expansão do reticulado cristalino CFC. Para o aço inoxidável duplex AISI F51, os grãos de austenita se transformaram em austenita expandida pelo carbono e os grãos de ferrita se transformaram para ferrita expandida com a precipitação de carbonetos do tipo M23C6, na camada cementada. A dureza da camada cementada, no aço F51, atingiu 1600HV, devido ao efeito combinado da expansão dos reticulados cristalinos da austenita e da ferrita com a precipitação fina e

  7. Empleo de la cáscara de arroz en la fundición de piezas de acero al carbono//Using of rice husk in the carbon steel casting parts process

    Directory of Open Access Journals (Sweden)

    Juan Carlos Cruz-Pérez

    2012-05-01

    Full Text Available Los materiales auxiliares desempeñan un papel importante en el aumento de la eficiencia tecnológica del proceso de fundición de piezas de acero al carbono. En este artículo se exponen los primeros resultados del empleo de la cáscara de arroz como material termoaislante en la obtención de piezas fundidas de acero al carbono. En los experimentos se evaluó la influencia  de seis combinaciones de las variables espesor de pared del casquillo y capa de cobertura. En la confección de los casquillos se utilizó cáscara de arroz triturada, la que posteriormente fue aglutinada con silicato de sodio, apisonada y endurecida con CO2, mientras que la cobertura se utilizó sin procesamiento previo. El mayor nivel de entrega de acero se obtuvo al emplear un espesor de casquillo de 65 mm y una altura de cobertura de 85 mm. El valor del ASAF generado por las variantes experimentales resultó igual o inferior a 0,48. Palabras claves: casquillo termoaislante, polvo de cobertura, cáscara de arroz, acero fundido.______________________________________________________________________________ Abstract Feeding auxiliary materials perform a very important role in improves technological efficiency of carbon steel casting parts process. In this article are exposing the first results in the rice husk using as an insulating material in such process. The variables sleeve thickness and covering thickness’ influence were evaluated in six combinations by means of experiments. In sleeves preparation was used crushed rice husk, which was agglutinated with sodium silicate, compacted and hardened with CO2, meanwhile as covering it was uses without previous preparation. The mayor liquid steel delivering level was get employing 65 mm sleeve thickness and 85 mm covering thickness. The ASAF value generated for experimental variants was equal or inferior to 0.48. Key words: insulating sleeve, riser sleeve, hot topping, rice husk, steel cast.

  8. Objetivos y características de la química computacional y su aplicación al estudio de los materiales de carbono

    Directory of Open Access Journals (Sweden)

    D. Suarez

    2012-09-01

    Full Text Available El objetivo principal de la Química Computacional(QC es predecir todo tipo de propiedadesmoleculares de sistemas químicos. Adicionalmente,la QC ofrece información útil para racionalizar ointerpretar tendencias y enunciar relaciones deestructura-actividad. Para ello, la QC emplea unaamplia gama de técnicas teóricas en constantedesarrollo y mejora. La naturaleza del modelomolecular de interés y la del problema o propiedada estudiar condicionan la selección del método(s autilizar. Muchas de las herramientas de la QC puedenser aplicadas por todo tipo de científicos, no sólopor especialistas. Es necesario un conocimientobásico de los fundamentos de los métodos teóricos,capacidad de análisis crítico de los resultados, ciertahabilidad en el manejo del software y acceso arecursos de hardware optimizados para cálculo dealtas prestaciones. La caracterización de los nuevosmateriales de carbono (nanotubos, grafenos, etc.ha venido haciendo un uso intensivo de la QC. Perola aplicación de la QC es igualmente interesantepara comprender las bases moleculares delcomportamiento de todo tipo de materiales decarbono.

  9. Junção por difusão em estado sólido de Al2O3/aço inoxidável AISI 304, com intercamadas de alívio de tensões residuais

    Directory of Open Access Journals (Sweden)

    Travessa D. N.

    1999-01-01

    Full Text Available Discos de alumina sinterizada e de aço inoxidável AISI 304 foram unidos pelo processo de difusão em estado sólido utilizando inicialmente intercamada de Ti e diferentes tempos e temperaturas de junção. Ensaios de cisalhamento indicaram 800 oC/60 min como os mais favoráveis parâmetros de processo. Uma segunda série de experimentos de junção executados nessas mesmas condições teve como finalidade comparar a eficiência de diferentes construções de intercamadas de alívio das tensões residuais de origem térmica, tendo sido verificado a primazia do par Ti/Cu. Idêntico resultado foi obtido por simulação, utilizando o método dos Elementos Finitos. Observação micrográfica da interface Al2O3/Ti mostrou difusão de Al para o metal e a formação de precipitados Ti3Al, enquanto na interface Ti/AISI 304 verificou-se intensa difusão de Fe no Ti e conseqüente estabilização de Ti-b.

  10. Análisis del ciclo de carbono en embalses y su posible efecto en el cambio climático. Aplicación al embalse de Susqueda (río Ter, NE España)

    OpenAIRE

    Palau, Antoni; Alonso, Miguel; Corregidor, David

    2010-01-01

    Los embalses han sido considerados como sistemas emisores netos de carbono. Si bien es cierto que son sistemas forzados a descomponer toda la materia orgánica que queda cubierta por el agua tras la puesta en carga, esta fase inicial de maduración remite con los años hasta niveles de emisión de carbono similares a las de lagos de estado trófico equivalente. No todos los embalses tienen un comportamiento similar en el procesado de la materia orgánica carbonatada. El balance de ca...

  11. Procedimientos y análisis END y ED de soldaduras a tope SMAW, MAG y TIG, de acero al carbono F-114 para construcción

    OpenAIRE

    CLIMENT BALBASTRE, JUAN JOSÉ

    2011-01-01

    Trabajo científico técnico.El objeto del proyecto es la comparación entre tres chapas. Cada una de las chapas tiene un procedimiento de soldadura diferente: Chapa 1. Método SMAW. Chapa 2. Método MAG. Chapa 3. Método TIG. Una vez estas han sido soldadas, se procederá mediante ensayos no destructivos y ensayos destructivos a descubrir las características de estas. Al final de la realización de todos estos ensayos, se concluirá con la elección de la soldadura más apropiada para este acero. La...

  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

    Directory of Open Access Journals (Sweden)

    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. Al2O3-2SiO2 Nanoparticles with Defined AI-Si Ratio: Processing Optimization and Conversion

    Institute of Scientific and Technical Information of China (English)

    郑广俭; 崔学民; 张伟鹏; 童张法; 李峰

    2012-01-01

    Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane(TEOS) and aluminum nitrate(ANN) as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure(morphology) of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows:the molar ratio of water and ethanol to TEOS are 0:1 and 12:1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity(by CaCO3) of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.

  14. SIMULACIÓN EXPERIMENTAL Y NUMÉRICA DE UN PROCESO DE TREFILADO HÚMEDO DE UN ALAMBRE DE ACERO AL CARBONO EXPERIMENTAL AND NUMERICAL SIMULATION OF THE DAMP WIRE DRAWING PROCESS OF A CARBON STEEL

    Directory of Open Access Journals (Sweden)

    Ennio L Rojas

    2008-06-01

    Full Text Available En este trabajo se presenta un análisis experimental y numérico para la descripción del comportamiento mecánico de un alambre de acero al carbono durante un proceso industrial de trefilado húmedo. En primer lugar, se hizo una campaña experimental de mediciones de fuerza de trefilado de las doce reducciones presentes en el proceso. En segundo lugar, se llevaron a cabo ensayos de tracción con objeto de caracterizar el comportamiento mecánico del material en cada etapa de reducción. En estos ensayos se obtuvieron curvas de tensión-deformación que, en conjunto a las respuestas calculadas a partir de la simulación de los ensayos, permitieron derivar la evolución de los parámetros elásticos y plásticos característicos del material a medida que se reduce su diámetro. De dicha evolución se constató el gran endurecimiento que experimenta el material durante el proceso el que, a su vez, condiciona fuertemente su trefilabilidad. Las simulaciones se realizaron por medio de un modelo elastoplástico de grandes deformaciones implementado en un programa de cálculo preexistente, basado en el método de elementos finitos, denominado VULCAN. Luego, los parámetros del material obtenidos en los ensayos de tracción fueron considerados en la simulación del proceso de deformación que ocurre durante el paso del alambre a través de los dados. Los resultados de la simulación se consideran aceptables y representativos del comportamiento del alambre en el proceso.This paper presents an experimental and numerical analysis for the description of the mechanical behaviour of a carbon steel wire during an industrial process of damp drawing. Firstly, an experimental procedure aimed at measuring wire drawing forces in the twelve reductions present in the process was performed. Secondly, tensile tests were carried out in order to characterize the mechanical behavior of the material for each reduction step. The resulting stress-strain curves together with

  15. Influencia del cambio de uso sobre la erosión del suelo, carbono transportado por erosión y stocks de carbono en ambientes semiáridos mediterráneos

    OpenAIRE

    López Carratalá, Jorge

    2014-01-01

    A continuación se describen los temas principales que serán abordados en la tesis doctoral futura: - Relevancia del proceso de erosión hídrica en zonas semiáridas mediterráneas. - Influencia de la erosión en la dinámica del carbono. - Relaciones estructura-Erosión hídrica-Carbono. - Pools de carbono asociados con la erosión hídrica - Contribución de la erosión hídrica a la pérdida de carbono. - Cambio en las propiedades básicas del suelo debido al cambio de uso. - Cambios...

  16. The effect of thermal annealing on the adherence of $Al_2O_3$-films deposited by low-pressure, metal-organic, chemical-vapor deposition on AISI 304

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Vendel, van de D.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films, deposited at 280°C by low-pressure, metal-organic, chemical-vapor deposition on stainless steel, type AISI 304, were annealed at 0.17 kPa in a nitrogen atmosphere for 2,4, and 17 hr at 600, 700, and 800°C. The effect of the annealing process on the adhesion of the thin alumina fi

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

    Directory of Open Access Journals (Sweden)

    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.

  18. High temperature oxidation behavior of AISI 304 and AISI 430 stainless steels

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Reis de Carvalho

    2006-12-01

    Full Text Available The oxidation behavior of AISI 304 and AISI 430 stainless steels was investigated from 1100 °C up to 1200 °C. Mössbauer spectroscopy and x ray diffraction were used to access the phase composition of the formed scales. The main crystalline phases found in the oxidized materials at temperatures above 1100 °C were hematite and magnetite for AISI 430 steel, and hematite and a spinel-like phase for AISI 304 steel. Hematite was found to be the dominant oxide at lower temperatures, whereas magnetite preferentially forms at higher temperatures. The activation energy for oxidation is smaller for AISI 430 steel in relation to AISI 304 steel in the range of studied temperatures, and therefore the AISI 430 steel is less resistant towards oxidation at high temperatures.

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

    OpenAIRE

    Jose Luddey Marulanda-Arevalo; Saul Castañeda-Quintana; Francisco Javier Perez-Trujillo

    2015-01-01

    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 espe...

  20. Almacenamiento de carbono en pastos naturales de la subcuenca del Canipaco, Huancayo

    Directory of Open Access Journals (Sweden)

    Christian Quispe Navarro

    2015-12-01

    Full Text Available El objetivo de este estudio fue evaluar la correlación de pesos de biomasa aérea y radicular de las especies Calamagrostis vicunarum, Festuca dolichophylla y Muhlenbergia ligularis y sus capacidades de almacenamiento de carbono. La recolección de datos se realizó en tres zonas representativas tomando en cuenta factores como la fisonomía vegetativa, fisiografía, topografía y exposición hacia los puntos cardinales, denominándolas zonas I, II y III, equivalentes a tres poblaciones diferentes, las que fueron evaluadas aplicando el método de muestreo simple con distribución sistemática. Las unidades muestrales fueron parcelas cuadradas de 4m². La extracción de muestras vegetativas fueron tomadas al azar desde las parcelas, luego lavadas y oreadas a temperatura ambiente bajo techo antes de su traslado a laboratorios para el secado final, pesajes de biomasa y análisis del contenido de carbono. El procesamiento de datos del inventario para la estimación de la Biomasa y correlaciones fue por especie y zonas, luego a partir de los resultados de biomasa y mediante el factor de conversión se calcularon el contenido de carbono almacenado. Entre los resultados podemos mencionar que los promedios de carbono almacenados son: Calamagrostis vicunarum: 0,754 tC/ha; Festuca dolicophylla: 1,638 tC/ha y Muhlenbergia ligularis: 0,743 tC/ha. En conclusión, por la significancia de la correlación, el peso de la biomasa aérea puede permitir la estimación del peso de la biomasa radicular. El promedio de carbono almacenado por las tres especies juntas alcanza a 3,14 tC/ha.

  1. 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.

  2. A AMAZONIA E O MERCADO DE CARBONO

    OpenAIRE

    Lamarca Junior, Mariano Rua; Chalita, Marie Anne Najm; Godoy, Amalia Maria Goldberg; Silva, Cesar Roberto Leite da

    2008-01-01

    A Amazônia tem um destacado papel na crise ambiental global uma vez que, no Brasil, há mais emissões de carbono por o desmatamento e queimadas do que pela queima de combustíveis de origem fóssil. Para discutir a problemática e a importância da inserção da Amazônia no mercado de carbono, parte-se dos processos de ocupação e uso dos recursos naturais da floresta e das contradições na formulação das políticas para a região. Com base nos conceitos de direitos de propriedade, direitos econômicos e...

  3. 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.

  4. Secuestro de carbono en la biomasa aérea de un sistema agrosilvopastoril de Cocos nucifera, Leucaena leucocephala Var. Cunningham y Pennisetum purpureum Cuba CT-115

    Directory of Open Access Journals (Sweden)

    J. M. Anguiano

    2013-01-01

    Full Text Available Con el objetivo de estimar el secuestro de carbono en la biomasa aérea de un sistema agrosilvopastoril (sasp compuesto por cocotero (Cocos nucifera, Leucaena leucocephala Var. Cunningham sembrada en alta densidad y Pennisetum purpureum Cuba CT-115, se llevó a cabo un estudio en un suelo con textura franco arcillo- arenosa. Se utilizó un diseño en bloques al azar con arreglo en parcelas divididas con cuatro tratamientos 0, 40, 60 y 80 mil árboles de leucaena ha-1 y tres repeticiones; la evaluación duró desde su establecimiento hasta 340 días de edad. Los resultados muestran diferencia estadística (P<0.001 en el secuestro de carbono con 101.19d, 109.73c, 122.00b y 128.62a t C+ha-1año-1 para los sasp de 0, 40, 60 y 80 mil plantas de leucaena ha-1, respectivamente. El mayor aporte de secuestro de carbono lo realizó el cocotero que aportó del 60 al 80% del total del sasp y existió una relación inversa de secuestro de carbono de la gramínea al incrementar la densidad de la leguminosa. El tratamiento que incorpora la siembra en alta densidad de la leguminosa arbórea logró un mayor secuestro de carbono.

  5. Síntesis, caracterización y aplicaciones catalíticas de nanoestructuras de carbono y de carbono dopado con nitrógeno.

    OpenAIRE

    Nieto-Márquez Ballesteros, Antonio

    2010-01-01

    El presente trabajo forma parte de un amplio programa de investigación sobre la preparación de nanoestruturas de carbono y su aplicación en procesos de interés energético, industrial y medioambiental, que actualmente se está desarrollando en el Departamento de Ingeniería Química de la Universidad de Castilla-La Mancha desde el año 2003. Durante las últimas décadas se ha asistido al inicio de una revolución científica basada en la capacidad de medir, manipular y organizar la materia en la ...

  6. 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.

  7. 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.

  8. Aplicación de biosensores amperométricos de polisulfona/nanotubos de carbono en el análisis de muestras reales

    OpenAIRE

    Pérez Rafael, Sandra

    2012-01-01

    La investigación llevada a cabo en la presente tesis doctoral describe el desarrollo de biosensores basados en membranas de polisulfona y nanotubos de carbono (PS/CNT). Este tipo de membranas ha permitido la incorporación de diferentes biomoléculas como hormonas, anticuerpos y enzimas, de manera rápida y fácil gracias a la técnica de inversión de fase. Además, el uso de nanotubos de carbono confiere al material excelentes propiedades eléctricas, permitiendo su uso como transductor. Inicial...

  9. Uso de arcillas fibrosas como coadyuvantes para mejorar la dispersión y estabilidad coloidal de nanotubos de carbono de medios hidrofílicos

    OpenAIRE

    Moreira Martins Fernandes, Francisco Miguel; Ruiz-Hitzky, Eduardo

    2009-01-01

    Uso de arcillas fibrosas como coadyuvantes para mejorar la dispersión y estabilidad coloidal de nanotubos de carbono en medios hidrofílicos. La presente invención se refiere a una composición estable que comprende nanotubos de carbono en un medio líquido polar mediante su asociación a arcillas fibrosas (sepiolita o palygorskita) como coadyuvante para lograr dicha dispersión. La presente invención se refiere al procedimiento de obtención de la composición como una dispe...

  10. Cálculo de la Huella de Carbono del Máster en Ingeniería Ambiental de la Universidad de Valladolid. Curso 2014 - 2015

    OpenAIRE

    Bermejo Martínez, Beatriz

    2015-01-01

    Desde el siglo XIX, coincidiendo con la era de la industrialización, está clara la contribución de los gases de efecto invernadero al aumento del cambio climático natural. El cálculo de la huella de carbono es un muy indicador y una buena herramienta para identificar las fuentes de emisiones de gases de efecto invernadero de una organización, producto o evento. Por eso, se calcula la huella de carbono del Máster en Ingeniería Ambiental durante el curso 2014 - 2015. Más de la mitad de las emis...

  11. CARBONO LÁBIL COMO UN INDICADOR DE CAMBIOS EN DOS SUELOS BAJO DIFERENTES USOS

    Directory of Open Access Journals (Sweden)

    Milagros Ginebra Aguilar

    2015-01-01

    Full Text Available La materia orgánica en el suelo es un componente clave en la reserva y ciclo del carbono. En condiciones naturales el carbono se incorpora al suelo a través del aporte continuo de material orgánico; sin embargo, existen prácticas de uso de la tierra que generan una disminución del carbono orgánico en el tiempo, a la vez hay prácticas de uso sostenible que favorecen su captura y acumulación. La determinación de fracciones lábiles de carbono orgánico del suelo, constituye una práctica frecuente para evaluar cambios en la calidad de la materia orgánica bajo distintos manejos. Se comparó el contenido de carbono lábil (COS L en la capa 0-20 cm de un suelo Ferralítico Rojo Típico con el de un Ferrítico Rojo Oscuro Típico, sometidos a tres usos del suelo (sin explotación, cultivo diversificado y cultivo intensivo. La extracción del COS L se realizó por oxidación con permanganato de potasio a 0,02 mg L -1 y las determinaciones se hicieron colorimétricamente. Se encontró que independientemente del uso, el contenido de COS L fue superior en el suelo Ferralítico que en el Ferrítico y que para ambos suelos los contenidos disminuyeron en las áreas bajo cultivo intensivo con relación a las áreas sin explotación; además, en el sistema diversificado, donde se aplican principios de Manejo Sostenible de Tierras, este indicador tiende a recuperarse. Estos resultados sugieren la inclusión de la determinación del COS L , como indicador de alerta del efecto de los usos del suelo sobre su calidad

  12. Nanoestructuras de carbono con diferentes grupos funcionales

    OpenAIRE

    Vasilievna Kharissova, Oxana

    2013-01-01

    El carbono es uno de los elementos más interesantes en la Tabla Periódica. algunas de sus formas alotrópicas se conocen desde hace miles de años (diamante 3D y grafito 2D) y otras fueron descubiertas de entre 10 y 20 años atrás (fullerenos 0D y nanotubos 1D). Su nueva forma alotrópica, el grafeno 2D, fue descubierta en inglaterra por Geim & Novoselov en 2004 y actualmente es una estrella supernova en el horizonte de la ciencia de materiales y de la física de materia condensada. El grafeno...

  13. Characterization of AISI 4140 borided steels

    International Nuclear Information System (INIS)

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe2B 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 Fe2B 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 μm 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 KC(π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

  14. La Dieta del Dióxido de Carbono (CO2)

    OpenAIRE

    Jorge Medina Valtierra

    2010-01-01

    Hoy en día y frecuentemente estamos viviendo el incremento de los desastres naturales en nuestro planeta y además sabemos que esto se debe al fenómeno llamado calentamiento global. Si este fenómeno continúa en aumento, muy pronto se tendrá un resultado devastador en el clima de la Tierra, aún para un aumento global de tan solo 2 ºC en un tiempo corto. El dióxido de carbono (CO2) es un importante contaminante cuya concentración aumenta y contribuye notablemente a tal sistema anómalo. Pero, un ...

  15. 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.

  16. Corrosion of AISI 316 and AISI 304 stainless steel with iodine vapor

    International Nuclear Information System (INIS)

    The weight loss of stainless steel in corrosion with iodine vapor was studied at 500 to 10000C and an iodine vapor pressure range of 0.05 to 0.5 mm Hg, using a thermobalance. In the initial stage of corrosion, the weight loss rate is largely influenced by solution treatment or surface treatment; the induction period, observed for solution-treated samples, is shortened or eliminated by fission-fragment irradiation, ion-bombardment or mechanical polishing, and in some cases corrosion is even accelerated by the surface treatments. A constant weight loss region follows the initial stage of corrosion. In this region, the weight loss rate is not dependent on treatment to the samples, and has a linear relationship with the vapor pressure of iodine. The rate is the largest at about 800 and 7500C for AISI 316 s. s. and AISI 304 s. s. The rates in general are larger for AISI 304 s. s. than for AISI 316 s. s. below 7000C but almost the same above 8000C. Corrosion product layer is observed on the surface of the sample below 7000C. Based on these findings, the corrosion process is discussed. The deposition of corrosion product in a temperature gradient tube is also described

  17. Contribuição dos créditos de carbono na viabilidade econômica dos contratos de fomento florestal no sul da Bahia

    Directory of Open Access Journals (Sweden)

    Erlon Barbosa Valdetaro

    2011-12-01

    Full Text Available A região do extremo sul da Bahia é caracterizada por sua extensa produção de eucalipto. Grandes empresas do setor de celulose e papel desempenham importante função na economia da região através dos programas de fomento florestal. Além disso, tem-se que alguns produtores fomentados por essas empresas possuem interesse em incrementar o retorno financeiro de seus contratos de fomento florestal através do recebimento de crédito de carbono. Nesse contexto, este trabalho teve como objetivo avaliar a contribuição dos créditos de carbono na viabilidade econômica nos contratos de fomento florestal da região. O Valor Presente Líquido (VPL, a Taxa Interna de Retorno (TIR e o Valor Anual Equivalente (VAE foram os indicadores utilizados na avaliação financeira, a uma taxa de desconto de 10% ao ano, em 45 contratos de fomento distribuídos em 11 municípios da região, e estimou-se o potencial de estocagem de carbono utilizando dados de estoque de carbono do momento em que os contratos atingiram a idade técnica de corte. Os produtores florestais informaram dados referentes à produção, produtividade e rentabilidade do plantio de eucalipto em seus contratos de fomento. Os resultados da pesquisa mostram que a comercialização dos créditos de carbono pode aumentar consideravelmente a viabilidade financeira do contrato de fomento. Dessa forma, pode-se concluir que o comércio de créditos de carbono é uma atividade viável na região e aumentará os ganhos dos produtores fomentados.

  18. ALMACÉN DE CARBONO EN SISTEMAS AGROFORESTALES CON CAFÉ

    OpenAIRE

    William Espinoza-Domínguez; L. Krishnamurthy; Antonio Vázquez-Alarcón; Antonio Torres- Rivera

    2012-01-01

    El presente estudio se realizó con el objetivo de estimar el almacén de carbono en sistemas agroforestales (SAF) con base en café en la región de Huatusco, zona de mayor producción de café (Coffea arabiga L.) en el estado de Veracruz, México, a fin de obtener información cuantitativa sobre el potencial de mitigación de carbono en los SAF de la región. Para ello, se estimaron los reservorios de carbono en biomasa vegetal y la materia orgánica edáfica existentes en sistemas agroforestales de ca...

  19. Efecto de plantaciones dendroenergéticas en el carbono a nivel de suelo, en dos suelos contrastantes de la región de Biobío, Chile

    OpenAIRE

    Edwin Esquivel; Rafael Rubilar; Simón Sandoval; Eduardo Acuña; Jorge Cancino; Miguel Espinosa; Fernando Muñoz

    2013-01-01

    La biomasa forestal como fuente de energía proveniente de plantaciones dendroenergéticas, al compararla con combustibles fósiles, presenta la ventaja de producir energía carbono-neutral, dado el secuestro de carbono (C) fijado en la biomasa producida y los aportes al suelo. Plantaciones forestales de corta rotación, altas densidades, y localizadas en terrenos marginales pueden representar una excelente oportunidad de producción de biomasa para la producción de energía o combustibles. Sin emba...

  20. Ultrasonic evaluation of friction stud welded AA 6063/AISI 1030 steel joints

    International Nuclear Information System (INIS)

    Highlights: • Friction stud welding of AA 6063 and AISI 1030 was done successfully. • Ultrasonic evaluation of interfacial properties. • EDX analysis confirms intermetallic compound (FeAl) in the interfacial region. - Abstract: Friction stud welding is a promising technique in many applications related to oil and gas industries. It is used to attach grating to offshore oil platforms in areas where arc welding is not permitted because of the risk of causing a fire or explosion. Attachment of anodes inside seawater discharge pipelines in a gas processing plant is performed by this process. This solid state joining process permits metal combinations such as welding of aluminum studs to steel which would be problematic with arc welding because of the formation of thick and brittle inter-metallic compounds. In the present work, AA 6063 is joined to AISI 1030 steel using friction stud welding machine. Properties that are of interest to manufacturing applications such as Young’s modulus, longitudinal velocity, bulk modulus and shear modulus are evaluated by means of an ultrasonic flaw detector. At the interface of the joint, there is an increase of 4.4%, 1.8%, 1.15% and 4.42% is observed for the properties Young’s modulus, longitudinal velocity, bulk modulus and shear modulus respectively. This is due to the formation of intermetallic compound and increase in hardness at the interfacial region. Energy Dispersive X-ray analysis confirms the presence of FeAl as the intermetallic compound. Scanning Electron Microscope evaluation shows the presence of an unbound zone at the center of the inner region which is due to the minimum rotational speed and low axial load experienced at that point. In the unbound zone, there is an incomplete bond between dissimilar metals and it is detrimental to joint strength. Optimum value of friction time and usage of pure aluminum interlayer during the friction stud welding process hinders the formation of unbound zone and enhances the

  1. PRESUPUESTO DE CARBONO EN ARRECIFES CORALINOS DE MÉXICO

    OpenAIRE

    Héctor Reyes Bonilla; Luis E. Calderón Aguilera; M. Cecilia Mozqueda Torres; Carriquiry, José D.

    2014-01-01

    El carbono, elemento omnipresente en los arrecifes coralinos, se halla predominantemente en forma de carbonato de calcio, ya que los esqueletos de muchas especies y la estructura física del ecosistema están formados por este compuesto. Los tejidos de los seres vivos del arrecife contienen carbono adquirido por la fotosíntesis y la heterotrofia, procesos que constituyen la red trófica del ecosistema. Este trabajo describe dichos procesos y los servicios ambientales que ofrecen los arrecifes co...

  2. Comportamiento del monóxido de carbono y el clima en la ciudad de Toluca, de 1995 a 2001

    Directory of Open Access Journals (Sweden)

    Julio César Hernández Romero

    2004-01-01

    Full Text Available Uno de los gases contaminantes con mayor distribución y concentración en Toluca y su área metropolitana es el monóxido de carbono que, al igual que el dióxido de azufre y el dióxido de carbono, es generado principalmente por la combustión automotriz y, en segundo lugar por el sector industrial. Sin embargo, debido a la activa dinámica de los vientos en la mayor parte del año, estos gases tienden a dispersarse en todo el valle; solamente durante el invierno la concentración y la distribución del monóxido de carbono se encuentran por encima de las normas establecidas en la legislación vigente. Por eso se considera la calidad del aire como satisfactoria, aunque por su combinación con las bajas temperaturas del periodo invernal y la baja humedad del aire, tiende a representar riesgos para la salud humana.

  3. 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.

  4. La Dieta del Dióxido de Carbono (CO2

    Directory of Open Access Journals (Sweden)

    Jorge Medina Valtierra

    2010-01-01

    Full Text Available Hoy en día y frecuentemente estamos viviendo el incremento de los desastres naturales en nuestro planeta y además sabemos que esto se debe al fenómeno llamado calentamiento global. Si este fenómeno continúa en aumento, muy pronto se tendrá un resultado devastador en el clima de la Tierra, aún para un aumento global de tan solo 2 ºC en un tiempo corto. El dióxido de carbono (CO2 es un importante contaminante cuya concentración aumenta y contribuye notablemente a tal sistema anómalo. Pero, un aumento en la temperatura del aire incrementará también la cantidad de vapor de agua en la atmósfera, añadiendo con esto más "fuego" al fenómeno señalado.

  5. Estudio de las fuerzas de corte en el fresado de AISI 316

    OpenAIRE

    González López, Diego

    2015-01-01

    Este trabajo trata sobre el comportamiento que tiene un acero AISI 316-L ASS al ser fresado mediante dos tipos de procedimiento: fresado en concordancia y fresado en oposición. Para realizar este estudio se ha instalado un dinamómetro Kistler en la herramienta, con el objetivo de medir las fuerzas de corte que intervienen en el mecanizado.Estas fuerzas se procesan con el sistema de adquisición de datos " WaveBook-512" y se analizan posteriormente con el software " Dasylab 8.0", un sistema d...

  6. 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)

  7. Effect of temperature on the level of corrosion caused by heavy petroleum on AISI 304 and AISI 444 stainless steel

    OpenAIRE

    João Paulo Sampaio Eufrásio Machado; Cleiton Carvalho Silva; Ana Vládia Cabral Sobral-Santiago; Hosiberto Batista de Sant'Ana; Jesualdo Pereira Farias

    2006-01-01

    This work presents a study on the influence of national heavy petroleum in the corrosion of the AISI 444 and AISI 304 stainless steels in simulated refining operation conditions. The petroleum was first characterized through physicochemical analysis (density, fluidity point, viscosity, sulfur concentration). In an attempt to understand the corrosion effect of temperature and of the type of heating the referred types of steel thermal treatments were carried out at three levels of temperature (...

  8. Maximização do teor de carbono fixo em biocarvão aplicado ao sequestro de carbono

    Directory of Open Access Journals (Sweden)

    Alessandra L. da Róz

    2015-08-01

    Full Text Available RESUMOA emissão de dióxido de carbono é, atualmente, a principal causa do aquecimento global, devido ao efeito estufa. Ao redor do planeta pesquisadores têm-se esforçado na busca de soluções viáveis para o problema; com isto, o biocarvão está entre as mais recentes propostas de mitigação das mudanças climáticas em razão da sua simplicidade e eficiência. Desta forma, este trabalho teve, por objetivo, maximizar o teor de carbono fixo na produção de biocarvão. Para isso, analisaram-se sete tratamentos, temperaturas de pirólise: 200, 250, 300, 350, 400, 450 e 500 °C. A partir do rendimento gravimétrico de produção e do teor de carbono fixo calcularam-se os respectivos fatores de rendimento gravimétrico para cada tratamento, os quais indicam em qual temperatura se tem a maior quantidade de carbono fixo em função do biocarvão produzido. A pirólise com temperatura máxima de 300 °C indicou o maior fator de rendimento gravimétrico, atingindo 0,22672 C/biocarvão.

  9. Síntesis, Activación Química y Aplicaciones de Nanoestructuras de Carbono

    OpenAIRE

    Jiménez Cotillas, Vicente

    2011-01-01

    El presente trabajo forma parte de un amplio programa de investigación sobre la preparación de nanoestructuras de carbono y su aplicación en procesos de interés energético, industrial y medioambiental que, desde el año 2003 hasta la actualidad, se está desarrollando en el Departamento de Ingeniería Química de la Universidad de Castilla-La Mancha (UCLM). Durante las últimas décadas se ha asistido al inicio de una revolución científica basada en la capacidad de medir, manipular y organizar l...

  10. The global warming, public goods and carbon market; Calentamiento global, bienes publicos y mercado de carbono

    Energy Technology Data Exchange (ETDEWEB)

    Quadri de la Torre, Gabriel [EcoSecurities (Mexico)

    2007-07-15

    The global warming is an issue of the public goods, and demands an outstanding multilateral action, which must to ensure both efficiency and unchanging transition towards an economy of low intensity of carbon. The new system, which is going to replace the Kyoto Protocol, will have compromises for the developing countries and deep implication in the relative competitivity of the nations and companies. [Spanish] El calentamiento global es un problema de bienes publicos que exige una extraordinaria accion multilateral. Esta debe asegurar eficiencia y una transicion fluida hacia una economia de baja intensidad de carbono. El nuevo sistema que sucedera al Protocolo de Kyoto significara compromisos para los paises en vias de desarrollo, y tendra profundas implicaciones en la competitividad relativa de naciones y empresas.

  11. Flujo de Carbono Orgánico Total (COT en una cuenca andina: caso subcuenca Río Las Piedras

    Directory of Open Access Journals (Sweden)

    María Cristina Ordóñez Díaz

    2014-06-01

    Full Text Available El estudio se realizó para calcular el flujo de carbono transportado por la cuenca del río Las Piedras, típica representativa de los Andes tropicales suramericanos, reservorio estratégico del recurso hídrico. Se desarrolló una investigación observacional durante 20 meses sobre el recurso hídrico, mediante un diseño completamente aleatorio, estratificado por altura (msnm, analizando el contenido de COT, las propiedades físico-químicas del agua y variables hidrometeorológicas (caudal y variación estacional. La concentración promedio de COT aportada principalmente desde la zona alta fue 9 mgL-1. Se transporta en promedio un flujo de 2003,5 Kg.dia-1 de COT, asociado al caudal y la estacionalidad húmeda. El análisis en relación con variables físico-químicas permite concluir que el río disuelve CO2 en sus aguas. Este estudio contribuye al análisis del comportamiento de los ríos andinos y su aporte al ciclo global del carbono.

  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. The Effects of Cutting Tool Coating on the Surface Roughness of AISI 1015 Steel Depending on Cutting Parameters

    OpenAIRE

    Hasan GÖKKAYA

    2006-01-01

    The effects of a number of cutting tool coating materials on the surface quality of workpieces, depending on various cutting parameters, were investigated. AISI 1015 steel was processed without cooling on a lathe using 4 different cemented carbide cutting tools, i.e. uncoated, coated with AlTiN and coated with TiAlN using the PVD technique, and one with 3-layer coatings (outermost being TiN) applied by the CVD technique. Among the cutting parameters, the depth of cut was kept constan...

  14. Modelos para la estimación del carbono en la biomasa de los sistemas forestales : influencia de la selvicultura en los socks de carbono

    OpenAIRE

    Ruiz-Peinado Gertrudix, Ricardo

    2013-01-01

    Es ampliamente conocido y reconocido que los bosques tienen un papel fundamental en la mitigación del cambio climático. Funcionan como almacenes de carbono fijando el carbono que captan de la atmósfera en sus estructuras, conformando biomasa viva. El carbono de esta biomasa, una vez que esta muere, puede pasar de nuevo a la atmósfera o puede seguir almacenado durante años formando parte de productos forestales (madera, corcho, etc.) o en el suelo tras la descomposición de la materia orgánica....

  15. Estudo microestrutural do catalisador Ni/gama-Al2O3: efeito da adição de CeO2 na reforma do metano com dióxido de carbono Microstructural study of Ni/gamma-Al2O3 catalyst: addition effects of CeO2 on carbon dioxide reforming of methane

    Directory of Open Access Journals (Sweden)

    Antoninho Valentini

    2003-10-01

    Full Text Available The carbon dioxide reforming of methane was carried out over nickel catalysts supported on the gamma-Al2O3/CeO2 system prepared by wet impregnation. With the increase of the CeO2 weight in the catalyst, a higher stability was observed in the catalytic activity, together with an excellent resistance to carbon deposition and a better Ni dispersion. The catalysts were characterized by means of surface area measurements, TPR, H2 chemisorption, XRD, SEM, EDX, XPS and TEM. An interaction between Ni and CeO2 was observed to the Ni/CeO2 sample after activation in a H2 atmosphere above 300 ºC. Such behavior has a significantly influence on the catalytic activity.

  16. Procesos de certificación de proyectos de captura de gases de efecto invernadero (GEI En los Mercados Internacionales de Carbono

    Directory of Open Access Journals (Sweden)

    Sabogal Aguilar Javier

    2011-11-01

    Full Text Available En el marco de la mitigación al cambio climático, subyacen dos tipos de mecanismos destinados a disminuir las concentraciones de gases efecto invernadero: en primer lugar, la reducción de emisiones por las fuentes contaminantes; y en segundo lugar, el secuestro o captura de los gases de efecto invernadero (GEI cuantificados en CO2 equivalente en proyectos forestales (conocidos como LULUCF.Los proyectos de mitigación se abordan en el presente artículo por la comparación de los procesos de certificación que deben cumplir los proyectos de captura de gases de efecto invernadero, para acceder a los Mercados Internacionales de Carbono, tanto del Mecanismo de Desarrollo Limpio (MDL adoptado por el Protocolo de Kioto, como de los Mercados Voluntarios de Carbono (MVC.Como resultados, se presenta el aporte al desarrollo sustentable "local y regional": social, económico y ambiental en disponibilidad y mantenimiento de bienes y servicios ambientales; se resaltan las críticas a los esquemas de mercado analizados, y la incidencia del aporte a la sustentabilidad regional y local en la aprobación. De acuerdo con a lo anterior, los mercados voluntarios de carbono resultan ser más acordes con proyectos de pequeña y mediana escala mientras que el mecanismo de desarrollo limpio favorece en mayor medida aquellos proyectos de mediana y gran escala.

  17. Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

    Directory of Open Access Journals (Sweden)

    K. A. Habib

    2011-01-01

    Full Text Available The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3 scale totally disappeared and exclusively Fe2O3 was formed, in AISI 316 stainless steel some Cr2O3 persisted and Fe3O4 was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.

  18. 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...

  19. Chloroform fumigation-extraction labile C pool (microbial biomass C "plus" shows high correlation to microbial biomass C in Argentinian and Brazilian soils Alta correlación entre el "pool" de carbono lábil por fumigación con cloroformo-extracción (carbono de biomasa microbiana plus y carbono de biomasa microbiana en suelos de Argentina y Brasil

    Directory of Open Access Journals (Sweden)

    Helvécio De-Polli

    2007-07-01

    Full Text Available Chloroform fumigation-incubation and chloroform fumigation-extraction approaches have significantly contributed to assess soil microbial biomass. Some controversy is found in the literature about the suggestion to calculate microbial biomass carbon (MBC without the subtraction of the un-fumigated control, in opposition to the originally proposed method that requires such subtraction. Some authors consider the non-subtraction proceeding as a more robust method. Nevertheless, values obtained without subtraction of a control include other labile organic fractions of soil carbon besides microbial biomass. Therefore, due to the usefulness of this measurement we consider more appropriate to call it as chloroform-fumigation labile C pool or microbial biomass carbon "plus" (MBC PLUS. We used a vast series of data from soils of Argentina and Brazil under different management situations to verify whether MBC correlates to MBC PLUS. There was a significant statistical correlation between values of MBC obtained by fumigation-extraction method and the corresponding MBC PLUS. The MBC PLUS performed as well as MBC as an indicator to differentiate soil managements and their impact on soil quality.Los métodos de fumigación-incubación y fumigación extracción han contribuido significativamente a las determinaciones de biomasa microbiana del suelo. En la literatura se encuentran algunas controversias acerca de la sugerencia de calcular el carbono de biomasa microbiana (CBM sin la sustracción del control no fumigado, en oposición a las metodologías tradicionales que requieren de dicha sustracción. Algunos autores mencionan que el hecho de no realizar la sustracción hace al procedimiento más robusto. Sin embargo, los valores obtenidos sin la sustracción del control incluyen otras fracciones lábiles del carbono, además de la biomasa microbiana. Debido a lo útil que resulta esta medida consideramos adecuado llamarla "pool" de carbono lábil por fumigaci

  20. Colloquium on Large Scale Improvement: Implications for AISI

    Science.gov (United States)

    McEwen, Nelly, Ed.

    2008-01-01

    The Alberta Initiative for School Improvement (AISI) is a province-wide partnership program whose goal is to improve student learning and performance by fostering initiatives that reflect the unique needs and circumstances of each school authority. It is currently ending its third cycle and ninth year of implementation. "The Colloquium on Large…

  1. Huella hídrica y de carbono en cultivos extensivos de regadío en el sur de Navarra

    OpenAIRE

    Bermejo Ruiz, Irantzu

    2014-01-01

    Uno de los mayores retos de la agricultura europea en los próximos años consiste en la reducción de las emisiones de gases de efecto invernadero procedente de explotaciones agrarias y, al mismo tiempo, adaptarse al nuevo escenario que supone el cambio climático. Asimismo, se puede potenciar la rentabilidad económica y social de las explotaciones mediante la adopción de las oportunas prácticas agrarias sostenibles que reduzcan la huella de carbono de la agricultura y que potencien su efecto su...

  2. Distribución a profundidad del carbono orgánico en los suelos de México

    Directory of Open Access Journals (Sweden)

    Fernando Paz

    2016-07-01

    Full Text Available La caracterización de la distribución vertical del carbono orgánico en los suelos (COS en México es una tarea importante, dada la evidencia acumulada que muestra que el COS puede ser desestabilizado por diferentes mecanismos al incrementar la profundidad a la que se encuentra en el perfil. Con el objetivo de modelar la variación del COS con la profundidad, se analizó una base de datos de COS de perfiles de suelos distribuidos en todo México (base de datos INEGI-COLPOS. Esta base se depuró usando diferentes restricciones congruentes con el objetivo de desarrollar modelos matemáticos de la distribución del carbono con la profundidad (z. Los resultados de los ajustes estadísticos mostraron que modelo logarítmico, COS(z=a-b ln(z, resultó adecuado para lo planteado, por lo que se procedió a su síntesis. Se usó la propiedad de que un conjunto de rectas que se intersectan en un punto común, sus parámetros generan una línea recta. Con base en ella se desarrolló un esquema para estimar el carbono orgánico inerte (COI del espacio b-a del modelo logarítmico. Adicionalmente, para realizar estimaciones del COS a profundidad (hasta su valor máximo usando sólo el valor del COS de 0 a 30 cm, se desarrolló un método para realizar estas estimaciones a partir de parámetros asociados a los ecosistemas y tipos de vegetación. Los resultados de los ejercicios realizados para estimar el COI y el carbono orgánico a profundidad en los suelo usando sólo el COS 30 cm muestran ser adecuados y pueden ser implementados en forma operativa.

  3. Evaluación preliminar del potencial de indicadores de salud y calidad relacionados con el ciclo del carbono de suelos del humedal de Jaboque (Cundinamarca, Colombia

    Directory of Open Access Journals (Sweden)

    Pulido Barrios Hannier Wadith

    2006-06-01

    Full Text Available En el presente trabajo se evaluó el potencial de las actividades enzimáticas celulasa y ‚glucosidasa, de la
    biomasa microbiana por carbono, del porcentaje de carbono orgánico total y del pH en suelos y sedimentos aledaños al humedal de Jaboque (Bogotá-Colombia para determinar su posible utilidad como indicadores del estado de salud y calidad. Para ello se evaluaron los resultados obtenidos en dos épocas del año y en nueve puntos del humedal, que corresponden a problemáticas específicas: cuatro de ellos son suelos, dos son de carácter agrícola, mientras que los cinco puntos restantes son sedimentos. El análisis estadístico de los datos se realizó por el método no paramétrico de Kruskal-Wallis (p=0,05 arrojando diferencias significativas entre los diferentes puntos del humedal y los diferentes tiempos de muestreo, excepto para el parámetro ecofisiológico tasa metabólica (qCO2. La biomasa por carbono en general se relaciona con la respiración y el porcentaje de acumulación de la materia orgánica. Se encontró que las actividades enzimáticas junto con los otros parámetros medidos, exceptuando la tasa metabólica varían significativamente en los distintos puntos
    de muestreo y en las dos épocas de muestreo. Para todos los puntos de muestreo se hizo una aproximación al estado de los procesos involucrados en el ciclo de carbono en el humedal. Los porcentajes de carbono orgánico son significativamente altos, lo que estaría implicando una eutrofización generalizada para todo el humedal. Las diferencias significativas encontradas en los parámetros medidos dan cuenta de la sensibilidad de éstos al problema de contaminación del humedal.

  4. 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.

  5. 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.

  6. A comparative study of mechanical and tribological properties of AISI-304 and AISI-316 submitted to glow discharge nitriding

    Directory of Open Access Journals (Sweden)

    Fabiana Cristina Nascimento

    2009-06-01

    Full Text Available Mechanical and tribological properties os AISI 304 and AISI 316 stainless steels submited to glow discharge ion nitriding are reported.The atmosphere was 20:80 - N2:H2 with substrate temperatures ranging from 300 to 500 °C. Treatment at 300 °C produced expanded austenite (γN in both steels. Increasing the temperature, the phases γ´-Fe4N and - Fe2+xN were present and the latter is the major phase for AISI 304. At 500 °C, the CrN phase was also identified in both steels. Hardnesses of about 13-14 GPa at near surface regions were obtained in both steels. Moreover, AISI 316 nitrided at 500 °C has the deepest hard layer. Tribological tests showed that wear can be reduced by up to a factor of six after the nitriding processes, even for a working temperature of 300 °C. The profiles during and after nanoscratch tests did not reveal significant differences after nitriding processes in both steels.

  7. Sistemas híbridos de polianilina y nanoestructuras de carbono para su aplicación en músculos artificiales y supercondensadores

    OpenAIRE

    García Gallegos, Juan Carlos

    2012-01-01

    La presente tesis es el resultado del estudio de la síntesis de compuestos de polianilina (PAni) con nanoestructuras de carbono para su aplicación en músculos artificiales y electrodos de supercondensadores. Las nanoestructuras que se emplearon en los compuestos de PAni son nanotubos de carbono multicapa (MWCNT), nanotubos de carbono multicapa dopados con nitrógeno (CNx-MWCNT), nanotubos de carbono multicapa funcionalizados con grupos oxigenados (COx-MWCNT) nanotubos de carbono multicapa exfo...

  8. Caracterización del aceite de semilla de borraja extraído con dióxido de carbono supercrítico

    Directory of Open Access Journals (Sweden)

    Delgado Andújar, A.

    1999-08-01

    Full Text Available The present work is based on a comparative study of the borage seed's oil obtained with supercritical carbon dioxide by means of the conventional extraction using hexane as a solvent. In the optimal working conditions, the results obtained in the extraction with carbon dioxide are comparable to those obtained in the extraction with hexane, although the oil's quality is higher. Therefore, the process of supercritical extraction with carbon dioxide could be more effective than conventional extraction because the solvent removal is not necessary and several steps of the oil refining process can be reduced notably.

    En el presente trabajo se realiza un estudio comparativo de la calidad del aceite de semilla de borraja obtenido con dióxido de carbono supercrítico y mediante extracción convencional empleando hexano como disolvente. La calidad del aceite extraído con dióxido de carbono es superior. En las condiciones óptimas de operación, los rendimientos encontrados en la extracción con dióxido de carbono, son comparables a los obtenidos en la extracción con hexano, si bien la calidad del aceite es superior. Por tanto, el proceso de Extracción Supercrítica con dióxido de carbono, al eliminar la etapa de recuperación del disolvente y simplificar sensiblemente el proceso de refinado del aceite, se presenta como una alternativa competitiva con la extracción convencional.

  9. Cladding of aluminum on AISI 304L stainless steel by cold roll bonding: Mechanism, microstructure, and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Akramifard, H.R., E-mail: akrami.1367@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Mirzadeh, H., E-mail: hmirzadeh@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Parsa, M.H., E-mail: mhparsa@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-09-08

    The AA1050 aluminum alloy and AISI 304L stainless steel sheets were stacked together to fabricate Al/304L/Al clad sheet composites by the cold roll bonding process, which was performed at temperatures of ∼100 and 23 °C to produce austenitic and austenitic–martensitic microstructures in the AISI 304L counterpart, respectively. The peel test results showed that the threshold reduction required to make a suitable bond at room temperature is below 10%, which is significantly lower than the required reduction for cold roll bonding of Al sheets. The tearing of the Al sheet during the peel test signified that the bond strength of the roll bonded sheets by only 38% reduction has reached the strength of Al, which is a key advantage of the developed sheets. The extrusion of Al through the surface cracks and settling inside the 304L surface valleys due to strong affinity between Al and Fe was found to be the bonding mechanism. Subsequently, the interface and tensile behaviors of three-layered clad sheets after soaking at 200–600 °C for 1 h were investigated to characterize the effect of annealing treatment on the formation and thickening of intermetallic compound layer and the resultant mechanical properties. Field emission scanning electron microscopy, X-ray diffraction, and optical microscopy techniques revealed that an intermediate layer composed mainly of Al{sub 13}Fe{sub 4}, FeC and Al{sub 8}SiC{sub 7} forms during annealing at 500–600 °C. A significant drop in tensile stress–strain curves after the maximum point (UTS) was correlated to the interface debonding. It was found that the formation of intermediate layer by post heat treatment deteriorates the bond quality and encourages the debonding process. Moreover, the existence of strain-induced martensite in clad sheets was found to play a key role in the enhancement of tensile strength.

  10. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    Science.gov (United States)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  11. Cogeneration and Carbon bonds: clean development; Cogeneracion y bonos de carbono: desarrollo limpio

    Energy Technology Data Exchange (ETDEWEB)

    Navarro Perez, Nidia [Facultad de Contaduria y Administracion, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2004-06-15

    The growing preoccupation for the environment in our country and its interest to ratify the Kyoto Protocol with respect to the contamination of the atmosphere, offers great opportunities for the cogeneration so that it fortifies the scientific and technological research and gives a good international image about the sustainable development and care of the environment, so that companies that invest in clean technology will be able to assign a monetary value to their environmental patrimony, this through the so called Green Bonds or Carbon Bonds, this opens a new dimension to finance projects by means of these bonds that can be negotiated at an international level; by means of the Clean of Energy Production the investment can be stimulated and revenues for projects that contribute to the sustainable development of the country and the power efficiency. At the moment the country has at least 13 projects in different analysis stages to enter the carbon bond market, which are presented as co-generation projects of energy, in addition to the formation of the Mexican Committee for Projects of Reduction and Capture of Gas Discharges of Greenhouse Effect. [Spanish] La creciente preocupacion por el medio ambiente en nuestro pais y su interes por ratificar el Protocolo de Kyoto en lo referente a la contaminacion de la atmosfera, ofrece grandes oportunidades para la cogeneracion de manera que fortalezca la investigacion cientifica y tecnologica y dar una buena imagen internacional en torno a temas de desarrollo sustentable y cuidado del medio ambiente, de manera que empresas que invierten en tecnologia limpia podran asignar un valor monetario a su patrimonio ambiental, esto a traves de los llamados Bonos Verdes o Bonos de Carbono, esto abre una dimension nueva para financiar proyectos por medio de estos bonos que pueden negociarse a nivel internacional; por medio de la Produccion Limpia de energia se puede estimular inversion y ganancias para proyectos que contribuyan al

  12. Transporte electronico en nanoestructuras de carbono

    Science.gov (United States)

    Jodar Ferrandez, Esther

    transmission function. We analyze the influence of the width of the cavity and the distance between them (in the case of multiple cavities). Some interesting results are obtained in these calculations which have been published in international journals (Jodar et al. 2006, Jodar y Perez-Garrido 2007). We emphasize the presence of quasi-localized states in the cavities, which affects to the transmission function, the behaviour of some cavities formed with semi-conductor as quantum dots, or the study of the evolution of the system with multiple cavities to the limit of infinite cavities. (4) Chapter 4: Bloch Oscillations. In this chapter we investigate the properties of carbon nanotubes under a constant electric field. This configuration show Bloch oscillations, according to the work of Bloch and Zener. We study here the dynamics of these oscillations for different geometries as a function of the electric field applied. Specially, the behaviour of the occupation probability and the averaged quadratic displacement as a function of time. We have not found bibliography that deals with this phenomenon in Carbon Nanotubes, which is the aim of this chapter. We first study the behaviour of electrons in pure carbon nanotubes in a constant electric field, for different lengths of the CNT and different values of the electric field applied. We show how wavefunctions oscillate with a period that coincides with that given by theoretical expressions of Bloch oscillations for linear chains of atoms. Besides, we show the different kind of behaviour of localized and extended waves. In the final part of this chapter we apply a constant electric field to the structure studied in the chapter 3, i.e., the cavity. We show in this case that, besides Bloch oscillations, electrons can be confined in certain regions only by inserting the nanotube in an electric field.

  13. 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.

  14. Experimental evaluation of mechanical properties of friction welded AISI steels

    Directory of Open Access Journals (Sweden)

    Amit Handa

    2014-12-01

    Full Text Available In the present study, an experimental setup was designed and fabricated in order to accomplish friction welded joints between austenitic stainless steel and low-alloy steel. Thereafter, the effect of axial pressures on the mechanical properties of friction welded AISI 304 with AISI 1021 steels, produced by mechanical joining, have been investigated. Samples were welded under different axial pressures ranging from 75 to 135 MPa, at constant speed of 1250 rpm. The tensile strength, impact strength, and micro-hardness values of the weldments were determined and evaluated. Simultaneously, the fractrography of the tensile-tested specimens were carried out, so as to understand the failure analysis.

  15. 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.

  16. 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.

  17. Low temperature plasma carburizing of AISI 316L austenitic stainless steel and AISI F51 duplex stainless steel Cementação sob plasma à baixa temperatura do aço inoxidável austenítico AISI 316L e do aço inoxidável duplex AISI F51

    OpenAIRE

    Carlos Eduardo Pinedo; André Paulo Tschiptschin

    2013-01-01

    In this work an austenitic AISI 316L and a duplex AISI F51 (EN 1.4462) stainless steel were DC-Plasma carburized at 480ºC, using CH4 as carbon carrier gas. For the austenitic AISI 316L stainless steel, low temperature plasma carburizing induced a strong carbon supersaturation in the austenitic lattice and the formation of carbon expanded austenite (γC) without any precipitation of carbides. The hardness of the carburized AISI 316L steel reached a maximum of 1000 HV due to ∼13 at% c...

  18. An investigation on fatigue life of borided AISI 1010 steel

    Directory of Open Access Journals (Sweden)

    O.N. Celik

    2009-01-01

    Full Text Available Purpose: This study aims to investigate the fatigue life of box borided AISI 1010 steel materials.Design/methodology/approach: Fatigue specimens firstly have been prepared according to ASTM E466-96 standard and normalized. Then their surfaces have been cleaned by polishing. Boriding heat treatment has been applied in solid media with the help of Ekabor2 powder. Specimens have been borided at 1173-1223-1273 and 1323 K temperatures for 2-4 and 6 hours respectively. Fatigue tests have been made in rotating-bend test device. Separate S-N diagram has been formed for each boriding condition and then their results were compared with the results of the specimens on which any heat treatment has not been made.Findings: As a result it has been seen that boriding has no positive effect on fatigue life of AISI 1010 steel materials. And also it has been determined that fatigue life of the materials on which boriding heat treatment applied, decreases in between 14 %-55 %.Research limitations/implications: It can be noted that the reasons of short fatigue life determination are the boride layer’s much higher hardness than the substrate material’s, and the micro cracks existed between boride phases formed onto the surface.Originality/value: The investigations on fatigue life of borided AISI 1010 steel were made.

  19. Influencia de la cantidad de O2 adicionado al CO2 en el gas de protección sobre la microestructura del metal depositado en uniones soldadas de bordes rectos en aceros de bajo contenido de carbono con el proceso GMAW Influence of O2 content, added to CO2 in the shielding gas, on the microstructure of deposited metal in butt welded joint with straight edges, in low carbon steels using GMAW process

    OpenAIRE

    Eduardo Díaz-Cedré; Amado Cruz-Crespo; Félix Ramos Morales; Mauricio Tello Rico; Joel Chaparro Gonzáles; Manuel Rodríguez Pérez; Juan A. Pozo Morejón; Nancy M. Pérez Pino

    2010-01-01

    La presencia de ferrita acicular (FA) en la microestructura del cordón de soldadura, dentro de determinado rango de valores, eleva considerablemente la tenacidad de las uniones soldadas. Es por ello, que el presente trabajo trata sobre un estudio que relaciona la cantidad de ferrita acicular en el cordón en función del contenido de oxígeno presente en la mezcla activa CO2+O2, durante la realización de uniones soldadas de bordes rectos en aceros de bajo carbono con el proceso con electrodo fus...

  20. Effect of temperature on the level of corrosion caused by heavy petroleum on AISI 304 and AISI 444 stainless steel

    Directory of Open Access Journals (Sweden)

    João Paulo Sampaio Eufrásio Machado

    2006-06-01

    Full Text Available This work presents a study on the influence of national heavy petroleum in the corrosion of the AISI 444 and AISI 304 stainless steels in simulated refining operation conditions. The petroleum was first characterized through physicochemical analysis (density, fluidity point, viscosity, sulfur concentration. In an attempt to understand the corrosion effect of temperature and of the type of heating the referred types of steel thermal treatments were carried out at three levels of temperature (200, 300 and 400 °C. The procedure was done in conditions close to those in the distillation column. Heat was gradually increased from room temperature, and directly heated to working temperature. Each treatment took 4 hours to be completed. Scanning electronic microscopy (SEM and the analysis of X rays dispersive energy (EDX were used after the trials to characterize the samples. The results show that treatment temperature, as well as the type of heating, has distinct influences on each type of steel.

  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. El lago Chinchaycocha en el mercado de bonos de carbono

    Directory of Open Access Journals (Sweden)

    Wilfredo Bulege Gutiérrez

    2012-12-01

    Full Text Available El cambio climático como fenómeno global preocupa a todo el mundo y se manifiesta en lo cotidiano a través de diversos desórdenes del clima. El Panel Intergubernamental de Cambio Climático (IPCC, en su cuarto informe de evaluación presentado el 2007, y la Organización Mundial de Meteorología (OMM han establecido que desde el 2001 la temperatura media global en el planeta registra el nivel de aumento más alto de nuestra historia. A este ritmo, y por lo difícil que resulta encontrar una solución aun en el mediano plazo, todo indica que el 2013 no será la excepción. Las causas del cambio climático son atribuidas a factores naturales pero también antropogénicos; existe ya consenso respecto a la influencia de los gases de efecto invernadero (GEI, sobre todo el dióxido de carbono (CO2 en este proceso acelerado de calentamiento del planeta. Esta crisis del clima, como una forma de ser enfrentada, hoy está obligando a los países a promover proyectos que reduzcan las emisiones de GEI y permitan el almacenamiento de carbono. Uno de los mecanismos internacionales establecidos para concretar este objetivo son los bonos de carbono, iniciativa dispuesta por el Protocolo de Kioto, acuerdo jurídicamente vinculante firmado en 1997 y en vigor desde el 2005. Expiró el año pasado, pero la histórica Conferencia de Doha, Catar, decidió en diciembre último prorrogar la vigencia del tratado hasta el 2020. El protocolo, en su primera fase, exige a las grandes potencias reducir durante el período 2008-2012 la emisión de gases en un 5,2% por debajo del nivel de 1990. Lo interesante es que las empresas de tales potencias, para cumplir esta obligación, pueden hacerlo en cualquier lugar o comprar bonos de carbono de países que superen las metas exigidas. La emisión de estos bonos es, después de todo, una iniciativa de descontaminación, que permite que los países industrializados sigan con sus prácticas contaminantes, en tanto

  3. Simulación de los cambios de carbono orgánico del suelo en sistema de cultivo con higuerilla por el modelo RothC

    OpenAIRE

    Lucila González Molina; Esaú del C. Moreno Pérez; Laksmi Reddiar Krishnamurty; Aurelio Baéz Pérez; Acosta Mireles Miguel

    2012-01-01

    El objetivo del presente trabajo fue la simulación de los cambios del carbono orgánico del suelo (COS), por el modelo RothC, en razón del cambio de uso de suelo del sistema tradicional - asociación maíz-calabaza (TMC) - a sistemas con higuerilla (Ricinus communis): multiestratos (MUL), callejones (CALL) y monocultivo de higuerilla (HIG). Las simulaciones del COS se hicieron para las profundidades de suelo 0-20 y 0-40 cm, para el periodo de 1980-2040, considerándose como línea base al sistema ...

  4. Estudio del comportamiento a fluencia en caliente de un acero avanzado de alta resistencia de bajo contenido en carbono NiCrVCu microaleado con boro

    OpenAIRE

    González Sala, Sara

    2009-01-01

    Una de las líneas de investigación prioritarias en el contexto internacional es el desarrollo de aceros avanzados de alta resistencia (AHSS) con excelentes propiedades de resistencia y tenacidad para aplicaciones en la industria automotriz, naval, aeronáutica y de generación de energía, que permitan disminuir el peso de los componentes y sustituyan aceros tradicionales de contenidos mayores de carbono. Los aceros AHSS microaleados al boro, debido a sus cualidades, tecnología de...

  5. Tribological Properties of Nanometric Atomic Layer Depositions Applied on AISI 420 Stainless Steel

    Directory of Open Access Journals (Sweden)

    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

  6. Propriedades da madeira e estimativas de massa, carbono e energia de clones de Eucalyptus plantados em diferentes locais

    OpenAIRE

    Larissa Carvalho Santos; Ana Márcia Macedo Ladeira Carvalho; Bárbara Luísa Corradi Pereira; Aylson Costa Oliveira; Angélica de Cássia Oliveira Carneiro; Paulo Fernando Trugilho

    2012-01-01

    As diferentes espécies de Eucalyptus são aptas para os mais diversos usos, sendo sua madeira amplamente empregada na geração de energia a partir da sua queima direta na forma de lenha ou da sua conversão em carvão vegetal. Além das propriedades da madeira, informações a respeito da estimativa de massa, carbono fixado e quantidade de energia disponível por área de plantio são importantes para a previsão da quantidade de produtos a ser gerada por material genético em dado local. Diante da impor...

  7. Bonos de carbono: financiarización del medioambiente en México

    Directory of Open Access Journals (Sweden)

    Vania López-Toache

    2016-01-01

    Full Text Available El trabajo tiene como objetivo analizar las medidas de mitigación para la emisión de gases efecto invernadero ( GEI al medioambiente –bonos de carbono– establecidos en el Protocolo de Kyoto. Estos parten del estudio del Teorema de Coase, el cual plantea que el mercado asignará de manera adecuada los derechos de propiedad de las externalidades provocadas por los distintos agentes económicos. Por los resultados se puede afirmar que los bonos de carbono son una forma de financiarización del medioambiente, lo cual está creando en la práctica derechos de contaminación, lo que permite que los países industrializados y empresas contaminantes reduzcan sus emisiones de GEI en países subdesarrollados como México a través de proyectos de energía renovables donde les resulta más económico y rentable.

  8. Dissimilar friction welding of 6061-T6 aluminum and AISI 1018 steel: Properties and microstructural characterization

    International Nuclear Information System (INIS)

    Joining of dissimilar materials is of increasing interest for a wide range of industrial applications. The automotive industry, in particular, views dissimilar materials joining as a gateway for the implementation of lightweight materials. Specifically, the introduction of aluminum alloy parts into a steel car body requires the development of reliable, efficient and economic joining processes. Since aluminum and steel demonstrate different physical, mechanical and metallurgical properties, identification of proper welding processes and practices can be problematic. In this work, inertia friction welding has been used to create joints between a 6061-T6 aluminum alloy and a AISI 1018 steel using various parameters. The joints were evaluated by mechanical testing and metallurgical analysis. Microstructural analyses were done using metallography, microhardness testing, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray elemental mapping, focused ion beam (FIB) with ultra high resolution SEM and transmission electron microscopy (TEM) in TEM and STEM modes. Results of these analysis first suggested that joint strengths on the order of 250 MPa could be achieved. In addition, failures were seen in the plasticized layer on the aluminum side of the joint. Further, bond lines were characterized by a thin layer of formed Al-Fe intermetallic. This intermetallic layer averaged roughly 250 nm thick and compositionally appears related to the FeAl and Fe2Al5 phases.

  9. Gestión Ambiental empresarial: cálculo de la huella de carbono en la industria vitivinícola.

    Directory of Open Access Journals (Sweden)

    Rosa Ana Rodriguez

    2014-12-01

    Full Text Available La huella de carbono es un indicador ambiental que busca cuantificar la cantidad de emisiones de gases de efecto invernadero (GHG. Su medición se convierte en una herramienta que permite trabajar bajo el concepto de eco-eficiencia e identificar oportunidades de reducción de consumo energético, ya que este último es la principal fuente de emisión de GHG a nivel mundial. El presente trabajo aplica la metodología PAS 2050:2011 para la medición de la huella de carbono, en la producción del vino blanco. La misma excluye las emisiones asociadas con los insumos humanos de energía, el transporte de los consumidores al punto de venta y el transporte provisto por animales. Sin embargo, se consideran todas las emisiones involucradas con el ciclo de vida del producto. Como producto principal de este trabajo, se obtuvo una planilla de cálculo que puede aplicarse al cálculo de huella de carbono de cualquier producción de vino blanco, independientemente de su tamaño y proceso. Se incluyó una estimación de la emisión de GHG, teniendo en cuenta todas las posibles variantes que pudiese tener el proceso en la región de Cuyo, definiéndose los límites de la empresa y operaciones a evaluar, desde la vendimia hasta la disposición final.

  10. Microstructural Characteristic of Dissimilar Welded Components (AISI 430 Ferritic-AISI 304 Austenitic Stainless Steels) by CO2 Laser Beam Welding (LBW)

    OpenAIRE

    CALIGULU, Ugur; Dikbas, Halil; Taskin, Mustafa

    2012-01-01

    In this study, microstructural characteristic of dissimilar welded components (AISI 430 ferritic-AISI 304 austenitic stainless steels) by CO2 laser beam welding (LBW) was investigated. Laser beam welding experiments were carried out under argon and helium atmospheres at 2000 and 2500 W heat inputs and 100-200-300 cm/min. welding speeds. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and XRD analysis. The tensile strengt...

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

    OpenAIRE

    Francisco Javier Cárcel-Carrasco; Manuel Pascual-Guillamón; Miguel Angel Pérez-Puig

    2016-01-01

    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 i...

  12. 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.

  13. 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.

  14. 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

    Directory of Open Access Journals (Sweden)

    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.

  15. Caracterización del aceite de germen de trigo extraído con dióxido de carbono líquido y supercrítico.

    Directory of Open Access Journals (Sweden)

    Molero Gómez, A.

    1997-04-01

    Full Text Available In this work the quality of wheat germ oil obtained by extraction with liquid and supercritical carbon dioxide was studied. At the optimum operating conditions, the yield of supercritical extraction is similar to the conventional extraction by organic solvent, but the quality of the wheat germ oil extracted by supercritical carbon dioxide is higher. Furthermore, supercritical extraction could be more economical than organic extraction because the solvent removal by distillation is not necessary and several steps of the following oil refining process can be simplified.

    En el presente trabajo se realiza un estudio de la calidad del aceite de germen de trigo obtenido mediante la extracción con dióxido de carbono a alta presión. En las condiciones operativas óptimas del proceso, el rendimiento de la extracción con dióxido de carbono líquido y supercrítico es similar al de la extracción con disolventes orgánicos, si bien la calidad del aceite obtenido es superior. De ello se desprende el hecho de que el proceso de extracción utilizando dióxido de carbono, en condiciones sub- y supercríticas, puede resultar competitivo con el convencional al simplificar sustancialmente las etapas de refinado del aceite y eliminar la destilación del disolvente, las más costosas desde el punto de vista energético.

  16. COMPORTAMIENTO HIDRODINÁMICO Y ABSORCIÓN DE DIÓXIDO DE CARBONO MEDIANTE REACCIÓN QUÍMICA CON GLUCOSAMINA EN UN REACTOR AIR-LIFT

    Directory of Open Access Journals (Sweden)

    Alicia García-Abuín

    2010-01-01

    Full Text Available En el presente trabajo se ha estudiado el comportamiento de disoluciones acuosas de glucosamina como absorbente para la captura de dióxido de carbono, empleando un reactor “air-lift”. Los resultados experimentales indican que este reactivo (glucosamina muestra un comportamiento similar al observado para otras disoluciones acuosas de aminas ampliamente utilizadas para la captura de dióxido de carbono, en relación a la velocidad a la cual se produce la absorción. El valor de la velocidad de transferencia de masa ha sido determinado, así como el efecto de distintas condiciones de operación sobre el valor de este parámetro y del área interfacial gas-líquido, tales como concentración de amina, pH o caudal de gas alimentado.

  17. Relación de la captura de carbono en Saccharum officinarum con otros factores ambientales para el cultivo de caña panelera / Relation at carbon squestration in Saccharum officinarum with other environmental factors for cane crop

    OpenAIRE

    Sierra Cárdenas, Diana Carolina

    2010-01-01

    La caña panelera tiene un potencial como prestadora del servicio ambiental asociado a la capacidad de reducción de emisiones de CO2, dada la facultad que tiene la especie Saccharum officinarum para a la captura de carbono. El presente estudio identifica la relación de la captura de carbono con otros factores ambientales para el cultivo de caña panelera en Cundinamarca y la Hoya del Río Suárez, en donde la metodología principal se remite al análisis estadístico de los datos a través de los mét...

  18. Microstructure analysis of AISI 304 stainless steel produced by twin-roll thin strip casting process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The microstructure of AISI 304 austenite stainless steel fabricated by the thin strip casting process were investigated using optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD).The microstructures of the casting strips show a duplex structure consisting of delta ferrite and austenite. The volume fraction of the delta ferrite is about 9.74vol% at the center and 6.77vol% at the surface of the casting thin strip, in vermicular and band shapes. On account of rapid cooling and solidification in the continuous casting process, many kinds of inclusions and precipitates have been found. Most of the inclusions and precipitates are spherical complex compounds consisting of oxides, such as, SiO2, MnO, Al2O3,Cr2O3,and FeO or their multiplicity oxides of MnO·Al2O3,2FeO·SiO2, and 2MnO·SiO2. Many defects including dislocations and stacking faults have also formed during the rapid cooling and solidification process, which is helpful to improve the mechanical properties of the casting strips.

  19. Study on Submerged Arc Welding of AISI304%AISI304钢埋弧焊工艺的研究

    Institute of Scientific and Technical Information of China (English)

    唐利萍; 迟永军; 杨松

    2002-01-01

    本文对AISI 304钢薄板的埋弧焊工艺进行了试验研究.并对焊材性能进行了工艺试验,在对试验结果分析的基础上确定了最佳焊接工艺参数.焊接接头的各项力学性能实验结果完全满足图纸要求.通过采取先进的焊接工艺装备,成功实现不锈钢薄壁筒体的焊接.

  20. AVALIAÇÃO DA FORÇA DE RETENÇÃO DE COMPOSTOS ORGÂNICOS (COV EM NANOESTRUTURAS DE CARBONO “CUP STACKED”

    Directory of Open Access Journals (Sweden)

    Waldir Nagel Schirmer

    2008-12-01

    Full Text Available Adsorventes carbonados estão entre as melhores opções na remoção de compostos orgânicos voláteis (COV de correntes gasosas,pela boa afinidade que apresentam com compostos dessa natureza, além de baixo custo e disponibilidade. O presente trabalhoavalia o desempenho do ciclo adsorção/dessorção de dois compostos orgânicos voláteis (fenol e tolueno em nanotubos de carbono(NTC comparativamente a um carbono grafitizado de aplicação tipicamente analítica (Carbotrap. As metodologias deamostragem e análise empregadas compreendem a coleta de gases por bombeamento (amostragem ativa em cartuchos (tubos,contendo o material adsorvente com posterior análise por cromatografia gasosa e espectrometria de massa (CG/EM, de acordocom o Método TO-17 da USEPA. Em relação ao desempenho dos adsorventes, o nanotubo obteve clara vantagem em relação aoCarbotrap, conseguindo reter mais adsorbato por massa de adsorvente. Além disso, não foi verificada interação diferenciada dofenol e tolueno com os dois adsorventes, tanto na etapa de adsorção quanto na de dessorção.

  1. Fiber laser welding of AISI 304 stainless steel plates

    International Nuclear Information System (INIS)

    Compared with conventional lasers, fiber laser welding is characterized by high melting efficiency, deferent keyhole modes and power density characteristics, which could affect the heat and melt flow of the molten pool during welding. The objective of the present work was to study the fiber laser weldability of 5 mm thick AISI 304 austenitic stainless steel plates; therefore, bead-on-plate welding was exploited on AISI 304 stainless steel plates with different laser powers, welding speeds, defocused distances with different types of shielding gas and their effects on the weld zone geometry and properties and final solidification microstructure at room temperature. Laser power, welding speed and defocused distance have a great effect on the bead appearance and weld zone shape while almost no significant effect on both the type of microstructure and mechanical properties of welds. The microstructure of all laser welds was always austenitic including about 3-5 % ferrite. However, the lower the laser power and/or the higher the welding speed, the finer solidification structure, primary ferrite or mixed-mode solidification resulted in crack-free welds. (author)

  2. Crecimiento de nanotubos de carbono sobre materiales de uso convencional en ingeniería

    OpenAIRE

    García Ruiz, Máximo

    2012-01-01

    Los nanotubos de carbono son una forma alotrópica del carbono, como el diamante o el grafito, que, debido a sus propiedades físicas, mecánicas y eléctricas están generando un gran interés de investigación en los últimos años. Típicamente, éstos son formados a partir de precursores tales como el monóxido de carbono, metano, acetileno, tolueno, alcohol, etc. En este proyecto se utilizó tolueno para la síntesis, empleando ferroceno como catalizador. El método utilizado para llevarlo a cabo, fue ...

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

    Directory of Open Access Journals (Sweden)

    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. CAMBIOS EN LAS RESERVAS DE CARBONO ORGÁNICO DEL SUELO BAJO DIFERENTES COBERTURAS

    Directory of Open Access Journals (Sweden)

    José I. Bojórquez Serrano

    2015-01-01

    Full Text Available Las reservas de carbono orgánico en los suelos (COS y sus cambios en el tiempo son un tema ambiental de actualidad, asimismo las pérdidas de COS que ocurren con la conversión de ecosistemas naturales a agrosistemas, contribuyen con emisiones a la atmósfera, al calentamiento global y el cambio climático. El objetivo de este trabajo fue estudiar los cambios en las reservas de COS bajo diferentes coberturas de la cuenca del río Mololoa, Nayarit, México. El análisis de los cambios se realiza por diferencia en las reservas de COS en los primeros 20 cm de 13 perfiles de suelos con diferentes coberturas, dos en bosques de encino, dos en bosques de pino, uno en pastizal, uno en cultivo de aguacate y siete en terrenos cultivados con caña de azúcar. Las coberturas estables de bosque y pastizal generan ganancias en las reservas de COS; siendo el pastizal el que registra la mayor cantidad (2,65 Mg ha -1 año -1 , seguido por el bosque de encino (0,40-0,47 Mg ha -1 año -1 , el bosque de pino (0,15-0,38 Mg ha -1 año -1 y la arboleda de aguacate (0,29 Mg ha -1 año -1 . Mientras que la cobertura de cultivo de caña de azúcar generó pérdidas en las reservas de COS, entre 0,12-0,84 Mg ha -1 año -1

  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. La huella de carbono de la Universidad de Córdoba. 2013

    OpenAIRE

    Toro Jordano, Ana de; Gomera Martínez, Antonio; Aguilar Moreno, José Emilio; Guijarro Jiménez, Clara; Antúnez López, Miguel; Vaquero Abellán, Manuel

    2014-01-01

    La huella de carbono es un término usado para describir la cantidad de gases de efecto invernadero (GEI) que son liberados a la atmósfera directa o indirectamente como consecuencia de una actividad determinada, bien sea la fabricación de un producto, la prestación de un servicio, o el funcionamiento de una organización. Con el concepto huella de carbono de una organización se pretende describir el impacto total que una organización tiene sobre el clima en relación a las e...

  7. 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)

  8. Computer Aided Design of Heat Treatment for AISI P20+Ni Mold Steel with Good Machinability

    Institute of Scientific and Technical Information of China (English)

    HU Xin-bin; GAO Wen; HE Yan-lin; LI Lin

    2004-01-01

    Computer aided design of heat treatment for AISI P20 mold steel with good machinability is attempted to proceed by the commercial software package Thermo-Calc (TCP+DICTRA). Through experimental and theoretical analysis of phase transformation during heat treatment, further knowledge of designing proper heat treatment is obtained. Then the machinability of AISI P20+Ni steel under given heat treatment condition is studied and the influencing factors to their machinability are analyzed. It is shown that heat treatment designed by computer simulation of carbide transformation is applicable to AISI P20+Ni steel with good machinability; AISI P20+Ni steel with tempered sorbite treated by quenching &tempering has optimal machinability; normalizing at the temperature of 910℃ & tempering can avoid cracking and result in acceptable machinability in small thickness module.

  9. 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.

  10. CO2 laser welding of AISI 321stainless steel

    International Nuclear Information System (INIS)

    CO2 laser welding of AISI 321austenitic stainless steel has been carried out. Bead on plate welds on 2 mm thick steel were performed with 450W CO2 laser at speeds ranging from 200 to 900 mm/min. It was observed that weld depth and width was decreased with increasing the speed at constant laser power. Butt welds on different sheet thickness of 1, 2 and 2.5 mm were performed with laser power of 450 W and at speed 750, 275 and 175 mm/min, respectively. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy and SEM. The austenite/delta ferrite microstructure was reported in the welded zone. The microhardness and tensile strength of the welded joints were measured and found almost similar to base metal due to austenitic nature of steel

  11. Stress Ratio Effect on Ratcheting Behavior of AISI 4340 Steel

    Science.gov (United States)

    Divya Bharathi, K.; Dutta, K.

    2016-02-01

    Ratcheting is known as accumulation of plastic strain during asymmetric cyclic loading of metallic materials under non-zero mean stress. This phenomenon reduces fatigue life of engineering materials and thus limits the life prediction capacity of Coffin-Manson relationship. This study intends to investigate the ratcheting behavior in AISI 4340 steel which is mainly used for designing of railway wheel sets, axles, shafts, aircraft components and other machinery parts. The effect of stress ratio on the ratcheting behaviour in both annealed and normalised conditions were investigated for investigated steel. Ratcheting tests were done at different stress ratios of -0.4, -0.6 and -0.8. The results showed that the material responds to hardening behavior and nature of strain accumulation is dependent on the magnitude of stress ratio. The post ratcheted samples showed increase in tensile strength and hardness which increases with increasing stress ratio and these variations in tensile properties are correlated with the induced cyclic hardening.

  12. Simulation of Thermo-viscoplastic Behaviors for AISI 4140 Steel

    Science.gov (United States)

    Li, Hong-Bin; Feng, Yun-Li

    2016-04-01

    The thermo-viscoplastic behaviors of AISI 4140 steel are investigated over wide ranges of strain rate and deformation temperature by isothermal compression tests. Based on the experimental results, a unified viscoplastic constitutive model is proposed to describe the hot compressive deformation behaviors of the studied steel. In order to reasonably evaluate the work hardening behaviors, a strain hardening material constant (h0) is expressed as a function of deformation temperature and strain rate in the proposed constitutive model. Also, the sensitivity of initial value of internal variable s to the deformation temperature is discussed. Furthermore, it is found that the initial value of internal variable s can be expressed as a linear function of deformation temperature. Comparisons between the measured and predicted results confirm that the proposed constitutive model can give an accurate and precise estimate of the inelastic stress-strain relationships for the studied high-strength steel.

  13. Corrosion of AISI 304 stainless steel in polluted seawater

    International Nuclear Information System (INIS)

    The sequence of microbiofouling settlement on AISI 304 stain steel samples exposed to polluted harbor sea water of a power cooling water intake is studied. The firts sates of bacterial colonization are followed by means of scanning electron microscopy during two weeks of exposure. The relation between microbiofouling and corrosion is also followed by scanning electron microscopy and evaluated through electrochemical polarization experiments. The results obtained show that microbial colonization and extracellular polimeric substances forming the biofilms have a marked influence on the electrochemical behaviour of stainless steel in sea water. Laboratory experiments using inorganic chloride solutions or artificial sea water show a considerably lesser attack of the metal than those performed 'in situ' with natural sea water. Passivity breadown is highly facilitated when complex biological and inorganic deposits (fouling) have settled on the metal surface. (Author)

  14. 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.

  15. ESTUDIO DE LA SOLDABILIDAD Y CORROSIÓN DEL ACERO INOXIDABLE AISI 904L CON LOS AGENTES UTILIZADOS EN LA LIXIVIACIÓN DEL COBRE

    OpenAIRE

    Ramón Cortés P; Jaime Villanueva A; Ernesto Ponce L; Manuel Rojas M; Eduardo Rojas Z

    2004-01-01

    La alta agresividad de las soluciones utilizadas en el proceso de lixiviación del cobre y los cuidados especiales que se debe tener para evitar la formación de fases sensibles a estos agentes en la soldadura de aceros inoxidables, ha exigido el desarrollo de nuevos aceros inoxidables que sean más resistentes a la corrosión, manteniendo las propiedades de resistencia a la tracción, al impacto y ductilidad. Es el caso de acero inoxidable AISI 904L, un acero super austenítico de última generació...

  16. Coated carbide drill performance under soluble coconut oil lubricant and nanoparticle enhanced MQL in drilling AISI P20

    Science.gov (United States)

    Jamil, N. A. M.; Azmi, A. I.; Fairuz, M. A.

    2016-02-01

    This research experimentally investigates the performance of a TiAlN coated carbide drill bit in drilling AISI P20 through two different kinds of lubricants, namely; soluble coconut oil (SCO) and nanoparticle-enhanced coconut oil (NECO) under minimum quantity lubrication system. The tool life and tool wear mechanism were studied using various cutting speeds of 50, 100 and 150 m/min with a constant feed of 0.01 mm/rev. Since the flank wear land was not regular along the cutting edge, the average flank wear (VB) was measured at several points using image analysis software. The drills were inspected using a scanning electron microscope to further elucidate the wear mechanism. The result indicates that drilling with the nanoparticle- enhanced lubricant was better in resisting the wear and improving the drill life to some extent

  17. Linear friction welding of AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Research highlights: → Linear friction welding is a feasible process for joining AISI316L. → Most welds had tensile strengths superior to the parent material. → Welding parameters had a significant impact on weld microstructure. → 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 {1 1 1} 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.

  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. 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.

  20. 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.

  1. Influence of process parameters on torsional strength, impact toughness and hardness of dissimilar AISI 304 and AISI 1021 friction welded steels

    Directory of Open Access Journals (Sweden)

    Amit Handa

    2014-06-01

    Full Text Available In this present study an attempt was made to join austenitic stainless steel (AISI 304 with low alloy steel (AISI 1021 at different rotational speeds and at different axial pressures and then determining the strength of the joint by means of mechanical properties such as torsional strength, impact strength and micro hardness. The experimental results indicate that the rotational speed and the axial pressure have a significant effect on the mechanical properties of the joint and it is possible to improve the quality of the joint by selecting the optimum parameters.

  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.

    2016-01-01

    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. PMID:27158647

  3. 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)

  4. Sensores baseados em nanotubos de carbono funcionalizados por ligação não-covalente

    OpenAIRE

    Lage, Carla S. A.; Geraldo, M. Dulce

    2014-01-01

    A pesquisa na área dos nanomateriais de carbono, como os nanotubos de carbono (CNTs), tem crescido muito rapidamente devido às suas propriedades térmicas, eletrónicas e mecânicas. Muitos esforços têm sido realizados para aumentar a solubilidade destes materiais em diversos solventes e obter dispersões estáveis. Uma das estratégias para dispersar os CNTs consiste na funcionalização química, que apresenta como desvantagem a destruição da estrutura sp2 do carbono destes materiais. Ne...

  5. 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.

  6. Influencia de la cantidad de O2 adicionado al CO2 en el gas de protección sobre la microestructura del metal depositado en uniones soldadas de bordes rectos en aceros de bajo contenido de carbono con el proceso GMAW Influence of O2 content, added to CO2 in the shielding gas, on the microstructure of deposited metal in butt welded joint with straight edges, in low carbon steels using GMAW process

    Directory of Open Access Journals (Sweden)

    Eduardo Díaz-Cedré

    2010-12-01

    Full Text Available La presencia de ferrita acicular (FA en la microestructura del cordón de soldadura, dentro de determinado rango de valores, eleva considerablemente la tenacidad de las uniones soldadas. Es por ello, que el presente trabajo trata sobre un estudio que relaciona la cantidad de ferrita acicular en el cordón en función del contenido de oxígeno presente en la mezcla activa CO2+O2, durante la realización de uniones soldadas de bordes rectos en aceros de bajo carbono con el proceso con electrodo fusible y protección gaseosa (GMAW en condiciones invariables de parámetros de proceso (corriente de soldadura, voltaje de arco, velocidad de soldadura, longitud libre y flujo de gas protector. Como resultado del trabajo se estableció la relación gráfica existente entre la ferrita acicular y el contenido de oxígeno en la mezcla.The presence of acicular ferrite (AF in the microstructure of weld bead, in a specified range of values, increase considerably the toughness of welded joints. The present paper, for that reason, study the relationship between the acicular ferrite quantity in the deposited metal and the oxygen present in the active gas mixture of CO2+O2, during the execution of butt welded joints with straight edges, in low carbon steels with consumable electrode and gas protection (GMAW in invariable conditions of process parameters (welding current, arc voltage, welding speed, electrode extension, and gas flow. The graphic relation between the acicular ferrite and the oxygen content was established, as result of the research work.

  7. Reacciones de Formación de Enlaces Carbono-Carbono y Carbono-Heteroátomo Catalizadas por Complejos de Metales de Transición

    OpenAIRE

    Rodríguez Gimeno, Alejandra

    2015-01-01

    La investigación en catálisis conduce al desarrollo de procesos con elevada eficacia, en términos de consumo de energía así como en producción de residuos. La utilización del sistema catalítico adecuado disminuye la energía de activación de los procesos implicados lo que permite reducir la temperatura y/o los tiempos para una determinada transformación. Los catalizadores, al modificar las barreras energéticas de las diferentes vías de reacción posibles, puede dar lugar a cambios e...

  8. Depósito de capas de nitruro de carbono mediante ablación láser

    Directory of Open Access Journals (Sweden)

    Soto, R.

    1998-04-01

    Full Text Available The preparation of carbon nitride thin films by ablation of different target compounds (graphite, guanazole in a reactive atmosphere of ammonia with an ArF excimer laser (193 nm is reported. The films were deposited on different substrates (silicon wafers and aluminium plates and were analysed with different techniques such as profilometry, Fourier transform infrared (FTIR and energy dispersive X-ray spectroscopy (EDX. For both targets, a comparative study of the influence of the ammonia total pressure on the growth rate, composition and properties of the obtained material has been done. A gradual nitrogen incorporation in the films with increasing ammonia pressure and also the presence of nitrogen bonded to carbon in different configurations (simple, double and/or triple bonds was observed. The use of guanazole targets leads to higher efficiency in the nitrogen incorporation and in the formation of simple C-N bonds.

    Se presenta la preparación de capas finas de nitruro de carbono mediante la ablación de diferentes tipos de blancos (grafito, guanazol en una atmósfera reactiva de amoniaco utilizando un láser de excímero de ArF (193 nm. Las capas se han depositado sobre diferentes soportes (obleas de silicio y aluminio y se han analizado empleando técnicas de caracterización básicas como la espectroscopia infrarroja mediante transformada de Fourier (FTIR, espectroscopia de rayos X por dispersión de energía (EDX y perfilometría. Se ha realizado, para los dos blancos utilizados, un estudio comparativo de la influencia de la presión total de amoniaco en la velocidad de depósito, composición y propiedades del material obtenido. Se ha observado en ambos casos la progresiva incorporación de nitrógeno en las capas con el aumento de la presión de amoniaco, estando el nitrógeno enlazado al carbono en diferentes configuraciones (enlaces simples, dobles y/o triples. La utilización del blanco de guanazol se muestra más eficiente en

  9. Equilibrios químicos en disolución. Equilibrios concurrentes: solubilización del carbonato de calcio por presencia de dióxido de carbono.

    OpenAIRE

    Milla González, Miguel

    2016-01-01

    En la primera parte de este ejercicio deberá calcularse el pH teórico necesario para hacer desaparecer la última partícula de precipitado en una suspensión de carbonato de calcio 0.01 molar mediante adición de un ácido fuerte. En la segunda parte, hay que calcular la cantidad de esta sal que puede disolverse al saturar la disolución con dióxido de carbono. Algo de lo que ocurre en las aguas naturales carbonatadas cuando entran en contacto con el CO2 atmosférico y disuelven el carbonato de ca...

  10. PARÁMETROS CINÉTICOS Y PERFIL DE ÁCIDOS GRASOS DE CADENA CORTA DE BACTERIAS ÁCIDO LÁCTICAS TERMOTOLERANTES CON DIFERENTES FUENTES DE CARBONO

    OpenAIRE

    Juan DÍAZ-VELA; Lino MAYORGA-REYES; Alfonso TOTOSAUS S.; María de Lourdes PÉREZ-CHABELA

    2012-01-01

    Antecedentes: Los prebióticos son sustancias obtenidas de fuentes vegetales, las cuales son digeribles enel colon donde se sitúa el mayor número de flora intestinal. Las inulinas de achicoria y agave son utilizadas como prebióticos en distintos alimentos, proporcionando beneficios al aumentar la flora microbiana benéfica. Objetivos: Determinar el efecto de diferentes fuentes de carbono como inulina de agave, achicoria,y albedo de naranja sobre los parámetros cinéticos y el perfil de ácidos ...

  11. Effect of ferric ions in AISI 316L stainless steel pickling using an environmentally-friendly H{sub 2}SO{sub 4}-HF-H{sub 2}O{sub 2} mixture

    Energy Technology Data Exchange (ETDEWEB)

    Narvaez, L. [Metallurgical Institute, UASLP Avda. Sierra Leona 550, 78210 San Luis Potosi (Mexico); Cano, E.; Bastidas, J.M. [CENIM-National Centre for Metallurgical Research (CSIC) Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2003-02-01

    A mixture of hydrogen peroxide, sulphuric and hydrofluoric acids has been used as pickling solution at pH 2.0 for AISI 316L austenitic stainless steel (SS). The stability of the H{sub 2}SO{sub 4}-HF-H{sub 2}O{sub 2} mixture is assessed varying the ferric ions content from 0 to 40 g/L, the temperature from 25 to 60 C, and with and without stirring of the pickling solution. The AISI 316L SS pickling rate at 50 C was 2.6 and 0.2 mg/dm{sup 2} day (mdd) in the absence and presence of 40 g/L ferric ions, respectively. p-toluene sulphonic acid (PTSA) has been used as stabiliser of hydrogen peroxide. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Es ist ein Gemisch mit einem pH-Wert von 2.0 aus Wasserstoffperoxid, Schwefelsaeure und Fluorwasserstoffsaeure als Beizloesung fuer nichtrostenden Stahl AISI 316L angewandt worden. Die Stabilitaet des Gemisches H{sub 2}SO{sub 4}-HF-H{sub 2}O{sub 2} haengt vom Gehalt der dreiwertigen Eisenionen, zwischen 0 und 40 g/L, von der Temperatur, zwischen 25 und 60 C, und von der Ruehrintensitaet der Beizloesung ab. Die Beizgeschwindigkeit des nichtrostenden Stahls AISI 316L bei 50 C lag bei 2.6 bzw. 0.2 mg/dm{sup 2} taeglich (mdd), je nachdem, ob 40 g/L dreiwertige Eisenionen enthalten waren oder nicht. Als Stabilisator des Wasserstoffperoxids ist para-Toluensulfonsaeure (PTSA) eingesetzt worden. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  12. 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.

  13. Qualification criteria verification for aisi-4340 steel suspension lug

    International Nuclear Information System (INIS)

    All external loads carried underneath an aircraft are mounted onto it through mechanism generally known as suspension system. The externally mounted attachments like bombs, missiles and fuel tanks etc. experience enormous aerodynamic and inertial forces in the flights. These forces are transferred to the interface point of suspension system, known as 'Suspension Lug'. Thus lugs are considered critical component and have extremely stringent qualification criteria standards used in the aviation industry in USA, Europe, Russia, etc. Different standards prevail in different parts of the world about qualification and testing of these lugs. As Pakistan is entering into aviation industry, therefore there is a need to fulfill the requirements of these standards, to suit Pakistani environment. The suspension lug under study is 2000 Ibs. load class made from AISI-4340 Steel having good mechanical properties as per required standard. The manufacturing processes included forging, machining and vacuum heat treatment. The prototypes of suspension lugs were manufactured in the local industry and subjected to the required mechanical tests such as tensile testing at 5 to 35 degree angles. Impact testing at cryogenic temperatures of -50 to -70 degree C, and breaking load testing were performed. The acceptable results were obtained and mechanical testing for qualification of lugs was finalized and standardized. The options were compared with practical viability, utilization of product and cost effectiveness. (author)

  14. 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.

  15. Environment-tensile property relationship in AISI 1018 steel

    International Nuclear Information System (INIS)

    Environment-material interaction depends on several concurrent and mutually competitive variables ranging from nature of the environment to composition of the steel and including: the test temperature; the time of exposure of the material to the environment; the deformation rate; and intrinsic microstructural effects; The present work is a characterization of strain rate and environment influences on the tensile properties of a steel, AISI 1018, having a fully spheroidized microstructure. Tensile tests were performed at ambient temperature (300 K) in environments which are mildly aggressive (moist laboratory air-relative humidity 50%) and inert (dry gaseous nitrogen). The specimens were deformed to failure at strain rates of 10-4sec-1 and 10-5sec-1. No appreciable increase in yield and tensile strengths was observed at the strain rate of 10-4sec-1. However, the increase in both was of the order of 10 to 12% at the strain rate of 10-5sec-1. Ductility showed no variation with strain rate, but increased in the inert environment at both strain rates. Both environment and strain rate were found to have little to no influence on reduction in area of the test specimens. The true fracture stress followed a similar trend to the yield strength and ultimate tensile strength. (author)

  16. 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.

  17. Characterization of AISI 1005 corrosion films grown under cyclic voltammetry of low sulfide ion concentrations

    International Nuclear Information System (INIS)

    Highlights: •The corrosion of AISI 1005 in sulfide solutions was investigated. •The mechanism of film growth on carbon steel in sulfide solutions was studied. •Film growth was characterized using SEM, EDX, XRD and Mössbauer spectroscopy. •Growth of AISI 1005 corrosion films under cyclic voltammetry. -- Abstract: The mechanism of AISI 1005 corrosion in sulfide ion solutions has been investigated using cyclic voltammetry, electrochemical impedance spectroscopy, X-ray diffraction (XRD) and Mössbauer spectroscopy (MS). The proposed mechanism occurs with the initial formation of oxygenated ferrous species followed by adsorption of HS− species, precipitation of iron monosulfides and their partial conversion to bisulfide iron. This mechanism was demonstrated by XRD results that revealed Fe-O and Fe-S phases and by MS results that detected pyrite as the major proportion (94%) of the iron species in the corrosion product

  18. O balanço de carbono da Amazônia brasileira

    OpenAIRE

    Nobre, Carlos A.; Antônio D. Nobre

    2002-01-01

    GLOBALMENTE, a biota terrestre é um sumidouro significativo de dióxido de carbono (CO2) atmosférico. Estudos recentes do IPCC para a década de 1990 estimam a biota terrestre com sendo um sumidouro líquido de aproximadamente 1,4 gigatonelada de carbono por ano (assimilação líquida pela biota terrestre menos as emissões devidas às mudanças dos usos da terra). É provável que a maior parte desse suposto sumidouro aconteça nas florestas das latitudes médias e dos trópicos. Estudos do ciclo do carb...

  19. Carbono orgânico e biomassa microbiana do solo em plantios de Acacia mangium no Cerrado de Roraima Soil organic carbon and soil microbial biomass in Acacia mangium plantation in the Savanna of Roraima

    Directory of Open Access Journals (Sweden)

    Sara Magda Oliveira Simões

    2010-03-01

    Full Text Available O objetivo do estudo foi avaliar os efeitos de plantios de Acacia mangium, localizados no cerrado em Roraima, sobre o carbono orgânico e biomassa microbiana do solo. Foram realizadas amostragens de solo nas profundidades de 0-20 cm e 20-40 cm em dois plantios de A. mangium com cerca de cinco anos de idade, e em duas áreas de Cerrado nativo consideradas referência. Um dos plantios de A. mangium (localizado na Fazenda Cigolina correspondeu a um plantio homogêneo (espa��amento de 3,6 m entre linhas e 2,0 m entre plantas enquanto que o outro (localizado no Campo Experimental Água Boa - CEAB correspondeu a um plantio em faixas com duas linhas de plantio (espaçamento de 6 m entre linhas, 2,5 m entre plantas e cerca de 30 m entre faixas. As amostras de solo foram analisadas quanto ao carbono orgânico, carbono da biomassa microbiana, respiração basal do solo e quociente metabólico, além de atributos químicos de fertilidade. Foi verificado que os plantios de A. mangium não proporcionaram aumentos significativos do carbono orgânico do solo em comparação às áreas de referência. Entretanto, na média geral, esses plantios proporcionaram aumento do carbono da biomassa microbiana do solo e redução do quociente metabólico, indicando a possibilidade de acúmulo de carbono orgânico no solo em longo prazo. Também foi observado que, em comparação ao plantio da fazenda Cigolina e às áreas de referência, o carbono microbiano do solo foi maior e acompanhado de menor quociente metabólico no plantio de A. mangium no CEAB, mostrando que a estrutura de plantio exerceu influência sobre a biomassa microbiana do solo.The aim of this study was to evaluate the effects of Acacia mangium plantation in the Roraima's Savanna, on soil organic carbon and soil microbial biomass. Soil samplings were collected on the depths of 0-20 cm and 20-40 cm in two Acacia mangium plantation sites, about five years old, and in two sites of native savanna as

  20. Resistência à corrosão de pós metálicos em concretos refratários contendo elevado teor de carbono Corrosion resistance of metal powders in high-carbon containing castables

    Directory of Open Access Journals (Sweden)

    V. G. Domiciano

    2006-09-01

    Full Text Available Os benefícios proporcionados pela adição de carbono em concretos refratários têm ampliado a utilização destes materiais em aplicações siderúrgicas. Contudo, um dos problemas que ainda limita o emprego de concretos refratários contendo elevado teor de carbono é a corrosão de pós metálicos comumente empregados para conter a oxidação do carbono a altas temperaturas. Estudos preliminares mostraram que a corrosão das partículas metálicas é diretamente afetada pelas condições alcalinas promovidas pela presença de cimento. Diante disso, o objetivo deste trabalho foi avaliar o efeito da temperatura e a influência de diferentes agentes ligantes sobre a resistência à corrosão de pós metálicos (Al e Si em água e em concretos refratários contendo elevado teor de carbono. Para isso, foi empregada uma técnica capaz de detectar a liberação de gás H2 como produto da reação de corrosão dos metais. Os resultados obtidos revelaram a possibilidade de aplicação dos pós metálicos em concreto refratário através da escolha de um ligante apropriado.The benefits promoted by carbon addition in refractory castables have led to an increase in the use of such materials in the steel making industry. Nevertheless, one of the problems that still hinder the use of high-carbon-containing castables is the corrosion of metal powders commonly used to prevent carbon oxidation at high temperatures. Preliminary studies have pointed out that the metal powders corrosion within the castables is affected by the aggressive alkaline conditions promoted by cement hydration. The present work aimed to evaluate the effect of temperature as well as the influence of different binders on the corrosion resistance of Al and Si powders in water and in high-carbon containing castables. A technique able to detect the H2-gas release was used to identify the metal powders corrosion. The results revealed the possibility of applying Al or Si powders in these

  1. Renovação do carbono-13 em figueiras 'Roxo de Valinhos'

    Directory of Open Access Journals (Sweden)

    Andréa Carvalho da Silva

    2011-06-01

    Full Text Available O objetivo do trabalho foi determinar a taxa de renovação do carbono-13 ("turnover", dos diferentes órgãos da figueira 'Roxo de Valinhos'. O experimento foi conduzido no pomar da Faculdade de Ciências Agronômicas, FCA/UNESP, Câmpus de Botucatu-SP. Determinou-se previamente, através das trocas gasosas com um medidor aberto portátil de fotossíntese, IRGA, a principal folha fotossinteticamente ativa. Essa folha foi colocada em uma câmara onde ocorreu a injeção do gás enriquecido. O tempo de enriquecimento da folha foi de 30 minutos. Os tratamentos foram constituídos por sete plantas de figueira, que foram retiradas do solo após: 6; 24; 48; 72; 120; 168 e 360 horas do enriquecimento com 13C, e suas partes seccionadas em: gema apical, folha jovem, folhas adultas (fotossinteticamente ativas, brotações laterais, frutos e ramo. Os resultados obtidos permitiram o estabelecimento da sequência de metabolização do carbono-13 nas partições estudadas: Folhas novas > Frutos > Brotações > Folhas Adultas > Gema Apical > Ramo > Folha marcada. Plantas de figueira 'Roxo de Valinhos' apresentam reciclagem do 13C de 24 horas e um tempo de meia-vida de duração do carbono-13 inferior a 11 horas.

  2. 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.

  3. Corrosion Behavior of TiN Coated AISI D2 Steel

    OpenAIRE

    ÇEĞİL, Özkan; Şen, Şaduman

    2014-01-01

    In this study, the corrosion behaviors of nitride and titanium nitride (TiN) layers deposited on AISI D2 steel samples are reported. Steel was at first nitrided in a nitrogen and ammonia atmosphere at 575 °C for 8 h and then titanium nitride coating treatment was performed in the powder mixture consisting of ferro-titanium, ammonium chloride and alumina at 1000°C for 2h by pack diffusion coating. TiN coating layer thickness realized on the AISI D2 steel is 6,71 ± 0,9 μm. The hardness of TiN l...

  4. 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.

  5. Creep behaviour and microstructural evolution in AISI 316LN+Nb steels at 650 degrees C

    OpenAIRE

    Vodárek, Vlastimil

    2011-01-01

    The paper deals with the effect of niobium in the wrought AISI 316LN steels on the long-term creep characteristics at 650 °C. Casts B and C contained 0.1 and 0.3 wt.%Nb, respectively. As a reference material the niobium free Cast A was used. Small additions of niobium to the AISI 316LN steel resulted in a significant reduction of the minimum creep rate and shortening of the tertiary creep stage. At time to rupture exceeding 104 h the creep rupture strength of the niobium-bearing Casts B and C...

  6. 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.

  7. 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

  8. 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.

  9. Study of radiation damages in AISI 316 and 347 steels

    International Nuclear Information System (INIS)

    The CV-28 cyclotron at IEN (Nuclear Engineering Institute) has been used to simulated, in a short time scale, uniform He concentrations produced during neutron irradiation of metals by (n, α) reactions. Helium was implanted at concentrations of 1 to 300 ppm in 100 μm thick sheet samples of AISI 316 and 347 S S by degrading a 28 MeV alpha particle beam with a rotating energy degrader. The effects of He on the mechanical properties of the steels were studied by both non-destructive (positron annihilation) and destructive tests (tensile, creep, TEM and SEM). The positron lifetime measurements of irradiated and annealed samples were used as the base to discuss the He diffusion mechanism. Activation energies of 0.34±0.04 eV for 316 S S and 0.57±0.06 eV for 347 S S, characterized a dissociative process above 6500 C. TEM analyses have suggested the Ostwald ripening process for bubble growth over the full range of He concentrations studied. It was shown, in agreement with theoretical calculations that, by themselves the displacements produced during the helium implantation, at rate of 1.8 x 10-3 d pa/ppm, were not sufficient to cause significant changes in ductility. However, a strong ductility loss with increasing He concentration was observed for both types of steel for tensile tests at 250 C, as well as in creep at 7500 C over the range of strain (100 to 200 MPa). Finally, it was shown that charged particle simulation associated with positron annihilation techniques provides a fast, relatively low cost, and useful method to study different kinds of neutron damage in materials. (author)

  10. La huella del carbono vinculada a la viticultura

    OpenAIRE

    Sotés Ruiz, Vicente

    2011-01-01

    El cambio climático afecta al viñedo en varios aspectos con posibles consecuencias económicas y tecnológicas, por lo que muchos productores son conscientes de la problemática y están estudiando el desarrollo de diversas alternativas. A nivel político global existen dos tipos de actuaciones para limitar el cambio climático, la mitigación (reducción de las emisiones de gases de efecto invernadero –GEI–) y la adaptación (medidas para reducir los impactos, riesgo de daños y la vulnerabilidad al c...

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

    Directory of Open Access Journals (Sweden)

    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.

  12. THE EFFECT OF SMALL AMOUNTS OF ELEMENTS ON SHAPES OF POTENTIODYNAMIC AND POTENTIOSTATIC CURVES OF AISI 304L AND AISI 316L STAINLESS STEELS IN CHLORIDE MEDIA

    Directory of Open Access Journals (Sweden)

    D. Pulino-Sagradi

    1997-06-01

    Full Text Available Abstract - Samples of high purity grade and commercial purity grade type AISI 304L and AISI 316L steels were studied by the potentiodynamic and potentiostatic techniques in a naturally aerated 3.5% NaCl aqueous solution at a controlled temperature of (23±2°C. The anodic polarization curves of the potentiodynamic technique showed that not always is it possible to determine pitting potential: most of the curves of commercial purity grade steels displayed a smooth curvature in the region where the current density should increase sharply. The density current versus time potentiostatic curves also showed different shapes according to the purity grade steels: for the commercial purity grade steels, the current density showed large oscillations with time (related to unstable pits, whereas for the high purity grade steels, a regular behavior of current density as a function of time was found (related to stable pits

  13. Research on the Heat Treatment Process of AISI 4130 Material%AISI4130材料热处理工艺试验研究

    Institute of Scientific and Technical Information of China (English)

    杨志荣; 刘艳斌; 李军

    2014-01-01

    By researching on three heat treatment processes of quenching& tempering , normalizing +quenching&tempering , spheroidizing annealing +quenching&tempering , for the AISI4130 material which has serious segrega-tion, analyzing the effect of the heat treatment on the material , it is determined that optimal heat treatment is spherodiz-ing annealing +quenching&tempering .%通过对偏析现象严重的AISI4130材料进行调质、正火+调质、球化退火+调质三种形式的热处理工艺研究,分析不同热处理工艺对材料性能的影响,确定最佳的热处理工艺是球化退火+调质。

  14. Hot Corrosion Behavior of Friction Welded AISI 4140 and AISI 304 in K2SO-60% NaC1 Mixture

    Institute of Scientific and Technical Information of China (English)

    N. Arivazhagan; K. Senthilkumaran; S. Narayanan; K. Devendranath Ramkumar; S.Surendra; S. Prakash

    2012-01-01

    Understanding the behavior of weldment at elevated temperatures and especially the corrosion behavior has become an object of scientific investigation recently. Investigation has been carried out on friction welded AISI 4140 and AISI 304 in molten salt of K2SO4-60% NaCI environment at 550, 600 and 650 ℃ under cyclic condition. The resulted oxide scales in the weldment have been characterized systematically by surface analytical techniques. From the results of the experiments~ it is observed that the scale thickness on low alloy steel side was higher than that on stainless steel side. Furthermore, weld interface has been found to be more susceptible to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound. The influences of welding parameters and the temperature of exposure on the hot corrosion behavior of the weldment were discussed in this paper.

  15. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars

    International Nuclear Information System (INIS)

    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.

  16. Almacenamiento de carbono en especies predominantes de flora en el lago Chinchaycocha

    Directory of Open Access Journals (Sweden)

    Ronald Medrano Yanqui

    2012-12-01

    Full Text Available Objetivos: Evaluar la cantidad de carbono que almacenan las especies predominantes de flora del lago Chinchaycocha. Métodos: La investigación fue de tipo básica, de corte transversal y con un nivel exploratorio-comparativo. El estudio se hizo en tres ecosistemas dentro del humedal: bofedal, pajonal y totoral, las áreas fueron identificadas con ayuda de imágenes satelitales Landsat. El procedimiento estuvo basado en la recolección de muestras divididas en: biomasa aérea, biomasa radicular y muestras de suelo, hallándose el contenido de carbono de cada una. Resultados: En el totoral se obtuvo que Schoenoplectus californicus Var. Tatora almacena 30,65 tC/ha y Juncos arcticus Var. Andicola 8,70 tC/ha. En el pajonal Deyeuxia recta Kunth almacena 7,02 tC/ha en su biomasa aérea y 8,41 tC/ha en su biomasa radicular. En el bofedal: Plantago tubulosa almacena 0,81 t C/ha en su biomasa aérea y 1,88 t C/ha en su biomasa radicular, Eleocharis albibracteata almacena 0,22 t C/ha en su biomasa aérea y 2,95 tC/ha en su biomasa radicular, y Limosella australis almacena 0,22 tC/ha en su biomasa aérea y 0,38 tC/ha en su biomasa radicular. En el almacenamiento de carbono en suelos se determinó 774,76 tC/ ha en pajonales y 684,58 tC/ha en bofedales. Conclusiones: Se concluye que en el lago Chinchaycocha el ecosistema que brinda mayor almacenamiento de carbono es el totoral, seguido por el pajonal y en menor proporción el bofedal. Asimismo los suelos son considerados los mayores sumideros de carbono.

  17. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  18. O balanço de carbono da Amazônia brasileira

    Directory of Open Access Journals (Sweden)

    Carlos A. Nobre

    2002-08-01

    Full Text Available GLOBALMENTE, a biota terrestre é um sumidouro significativo de dióxido de carbono (CO2 atmosférico. Estudos recentes do IPCC para a década de 1990 estimam a biota terrestre com sendo um sumidouro líquido de aproximadamente 1,4 gigatonelada de carbono por ano (assimilação líquida pela biota terrestre menos as emissões devidas às mudanças dos usos da terra. É provável que a maior parte desse suposto sumidouro aconteça nas florestas das latitudes médias e dos trópicos. Estudos do ciclo do carbono do Experimento LBA estão mostrando que as florestas não-perturbadas da Amazônia comportam-se com um forte sumidouro de carbono, com taxas na faixa de 1 a 7 toneladas por hectare por ano, ao passo que as áreas inundadas e os rios podem estar agindo como fonte de carbono de até 1,2 tonelada por hectare por ano. O desmatamento e a queima de biomassa representam uma emissão líquida de aproximadamente 0,2 gigatonelada de carbono por ano na Amazônia brasileira. Ainda que se leve em conta as grandes incertezas existentes sobre essas medidas, o balanço das evidências observacionais aponta para a possibilidade de que as florestas tropicais da América do Sul estejam funcionando como sumidouros de carbono da atmosfera.GLOBALLY, the terrestrial biota acts as a significant carbon sink for atmospheric carbon dioxide (CO2. The most recent estimate from IPCC for the 1990's puts the terrestrial biota at a net sink of 1.4 gigaton of carbon per year (net carbon uptake by the biota minus emissions from land use changes. It is likely that most of this presumed sink takes place in mid-latitude and tropical forests. Carbon cycle studies in the LBA Experiment indicate that the undisturbed forest of Amazonia may be a strong sink of carbon, at rates from 1 to 7 tons per hectare per year, whereas the wetlands may act as a source of carbon into the atmosphere of up to 1.2 ton per hectare per year. Deforestation and biomass burning in Brazilian Amazonia

  19. EVALUACIÓN DE PARÁMETROS DE CALIDAD PARA LA DETERMINACIÓN DE CARBONO ORGÁNICO EN SUELOS

    Directory of Open Access Journals (Sweden)

    johnbrynner García Galvis

    2008-03-01

    Full Text Available En el estudio de la cuantificación de carbono orgánico en suelos por el método Walkley-Black se compararon dos técnicas de análisis (colorimetría y volumetría con el fin de evaluar los parámetros de calidad y así indicar la técnica más conveniente para implementarla en el análisis de suelos. Se determinó un intervalo lineal de 5 a 50 mg/mL de sacarosa a una longitud de onda de máxima absorción de 585 nm del ácido crómico reducido. Al comparar los dos métodos de cuantificación se encontraron evidencias de errores sistemáticos en el método volumétrico para los niveles evaluados (alto, medio y bajo de concentración de sacarosa, mientras que por el método colorimétrico la cuantificación fue más exacta y además los valores de desviación estándar y coeficientes de variación fueron menores, parámetros que lo catalogan como el método más preciso. Además, para tener un mayor soporte analítico se implementaron las metodologías en diferentes tipos de suelos; los resultados indicaron que el método colorimétrico para la determinación de carbono orgánico en suelos presentó menores costos y número de reactivos por análisis, y a su vez fue el que ofreció la mejor repetibilidad.

  20. Óxidos de hierro libres asociados a carbono orgánico en agregados de suelos del partido de Balcarce Free iron oxides associated to organic carbon in soils aggregates in Balcarce county

    Directory of Open Access Journals (Sweden)

    Fabián Néstor Cabria

    2005-07-01

    Full Text Available Cuando la materia orgánica es el agente estabilizador principal y la estructura de los agregados es jerárquica, el mecanismo de formación de los agregados conduce a recluir el carbono orgánico en macroagregados estables. Este concepto surge de investigaciones que estudiaron el modo en que la labranza altera la formación y degradación de agregados y, consecuentemente, la dinámica natural de la materia orgánica particulada y asociaciones órgano-minerales. No contando con información local que corrobore cual es el contenido de carbono orgánico asociado a minerales dentro de los agregados y, además, entendiendo que una mejor información sobre la naturaleza y dinámica de las asociaciones órgano-minerales redundará en el entendimiento de la dinámica de la estructura y del secuestro y ciclo del carbono en los suelos, en este trabajo se extrajeron químicamente óxidos de hierro asociados al carbono orgánico en distintos tamaños de agregados en tres series de suelos bajo agricultura continua con labranza convencional (ACLC y paturras cultivadas (PC. Los resultados conducen a entender que la ferrihidrita, óxido de hierro paracristalino, sería un constituyente de las asociaciones órgano-minerales. La cantidad de este mineral disminuiría bajo ACLC, pero la magnitud de este resultado no fue similar en las tres series de suelo. En los dos sistemas de manejo el hierro removido desde los óxidos de hierro asociados al carbono orgánico fue más abundante en los macroagregados que en los microagregados. Bajo ACLC el hierro disminuyó en los macroagregados y aumento en los microagregados. Nosotros sugerimos que en los suelos disturbados el secuestro de carbono orgánico asociado a minerales, ferrihidrita, entre otros, ocurriría dentro de los microagregados que finalmente son recluidos en macroagregados estables.When organic matter is the principal stabilizing agent and soil aggregates structure is hierarchical, the mechanism of formation

  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. On the oxide formation on stainless steels AISI 304 and incoloy 800H investigated with XPS

    NARCIS (Netherlands)

    Langevoort, J.C.; Sutherland, I.; Hanekamp, L.J.; Gellings, P.J.

    1987-01-01

    The influence of cold work on the initially formed oxide layer on the stainless steels AISI 304 and Incology 800H has been studied by XPS. Oxidations were performed at pressures of 10-6-10-4 Pa and temperatures of 300–800 K. All samples showed a similar oxidation behaviour. The oxidation rates of ir

  3. Studies on the Sliding Wear Performance of Plasma Spray Ni-20Cr and Ni3Al Coatings

    Science.gov (United States)

    Kaur, Maninder; Singh, Harpreet; Singh, Balraj; Singh, Bhupinder

    2010-01-01

    Two metallic powders namely Ni-20Cr and Ni3Al were coated on AISI 309 SS steel by shrouded plasma spray process. The wear behavior of the bare, Ni-20Cr and Ni3Al-coated AISI 309 SS steel was investigated according to ASTM Standard G99-03 on a Pin-on-Disc Wear Test Rig. The wear tests were carried out at normal loads of 30 and 50 N with a sliding velocity of 1 m/s. Cumulative wear rate and coefficient of friction (μ) were calculated for all the cases. The worn-out surfaces were then examined by scanning electron microscopy analysis. Both the as-sprayed coatings exhibited typical splat morphology. The XRD analysis indicated the formation of Ni phase for the Ni-20Cr coating and Ni3Al phase for the Ni3Al coating. It has been concluded that the plasma-sprayed Ni-20Cr and Ni3Al coatings can be useful to reduce the wear rate of AISI 309 SS steel. The coatings were found to be adherent to the substrate steel during the wear tests. The plasma-sprayed Ni3Al coating has been recommended as a better choice to reduce the wear of AISI 309 SS steel, in comparison with the Ni-20Cr coating.

  4. DISTRIBUCIÓN DEL CARBONO ORGÁNICO EN LOS DIFERENTES TAMAÑOS DE PARTÍCULAS DEL SUELO: MODELO SIMPLE DE CINÉTICA LINEAL

    Directory of Open Access Journals (Sweden)

    Fernando Paz Pellat

    2014-06-01

    Full Text Available La modelación de la dinámica del carbono orgánico en los suelos (COS permite establecer ganancias y pérdidas asociadas a perturbaciones de la vegetación y prácticas de manejo. En especial, la estimación de cambios en los reservorios de carbono, lábiles y recalcitrantes, sin consideraciones de estados de equilibrio, plantea la necesidad de establecer un modelo de distribución del COS en las fracciones físicas de los suelos (tamaño de partículas que pueda ser parametrizado con la información disponible en los inventarios nacionales (COS total y textura. En este trabajo se propone un modelo simplificado de la distribución del COS, el cual es producto del balance de masa entre las fracciones de carbono del suelo, el cual se plantea como directamente asociado al tamaño de las partículas y no a su distribución de masa. El modelo fue calibrado usando una base de datos de fraccionamientos físicos en Andosoles, Cambisoles y Acrisoles en sistemas agrícolas y forestales en Atécuaro, Michoacán, México, considerando solo el COS asociado a la parte organomineral y el total (organomineral + particulada. El modelo de la distribución del COS por tamaño de las partículas del suelo fue ajustado a datos experimentales. El mismo parte del conocimiento del COS total y del COS para un tamaño de partícula de referencia, estimada experimentalmente o supuesta. Los resultados mostraron que para el caso de los sistemas agrícolas el modelo se ajustó bien a las mediciones (R2 > 0.999. Para el caso de los sistemas forestales, las estimaciones son buenas (R2 > 0.97. Al final se discuten las implicaciones del modelo desarrollado, donde el concepto clásico de saturación de COS de los suelos es cuestionado y explicado en términos de las tasas de descomposición y asimilación de la fracción particulada y organomineral; asimismo, la relación entre la textura del suelo y el COS asociado al tamaño de las partículas no es soportada, al considerar a

  5. Incentivos econômicos e projeto de supply chain para captura e sequestro de carbono: caso Brasil

    Directory of Open Access Journals (Sweden)

    Ernesto del Rosario Santibañez Gonzalez

    2014-12-01

    Full Text Available Neste artigo, analisamos uma estratégia para reduzir as emissões de carbono que combina simultaneamente a criação de políticas de incentivo econômico e o desenvolvimento de uma infraestrutura de rede para captura e sequestro de carbono (CCS. Propomos um modelo de otimização linear inteira mista que considera aspectos técnicos e teóricos e permite analisar simultaneamente os efeitos de estabelecer preços para as emissões de carbono (carbon tax em conjunto com uma estratégia de implementação de uma rede de supply chain para capturar, transportar e sequestrar CO2 em reservatórios geológicos. Apresentamos resultados para o caso da indústria de cimento do Brasil usando CO2 tax estabelecidas atualmente em outros países.

  6. Calidad del carbono orgánico del suelo en diferentes técnicas de manejo de residuos forestales

    Directory of Open Access Journals (Sweden)

    Ana Maria Lupi

    2012-06-01

    Full Text Available http://dx.doi.org/10.5902/198050985736Las distintas técnicas de cosecha y manejo de residuos pueden provocar cambios en la cantidad y calidad de la materia orgánica (MO del suelo. El objetivo de este trabajo fue evaluar las modificaciones en la concentración y la calidad de la MO en un Ultisol con diferentes manejos de los residuos de la cosecha forestal del Pinus elliottii Engelm, al inicio de la segunda rotación. Los tratamientos analizados fueron: a extracción manual de los residuos de la cosecha y del piso forestal, suelo descubierto (ER, b quema de residuos y del mantillo, y laboreo con rastra (PI, c conservación de residuos y del mantillo sobre el suelo (PC. Se determinó el carbono orgánico (CO en todo el suelo y en las fracciones de ácidos fúlvicos (AF, ácidos húmicos (AH, huminas (HU y en la fracción liviana (CL. La conservación de los residuos de la cosecha no aumentó el CO ni el CL. Se observó una pérdida de la fracción de ácidos fúlvicos (AF particularmente en PI. Los tratamientos sin residuos forestales (ER y PI muestran un aumento en el grado de estabilización de la MO con un incremento de las HU y de la relación CAH/CAF.

  7. Pegada de carbono da Quinta da Gruta: quantificação e compensação

    OpenAIRE

    Silva, Mafalda Diana das Dores Rocha e

    2011-01-01

    A presente dissertação resulta de uma proposta feita por parte da Câmara Municipal da Maia, para a realização de um estudo sobre a pegada de carbono na Quinta da Gruta, um centro de educação ambiental localizado na freguesia de Avioso (Santa Maria), na Vila do Castêlo da Maia. Neste sentido, após uma revisão de literatura no âmbito das metodologias actualmente usadas no cálculo da pegada de carbono, foram calculadas as emissões totais anuais decorrentes da actividade da Quinta da Gruta, pa...

  8. Analysis of the specific consumption of energy and of carbon specific emissions of the mexican Iron and steel industry; Analisis del consumo especifico de energia y de las emisiones especificas de carbono de la industria siderurgica mexicana

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, L; Sheinbaum, C. [Instituto de Ingenieria de la UNAM, Mexico, D. F. (Mexico)

    1999-07-01

    electricidad. Se observo que las disminuciones tanto en el consumo especifico de energia como en las emisiones especificas de carbono se debieron principalmente a mejoras tecnologicas en la fabricacion del acero: la sustitucion completa de los hornos de hogar abierto y una amplia penetracion de la colada continua. A pesar de estas mejoras en le eficiencia energetica y a la paulatina sustitucion del coque por gas natural al aumentar la produccion de hierro de reduccion directa. Sin embargo, el factor de emision de la electricidad se incremento debido a una mayor participacion de las plantas termoelectricas en 1995 en comparacion a 1970. Se compararon los indicadores de eficiencia energetica de esta industria con otros paises tomando en cuenta su propia estructura. Finalmente se hacen recomendaciones de medidas de ahorro de energia.

  9. Effect of heat treatment on an AISI 304 austenitic stainless steel evaluated by the ultrasonic attenuation coefficient

    International Nuclear Information System (INIS)

    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.

  10. 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.

  11. Nanotubos de carbono aplicados às neurociências: perspectivas e desafios

    OpenAIRE

    Virginia Oliveira; Michele Munk Pereira; Humberto de Mello Brandão; Marcos Antônio Fernandes Brandão; Wagner Farid Gattaz; Nádia Rezende Barbosa Raposo

    2011-01-01

    INTRODUÇÃO: Os nanotubos de carbono (NTCs) são os nanomateriais mais promissores para aplicação terapêutica em doenças neurodegenerativas. Aplicações potenciais incluem sistemas de liberação controlada de fármacos, interfaces elétricas e substratos para crescimento celular. OBJETIVO: Descrever o estado da arte e as perspectivas e desafios da aplicação dos NTCs nas neurociências. MÉTODO: Procedeu-se a uma busca sistemática nos indexadores Medline, Lilacs e SciELO, utilizando os descritores "ca...

  12. FINANCIAMIENTO DE PROYECTOS URBANO-ECOLÓGICOS MEDIANTE INTERCAMBIO DE BONOS DE CARBONO

    Directory of Open Access Journals (Sweden)

    Gino Pérez Lancellotti

    2010-01-01

    a diversas escalas, nos concentraremos específi camente en proyectos a escala urbana, los llamados proyectos "Ecociudad". Los bonos verdes o bonos de carbono, son instrumentos fi nancieros hasta hoy muy utilizados en proyectos más bien ligados a la generación de energías renovables. Este trabajo, revisará principalmente algunos proyectos de Ecociudad que se están llevando, a cabo y específi camente el caso de Dongtan en China.

  13. Sistema de seguridad para elaborar nanopartículas de carbono a escala de laboratorio

    OpenAIRE

    Dania Soguero González; Jorge Castillo Álvarez; Luis Felipe Desdín García

    2012-01-01

    Las nanopartículas de carbono (NPC) han sido de las más utilizadas, debido a sus propiedades. Muchas de estas propiedades que hacen tan útil a las NPC también pueden hacerlas tóxicas para las células y el organismo y por lo tanto deben ser manipuladas con precaución. El Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN) está desarrollando un programa de investigación que incluye la síntesis NPC usando el método de descarga de arco sumergida en agua. En este trabajo se describe ...

  14. Projecto e desenvolvimento de reactor HFCVD para revestimentos à base de carbono

    OpenAIRE

    Santos, José Augusto Machado Figueiredo dos

    2007-01-01

    O presente trabalho teve como objectivo fundamental o projecto e construção de um reactor para deposição química de filmes à base de carbono em fase vapor, bem como o desenvolvimento do respectivo sistema de controlo e monitorização. Para efeitos, foi necessário, numa primeira fase de trabalho, realizar um estudo aprofundado sobre os mecanismos físico-químicos de crescimento de filmes de diamante segundo a técnica referida que serviu de base ao dimensionamento do reactor....

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

    OpenAIRE

    José Luddey Marulanda Arevalo; Francisco Javier Pérez Trujillo; Aduljay Remolina Millán

    2013-01-01

    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...

  16. Application of response surface methodology for determining cutting force model in turning hardened AISI H11 hot work tool steel

    Indian Academy of Sciences (India)

    B Fnides; M A Yallese; T Mabrouki; J-F Rigal

    2011-02-01

    This experimental study is conducted to determine statistical models of cutting forces in hard turning of AISI H11 hot work tool steel (∼ 50 HRC). This steel is free from tungsten on Cr–Mo–V basis, insensitive to temperature changes and having a high wear resistance. It is employed for the manufacture of highly stressed diecasting moulds and inserts with high tool life expectancy, plastic moulds subject to high stress, helicopter rotor blades and forging dies. The workpiece is machined by a mixed ceramic tool (insert CC650 of chemical composition 70%Al23+30%TiC) under dry conditions. Based on 33 full factorial design, a total of 27 tests were carried out. The range of each parameter is set at three different levels, namely low, medium and high. Mathematical models were deduced by software Minitab (multiple linear regression and response surface methodology) in order to express the influence degree of the main cutting variables such as cutting speed, feed rate and depth of cut on cutting force components. These models would be helpful in selecting cutting variables for optimization of hard cutting process. The results indicate that the depth of cut is the dominant factor affecting cutting force components. The feed rate influences tangential cutting force more than radial and axial forces. The cutting speed affects radial force more than tangential and axial forces.

  17. Surface roughness and cutting forces modeling for optimization of machining condition in finish hard turning of AISI 52100 steel

    Energy Technology Data Exchange (ETDEWEB)

    Azizi, Mohamed Walid; Belhadi, Salim; Yallese, Mohamed Athmane [Univ. of Guelma, Guelma (Algeria); Mabrouki, Tarek; Rigal, Jean Francois [Univ. of Lyon, Lyon (France)

    2012-12-15

    An experimental investigation was conducted to analyze the effect of cutting parameters (cutting speed, feed rate and depth of cut) and workpiece hardness on surface roughness and cutting force components. The finish hard turning of AISI 52100 steel with coated Al2O3 + TiC mixed ceramic cutting tools was studied. The planning of experiment were based on Taguchi's L27 orthogonal array. The response table and analysis of variance (ANOVA) have allowed to check the validity of linear regression model and to determine the significant parameters affecting the surface roughness and cutting forces. The statistical analysis reveals that the feed rate, workpiece hardness and cutting speed have significant effects in reducing the surface roughness; whereas the depth of cut, workpiece hardness and feed rate are observed to have a statistically significant impact on the cutting force components than the cutting speed. Consequently, empirical models were developed to correlate the cutting parameters and workpiece hardness with surface roughness and cutting forces. The optimum machining conditions to produce the lowest surface roughness with minimal cutting force components under these experimental conditions were searched using desirability function approach for multiple response factors optimization. Finally, confirmation experiments were performed to verify the pertinence of the developed empirical models.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

  20. 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.

  1. Hot rolling of the superaustenitic stainless steel AISI 904L: Vroče valjanje superavstenitnega nerjavnega jekla AISI 904L:

    OpenAIRE

    Arh, Boštjan; Burja, Jaka; PODGORNIK, Bojan; Tehovnik, Franc; Žužek, Borut

    2014-01-01

    The AISI 904L superaustenitic stainless steel has a narrow processing window. In this work the hot rolling of steel, specifically the hot deformation behavior, is investigated. Specimens of steel were hot rolled at temperatures from 1000 °C to 1250 °C with 50 °C increments and the rolling loads were measured and recorded. Microstructural changes were examined, with the accent on the recrystallization. From changes of the hot-rolling loads and microstructure it is concluded that the recrystall...

  2. Caracterización del aceite de semilla de uva extraído con dióxido de carbono supercrítico

    Directory of Open Access Journals (Sweden)

    Molero Gómez, A.

    1995-02-01

    Full Text Available In this work the quality of grape seed oil obtained by extraction with supercritical carbon dioxide was studied. At the optimun operating conditions (313 K and 25 MPa, the yield of supercritical extraction is similar to the conventional extraction by liquid solvent, but the quality of the grape seed oil extracted by supercritical carbon dioxide is higher.
    Furthermore, supercritical extraction could be more economical than liquid extraction because the solvent removal by distillation is not necessary and several steps of the subsequent oil refining process can be eliminated.

    En este trabajo se realiza un estudio de la calidad del aceite de semillas de uva obtenido por extracción con dióxido de carbono supercrítico. En las condiciones operativas óptimas del proceso (313 K y 25 MPa el rendimiento de la extracción supercrítica es similar al de la extracción con disolventes líquidos, pero la calidad del aceite es muy superior.
    En consecuencia, el proceso supercrítico resulta competitivo con el convencional al reducir las etapas de refinado del aceite y eliminar la destilación del disolvente, las más costosas desde el punto de vista energético.

  3. Martensitic transformation on AISI 304 stainless steel produced by a coaxial plasma gun

    International Nuclear Information System (INIS)

    Full text: In a previous paper, a surface treatment of AISI 304 stainless steel irradiated by a Nitrogen ion beam generated in a coaxial plasma gun has been reported. The device is operated with a Titanium insert at the end of the inner electrode, producing a TiN coating on the surface of the sample. Because of the ion and plasma energy deposition, the sample surface is strongly heated during the treatment resulting in titanium diffusion. Preliminary X-ray diffraction (XRD) studies have shown the presence of a martensitic transformation on AISI 304 samples, probably induced by Ti atoms. In this work, the transformation depth is studied with grazing-incidence XRD on samples subjected to several superimposed shots. For this purpose, multiple low angles of incidence are used, allowing the analysis at different depths of the substrate

  4. 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.

  5. Experimental Investigation of the Effect of Burnishing Force on Service Properties of AISI 1010 Steel Plates

    Science.gov (United States)

    Gharbi, F.; Sghaier, S.; Morel, F.; Benameur, T.

    2015-02-01

    This paper presents the results obtained with a new ball burnishing tool developed for the mechanical treatment of large flat surfaces. Several parameters can affect the mechanical behavior and fatigue of workpiece. Our study focused on the effect of the burnishing force on the surface quality and on the service properties (mechanical behavior, fatigue) of AISI 1010 steel hot-rolled plates. Experimental results assert that burnishing force not exceeding 300 N causes an increase in the ductility. In addition, results indicated that the effect of the burnishing force on the residual surface stress was greater in the direction of advance than in the cross-feed direction. Furthermore, the flat burnishing surfaces did not improve the fatigue strength of AISI 1010 steel flat specimens.

  6. 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.

  7. Analysis of pulsed Nd:YAG laser welding of AISI 304 steel

    International Nuclear Information System (INIS)

    Pulsed laser welding of AISI 304 stainless steel plate was simulated using commercial finite element software to determine the optimal welding conditions. Due to geometric symmetry, only one plate was modeled to reduce the simulation computation time. User subroutines were created to account for a moving three-dimensional heat source and to apply boundary conditions. The material properties such as conductivity, specific heat, and mass density were determined as functions of temperature. The latent heat was considered within the given temperature range. The three-dimensional heat source model for pulsed laser beam butt welding was designed by comparing the finite element analysis results and experimental data. This successful simulation of pulsed Nd:YAG laser welding for AISI 304 stainless steel will prove useful for determining optimal welding conditions

  8. 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)

  9. INFLUENCE OF AISI 316Ti STAINLESS STELL SURFACE TREATMENT ON PITTING CORROSION IN VARIOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Pavol Fajnor

    2010-12-01

    Full Text Available Investigation of the surface treatment effect on the resistance of AISI 316Ti stainless steel to pitting corrosion is presented in this paper. The grinded surfaces without additional chemical treatment, grinded and pickled, grinded, pickled and passivated surfaces are tested. The corrosion tests are carried out by exposition in solution which evoke pitting and by electrochemical cyclic potential - sweep method. According to the results the surface treatment has a great influence on the resistance of the tested material to pitting. It is not possible to estimate the best surface treatment because behavior of AISI 316Ti stainless steel with different surface state depends on the mechanism of corrosion processes which vary in the used experimental methods.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Oxidation behavior of 26Cr-16Ni and AISI 309 austenitic stainless steels in air flow at 1,173 K

    International Nuclear Information System (INIS)

    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 cm3 x min-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 10-6, 4.02 x 10-5 and 4.35 x 10-5 g x cm-2 x s-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.

  15. 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.

  16. Laser welding of butt joints of austenitic stainless steel AISI 321

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2007-11-01

    Full Text Available Purpose: of this paper: A study of an automated laser autogenous welding process of butt joints of austenitic stainless steel AISI 321 sheets 0.5 [mm] and 1.0 [mm] thick using a high power diode laser HPDL has been carried out.Design/methodology/approach: Influence of basic parameters of laser welding on shape and quality of the butt joints and the range of optimal parameters of welding were determined.Findings: It was showed that there is a wide range of laser autogenous welding parameters which ensures high quality joints of mechanical strength not lower than the strength of the base material (BM. The butt joints of austenitic steel AISI 321 sheets welded by the HPDL diode laser at optimal parameters are very high quality, without any internal imperfections and the structure and grain size of weld metal and HAZ is very small and also the HAZ is very narrow and the fusion zone is very regular.Research limitations/implications: Studies of the weldability of stainless steels indicate that the basic influence on the quality of welded joints and reduction of thermal distortions has the heat input of welding, moreover the highest quality of welded joints of austenitic stainless steel sheets are ensured only by laser welding.Practical implications: The technology of laser welding can be directly applied for welding of butt joints of austenitic steel AISI 321 sheets 0.5 and 1.0 [mm] thick.Originality/value: Application of high power diode laser for welding of austenitic stainless steel AISI 321.

  17. Structure and properties of the Stainless steel AISI 316 nitrided with microwave plasma

    International Nuclear Information System (INIS)

    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 γN which has been reported that produces such effect without affect the corrosion resistance proper of this material. (Author)

  18. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    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....

  19. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    OpenAIRE

    Rômulo Ribeiro Magalhães de Sousa; Francisco Odolberto de Araújo; José Alzamir Pereira da Costa; Antonio Maia de Oliveira; Mineia Sampaio Melo; Clodomiro Alves Junior

    2012-01-01

    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.

  20. 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.

  1. AN ELECTROCHEMICAL PROCESSING STRATEGY FOR IMPROVING TRIBOLOGICAL PERFORMANCE OF AISI 316 STAINLESS STEEL UNDER GREASE LUBRICATION

    OpenAIRE

    JIAOJUAN ZOU; MAOLIN LI; NAIMING LIN; XIANGYU ZHANG; LIN QIN; BIN TANG

    2014-01-01

    In order to improve the tribological performance of AISI 316 stainless steel (316 SS) under grease lubrication, electrochemical processing was conducted on it to obtain a rough (surface texturing-like) surface by making use of the high sensitivity of austenitic stainless steel to pitting corrosion in Cl--rich environment. Numerous corrosion pits or micro-ditches acted as micro-reservoirs on the obtained surface. While the grease could offer consistent lubrication, and then improve the tribolo...

  2. Characterising μ-AlTiN coating and assessing its performance during Ti-6Al-4V milling

    OpenAIRE

    Carlos Mauricio Moreno Téllez; José Manuel Sánchez; Oscar Fabián Higuera Cobos

    2012-01-01

    This study investigated the mechanical properties and performance of μ-AlTiN coating deposited by PVD cathodic arc technique for a specific Al0, 67Ti0, 33N composition deposited on a WC-Co and AISI D2 steel substrate. The structure of the coating was analysed using SEM, EDAX, XRD, AFM and TEM. Nano indentation measurements were used for analysing mechanical properties; the coating’s performance was evaluated during the milling of a titanium alloy (Ti6Al4V). The TiN film was initially deposite...

  3. Avaliação da correlação entre o dióxido de carbono expirado e o débito cardíaco em pacientes submetidos à cirurgia cardíaca com circulação extracorpórea Evaluación de la correlación entre el dióxido de carbono expirado y el débito cardíaco en pacientes sometidos a la cirugía cardíaca con circulación extracorpórea Correlation between end-tidal carbon dioxide levels and cardiac output during cardiac surgery with cardiopulmonary bypass

    OpenAIRE

    Karina Takesaki Miyaji; Roberto Iara Buscati; Antônio José Arraiz Rodriguez; Luciano Brandão Machado; Luiz Marcelo Sá Malbouisson; Maria José Carvalho Carmona

    2004-01-01

    JUSTIFICATIVA E OBJETIVOS: O CO2 expirado (P ET CO2) reflete, além da ventilação pulmonar (eliminação), a produção de dióxido de carbono (metabolismo) e o fluxo sangüíneo pulmonar (circulação). Quando o metabolismo e a ventilação são constantes, o CO2 expirado reflete o fluxo sangüíneo pulmonar e, desta forma, o débito cardíaco (DC). Este estudo tem como objetivo a avaliação da correlação entre o dióxido de carbono expirado (P ET CO2) e o débito cardíaco em pacientes submetidos à cirurgia car...

  4. Structure and low-cycle fatigue of steel AISI 316 after ECAP

    Directory of Open Access Journals (Sweden)

    M. Greger

    2008-05-01

    Full Text Available Purpose: Main aim of this paper is to describe the plastic deformation executed by ECAP on low cycle fatigueof steel AISI 316. Among others was attention fixed on mechanical properties after this treatment.Design/methodology/approach: Experiments were planned and realised at the temperature ranging fromroom temperature up to 280 °C. After application of deformation the structure was investigated in dependence onaccumulation of deformation and deformation temperature as well as abovementioned final properties.Findings: Accumulated real (logarithmic deformation varied from the value 2 to 8. Investigation of structure byelectron microscopy was made with use of microscope JEOL JEM 2100. Mechanical properties were investigatedby conventional tensile test and penetration test. Selected samples were subjected to low-cycle fatigue. Statisticevaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction(EBSD in combination with scanning electron microscope FEG SEM Philips.Practical implications: The Technology ECAP was applied on austenitic steel AISI 316. It was verificationof ECAP application possibility on steel AISI 316 importantly for following applying on similar kinds of steel,because ECap technology influence on fatigue properties was confirmed.Originality/value: It can be predicted on the basis of obtained results that, contrary to low-cycle fatigue theultra-fine grained material will manifest at fatigue load in the mode of constant amplitude of stress higher fatiguecharacteristics, particularly fatigue limit.

  5. The structure of austenitic steel AISI 316 after ECAP and low-cycle fatigue

    Directory of Open Access Journals (Sweden)

    L. Kander

    2008-06-01

    Full Text Available Purpose: The article presents results of investigation of structure and properties of austenitic steel grade AISI 316 after application of Equal Channel Angular Pressing (ECAP at the temperature of approx. 290ºC.Design/methodology/approach: The ECAP method led to significant improvement of strength of investigated material. Experiments were planned and realised at the temperature ranging from room temperature up to above mentioned temperature.Findings: It was established with use of the EBSD technique that after 8 passes through the ECAP die the sub-grains with an angle of disorientation smaller than 10º formed less than 20% of resulting structure. Average size of austenitic grains with high angle boundary after 8 passes was approx. 0.32 µm. It was proven that the ECAP method enables obtaining of ultra fine-grained austenitic structure formed by recrystallised grains with very low density of dislocations.Practical implications: The Technology ECAP was applied on austenitic steel AISI 316. It was verification of ECAP application possibility on steel AISI 316 importantly for following applying on similar kinds of steel, because ECAP technology influence on fatigue properties was confirmed.Originality/value: It can be predicted on the basis of obtained results that, contrary to low-cycle fatigue the ultra-fine grained material will manifest at fatigue load in the mode of constant amplitude of stress higher fatigue characteristics, particularly fatigue limit.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Non local approach in crystalline plasticity: study of mechanical behaviour of AISI 316LN stainless steel during low cycle fatigue

    International Nuclear Information System (INIS)

    If fatigue crack initiation is currently quite well understood for pure single crystals, its comprehension and prediction in cases of polycrystal alloys such as AISI 316LN stainless steel remain complicated. Experimentally our study focuses on the characterisation of the mechanical behaviour and on the study at different scales of the phenomenon leading to low cycle fatigue crack initiation in 316LN stainless steel. For straining amplitudes of?e/2 = 0,3 and 0,5%, the cyclic softening observed during testing has been related to the organisation of dislocations in band structures. These bands, formed due to the activation of slip systems having the greatest Schmid's factor, carry the most part of the deformation. Their emergence at free surfaces leads to the formation of intrusions and extrusions which help cracks initiate and spread. Numerically we worked on the mesoscopic scale, proposing a new model of crystalline plasticity. This model integrates geometrically necessary dislocations (GND) directly computed from the lattice curvature. Implemented in the finite element code AbaqusTM and Cast3mTM, it is based on single crystal finite deformations laws proposed by Peirce et al. (1983) and Teodosiu et al. (1993). Extended for polycrystals by Hoc (2001) and Erieau (2003), it has been improved by the introduction of GND (Acharya and Bassani, 2000). The simulations performed on different types of aggregates (2D/3D) have shown that taking GND into account enables:- the prediction of the grain size effect on a macroscopic and on a local scale,- a finer computation of local stress field.The influence of the elasticity and interaction matrices on the values and the evolution of the isotropic and kinematic mean stresses has been shown. The importance of boundary conditions on computed mechanical fields could also be pointed out. (author)

  11. 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.

  12. A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F

    Science.gov (United States)

    Romoli, L.; Rashed, C. A. A.; Lovicu, G.; Ishak, R.

    2015-05-01

    Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

  13. Atomic Force Microscopy, Scanning Kelvin Probe Force Microscopy and magnetic measurements on thermally oxidized AISI 304 and AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Research highlights: → The surface roughness of the bare substrate influence the oxide layer growth. → The oxide layer roughness follows power laws and belongs to universality class. → At low growth temperature, the p-n heterojunction disappears in some places. → SKPFM images allow the direct visualization of local corrosion sites. → Presence of a magnetite phase in the outer iron rich layer of the oxide thin film. - Abstract: Thermally oxidized AISI304 and AISI316 stainless steels are studied by Atomic Force Microscopy, Scanning Kelvin Probe Force Microscopy (SKPFM) and Magneto-Optical Kerr effect as a function of their growth temperature. The surface roughness is a competition between the roughness of the bare substrate and the roughness resulting from the oxide layer growth. Cr oxide is present at some places on the surface at low growth temperature as shown by SKPFM. The observed decrease of surface potential with the oxide layer thickness indicates an effective protection against corrosion. Magnetic measurements demonstrate that the outer layer contains a magnetite phase (in-plane magnetization).

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Dinámica del carbono (almacenes y flujos en manglares de México

    Directory of Open Access Journals (Sweden)

    Jorge A. Herrera Silveira

    2016-03-01

    Full Text Available La cobertura de los manglares de México los coloca en cuarto lugar a nivel mundial. Se reconocen sus múltiples servicios ecosistémicos, pero también altas tasas de deforestación. Evaluaciones en otras partes del mundo destacan el papel de los manglares en el ciclo del carbono, principalmente como almacenes de carbono orgánico (Corg en los sedimentos y exportadores de Corg disuelto y particulado. Para estimar la contribución de los manglares, a escala local, regional y de país, en estrategias como la Reducción de Emisiones por Deforestación y Degradación (REDD+, es indispensable determinar los almacenes de Corg como línea base de emisiones. En este estudio se realizó una búsqueda bibliográfica sobre almacenes y flujos de carbono en manglares de México mediante diferentes fuentes de información. De más de 200 estudios, solo 48 contenían datos o información para hacer una revisión del estado que guarda el conocimiento de almacenes y flujos de Corg en los manglares de México. Regionalmente, la zona del Pacífico Central tiene menos información y la Península de Yucatán donde más datos existen. Los mayores almacenes de Corg total se localizan en el Golfo de México y en los manglares de tipo ribereño (>1200 Mg C ha-1. Existe menos información sobre flujos de Corg, dominando los relacionados con la caída de hojarasca. En la zona del Pacífico Sur y en el manglar ribereño se observaron los valores más altos. La extensión y variabilidad de condiciones ambientales en los manglares de México son una oportunidad para desarrollar múltiples temas de investigación, como la caracterización de paisajes y mapas locales de coberturas relacionados con variables del agua (hidroperíodo, del suelo (topografía y procesos microbiológicos. La extensión y distribución de los manglares ofrecen la oportunidad para formar grupos de investigadores a escala regional y abordar de forma consensada estudios bajo una estrategia metodol

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Análisis de Ciclo de Vida en la determinación de la energía contenida y la huella de carbono en el proceso de fabricación del hormigón premezclado. Caso estudio planta productora Región del Bío Bío, Chile

    Directory of Open Access Journals (Sweden)

    Claudia Muñoz Sanguinetti

    2015-03-01

    Full Text Available El presente artículo muestra resultados acerca de la determinación de la energía contenida y la huella de carbono asociadas al proceso de fabricación de hormigones, en una planta premezcladora en la región del Biobío, Chile, a través de un Análisis de Ciclo de Vida simplificado. El inventario ambiental consideró primordialmente: transporte de materias primas, proceso de dosificación, carguío y despacho de los principales insumos materiales. Para todas estas actividades se cuantificaron consumos energéticos y emisiones de CO2 durante un año de producción, excluyendo consumo energético y huella de carbono corporativa. Al aplicar el “inventario ciclo de vida” (ICV, según IS0 14.040-2006, el caso de estudio mostró que para producir un metro cúbico de hormigón premezclado se requieren 342 MJ, lo que genera una huella de carbono de 26 Kg/CO2. Al comparar este resultado con bases de datos internacionales, el mismo caso demostró ser un 37,5% más bajo en energía contenida y más de un 50% inferior en emisiones de CO2. Esta investigación permitió concluir que el proceso unitario con mayor impacto ambiental desde el punto de vista del consumo energético y emisiones de CO2, está constituido por los transportes indirectos de las materias primas, principalmente áridos, que representan un 46% del total del sistema estudiado.

  18. Diseño de polvos de molde para colada continua de slabs de aceros bajo carbono

    Directory of Open Access Journals (Sweden)

    Cruz-Ramírez, A.

    2004-02-01

    Full Text Available Commercial fluxes were characterized by laboratory tests, and their original properties were changed with additions of chemical reagents in order to establish criteria and design strategies to produce new fluxes. The characterization of the commercial fluxes reveals that they are produced by simple mechanical blend of minerals, using feldspars and clays as base materials, containing SiO2, Al2O3, Na2 O and in less quantity K2O, MgO, Fe2 O3and MnO; limestone as the main source of CaO, fluorspar (CaF2 used to control the viscosity and graphite as carbon source. Melting-solidification tests revealed melting and fluidity temperatures and the existence of abundant mineralogical phases formed during the flux solidification. Some important mineralogical compounds are the nepheline (NaAlSiO4 and cuspidine (Ca4Si2O7F2; these species have a direct influence on the heat transfer phenomena from strand to mold and therefore on the phase transformations and the shrinkage of the steel.

    A partir de la caracterización de polvos comerciales mediante pruebas de laboratorio y la modificación de sus propiedades mediante adiciones de compuestos químicos, se identificaron y desarrollaron criterios y estrategias de diseño que sirvieron de base para elaborar nuevos polvos. La caracterización de los polvos comerciales indica que se fabrican por simple mezcla mecánica de minerales, utilizando feldespatos y arcillas como materiales base, que contienen SiO2, Al2O3, Na2 O y, en menor proporción, K 2O, MgO, Fe2 O3 y MnO, caliza como fuente principal de CaO, fluorita (CaF2 como fluidificante y grafito como fuente de carbono. Mediante pruebas de fusión-solidificación se determinaron las temperaturas de fusión y fluidez de los polvos y

  19. Carbon Bonds and the saving of energy; Bonos de carbono y el ahorro de energia

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Ramirez, Alejandro [NovaEnergia (Mexico)

    2005-07-01

    This document deals with the development of the carbon bond project, the energy saving and the entry into force of the Kyoto Protocol at a world-wide level. In this project Mexico opts for a development model in which the economic growth brakes ties with the discharge of greenhouse effect gases and in which the progress does not mean more damages to our planet. [Spanish] Este documento trata sobre el desarrollo del proyecto de bonos de carbono, ahorro de energia y la entrada en vigor del Protocolo de Kyoto a nivel mundial, en el cual Mexico opta por un modelo de desarrollo en el que el crecimiento economico esta desvinculado de la emision de gases de efecto invernadero y en donde el progreso no signifique mas danos a nuestro planeta.

  20. CAPTURA E ARMAZENAMENTO DE CO2 EM PORTUGAL: UMA PONTE PARA UMA ECONOMIA DE BAIXO CARBONO

    OpenAIRE

    Seixas, Júlia; Fortes, Patricia; Dias, Luís; Carneiro, Júlio; Mesquita, Paulo; Marques, Ferreira; Fernandes, Vítor; Helseth, Jonas; Ciesielska, Joanna; Whiriskey, Keith

    2015-01-01

    As atuais projeções indicam que são necessários esforços adicionais para atingir os objetivos de mitigação acordados para 2030 bem como a ambição de reduzir as emissões de gases com efeito de estufa da UE em 80 a 95% em 2050, face a 1990, sendo este o objetivo necessário a longo prazo para descarbonizar o sistema energético e industrial Europeu consentâneo com uma trajetória de estabilização climática do Planeta. Este estudo mostra como as tecnologias de baixo carbono contribuem para atingir ...

  1. Comportamento de cilindros de carbono/epóxi submetidos a cargas compressivas axiais Mechanical behavior of carbon/epoxy cylinders under axial compressive loads

    Directory of Open Access Journals (Sweden)

    Adriano Gonçalves

    2001-06-01

    Full Text Available Para estruturas utilizadas no setor aeroespacial, os requisitos de baixo peso, alta resistência e rigidez, além de estabilidade dimensional, têm propiciado o aumento da utilização de materiais compósitos nas suas manufaturas. Em particular, cascas cilíndricas ou estruturas construídas pela junção de cilindros de paredes finas, confeccionadas em fibra de carbono e resina epóxi, são amplamente utilizadas neste tipo de aplicação. Neste trabalho, um programa experimental foi desenvolvido para determinar as tensões de falha, os módulos de elasticidade e o modo de falha de 47 cilindros com diâmetro interno de 40 mm e espessura nominal de 0,6 mm (com exceção de 2 corpos de prova, fabricados em carbono/epóxi, quando submetidos a cargas compressivas uniaxiais. Os espécimes testados possuíam diferentes razões entre comprimento e diâmetro (variando de 2,50 a 11,25 e seqüências de laminação variadas (orientações de camadas. Os resultados dos ensaios foram comparados aos obtidos em análises realizadas com programas de elementos finitos e os fatores que influenciaram o comportamento mecânico destes cilindros foram analisados.The requirements of low weight and dimensional stability, combined with high strength and stiffness, for aerospace structures has prompted an increasing use of fiber reinforced materials in manufacturing such structures. In particular, carbon/epoxy cylinders have been widely used in aerospace applications. In this work, an experimental program was developed to determine failure loads, modulus of elasticity and failure modes of 47 carbon/epoxy cylinders shells under compressive loads. The specimens tested had several different length/diameter (from 2.50 to 11.25 ratios and laminate lay-up. These results were compared to the analytical results from finite element code and the most important factors influencing the mechanical behavior of this type of structure were analyzed.

  2. 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)

  3. Promoción de la Conservación de Bosque Natural de Roble mediante el pago por el Servicio Ambiental de Almacenamiento de Carbono: Un Ejercicio de Optimización Dinámica Aplicado en el Corredor Ecológico Guantiva-La Rusia-Iguaque (Colombia)

    OpenAIRE

    Alvarez, Andres Camilo

    2013-01-01

    Reducir la deforestación del bosque natural implica conservar la biodiversidad y mantener almacenado el carbono reduciendo las emisiones de Gases de Efecto Invernadero. Los pagos por servicios ambientales –PSA– fortalecerían los mecanismos de regulación directa para la conservación ya que: reflejan el costo de oportunidad de conservar, minimizan costos de transacción, son efectivos al conservar áreas mayores y establecen niveles sostenibles de aprovechamiento forestal. Usando un modelo de opt...

  4. Simulación de los cambios de carbono orgánico del suelo en sistema de cultivo con higuerilla por el modelo RothC Simulation of soil organic carbon changes in crop systems with castor bean using the RothC model

    OpenAIRE

    Lucila González Molina; Esaú del C. Moreno Pérez; Laksmi Reddiar Krishnamurty; Aurelio Baéz Pérez; Acosta Mireles Miguel

    2012-01-01

    El objetivo del presente trabajo fue la simulación de los cambios del carbono orgánico del suelo (COS), por el modelo RothC, en razón del cambio de uso de suelo del sistema tradicional - asociación maíz-calabaza (TMC) - a sistemas con higuerilla (Ricinus communis): multiestratos (MUL), callejones (CALL) y monocultivo de higuerilla (HIG). Las simulaciones del COS se hicieron para las profundidades de suelo 0-20 y 0-40 cm, para el periodo de 1980-2040, considerándose como línea base al sistema ...

  5. Formas de carbono orgánico en suelos con diferentes usos en el departamento del Magdalena (Colombia

    Directory of Open Access Journals (Sweden)

    José Rafael Vásquez-Polo

    2011-12-01

    Full Text Available Las fracciones de materia orgánica del suelo (MOS lábiles y humificadas pueden ser afectadas por las prácticas de uso y manejo; sin embargo el impacto de estos cambios no se ha evaluado en suelos y ambientes tropicales. El presente estudio tuvo como objetivo evaluar los contenidos y algunas formas de carbono orgánico del suelo (COS en cinco zonas de clima cálido tropical (0 - 1110 m.s.n.m. del departamento del Magdalena (Colombia y el efecto que sobre ellas han tenido las prácticas asociadas a suelos cultivados con café (Coffea arabica, banano (Musa sp., palma africana (Elaeis guineensis y sábila (Aloe vera, comparados con suelos de bosques naturales. No se encontraron diferencias (P < 0.05 tanto entre zonas como entre usos del suelo, se presentaron valores medios a bajos de MOS en las zonas de estudio y contenidos de carbono total (Ct mayores en suelos de bosques que en suelos cultivados, así los suelos de bosques presentan una acumulación media de Ct de 42.4 mg/ha a 20 cm, frente a 33.8 mg/ha en los suelos cultivados, esto equivale a una pérdida media de Ct del 23% por efecto del manejo de los cultivos. En relación con el carbono extraíble con pirofosfato sódico altamente relacionado con las fracciones humificadas de la MOS (Cp se observaron valores muy bajos en los suelos cultivados y casi nulos en suelos de bosques; sin embargo estos últimos presentan mayor contenido de formas de carbono no-oxidables o estables (Cnox determinado por diferencia entre Ct - carbono oxidable (Cox. En el suelo cultivado con banano, el Ct corresponde en su totalidad a formas de Cox; mientras que en el suelo cultivado con palma africana las formas estables Cnox representaron 83% del carbono total.

  6. Formas de carbono orgánico en suelos con diferentes usos en el departamento del Magdalena (Colombia

    Directory of Open Access Journals (Sweden)

    Menjivar Flores Juan Carlos

    2011-12-01

    Full Text Available Las fracciones de materia orgánica del suelo (MOS lábiles y humificadas pueden ser afectadas por las prácticas de uso y manejo; sin embargo el impacto de estos cambios no se ha evaluado en suelos y ambientes tropicales. El presente estudio tuvo como objetivo evaluar los contenidos y algunas formas de carbono orgánico del suelo (COS en cinco zonas de clima cálido tropical (0 - 1110 m.s.n.m. del departamento del Magdalena (Colombia y el efecto que sobre ellas han tenido las prácticas asociadas a suelos cultivados con café (Coffea arabica, banano (Musa sp., palma africana (Elaeis guineensis y sábila (Aloe vera, comparados con suelos de bosques naturales. No se encontraron diferencias (P < 0.05 tanto entre zonas como entre usos del suelo, se presentaron valores medios a bajos de MOS en las zonas de estudio y contenidos de carbono total (Ct mayores en suelos de bosques que en suelos cultivados, así los suelos de bosques presentan una acumulación media de Ct de 42.4 mg/ha a 20 cm, frente a 33.8 mg/ha en los suelos cultivados, esto equivale a una pérdida media de Ct del 23% por efecto del manejo de los cultivos. En relación con el carbono extraíble con pirofosfato sódico altamente relacionado con las fracciones humificadas de la MOS (Cp se observaron valores muy bajos en los suelos cultivados y casi nulos en suelos de bosques; sin embargo estos últimos presentan mayor contenido de formas de carbono no-oxidables o estables (Cnox determinado por diferencia entre Ct - carbono oxidable (Cox. En el suelo cultivado con banano, el Ct corresponde en su totalidad a formas de Cox; mientras que en el suelo cultivado con palma africana las formas estables Cnox representaron 83% del carbono total.

  7. Simulación de los cambios de carbono orgánico del suelo en sistema de cultivo con higuerilla por el modelo RothC

    Directory of Open Access Journals (Sweden)

    Lucila González Molina

    2012-11-01

    Full Text Available El objetivo del presente trabajo fue la simulación de los cambios del carbono orgánico del suelo (COS, por el modelo RothC, en razón del cambio de uso de suelo del sistema tradicional - asociación maíz-calabaza (TMC - a sistemas con higuerilla (Ricinus communis: multiestratos (MUL, callejones (CALL y monocultivo de higuerilla (HIG. Las simulaciones del COS se hicieron para las profundidades de suelo 0-20 y 0-40 cm, para el periodo de 1980-2040, considerándose como línea base al sistema TMC. Las tasas de cambio de COS estimadas con el RothC, en ambas profundidades de suelo, estuvieron en 0,5-1,2, 0,4-0,8, 0,3-0,5 y 0,04-0,1 Mg ha-1 de C por año en los sistemas HIG, MUL, CALL y TMC, respectivamente, y fueron consistentes con las reportadas en la literatura. El desempeño del RothC tuvo 89% de eficiencia (EF, con R²=0,9, lo que muestra que este modelo puede usarse con información temporal del COS escasa, información de la historia de uso de suelo y mediciones de la entrada de residuos vegetales aéreos y subterráneos en el suelo.

  8. Almacenes y dinámica del carbono orgánico en ecosistemas forestales tropicales de México

    Directory of Open Access Journals (Sweden)

    Julio Campo

    2016-03-01

    Full Text Available El efecto del régimen de precipitación en la dinámica del carbono en los bosques tropicales es poco conocido a pesar de su importante papel en el ciclo global del C. El objetivo del presente estudio fue determinar si existe un efecto de la lluvia y del uso de la tierra en el ciclo del C. También se analizó la recuperación de los almacenes del C luego del abandono del pastoreo por ganado en regiones tropicales forestales distribuidas en un amplio rango de precipitación media anual. Se analizaron datos publicados de ocho bosques tropicales mexicanos, que incluyó un intervalo de precipitación media anual entre 642 y 4725 mm. El análisis indicó que el C en la biomasa aumentó con la precipitación media anual. La concentración de C en los primeros 20 cm del suelo tendió a aumentar con la precipitación media anual, pero presentó un pico también en el extremo más seco del gradiente, probablemente debido a su limitada descomposición. El almacén total de C en el suelo aumentó con la precipitación y, en particular, en el subsuelo (>30 cm, donde se acumuló del 49 al 60% del total. Los efectos del uso del suelo en el C parecen depender del régimen de precipitación. En contraste, el C del suelo durante la sucesión secundaria no varió con la intensidad de la sequía, aun cuando el número de estudios fue muy limitado. El análisis sugiere que el régimen de precipitación juega un papel central en la dinámica del ciclo del C en los bosques tropicales.

  9. Tendencies in the energy consumption and in the carbon dioxide emissions in the Mexican cement industry; Tendencias del consumo de energia y emisiones de bioxido de carbono de la industria cementera mexicana

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa M, Leticia; Sheinbaum P, Claudia [Instituto de Ingenieria UNAM, Mexico, D. F. (Mexico)

    1996-12-31

    This paper analyzes the changes occurred in the energy consumption and carbon dioxide in the Mexican cement industry. For this purpose, the energy consumption and the emissions are broken up into three types of changes that affect the energy demand of an industry: activity, structure and energy intensity. According to this analysis it is found that the Mexican cement industry has suffered an important reduction in the energy intensity as a result of the disappearance, almost complete, of the wet production process, of the increment in the production of pozzolanic cement and in the opening of new high technology industries. With respect to the intensity of carbon dioxide emissions it does not decrease at the same rate than the energy intensity due to the increased consumption of the fuel oil over the natural gas. At the end of this paper an international comparison is presented of the energy specific consumption and of its emissions. [Espanol] En este articulo se analizan los cambios ocurridos en el consumo de energia y emisiones de bioxido de carbono de la industria cementera mexicana. Para ello, se desagrega el consumo de energia y las emisiones en tres tipos de cambios que influyen en la demanda energetica de una industria: actividad, estructura, e intensidad energetica. De acuerdo con este analisis se encuentra que la industria cementera mexicana ha sufrido un importante decremento en la intensidad energetica producto de la desaparicion, casi por completo, del proceso de produccion por via humeda, del incremento en la produccion del cemento puzolanico y de la apertura de nuevas industrias con alta tecnologia. Por su parte, la intensidad en las emisiones de bioxido de carbono no disminuye a la misma tasa que la intensidad energetica debido al incremento en el uso del combustoleo sobre el gas natural. Al final del articulo se presenta una comparacion internacional del consumo especifico de energia y de las emisiones.

  10. Efecto de plantaciones dendroenergéticas en el carbono a nivel de suelo, en dos suelos contrastantes de la región de Biobío, Chile

    Directory of Open Access Journals (Sweden)

    Edwin Esquivel

    2013-12-01

    Full Text Available La biomasa forestal como fuente de energía proveniente de plantaciones dendroenergéticas, al compararla con combustibles fósiles, presenta la ventaja de producir energía carbono-neutral, dado el secuestro de carbono (C fijado en la biomasa producida y los aportes al suelo. Plantaciones forestales de corta rotación, altas densidades, y localizadas en terrenos marginales pueden representar una excelente oportunidad de producción de biomasa para la producción de energía o combustibles. Sin embargo, los beneficios en el corto plazo del aumento del C a nivel de suelo en sitios marginales han sido cuestionados. Se establecieron plantaciones dendroenergéticas con las especies Eucalyptus camaldulensis, E. nitens, E. globulus, y Acacia melanoxylon a densidades de 5.000, 7.500 y 10.000 plantas por hectárea, en dos sitios de producción forestal marginal con suelos contrastantes (arenales y granítico localizados en la Región del Biobío de Chile. Evaluaciones periódicas durante 4 años a 0-20 y 20-40 cm de profundidad, del nivel de C en cada uno de los suelos evaluados, sugiere efectos de la edad (tiempo desde el establecimiento de la plantación (P < 0,001. A pesar de los cambios observados en el tiempo, la escasa diferencia en los niveles observados de C en el suelo mineral para los 48 meses de estudio comparados a los primeros 2 meses post-plantación, sugiere una rápida capacidad de recuperación de los niveles de C del suelo en un corto periodo.

  11. 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)

  12. AISI 304奥氏体不锈钢活性屏离子渗碳%Active Screen Plasma Carburizing of AISI 304 Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    王建青; 王璐璐; 赵程

    2010-01-01

    利用活性屏离子热处理技术对AISI 304奥氏体不锈钢进行低温离子渗碳(ASPC)处理,可以在不锈钢表面形成一层无碳化铬析出的碳的过饱和固溶体(Sc相).处理后的奥氏体不锈钢可以在不降低耐蚀性能的基础上大幅度提高不锈钢表面的硬度,并解决了不锈钢直流离子渗碳温度均匀性差,工件存在边缘效应等问题,ASPC渗碳试样表面基本可以保持原色.

  13. Disclosure of carbon credit operations in management publications Divulgación de las operaciones con créditos de carbono en los in informes de la administración y las notas explicativas Evidenciação das operações com crédito de carbono nos relatórios da administração e nas notas explicativas

    Directory of Open Access Journals (Sweden)

    Vanderlei dos Santos

    2011-03-01

    Full Text Available This study identifies the level of disclosure in management reports and explanatory notes regarding carbon credit operations as related to projects, funding, markets, accounting and taxation. A descriptive research with a qualitative approach was carried out in document analysis of 14 Brazilian companies, publicly traded, that have Clean Development Mechanism projects approved by the Interministerial Commission of Global Climate Change as listed by the Ministry of Science and Technology. By November28, 2008, 195 projects had been approved, 25 of these belonged to these 14 companies. Content analysis technique for management reports and explanatory notes was used for collection of data from the first carbon credits up to the third quarter of 2008. Results show that these companies do not disclose accounting and taxation of the carbon credit transactions in their reporting. Information most often published related to the form of generation of these credits and cost of investment. In conclusion, it is evident that management reports and explanatory notes of these companies with respect to transactions with carbon credits do not respect the full disclosure principleEl estudio tiene el objetivo de identificar el nivel de divulgación, en los informes de la administración y en las notas explicativas, de las operaciones con créditos de carbono relacionadas a los proyectos, medios de financiamiento y mercado, contabilización y tributación. Se realizó una investigación descriptiva, con abordaje cualitativo, mediante análisis de documentos, en las 14 empresas brasileñas de capital abierto que poseen proyectos de Mecanismo de Desarrollo Limpio (MDL aprobados por la Comisión Interministerial de Mudanza Global del Clima, de acuerdo al listado del Ministerio de Ciencia y Tecnología. El 28 de noviembre de 2008 había 195 proyectos aprobados, 25 de los cuales pertenecían a 14 empresas de capital abierto. Para la recogida de los datos, se aplicó la t

  14. 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

    OpenAIRE

    Maritza Mariño-Cala; Yanier Sánchez-Hechavarría

    2015-01-01

    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 perpend...

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

    Energy Technology Data Exchange (ETDEWEB)

    Pascual, M.; Salas, F.; Carcel, F.J.; Perales, M.; Sanchez, A.

    2010-07-01

    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. (Author). 12 refs.

  16. 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.

  17. Surface Roughness and Tool Wear Study on Milling of AISI 304 Stainless Steel Using Different Cooling Conditions

    Directory of Open Access Journals (Sweden)

    P. Chockalingam

    2012-08-01

    Full Text Available This research deals with the effect of different coolant conditions on milling of AISI 304 stainless steel. Cooling methods used in this investigation were flooding of synthetic oil, water-based emulsion, and compressed cold air. Cutting forces and the surface roughness were studied and tool flank wears observed. In this study, the comparison between different coolants’ effect to the milling of AISI 304 stainless steel is done and the results from the study can provide very useful information in manufacturing field. The experiment results showed that water-based emulsion gave better surface finish and lower cutting force followed by synthetic oil and compressed cold air. Different cooling condition required different parameters in order to obtain lower surface roughness and cutting force. Chipping was the initial wear mode in the milling of AISI 304 stainless steel.

  18. Effect of aging at 700 deg. C on precipitation and toughness of AISI 321 and AISI 347 austenitic stainless steel welds

    International Nuclear Information System (INIS)

    A detailed knowledge of changes in microstructures and mechanical behaviour that occur in austenitic stainless steels with or without Nb/Ti-stabilized weld during heat treatment is of great interest, since the ductility and toughness of the material may change drastically after long aging times. Two kinds of materials, i.e. AISI 321 base and without Ti-stabilized weld steel and AISI 347 base with Nb-stabilized weld steel, were compared during aging at 700 deg. C up to 6000 h. Both materials present increased amount of precipitate and decreased impact energy as the aging time increases. The decreased extent of impact energy with aging is almost the same for both base materials. However, it presents differences for 347 and 321 weld samples. The latter shows a more drastic decrease of impact energy than the former due to the different amount of precipitates. 321 weld sample precipitates more numerously than 347 weld sample due to the absence of stabilized Ti/Nb on the former. Large amount of carbides is formed on 321 weld sample immediately after welding. The carbides are transformed to sigma phase, which is mainly responsible for the much more sigma phase precipitation compared with other samples, after high-temperature aging. The fractographs showed, in general, brittle fracture mode in 321 weld impact-fractured specimens after aging at 700 deg. C for 6000 h. However, other samples show ductile fracture mode in general. Several approaches should be employed to control sigma phase precipitation in weld material. These approaches include: decreasing content of ferrite and M23C6 carbide in weld and selecting Nb added weld wire during welding

  19. 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.

  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. Effect of Al added to a NiCrMo alloy on the development of the oxide layer of intermetallic coatings; Efeito do teor de Al adicionado a liga NiCrMo no desenvolvimento dos filmes de oxidos em revestimentos intermetalicos

    Energy Technology Data Exchange (ETDEWEB)

    D' Oliveira, A.S.C.M.; Cangue, F.J.R. [Universidade Federal do Parana (DEM/UFPR), Curitiba, PR (Brazil). Dept. de Engenharia Mecanica; Clark, E.; Levi, C. [University of California, Santa Barbara, CA (United States)

    2010-07-01

    Components performance in different environment is strongly dependent on oxides that develop on their surfaces. This study analyzed the oxide layer that develops on coatings processed with mixtures of an atomized Hastelloy C alloy with Al powders. Powder mixtures containing 10, 20 and 30wt%Al were deposited on AISI 1020 and AISI304 steel plates. Coatings were subsequently exposed to 850 deg C for two hours in a low PO{sub 2} environment. X-ray diffraction was used to identify the phases that developed in the coating during processing and Raman analysis and Scanning Electron Microscopy were used to characterize the oxide layers. The results showed that coatings processed with the richer Al mixtures, 30wt%Al, which developed NiAl aluminides, reduced the development of {alpha} alumina when processing was done on AISI 304. Coatings processed on AISI 1020 with the three powder mixtures tested developed the different allotropic forms of alumina, as predicted for the tested temperature. (author)

  2. 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.

  3. Creep behaviour and microstructural evolution in AISI 316LN + Nb steels at 650 deg. C

    International Nuclear Information System (INIS)

    Research highlights: → We studied the effect of Nb additions to AISI 316LN steels on creep and microstructure at 650 deg. C. → Nb additions resulted in a reduction of secondary creep rate and shortening of the tertiary stage. → Two nitrogen rich minor phases were present in the niobium-bearing casts: Z-phase and M6X. → The dimensional stability of Z-phase during creep at 650 deg. C was much better than that of M6X. → Nb accelerated σ-phase and η-Laves formation and this surpassed the positive effect of Z-phase. - Abstract: The paper deals with the effect of niobium in the wrought AISI 316LN steels on the long-term creep characteristics at 650 deg. C. Casts B and C contained 0.1 and 0.3 wt.%Nb, respectively. As a reference material the niobium free Cast A was used. Small additions of niobium to the AISI 316LN steel resulted in a significant reduction of the minimum creep rate and shortening of the tertiary creep stage. At time to rupture exceeding 104 h the creep rupture strength of the niobium-bearing Casts B and C was slightly inferior to the Cast A. Two nitrides formed in the Casts B and C: Z-phase and M6X. The minimum creep rate in niobium-bearing casts was favourably affected by precipitation of the Z-phase. The dimensional stability of Z-phase particles was very high, but niobium additions also accelerated the formation and coarsening of η-Laves and σ-phase. Coarse σ-phase particles at grain boundaries contributed significantly to the shortening of the tertiary creep stage.

  4. Stress corrosion crack growth studies on nitrogen added AISI type 316 stainless steel and its weld metal in boiling acidified sodium chloride solution using the fracture mechanics approach

    Energy Technology Data Exchange (ETDEWEB)

    Shaikh, H.; George, G.; Khatak, H.S. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany). Inst. fuer Metallische Werkstoffe

    2000-10-01

    Compact tension specimens of nitrogen-added AISI type 316 austenitic stainless steel and its weld metal were subject to stress corrosion cracking (SCC) testing in a boiling solution containing 5 M sodium chloride + 0.15 M sodium sulphate + 2.5 ml/l hydrochloric acid solution using the constant extension rate testing (CERT) technique. The extension rate of testing was 10 microns per hour. The threshold values of stress intensify factor (K{sub ISCC}) and J-integral (J{sub ISCC}) were taken as those values of K{sub I} and J{sub I} at which about 25 microns of SCC crack growth was observed. These threshold values were about four times higher and plateau crack growth rates (PCGR) were nearly one order of magnitude lower for the base metal vis-a-vis the weld metal. Fractographic observations indicated failure by transgranular SCC (TGSCC) of austenite in both the base and weld metal. No stress-assisted dissolution of delta-ferrite or its interface with austenite, was observed. (orig.) [German] CT-Proben von Grund- und Schweissnahtwerkstoff des stickstoffhaltigen Stahles AISI 316 LN wurden Spannungsrisskorrosionstests in siedender chloridhaltiger Loesung (5 M Natriumchlorid/0,15 M Natriumsulfat/0,03 M Salzsaeure) unterzogen. Die Tests erfolgten bei konstanter Dehnrate (CERT-Test) von 10 {mu}m/h. Als Schwellwerte der Initiierung von Spannungsrisskorrosion K{sub ISCC} und I{sub ISCC} wurden die Werte des Spannungsintensitaetsfaktors K{sub I} und des J-Integrals J{sub I} ermittelt, bei denen ein Risswachstum von 25 {mu}m auftrat. Dabei wies der Grundwerkstoff 4-fach hoehere Schwellwerte K{sub ISCC} und J{sub ISCC} auf als der Schweissnahtwerkstoff. Auch die Risswachstumsraten im Plateaubereich der Risswachstumsrate-Spannungsintensitaetskruven waren am Grundwerkstoff um eine Groessenordnung geringer als am Schweissnahtwerkstoff. Die fraktorgrahischen Untersuchungen zeigten an beiden Materialien Schaedigung durch transkristalline Spannungsrisskorrosion. Eine

  5. Numerical Simulation on Temperature and Microstructure during Quenching Process of Large-sized AISI P20 Steel Die Blocks

    Institute of Scientific and Technical Information of China (English)

    SONGDong-li; GUJian-feng; ZHANGWei-min; LIUYang; PANJian-sheng

    2004-01-01

    In this paper, a model of coupled thermal and phase transformation is described. The temperature and microstructure during the quenching process for large-sized AISI P20 steel die blocks have been simulated using the finite element method (FEM). The optimum quenching technology of large-sized AISI P20 steel die blocks has been proposed based on the simulation results, which not only can effectively avoid quenching cracks and obtain deeper hardened depth, but also can improve the microstructure and properties of the large-sized die blocks.

  6. Numerical Simulation on Temperature and Microstructure during Quenching Process of Large-sized AISI P20 Steel Die Blocks

    Institute of Scientific and Technical Information of China (English)

    SONG Dong-li; GU Jian-feng; ZHANG Wei-min; LIU Yang; PAN Jian-sheng

    2004-01-01

    In this paper, a model of coupled thermal and phase transformation is described. The temperature and microstructure during the quenching process for large-sized AISI P20 steel die blocks have been simulated using the finite element method (FEM). The optimum quenching technology of large-sized AISI P20 steel die blocks has been proposed based on the simulation results, which not only can effectively avoid quenching cracks and obtain deeper hardened depth,but also can improve the microstructure and properties of the large-sized die blocks.

  7. In-situ investigation of martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen;

    2013-01-01

    Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature...... of the martensitic transformation. The kinetics of the transformation is interpreted in terms of a-thermal nucleation and thermally activated growth of lenticular martensite.......Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature...

  8. 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.

  9. Effects of ageing on the ductile fracture of AISI type 316 stainless steel

    International Nuclear Information System (INIS)

    The micromechanisms of ductile fracture have been studied in a commercial AISI type 316 austenitic stainless steel. Tensile, Charpy impact and ductile fracture toughness testing has been performed on unaged material and samples aged at 7000C for times up to 4380 h. Examination of the specimens after testing has demonstrated that the microstructural changes occurring at grain boundaries are reponsible for the observed losses of ductility and crack growth resistance. The relative magnitude of the observed changes in mechanical properties has been accounted for using a simple model to describe the ductile fracture process. (author)

  10. Impact energy absorption of aluminium foam fitted AISI 304L stainless steel tube

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, R. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam 603 102, Tamilnadu (India)], E-mail: rajurajendr@yahoo.co.in; Prem Sai, K.; Chandrasekar, B. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam 603 102, Tamilnadu (India); Gokhale, A. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Basu, S. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam 603 102, Tamilnadu (India)

    2009-05-15

    Closed cell aluminium foam fitted AISI 304L stainless steel tube was investigated for its impact energy absorption characteristics. Quasi-static load-deflection tests were employed to establish the foam-tube interaction factor. Drop experiments were carried out using a free flight drop tower on aluminium foam fitted stainless steel tube to obtain the acceleration-time history of the hammer. Estimated deflections compared well with the experimental values. Adequate force reduction factor indicated that the foam-tube configuration is a potential energy absorber candidate for the nuclear transportation cask.

  11. 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.

  12. Anodic behaviour of the stainless steel AISI 430 in aqueous solutions of chloride and sulphate ions

    International Nuclear Information System (INIS)

    The kinetics of the dissolution of stainless steel AISI 430 in the presence of chloride and sulphate ions has been studied in terms of the ion concentration, the pH variation, and the velocity of the working electrode. The experimental method utilized was the potentiostatic anodic polarization, and the reactants used were NaCl and Na2 SO4 at room temperature. Atomic Absorption spectrophotometry and Auger Electrons spectroscopy (AES) analyses were made in order to support the interpretation of results obtained by means of the potentiostatic polarization method. (author)

  13. Microstructural changes due to laser surface melting of an AISI 304 stainless steel

    Directory of Open Access Journals (Sweden)

    A.S.C.M. d’Oliveira

    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.

  14. 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.

  15. XPS Analysis of AISI 304L Stainless Steel Surface after Electropolishing

    Directory of Open Access Journals (Sweden)

    Rokosz K.

    2015-03-01

    Full Text Available In the paper, the passive surface layers of AISI 304L after standard (EP50 and very-high-current density electropolishing (EP1000 in a mixture of orthophosphoric and sulfuric acids in a 1:4 ratio, are presented. The main finding of the presented studies is enrichment of the steel surface film in chromium: total chromium to total iron ratio was equal to 6.6 after EP50 and to 2.8 after EP1000; on the other hand, chromium compounds to iron compounds ratio was equal to 10.1 after EP50, and 3.9 after EP1000.

  16. Behavior of AISI 316L Steel Subjected to Uniaxial State of Stress at Elevated Temperatures

    Institute of Scientific and Technical Information of China (English)

    Josip Brnic; Jitai Niu; Marko Canadija; Goran Turkalj; Domagoj Lanc

    2009-01-01

    This paper presents an experimental investigation on an AISI 316L stainless steel regarding mechanical properties and short uniaxial creep tests at elevated temperatures. The short time creep tests were carried out under different but constant stresses. The obtained data of ultimate tensile strength, yield strength, creep curves and effects of elevated temperatures on mechanical properties were presented. For a selected rheological model,material parameters were obtained. As a justification, such rheological model is implemented in the finite element procedure for an uniaxially stressed specimen in selected environmental conditions.

  17. Martensitic stainless steel AISI 420—mechanical properties, creep and fracture toughness

    Science.gov (United States)

    Brnic, J.; Turkalj, G.; Canadija, M.; Lanc, D.; Krscanski, S.

    2011-11-01

    In this paper some experimental results and analyses regarding the behavior of AISI 420 martensitic stainless steel under different environmental conditions are presented. That way, mechanical properties like ultimate tensile strength and 0.2 percent offset yield strength at lowered and elevated temperatures as well as short-time creep behavior for selected stress levels at selected elevated temperatures of mentioned material are shown. The temperature effect on mentioned mechanical properties is also presented. Fracture toughness was calculated on the basis of Charpy impact energy. Experimentally obtained results can be of importance for structure designers.

  18. Laser welding of butt joints of austenitic stainless steel AISI 321

    OpenAIRE

    A. Klimpel; A. Lisiecki

    2007-01-01

    Purpose: of this paper: A study of an automated laser autogenous welding process of butt joints of austenitic stainless steel AISI 321 sheets 0.5 [mm] and 1.0 [mm] thick using a high power diode laser HPDL has been carried out.Design/methodology/approach: Influence of basic parameters of laser welding on shape and quality of the butt joints and the range of optimal parameters of welding were determined.Findings: It was showed that there is a wide range of laser autogenous welding parameters w...

  19. Wear Properties of TiN Coating Formed on AISI D2 Surface

    OpenAIRE

    ÇEĞİL, Özkan; KILINÇ, Bülent; Şen, Şaduman

    2014-01-01

    In this work, the wear test of uncoated and titanium nitride coated AISI D2 cold work tool steel against silicon nitride ball was realized at 0.3 m/s sliding speed and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then titanium nitride coating was performed by pack diffusion coating in a powder mixture consisting of ferro-titanium, ammonium chloride and alumina at 1000°C for 2h. Nitro-titanized samples were char...

  20. 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.

  1. Microstructural Evolution and Wear Resistance of Friction Stir-Processed AISI 52100 Steel

    Science.gov (United States)

    Seraj, R. A.; Abdollah-zadeh, A.; Hajian, M.; Kargar, F.; Soltanalizadeh, R.

    2016-07-01

    Friction stir processing (FSP) was successfully applied on AISI 52100 steel. The influence of process parameters on the microstructure and mechanical properties of the material was evaluated. It was observed that the initial ferritic-pearlitic microstructure of the base metal is transformed to the martensitic microstructure with retained austenite in the stir zone. The results also showed that microhardness and wear resistance of the FSP samples are, respectively, at least 2 and 15 times higher than those of the base metal. The improvement of the mechanical properties of FSP samples was attributed to their microstructural characteristics. The mechanisms controlling the wear behavior of the base metal and FSP samples were also discussed.

  2. 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...

  3. 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.

  4. Effect of Niobium on Microstructure of Cast AISI H13 Hot Work Tool Steel

    Institute of Scientific and Technical Information of China (English)

    Shahram Kheirandish; Ahmad Noorian

    2008-01-01

    The effect of niobium addition on the microstructure of cast AISI H13 hot work tool steel was evaluated by using EDX analyzer attached to the scanning electron microscope.The volume percent of eutectic area and eutectic cell size and also volume percent of different carbides of new steel,which is heat treated under different conditions,are also determined.The results show that the a niobium addition modifies the cast structure of Nb-alloyed hot work tool steel,and reduces the size and volume of eutectic cells,and increases the maximum hardness of the steel.

  5. Two-scale approach to dynamic localization failure of AISI 316H stainless steel sheets

    Directory of Open Access Journals (Sweden)

    Gambin W.

    2008-01-01

    Full Text Available Dynamic localization failure of a thin sheet made of AISI 316H steel is considered on the macroscopic and mesoscopic level for proportional and nonproportional stress paths. On the macroscopic level, we propose: (1 the replacement of time as independent variable by a function of plastic dissipation and (2 dependence of the initial equivalent yield stress on stress rate. On the mesoscopic level - the regularized Schmid model for description of the single grain behavior is used and the polycrystalline yield surface generated by the texture development enables to improve the Forming Limit Diagrams for the sheet element.

  6. Microstructural origins of yield strength changes in AISI 316 during fission or fusion irradiation

    International Nuclear Information System (INIS)

    The changes in yield strength of AISI 316 irradiated in breeder reactors have been successfully modeled in terms of concurrent changes in microstructural components. Two new insights involving the strength contributions of voids and Frank loops have been incorporated into the hardening models. Both the radiation-induced microstructure and the yield strength exhibit transients which are then followed by saturation at a level dependent on the irradiation temperature. Extrapolation to anticipated fusion behavior based on microstructural comparisons leads to the conclusion that the primary influence of transmutational differences is only to alter the transient behavior and not the saturation level of yield strength

  7. Reserva de carbono en biomasa forestal y suelos minerales en el Parque Nacional Malinche (México

    Directory of Open Access Journals (Sweden)

    María Eugenia Valdez Pérez

    2016-01-01

    Full Text Available Las áreas naturales protegidas representan una de las estrategias para la mitigación del cambio climático. El objetivo de esta investigación consistió en estimar el contenido de carbono en biomasa forestal en suelos minerales y calcular las pérdidas de carbono por cambios de uso del suelo en el Parque Nacional Malinche (PNM. La superficie de bosque del PNM es de 17.496,34 ha y almacena 1.544.377,66 mg en bosque y 4.148.985,97 mg en suelos. Para estimar el contenido de biomasa forestal se aplicaron ecuaciones alométricas y se trabajó con la cartografía del Instituto Nacional de Estadística y Geografía (INEGI en el análisis espacio-temporal de los cambios de uso de suelo. Para el carbono en suelos se aplicaron los valores del Panel Intergubernamental de Cambio Climático (IPCC.

  8. Solubilização de fostatos por microrganismos na presença de fontes de carbono

    Directory of Open Access Journals (Sweden)

    G. N. Silva Filho

    2000-06-01

    Full Text Available O potencial de solubilização de fosfatos por bactérias e fungos cultivados em meio de cultura GEL (Glicose-Extrato de Levedura, suplementado com diferentes formas de fosfatos (cálcio, alumínio e ferro e fontes de carbono (celulose, amido, sacarose, glicose, frutose e xilose, foi avaliado em laboratório. O crescimento, o diâmetro da área solubilizada e a relação halo/colônia variaram conforme o tipo de microrganismo e a fonte de fósforo e de carbono. Dos 57 isolados utilizados, 56 formaram halo na presença de fosfato de cálcio e cinco apenas na presença de fosfato de alumínio e nenhum foi capaz de solubilizar fosfato de ferro. Contudo, seis isolados cresceram melhor no meio com fosfato de ferro em comparação com o meio testemunha. As maiores colônias e halos foram observados nos isolados de Rhizopus e Aspergillus, enquanto as maiores relações halo/colônia foram encontradas em Paecilomyces e Penicillium. Todos os isolados cresceram no meio GEL base (testemunha sem açúcar, mas a solubilização ocorreu apenas na presença de carbono adicionado ao meio, destacando-se xilose, glicose, frutose e sacarose.

  9. Huella del Carbono. Parte 1: Conceptos, Métodos de Estimación y Complejidades Metodológicas Carbon Footprint. Part 1: Concepts, Estimation Methods and Methodological Complexities

    Directory of Open Access Journals (Sweden)

    César Espíndola

    2012-01-01

    Full Text Available Se presenta y analiza el concepto de huella del carbono, su origen, su relación con los gases efecto invernadero, y sobre los procedimientos para cuantificarla. El efecto invernadero provoca que la energía que llega a la Tierra sea devuelta más lentamente, por lo que es mantenida más tiempo junto a la superficie elevando la temperatura. Es aceptado hoy en día que este efecto es producido por algunos gases liberados en forma natural o por las acciones humanas. La Huella de Carbono es considerada una de las más importantes herramientas para cuantificar las emisiones de gases efecto invernadero y en forma muy general, representa la cantidad de gases efecto invernadero emitidos a la atmósfera derivados de las actividades de producción o consumo de bienes y servicios. Al no existir consenso en cuanto a la definición y menos en la cuantificación de la huella del carbono, la primera parte de este trabajo analiza las principales corrientes y enfoques actuales.The concept of Carbon Footprint, its origin, its relation with greenhouse gases and the methods to quantify it are presented and analyzed. The so-called greenhouse effect causes that the energy that reaches the earth at a certain rate is returned to a slower rate, increasing the temperature of the earth surface. Additionally, it is nowadays accepted that this effect is produced by some gases that are naturally emitted or produced by human actions. The Carbon Footprint is considered to be one of the most important tools for quantifying greenhouse emissions and in a general form it represents the quantity of gases emitted to the atmosphere and that is produced by human activities, and by goods and service consumption. Since there is no consensus about the definition of Carbon Footprint or the forms of quantifying it, this first part of the paper series analyzes the main concept and the main present views on the Carbon Footprint.

  10. 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.

  11. 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)

  12. OPTIMIZATION OF PROCESSING PARAMETERS IN ELECTROCHEMICAL MACHINING OF AISI 202 USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    V. SATHIYAMOORTHY

    2015-06-01

    Full Text Available This paper attempts to optimize the predominated machining parameters in Electro Chemical Machining (ECM of AISI 202 Austenitic stainless steel using Response Surface Methodology (RSM. The chosen material has been used in railway rolling stock. The selected influencing parameters are applied voltage, electrolyte discharge rate with three levels and tool feed rate with four levels. Thirty six experiments were conducted through design of experiments and central composite design in RSM was applied to identify the optimum conditions which turn into the best Material Removal Rate (MRR and Surface roughness (SR. The experimental analyses reveal that applied voltage of 16 V, tool feed rate of 0.54 mm/min and electrolyte discharge rate of 10 L/min would be the optimum values in ECM of AISI 202 under the selected conditions. For checking the optimality of the developed equation, MRR of 298.276 mm3/min and surface roughness Ra of 2.05 µm were predicted at applied voltage of 12.5 V, tool feed rate of 0.54 mm/min and electrolyte discharge rate of 11.8 L/min with composite desirability of 98.05%. Confirmatory tests showed that the actual performance at the optimum conditions were 291.351 mm3/min and 2.17 µm. The deviation from the predicted performance is less than 6% which proves the composite desirability of the developed models for MRR and surface roughness.

  13. Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

    Science.gov (United States)

    Kon, O.; Pazarlioglu, S.; Sen, S.; Sen, U.

    2015-03-01

    In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000oC for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1-4 h. The presence of the niobium boride layers such as NbB, NbB2 and Nb3B4 and also iron boride phases such as FeB, Fe2B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurements were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV0.005.

  14. Microstructure evolution in nano/submicron grained AISI 301LN stainless steel

    International Nuclear Information System (INIS)

    The phase and microstructure evolution of a heavily cold-rolled AISI 301LN stainless steel (SS), before and after annealing is discussed. AISI 301LN SS has been cold-rolled to 63% rolling reduction and subsequently annealed from 600 to 1000 deg. C for short annealing durations (1-100 s). Phase analysis indicates that the cold-rolled sheet comprises almost 100% martensite, while transmission electron microscopy examination reveals its morphology to be of dislocation cell- and heavily deformed lath-type martensite. The martensite → austenite reversion upon annealing at 600 deg. C for 1 and 10 s is negligible, but nanoscale austenite grains are formed in the martensitic matrix. Partial reversion to nano/submicron austenite grains is observed for samples annealed at 600 deg. C for 100 s, and 700 deg. C for 1 s. Samples annealed at higher temperatures exhibit a complete reversion to submicron/nano-austenite grains with a large grain size variation, as well as secondary phase chromium nitride precipitates.

  15. 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.

  16. 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.

  17. 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.

  18. Improvement in cavitation erosion resistance of AISI 316L stainless steel by friction stir processing

    Science.gov (United States)

    Hajian, M.; Abdollah-zadeh, A.; Rezaei-Nejad, S. S.; Assadi, H.; Hadavi, S. M. M.; Chung, K.; Shokouhimehr, M.

    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.

  19. 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.

  20. Using Mather-Type Plasma focus Device for Surface Modification of AISI304 Steel

    International Nuclear Information System (INIS)

    A 8.8 kJ plasma focus device with a nitrogen gas filling and a copper anode capsulated by aluminum was used to modify the surface of AISI304 steel substrate, in order to improve its properties. The treatment was carried out using a various number of nitrogen plasma focus shots at a pressure of 0.5 mbar and at two steel sample distances (20 and 40 mm) from the anode. The plasma diagnostics was made using the voltage and current curves recorded by a voltage divider, Rogowski coil, accompanied with calculations using a five phase radiative Lee model (RADPF5.15a) to determine the temperature and plasma density. The surface hardness of AISI304 steel was increased by 175% after plasma treatment and the thickness of the treated layers was about 1-2 μ. Results show that the surface hardness is increased with increasing shot number and decreased with increasing distance from the anode. Changes in surface morphology and the elemental composition were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). (author)

  1. Efeitos do carbono na evolução de segundas-fases e na densificação do nitreto de alumínio com Y2O3 Effects of carbon on second-phase evolution and densification of aluminum nitride with Y2O3

    Directory of Open Access Journals (Sweden)

    A. L. Molisani

    2010-12-01

    Full Text Available Foi investigado o efeito da adição do carbono na evolução de segundas-fases e na densificação do AlN com 4% em massa de Y2O3. A mudança de composição da segunda-fase do AlN com Y2O3 foi induzida pela adição de 0,5% e 1,0% em massa de carbono. A sinterização sob atmosfera de nitrogênio foi realizada em forno com elemento resistivo de tungstênio entre 1650 ºC e 1850 ºC. A evolução de segunda-fase mostrou uma tendência para formar fases mais ricas em ítrio com o aumento do teor de carbono, o que atrasou a densificação do AlN com Y2O3 devido ao aumento da temperatura de formação de fase líquida. O efeito prejudicial causado pela adição de carbono diminuiu com o aumento da temperatura de sinterização, pois todas as amostras atingiram quase completa densificação após sinterização a 1800 ºC. A adição de carbono induziu uma evaporação significativa de compostos durante a sinterização, mas o comportamento de densificação foi pouco influenciado pela redução na fração de fase líquida existente na temperatura de sinterização e pelo gás aprisionado no interior dos poros fechados.The effect of carbon addition on the second-phases evolution and on the densification of AlN with 4wt.%.Y2O3 was investigated. The change of second-phase composition of AlN with Y2O3 was induced by the addition of 0.5wt.% and 1.0wt.% carbon. Sintering under nitrogen atmosphere was performed in tungsten heated furnace between 1650 ºC and 1850 ºC. The second-phase evolution had a tendency to form Y-richer phases with increasing carbon content, which delayed the densification of AlN with Y2O3 due to the increase of liquid-phase formation temperature. The harmful effect caused by the addition of carbon was diminished with increasing sintering temperature, since all samples achieved almost full densification after sintering at 1800 ºC. The addition of carbon induced significant evaporation of compounds during sintering, but the

  2. Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials

    Science.gov (United States)

    Townsend, D. P.

    1985-01-01

    Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.

  3. 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.

  4. Atributos químicos e estoques de carbono e nitrogênio em argissolo vermelho-amarelo sob sistemas agroflorestais e agricultura de corte e queima no norte do Piauí

    Directory of Open Access Journals (Sweden)

    Sandra Santana de Lima

    2011-02-01

    Full Text Available A prática da agricultura de corte e queima tem causado a degradação do solo no Estado do Piauí, e isso tem estimulado a adoção de alternativas sustentáveis de uso da terra, como os Sistemas Agroflorestais. Este trabalho objetivou avaliar as mudanças nas características químicas e nos estoques de carbono (COT e nitrogênio (NT de um Argissolo Vermelo-Amarelo sob sistemas agroflorestais com seis (SAF6 e 10 (SAF10 anos de adoção, sistema com base ecológica com três anos de adoção (SE3, agricultura de corte e queima (ACQ e floresta nativa (FN, no Norte piauiense. Foram coletadas amostras de solo nos períodos seco e chuvoso na profundidade de 0-10 cm, para a avaliação dos atributos químicos do solo e dos estoques totais de carbono (COT e nitrogênio (NT. O SAF10 apresentou menor teor de Al+3 (0,02 cmol c dm-3. O teor de P no SAF10 (12,27 mg dm-3, no período seco, foi seis a sete vezes maior do que ACQ e FN, respectivamente. Os maiores estoques de COT e NT foram observados no período seco, respectivamente no SAF10 (48,54 Mg ha-1 e 4,43 Mg ha-1 e SAF6 (43,30 Mg ha-1 e 3,45 Mg ha-1. Os sistemas agroflorestais melhoraram a qualidade do solo e podem ser considerados como estratégia conservacionista para o Norte do Piauí.

  5. Almacén y dinámica del carbono orgánico del suelo en bosques templados de México

    Directory of Open Access Journals (Sweden)

    Leopoldo Galicia

    2016-03-01

    Full Text Available Los bosques templados se establecen sobre diversos tipos de suelo, sin embargo la información sobre las características físicas, químicas y biológicas de estos suelos y su influencia en el ciclo del carbono es escasa. El objetivo de la presente revisión fue conocer el almacenamiento de carbono en suelos cubiertos por bosques templados. Estos bosques se distribuyen sobre 23 tipos de suelo, principalmente Leptosoles, Regosoles, Luvisoles, Phaeozems, Cambisoles, Umbrisoles y Andosoles formados a partir de materiales volcánicos en el centro del país, sedimentarios en la Sierra Madre Oriental y una variedad amplia de sustratos en la Sierra Madre Occidental. La información sobre el potencial de captura de carbono en los bosques templados está sesgada a la biomasa aérea; y existe menos información sobre los almacenes de carbono edáficos y un escaso entendimiento de los procesos de su estabilización. El almacenamiento de carbono del suelo varió con el tipo de suelo, la composición de especies y el relieve. Los Andosoles, a pesar de su escasa abundancia, son los suelos con la mayor capacidad de almacenar carbono debido a sus características mineralógicas. Los cambios en el carbono orgánico del suelo y los flujos de carbono en los bosques templados en México son el resultado de cambios locales, generados por las actividades humanas como el cambio de uso, el manejo forestal, los incendios, la regeneración y la sustitución de especies. El cambio de uso de suelo es uno de los principales factores que explican los flujos de carbono en estos ecosistemas, sin embargo, aún no existe evidencia clara de que sea en sentido negativo. Esta revisión resume la información existente y propone investigaciones futuras que permitan conocer mejor los procesos de estabilización de la materia orgánica en los suelos de bosques templados.

  6. Pelapisan Alloy FeNiAl Menggunakan Metode Detonation Gun (D-Gun)

    OpenAIRE

    M.R.T. Siregar; F.W. Machmud; Muchiar Muchiar; G.E. Timuda; Cece Cece

    2012-01-01

    Pelapisan material alloy Fe38Ni10Al dilakukan dengan metode D-Gun untuk meningkatkan kekerasan material Stainless Steel AISI 316 L. Analisis parameter proses dilakukan dengan perangkat statistik ANOVA (Analysis of Variance) – Taguchi untuk memperoleh ukuran kristal, ketebalan dan tingkat kekerasan yang optimum. Lapisan paling tebal dimiliki oleh sampel SS03 sebesar 280 mikron, sedangkan sampel SS02 memiliki ketebalan paling rendah, 97 mikron. Ketebalan lapisan sangat dipengaruhi oleh laju a...

  7. Utilización del mineral de manganeso (pirolusita) en la producción de aceros al carbono

    OpenAIRE

    Aerles Batista-Cabrera; Efraín Navas-Medina

    2003-01-01

    Los métodos tradicionales de producción de acero utilizan el ferromanganeso para obtener el porcentaje de Mn en la marca establecida según la norma cubana, pero este compuesto es altamente costoso. Se ensayó, en la producción del Ac 35, sustituir el ferromanganeso por el mineral pirolusita (MnO2) con el fin de reducir los costos. Se evaluaron dos variantes de sustitución: la primera consiste en añadir el mineral con virutas de aluminio y coque (o residuos de electrodos) sobre la escoria del m...

  8. El valor de las emisiones de carbono asociadas al sistema agrícola de roza, tumba y quema

    NARCIS (Netherlands)

    Borrego, A.; Salinas Melgoza, M.A.; Skutsch, M.; Paz Pellat, F.; Wong Gonzalez, J.C.; Torres Alamilla, R.

    2015-01-01

    A large part of Mexico´s forests are degraded but present the opportunity for recuperation of carbon stocks through natural growth, once the drivers of degradation are removed. However, there are opportunity costs involved since most of the drivers are related to economic activities including shifti

  9. El valor de las emisiones de carbono asociadas al sistema agrícola de roza, tumba y quema

    OpenAIRE

    A. Borrego; Salinas Melgoza, M.A.; Skutsch, M.; Paz Pellat, F.; Wong Gonzalez, J.C.; Torres Alamilla, R.

    2015-01-01

    A large part of Mexico´s forests are degraded but present the opportunity for recuperation of carbon stocks through natural growth, once the drivers of degradation are removed. However, there are opportunity costs involved since most of the drivers are related to economic activities including shifting cultivation and cattle grazing. The study calculates the economic costs of sequestration of carbon in tropical dry forest (TDF) in western Mexico based on an analysis of such opportunity costs. ...

  10. Symptomatic nucleus of homeopathic remedies derived from carbon. Nucleo sintomático de los medicamentos homeopaticos derivados de carbono Núcleo sintomático dos medicamentos homeopáticos derivados do Carbono

    Directory of Open Access Journals (Sweden)

    Luciana Costa Lima Thomaz

    2009-03-01

    style="font-size:1.8em; font-weight:normal; line-height:1.35em; margin:0 1em 0.25em 0; padding-top:0.75em;"> Nucleo sintomático de los medicamentos homeopaticos derivados de carbono

    Resumen


    La praxis homeopática exige simultáneamente rapidez y precisión en el diagnóstico y prescripción del tratamiento en consultas en tiempo real. Por eso, diversas estrategias han sido buscadas para facilitar este proceso, incluyendo criterios para agrupar los medicamentos homeopáticos. El presente estudio se propuso establecer si clasificaciones basadas en la composición química de las sustancias utilizadas como base de los medicamentos homeopáticos tienen correlación con la materia médica homeopática experimental. Métodos: como estudio de caso, fueron seleccionados los medicamentos homeopáticos derivados de carbono; los síntomas experimentales de estos medicamentos fueron comparado de manera a definir un núcleo de síntomas común al grupo; este núcleo fue comparado a los correspondientes a los síntomas experimentales de los medicamentos homeopáticos derivados de azufre y fósforo, con el propósito de determinar la especificidad cualitativa del núcleo carbónico propuesto; finalmente, el núcleo propuesto fue comparado con el cuadro tradicional atribuido a la así llamada constitución carbónica homeopática, con el propósito de establecer si ésta última tiene fundamentos experimentales. Resultados: fue encontrado efectivamente un núcleo sintomático común a los medicamentos homeopáticos derivados de carbono, cualitativamente diferente de los núcleos sintomáticos de los medicamentos homeopáticos derivados de azufre y fósforo; no fue detectada correlación entre este núcleo y el cuadro clínico de la así llamada constitución carbónica.
  1. Effects of hydrogen charging methods on ductility and fracture characteristics of AISI 9840 steel

    Energy Technology Data Exchange (ETDEWEB)

    Biggiero, G.; Borruto, A.; Taraschi, I. [Rome Univ. (Italy). Ist. di Metallurgia e Metallografia

    1995-06-01

    Two different methods were used in the tests: the premature fracture method and the tensile test under hydrogen charging method, on AISI 9840 steel corrosion specimens. The aim of this work was to reveal the hydrogen effects on plastic deformation in tensile tests with or without simultaneous hydrogen charging. True stress-true strain curves have clearly shown the material`s different behaviour in the two tests: in the case of premature fracture tests, during plastic deformation, dislocations glide and allow hydrogen to escape and the material to partially regain its properties more rapidly; on the contrary, in the case of tensile tests under hydrogen charging, the interaction between the penetrating hydrogen and the Cottrell clouds (pre-existing hydrogen) slackens dislocation glide, so that plastic deformation is greatly reduced, as is shown both from the diagrams and the SEM analyses. (author)

  2. 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......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...... 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Surface effects induced by cathodic hydrogenation in type AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Cathodic hydrogen charging of type AISI 304 stainless steel modified its austenitic structure, giving rise to the formation of two new martensitic phases and the appearance of cracks, in most cases delayed. As electrolyte a 1 N H2 S O4 solution containing As2 O3 was employed. The cathodic hydrogenation was carries out at room temperature. The transformed phases were identified with black and white and coloured metallographic techniques, as well as by X-ray diffraction. The effect of cathodic hydrogenation in samples uniaxially tensile tested with constant nominal strain rate was investigated. It was concluded that the number of cracks per unit surface area changes with hydrogenation conditions and that hydrogen should be present for the embrittlement to occur. (author)

  8. Effect of Starch Binders in Alumina Coatings on Aisi 316 L Stainless Steel for Medical Application

    Science.gov (United States)

    Ghazali, M. J.; Pauzi, A. A.; Azhari, C. H.; Ghani, J. A.; Sulong, A. B.; Mustafa, R.

    A slurry immersion technique of alumina coatings was carried out on several AISI 316 L stainless steels using two types of binding agents; commercial starch and Sarawakian starch (sago), which were also mixed with polyvinylchloride (PVA) for strengthening purposes. The sintering temperatures in this work were varied from 500 to 1000°C. Prior to sintering process, all stainless steels were metallographically ground and polished to approximately 0.6 µm of average roughness. Detailed characterisations on the sintered specimens were carried out with the aid of the secondary electron microscopy (SEM), microhardness and a profilometer. The results revealed that coated steels using sago binder showed improved adhesion and homogenous microstructures with greater hardness of 2642 HV than those found in coated steel with commercial starch after sintering process.

  9. 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.

  10. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel

    Directory of Open Access Journals (Sweden)

    Ahmet Cakan

    2008-11-01

    Full Text Available Hard coatings such as titanium nitride (TiN and chromium nitride (CrN are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM, line scan analyses and X-ray diffraction (XRD. The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  11. An investigation of the aseptic loosening of an AISI 316L stainless steel hip prosthesis

    International Nuclear Information System (INIS)

    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.

  12. 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.

  13. Effect of rare earth oxide additions on oxidation behavior of AISI 304L stainless steel

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2006-12-01

    Full Text Available AISI 304L stainless steel powder compacts containing 2 vol% high purity rare earth oxides were prepared by mixing the different powders in a vibratory mill followed by pressing. The compacts thus obtained were sintered in a vacuum furnace and isothermal oxidation measurements were carried out in a muffle furnace, in air, up to 200 hours at 900 °C. The oxidized surfaces were examined in a scanning electron microscope and micro regions of the reaction products were studied using energy dispersive analysis. The addition of rare earth oxides decreased the oxidation rate of the stainless steel. Further evidence of predominant oxygen ion diffusion controlling the overall oxidation process in rare earth containing chromium oxide forming alloys has been observed.

  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. The effect of internal hydrogen on surface slip localisation on polycrystalline AISI 316L stainless steel

    International Nuclear Information System (INIS)

    A statistical analysis of the effect of internal hydrogen on the surface slip morphology of relatively high nickel content AISI 316L type austenitic stainless steel was carried out on high resolution data obtained by atomic force microscopy. Surface plastic strain localisation was studied for different hydrogen contents, two grain sizes, and two plastic strain levels. The height and spacing of approximately 8000 slip bands, observed on 12 specimens, are shown to follow log-normal distributions. Hydrogen increased the mean slip-band height and the mean slip-band spacing for the two macroscopic plastic strain levels considered, and for the two hydrogen concentrations in coarse-grained specimens. The hydrogen effect was also observed for fine-grained specimens, but only for the highest hydrogen concentration. In addition, the emerging dislocation velocity increased by a factor 3 for high hydrogen content.

  16. Effect of constraint on fracture behavior of welded 17mn4 and AISI304 steels

    International Nuclear Information System (INIS)

    In this study, 17Mn4 (P295GH) pressure vessels steel and AISI304 stainless steel were welded with ER309L austenitic consumable. In experimental part of the study, tensile tests were conducted on welded plates and variation of hardness values along specimen was measured. J-integral fracture toughness values were investigated for different crack locations. In order to determine the regions where plastic deformation did not take place due to constraint, uni-axial tensile test was performed on welded tensile specimen after attaching strain gauges. In numerical part of the study, finite element (FE) analyses were conducted by fixing 2-D models precracked on different locations by using ANSYS software. In these models, stress triaxiality and plastic deformation characteristics around crack tip were determined for each crack locations after stress and strain analyses. The limitation on the extension of plastic deformation at diffusion line causes extra increase in stress triaxiality at crack tip

  17. Application of radionuclide techniques on AISI 316 stainless steel wear measurements

    International Nuclear Information System (INIS)

    In the last years a wide development in the area of surfaces treatment was observed in order to reduce the wear phenomena in machine components, motors, tools. In this work, sheets of stainless AISI 316 with thickness of 12,5 μm, which simulates successive and equal cuts in a block, were irradiated with 9 MeV protons at the CV-28 cyclotron. The induced activity in each foil was measured with a Ge(Li) detector, and the variation of this activity, as function of irradiated depth, was followed. In this activation with protons nominated thin layer activation has some advantages when compared to neutron activation. In the case the activation of foils of stainless steel 316 the peaks related to 52 Mn, 56 Co, 57 Co and 58 Co were clearly discriminated in the spectrum and this fact is used to establish a calibration curve for wear measurements. (author)

  18. 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.

  19. 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.

  20. 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.

  1. The fracture toughness of Fe{sub 2}B formed on boronized AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    Topuz, Polat; Guendogdu, Emine; Yilamz, Eren; Guemues, Emre [Gedik Univ., Pendik Istanbul (Turkey). Gedik Vocational School

    2014-10-01

    In this study, the fracture toughness of Fe{sub 2}B boride layer on boronized AISI 304 stainless steel was investigated. Samples were boronized in an indirect heated fluidized bed furnace with Ekabor 1 trademark boronizing agent at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h, respectively. The boride phases were investigated by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indentation. With increasing boriding temperature and time the fracture toughness values were reduced. The boride layer thickness formed on the boronized samples ranged between 12 μm and 176 μm. The hardness of the borides ranged between 1709 HV{sub 0.1} and 2119 HV{sub 0.1} and fracture toughness was in the range of 2.19-4.47 MPa x m{sup 1/2} depending on the layer thickness and hardness.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Effect of Nitridation Time on the Surface Hardness of Medium Carbon Steels (AISI 1045)

    International Nuclear Information System (INIS)

    It has been investigated the effect of nitridation time on the surface hardness of medium carbon steels (AISI 1045). Parameters determining to the results were flow rate of the nitrogen gas, temperature and time. In this experiments, sample having diameter of 15 mm, thick 2 mm placed in tube of glass with diameter 35 mm heated 550 oC, flow rate and temperature were kept constants, 100 cc/minutes and 550 oC respectively, while the time were varied from 5, 10, 20 and 30 hours. It was found, that for the nitridation time of 5, 10, 20, and 30 hours, the surface hardness increased from 145 VHN to, 23.7, 296.8, 382.4 and 426.1 VHN, respectively. (author)

  7. 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.

  8. 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.

  9. Diffusion characteristics of plasma nitrided hard chromium on AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electronic Engineering Dept.; Kocabas, Mustafa; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey)

    2015-06-01

    In order to investigate the different Cr-N formation characteristics of plasma nitrided hard Cr coatings, Cr was electrodeposited on AISI 1010 steel and plasma nitrided at 600, 700 and 800 C for 3 h, 5 h and 7 h, respectively. Phase analyses of resulting Cr-N phases and grain size of Cr layer before and after nitriding process were calculated by X-ray diffraction analysis. Structure of nitride layer and its thickness were analyzed using scanning electron microscopy micrographs. The micrographs indicated that samples consisted of three distinctive layers. In order to distinguish these layers, scanning electron microscopy and energy dispersive spectroscopy (EDX) analysis were used as well as elemental distribution versus depth was plotted. The Cr-N diffusion was investigated by layer thickness measurements, and diffusion coefficient as well as activation energies were calculated.

  10. Effect of plasma nitriding time on surface properties of hard chromium electroplated AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Mustafa [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical and Materials Engineering Dept.; Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electrical and Electronic Engineering Dept.; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey); Uelker, Suekrue [Afyon Kocatepe Univ. (Turkey). Dept. of Mechanical Engineering

    2015-06-01

    Properties of steel can be enhanced by surface treatments such as coating. In some cases, further treatments such as nitriding can also be used in order to get even better results. In order to investigate the properties of nitride layer on hard Cr coated AISI 1010 steel, substrates were electroplated to form hard Cr coatings. Then hard Cr coatings were plasma nitrided at 700 C for 3 h, 5 h and 7 h and nitride phases on the coatings were investigated by X-ray diffraction analysis. The layer thickness and surface properties of nitride films were investigated by scanning electron microscopy. The hardness and adhesion properties of Cr-N phases were examined using nano indentation and Daimler-Benz Rockwell C adhesion tests. The highest measured hardness was 24.1 GPa and all the three samples exhibited poor adhesion.

  11. 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.

  12. 3DII implantation effect on corrosion properties of the AISI/SAE 1020 steel

    Energy Technology Data Exchange (ETDEWEB)

    Dulce M., H.J.; Rueda V., Alejandro [Universidad Francisco de Paula Santander, A.A. 1055, Cucuta (Colombia); Dougar-Jabon, Valeri [Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia)

    2005-08-01

    The three dimensional ion implantation technology (3DII) is one of the methods of improving the tribological characteristics and resistance to hydrogen embrittlement processes in metals. In this report, some results concerning the resistance effect of nitrogen ion implantation to oxidation of the sample, made of AISI/SAE 1020 steel, are given. The nitrogen ions were implanted in the discharge chamber of the JUPITER reactor. Both the treated and untreated samples were tested through potential-static measurements, which permitted to determine the corrosion current, the slopes that characterise the braking level of anode and cathode reactions. The polarization resistance near the corrosion potential is calculated. The results of the study encourage to consider the nitrogen ion implantation in high voltage and low pressure discharges as one of the methods of anticorrosive protection which do not change the geometric configuration of the treated steel pieces. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  16. Niveles de carbono orgánico total en el Suelo de Conservación del Distrito Federal, centro de México

    OpenAIRE

    Gilberto Vela Correa; Jorge López Blanco; María de Lourdes Rodríguez Gamiño

    2012-01-01

    El Suelo de Conservación (SC) del Distrito Federal es un reservorio de carbono, por lo que es importante contar con datos sobre su capacidad de almacenamiento bajo diferentes tipos de cobertura vegetal. En este trabajo se estimó el contenido de carbono orgánico total en suelos (COS) de áreas con cobertura de bosque, uso agrícola y en áreas reforestadas. Se delimitaron unidades geomorfogenéticas que sirvieron de base para el muestreo de suelos. En total se estudiaron 50 sitios con muestras ...

  17. A incorporação de calcário em sistema plantio direto consolidado reduz o estoque de carbono em macroagregados do solo

    OpenAIRE

    Renato Yagi; Jonez Fidalski; Cássio Antonio Tormena

    2014-01-01

    Estoques de carbono em macroagregados do solo possuem relação com a taxa de sequestro de C no solo em sistema plantio direto. Objetivou-se avaliar os estoques de carbono em macroagregados (12,5-19,0mm) em função do revolvimento ocasional e/ou da calagem de um Latossolo Vermelho Distroférrico típico textura muito argilosa, sob sistema plantio direto há 17 anos em Pato Branco, sudoeste do Paraná. A partir de outubro de 2009, foi avaliado um experimento em parcelas sub-subdivididas, tendo como p...

  18. El uso de las cubiertas verdes como reducción de la huella de carbono por absorción vegetal. Caso de Villaverde

    OpenAIRE

    Jorge Miguel Carretero Monteagudo

    2013-01-01

    ResumenEl tema de este trabajo es a grandes rasgos la comprobación de la eficacia de las cubiertas verdes en la reducción de la huella de carbono, centrándonos exclusivamente en las capacidades asimilativas del dióxido de carbono de la vegetación contenida sobre estas cubiertas. La presente comprobación de la eficacia de las cubiertas verdes, fue realizada sobre el contexto del distrito de Villaverde en la Periferia Sur de Madrid. Sobre este distrito, se analizaron diferentes factores en rela...

  19. Valoración económica del manglar por el almacenamiento de carbono, Ciénaga Grande de Santa Marta.

    OpenAIRE

    Arnold De la Peña; Cesar Augusto Rojas; Marlon De la Peña

    2010-01-01

    La Ciénaga Grande de Santa Marta (CGSM) genera diferentes bienes y servicios ambientales, por ejemplo, sumidero de carbono, hábitat de flora y fauna, despensa de alimentos y materias primas, entre otros. Se presenta una aproximación a la cuantificación monetaria del servicio de almacenamiento de carbono, con el fin de establecer información base para las decisiones de su uso. Lo anterior se hizo con base en muestreo de campo de 15 árboles de manglar y en mediciones realizadas en cuatro estaci...

  20. Oxidação electrocatalítica de hidratos de carbono utilizando complexos de metais de transição

    OpenAIRE

    Cunha, Paula Cristina Bastos Ferreira Leal

    2006-01-01

    Os hidratos de carbono podem ser convertidos em produtos químicos, energia, têxteis, materiais de construção, papel e muitos outros produtos industriais. Estes constituem uma matéria prima barata, renovável e facilmente disponível. No início dos anos noventa, 95% da biomassa produzida eram hidratos de carbono e correspondiam a duzentos biliões de toneladas. Nos dias de hoje, apenas 3 a 5% desta biomassa são utilizados em termos industriais. Os restantes sofrem degradação e são reciclado...

  1. Tecnologías de membranas para la recuperación de hidrógeno y monóxido de carbono de gases residuales

    OpenAIRE

    David, Oana Cristina

    2012-01-01

    RESUMEN: Esta tesis doctoral está enfocada hacia la separación y recuperación de hidrogeno y monóxido de carbono de efluentes gaseosos residuales procedentes de procesos industriales de combustión mediante la tecnología de membranas. Se ha definido como caso de estudio la corriente de gases generada en la fabricación de negro de carbono. Se espera que el uso de tecnologías de separación con membranas permita obtener en el lado del permeado de la membrana una corriente enriquecida en hidrógeno...

  2. Gestión ambiental empresarial: cálculo de la huella de carbono en la industria vitivinícola.

    OpenAIRE

    Rosa Ana Rodriguez; Adriana Belfort Martinez; Stella Maris Udaquiola

    2014-01-01

    La huella de carbono es un indicador ambiental que busca cuantificar la cantidad de emisiones de gases de efecto invernadero (GHG). Su medición se convierte en una herramienta que permite trabajar bajo el concepto de eco-eficiencia e identificar oportunidades de reducción de consumo energético, ya que este último es la principal fuente de emisión de GHG a nivel mundial. El presente trabajo aplica la metodología PAS 2050:2011 para la medición de la huella de carbono, en la producción del vino ...

  3. Experimental and numerical study on plasma nitriding of AISI P20 mold steel

    Science.gov (United States)

    Nayebpashaee, N.; Vafaeenezhad, H.; Kheirandish, Sh.; Soltanieh, M.

    2016-09-01

    In this study, plasma nitriding was used to fabricate a hard protective layer on AISI P20 steel, at three process temperatures (450°C, 500°C, and 550°C) and over a range of time periods (2.5, 5, 7.5, and 10 h), and at a fixed gas N2:H2 ratio of 75vol%:25vol%. The morphology of samples was studied using optical microscopy and scanning electron microscopy, and the formed phase of each sample was determined by X-ray diffraction. The elemental depth profile was measured by energy dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and glow dispersive spectroscopy. The hardness profile of the samples was identified, and the microhardness profile from the surface to the sample center was recorded. The results show that ɛ-nitride is the dominant species after carrying out plasma nitriding in all strategies and that the plasma nitriding process improves the hardness up to more than three times. It is found that as the time and temperature of the process increase, the hardness and hardness depth of the diffusion zone considerably increase. Furthermore, artificial neural networks were used to predict the effects of operational parameters on the mechanical properties of plastic mold steel. The plasma temperature, running time of imposition, and target distance to the sample surface were all used as network inputs; Vickers hardness measurements were given as the output of the model. The model accurately reproduced the experimental outcomes under different operational conditions; therefore, it can be used in the effective simulation of the plasma nitriding process in AISI P20 steel.

  4. Dislocation structure evolution and its effects on cyclic deformation response of AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Research highlights: → The cyclic deformation response of AISI 316L steel is investigated at 20 deg. C. → The corresponding microstructure evolution is characterised by electron microscopy. → A 3D representation of dislocation evolution is proposed based on the observation. → The 3D representation gives a good explanation of the microstructure complexity. → The cyclic deformation response is discussed based on the microstructure evolution. - Abstract: The cyclic deformation response of an austenitic stainless steel is characterised in terms of its cyclic peak tensile stress properties by three stages of behaviour: a hardening stage followed by a softening stage, and finally a stable stress response stage. A series of tests have been performed and interrupted at selected numbers of cycles in the different stages of mechanical response. At each interruption point, specimens have been examined by transmission electron microscopy (TEM) with different beam directions by means of the tilting function in order to investigate the formation and the development of dislocation structures from the as-received condition until the end of fatigue life. A new 3D representation of dislocation structure evolution during cyclic loading is proposed on the basis of the microstructural observations. The 3D representation provides a deeper insight into the development of dislocation structures in AISI 316L during low cycle fatigue loading at room temperature. By investigating the dislocation evolution, the study shows that the hardening response is mainly associated with an increase of total dislocation density, whereas the softening stage is a result of the formation of dislocation-free regions. Further development of the dislocation structure into a cellular structure is responsible for the stable stress response stage.

  5. 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)

  6. 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.

  7. Ensayo balístico de laminados de fibra de carbono y núcleo de Honeycomb

    OpenAIRE

    Armero Presa, Fernando

    2013-01-01

    Las estructuras sándwich son cada vez más utilizadas y están adquiriendo una gran importancia por sus particulares características de ligereza y alta resistencia. Este Proyecto Fin de Carrera se centra en el comportamiento de laminados de fibra de carbono con núcleo de honeycomb frente a impactos de alta velocidad, con el fin de estudiar la influencia del núcleo en estos casos, y obtener unas dimensiones óptimas de éste para alcanzar la mejor relación entre el peso del panel sá...

  8. Distribuição dos agregados e carbono orgânico influenciados por manejos agroecológicos.

    OpenAIRE

    Loss, Arcângelo; Pereira, Marcos Gervasio; Schultz, Nivaldo; Ferreira, Edilene Pereira; Silva, Eliane Maria Ribeiro da; Beutler, Sidinei Julio

    2009-01-01

    O objetivo deste estudo foi verificar a influência do manejo agroecológico na distribuição dos agregados estáveis em água e no teor de carbono orgânico dos agregados em diferentes coberturas vegetais. Foram selecionadas cinco áreas, a saber: sistema agroflorestal; cultivo de figo (Ficus carica L.); consórcio maracujá (Passiflora edulis S.)–Desmodium sp.; cultivo de feijão (Phaseolus vulgaris L.), em manejo convencional, e cultivo de milho (Zea mays L.), em plantio direto. Em cada área, foram ...

  9. Existencias y tasas de incremento neto de la biomasa y del carbono en bosques primarios y secundarios de Colombia

    OpenAIRE

    Orrego Suaza, Sergio Alonso; Del Valle Arango, Jorge Ignacio

    2002-01-01

    En 33 parcelas permanentes de 1000 m2 (0,1 ha) en bosques primarios y 77 parcelas permanentes de 500 m (0,05 ha) en bosques secundarios, para un área de muestreo de 7,15 ha, se estimaron las existencias de biomasa y del carbono almacenado en los siguientes compartimientos: biomasa aérea, necromasa, biomasa subterránea y suelo. La biomasa aérea total viva en los bosques primarios promedió 246,542 t/ha, representada 92,42% por árboles y arbustos dicotiledóneos, 5,93% en palmas (3,58% la pa...

  10. OPORTUNIDADES DO MERCADO DE CRÉDITO DE CARBONO PARA USINAS SUCROALCOOLEIRAS DO BRASIL

    Directory of Open Access Journals (Sweden)

    RODRIGUES, Elaine Miranda

    2009-04-01

    Full Text Available Because of production and competitiveness in industry and technology, the global climate is in constant change, involving important discussions about this issue, for example, the increaseof carbon dioxide released into the atmosphere by industrially countries. The questions have as objective to revert the situation, involving some steps and processes that demonstrate the importance of this discussion as an current model of sustainable use of nature. From these negotiations that Kyoto’s Protocol was created, generating new income resources. The general objective of this paper was to investigate, by literature, what opportunities are been created to the firms, specially of cane sugar cultivation – animportant segment to invest cause of the energy co-generation projects – with the purpose to reduce the environmental damage and increase the incomes, by the concept of Clean DevelopmentMechanism. After an important process of interviews we can conclude that there are opportunities to the firms of cane sugar process and cultivation, because of the national and international demand by clean energy use.Com o aumento da produção e competitividade no ramo industrial e tecnológico, o climado planeta vem passando por constantes transformações, envolvendo sérias discussões sobre o assunto, aexemplo disso, o aumento de gás carbônico lançado na atmosfera por países mais industrializados. Oquestionamento tem como relevância reverter à situação em que se encontra o mundo, envolvendoalgumas das etapas que demonstram a importância do assunto no modelo atual de consumo sustentável danatureza. E a partir de negociações como essas é que se deu a origem do Protocolo de Kyoto em 1997 noJapão, que estipula metas de redução das emissões de poluição para países mais desenvolvidos, ofertandoassim a possibilidade de países em desenvolvimento comercializarem emissões no Mercado de Crédito deCarbono, gerando uma nova fonte de renda. O

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Sistema de seguridad para elaborar nanopartículas de carbono a escala de laboratorio

    Directory of Open Access Journals (Sweden)

    Dania Soguero González

    2012-08-01

    Full Text Available Las nanopartículas de carbono (NPC han sido de las más utilizadas, debido a sus propiedades. Muchas de estas propiedades que hacen tan útil a las NPC también pueden hacerlas tóxicas para las células y el organismo y por lo tanto deben ser manipuladas con precaución. El Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN está desarrollando un programa de investigación que incluye la síntesis NPC usando el método de descarga de arco sumergida en agua. En este trabajo se describe el sistema de nanoseguridad implementado en los laboratorios del CEADEN para el desarrollo de las mejores prácticas con NPC. Dicho sistema se construyó sobre la base de un análisis de seguridad. Se usó el método ¿Qué pasa si? y un procedimiento que emplea un árbol de decisiones que permite clasificar los laboratorios en clases de acuerdo a niveles de peligrosidad. Se identificaron los peligros de importancia significativa. Para la estimación del riesgo de estas se construyó una matriz Probabilidad/Consecuencia, donde se reflejó el riesgo asociado a cada uno de los eventos analizados y se clasificó en las categorías de alto, medio y bajo riesgo. Finalmente, se procedió a implementar las medidas de protección personal, técnicas y organizativas definidas a partir del análisis de riesgo efectuado en forma de procedimientos.

  13. 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.

  14. 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

    Directory of Open Access Journals (Sweden)

    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.

  15. 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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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

  17. Fluxos de carbono na Amazônia e no Cerrado: um olhar socioecossistêmico Carbon flows in the Amazon and Cerrado biomes: a socioecosystemic view

    Directory of Open Access Journals (Sweden)

    Donald Sawyer

    2009-04-01

    Full Text Available Grande parte das análises de questões ambientais utiliza ferramentas das ciências naturais de forma isolada, com pouca integração mesmo entre estas ciências. As mudanças climáticas, questão nacional e internacional cada vez mais urgente, talvez sejam a questão ambiental mais distante das ciências sociais. Apesar de algumas tentativas de incluir nos estudos sobre ela as dimensões humanas ou socioeconômicas, as mudanças climáticas são tratadas principalmente por climatólogos, metereólogos e ecólogos, em termos de processos biofísicos. A abordagem utilizada aqui para focar fluxos de carbono nos dois maiores biomas brasileiros é socioecossistêmica, ou seja, uma abordagem integrada abrangendo amplos processos sociais, ecológicos e econômicos, em vez de enfoques pontuais ou setoriais. Além desta busca de interdisciplinaridade, a abordagem adotada considera o contexto nacional e global, em termos espaciais, e os processos históricos, em termos temporais, contemplando o passado e olhando para o futuro. Inicialmente, apresenta-se uma quantificação preliminar das emissões e do seqüestro de carbono nos biomas Amazônia e Cerrado, mostrando a importância pouco conhecida do Cerrado. Em seguida, são identificados os diversos impactos socioeconômicos e ambientais das dinâmicas em curso, chamando-se a atenção para suas interações e seus efeitos interregionais. Finalmente, apresentam-se propostas referentes a prioridades para pesquisa e políticas públicas que decorrem da análise socioecossistêmica.Most analyses of environmental issues use natural sciences in isolation, with little integration even among these sciences. Climate change, a national and international issue which is increasingly urgent, may be the environmental issue farthest removed from the social sciences. In spite of some attempts to include human dimensions or socioeconomic analysis, climate changes are usually dealt with by climatologists

  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. Analysis of a premature failure of welded AISI316L stainless steel pipes originated by microbial induced corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Otero, E.; Bastidas, J.M.; Lopez, V. [Centro Nacional de Investigaciones Metalurgicas, Madrid (Spain)

    1997-07-01

    This paper analyses the causes of the premature failure of welded AISI 316L stainless steel (ss) pipes which formed part of a sea water cooling circuit. The service time of the pipes was 8 months. The laboratory tests carried out consisted of metallography tests, {delta}-ferrite determination, intergranular corrosion susceptibility, cyclic anodic polarization curves, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photo-electron spectroscopy (XPS). The study presents typical forms of microbial induced corrosion (MIC) in AISI 308L and 316L ss in contact with natural sea water. The research is completed with the performance of bacteriological tests which demonstrate that the bacteria which cause the localized corrosion are of the sulphate-reducing genus ``desulfovibrio`` and the sulphide-oxidizing genus ``thiocapsa``. (orig.) 17 refs.

  20. 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.

  1. Study the influence of a new ball burnishing technique on the surface roughness of AISI 1018 low carbon steel

    Directory of Open Access Journals (Sweden)

    Abd Alkader Ibrahim

    2015-02-01

    Full Text Available Hard roller burnishing with a ball tool is a surface-finishing where a free-rotating tool rolls over the machined surface under high pressures and flattens the surface roughness peaks by cold work. In the present work, a new burnishing technique has been applied which enables both single and double ball burnishing process in site after turning without releasing the specimen. Sets of experiments are conducted to investigate the influence of burnishing force, feed, speed and number of tool passes on surface roughness of AISI 1018 Low Carbon Steel specimens. Burnishing results showed significant effectiveness of the new burnishing technique in the process. The results revealed that minimum surface roughness are obtained by applying the double ball burnishing process on AISI 1018 Low Carbon Steel specimens. Improvement in surface finish can be achieved in both single and double ball burnishing by increasing the number of burnishing tool passes. The results are presented in this paper.

  2. 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.

  3. 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.

  4. 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.

  5. Mathematical Modelling of Nitride Layer Growth of Low Temperature Gas and Plasma Nitriding of AISI 316L

    Directory of Open Access Journals (Sweden)

    Triwiyanto A.

    2014-07-01

    Full Text Available This paper present mathematical model which developed to predict the nitrided layer thickness (case depth of gas nitrided and plasma nitrided austenitic stainless steel according to Fick’s first law for pure iron by adapting and manipulating the Hosseini’s model to fit the diffusion mechanism where nitrided structure formed by nitrided AISI 316L austenitic stainless steel. The mathematical model later tested against various actual gas nitriding and plasma nitriding experimental results with varying nitriding temperature and nitriding duration to see whether the model managed to successfully predict the nitrided layer thickness. This model predicted the coexistence of ε-Fe2-3N and γ΄-Fe4N under the present nitriding process parameters. After the validation process, it is proven that the mathematical model managed to predict the nitrided layer growth of the gas nitrided and plasma nitrided of AISI 316L SS up to high degree of accuracy.

  6. Modifications on the behaviour of AISI 304 stainless steel submitted to creep caused by intermediate treatment of annealing

    International Nuclear Information System (INIS)

    Type AISI 304 austenitic stainless steel samples which have been previously creep deformed at 7500C, were annealed at 11000C. The effects of this heat treatment in the mechanical behavior of this material when retested in creep were investigated. The results were analysed by taking into account the structural modifications observed and the controlling mechanisms which operate during the deformation and fracture occurring in the creep process. (Author)

  7. In-situ investigation of martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature

    OpenAIRE

    Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen; Somers, Marcel A. J.

    2013-01-01

    Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature of the martensitic transformation. The kinetics of the transformation is interpreted in terms of a-thermal nucleation and thermally activated growth of lenticular martensite.

  8. Electrochemical deposition of black nickel solar absorber coatings on stainless steel AISI316L for thermal solar cells

    OpenAIRE

    Lira-Cantú, Monica; Morales Sabio, Angel; Brustenga, Alex; Gómez-Romero, P.

    2005-01-01

    We report the electrochemical deposition of nanostructured nickel-based solar absorber coatings on stainless steel AISI type 316L. A sol–gel silica-based antireflection coating, from TEOS, was also applied to the solar surface by the dip-coating method. We report our initial results and analyze the influence of the stainless steel substrate on the final total reflectance properties of the solar absorber. The relation between surface morphology, observed by SEM and AFM, the comp...

  9. Quantifying Cutting and Wearing Behaviors of TiN- and CrN-Coated AISI 1070 Steel

    OpenAIRE

    Ahmet Cakan; Yildirim, Mustafa M.; Vedat Ozkaner

    2008-01-01

    Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscop...

  10. Microstructure and Mechanical Properties of Laser Clad and Post-cladding Tempered AISI H13 Tool Steel

    Science.gov (United States)

    Telasang, Gururaj; Dutta Majumdar, Jyotsna; Wasekar, Nitin; Padmanabham, G.; Manna, Indranil

    2015-05-01

    This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 tool steel substrate following laser cladding with AISI H13 tool steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 °C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 tool steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 × 10-3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 ± 15 MPa, which reduces to 580 ± 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 tool steel.

  11. Kajian Sub – Permukaan Baja Paduan Kekerasan Tinggi AISI 4140 Hasil Pembubutan Laju Tinggi Dan Kering Menggunakan Pahat CBN

    OpenAIRE

    Siahaan, Enzo Wiranta Battra

    2012-01-01

    The integrity of the sub - surface plays an important role in product quality. In this study, the impact of rate cuts, feed motion, depth of cut, cutting tool wear and tear on the sub - surface machining of steel AISI 4140 on the end for high speed machining, hard machining and dry machining studied experimentally using CBN cutting tool material. Four test parameters with three levels of cutting speed is low, medium and high. Conducted the data analysis of quantitative and qualitative. Quanti...

  12. 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...... with any of the investigated carbides, that carbon has a strong affinity for chromium, i.e. short range order, and that carbon is in solid solution....

  13. DESCRIPCIÓN DE LA DINÁMICA DE CARBONO EN SUELOS FORESTALES MEDIANTE UN MODELO DE RESERVORIOS

    Directory of Open Access Journals (Sweden)

    Gustavo Orellana-Rivadeneyra

    2012-01-01

    Full Text Available Se propone una aproximación sobre variables medioambientales mediante funciones de distribución dependientes del tiempo para simplificar un modelo de la dinámica del carbono orgánico en el suelo. El modelo se basa en el concepto de reservorios, que supone que los diferentes estados de la materia orgánica del suelo constituyen masas homogéneas. Este modelo se enfoca en el intercambio de materia orgánica entre dichas masas, estableciendo relaciones de contacto. Usando el modelo simplificado se calculó la acumulación de materia orgánica en el suelo y la emisión de CO2 desde un ecosistema de bosque de pino (Pinus elliottii ubicado en Gainesville, Florida, EU. Se verificó la viabilidad de las aproximaciones en el modelo para estudiar la dinámica del carbono orgánico en suelos forestales. Se calculó la acumulación relativa de materia orgánica en el suelo. Con esto se obtuvo una estimación de la actividad del bosque de P. elliottii como secuestrador.

  14. Influencia del carbono y el cromo en el comportamiento tribológico de aleaciones férreas

    Directory of Open Access Journals (Sweden)

    García, A.

    2005-12-01

    Full Text Available This study compares the abrasive wear resistance of a carbon steel, used in the linings of coal mills, and ferrous alloys with different chromium and carbon content. It also analyses the influence of chromium and carbon content on mechanical properties, such as hardness, and microstructure. The abrasive wear resistance of the different materials was determined by means of ASTM G 105, "Standard Test Method for Conducting Wet Sand/Rubber Wheel Abrasion Test". A blasting test was used to study erosive wear resistance.

    En este estudio se analiza la influencia, en las propiedades tribológicas, del contenido en carbono para distintas aleaciones férreas con similares contenidos en cromo, así como la influencia del cromo cuando el contenido en carbono es semejante. También, se analizó la influencia de estos elementos en propiedades como la dureza y en la microestructura de las aleaciones. Para el estudio tribológico se llevaron a cabo dos ensayos, el ensayo descrito en la norma ASTM G105: Standard Test Method for Conducting Wet Sand/Rubber Wheel Abrasion Test y ensayos de chorreo.

  15. Plasma nitriding process by direct current glow discharge at low temperature increasing the thermal diffusivity of AISI 304 stainless steel

    International Nuclear Information System (INIS)

    This work reports for the first time on the use of the open photoacoustic cell technique operating at very low frequencies and at room temperature to experimentally determine the thermal diffusivity parameter of commercial AISI304 stainless steel and AISI304 stainless steel nitrided samples. Complementary measurements of X-ray diffraction and scanning electron microscopy were also performed. The results show that in standard AISI 304 stainless steel samples the thermal diffusivity is (4.0 ± 0.3) × 10−6 m2/s. After the nitriding process, the thermal diffusivity increases to the value (7.1 ± 0.5) × 10−6 m2/s. The results are being associated to the diffusion process of nitrogen into the surface of the sample. Carrying out subsequent thermal treatment at 500 °C, the thermal diffusivity increases up to (12.0 ± 2) × 10−6 m2/s. Now the observed growing in the thermal diffusivity must be related to the change in the phases contained in the nitrided layer.

  16. Joining of Dissimilar alloy Sheets (Al 6063&AISI 304) during Resistance Spot Welding Process: A Feasibility Study for Automotive industry

    OpenAIRE

    Reddy Sreenivasulu

    2014-01-01

    Present design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to achieve higher fuel efficiency and to bring down vehicle emission. Although some other joining techniques are more and more being used, spot welding still remains the primary joining method in automobile manufacturing so far. Spot welds for automotive applications should have a sufficiently large diameter, so that nugget pullout mode is the dominant failure mode. Interfacial ...

  17. Almacenes y flujos de carbono en ecosistemas áridos y semiáridos de México: síntesis y perspectivas

    Directory of Open Access Journals (Sweden)

    Noé Manuel Montaño

    2016-03-01

    Full Text Available Los ecosistemas áridos y semiáridos constituyen un tercio de la superficie terrestre global y un 60% del territorio mexicano, pero poco se sabe sobre su importancia en el ciclo del carbono (C. Este trabajo sintetiza y analiza la información disponible sobre almacenes, flujos y controles de la dinámica del C en las regiones áridas y semiáridas de México. En estos ecosistemas, la productividad neta del ecosistema, la respiración del suelo, la producción y la descomposición de la hojarasca están determinadas por la variabilidad de la precipitación, aunque la descomposición depende también de la radiación solar y temperatura. El suelo es el principal almacén de C, representa 45 y 90% del C en la biomasa del matorral y pastizal, respectivamente. Las regiones semiáridas podrían almacenar más C orgánico e inorgánico que las regiones áridas. El cambio de uso de suelo disminuye hasta en 50% el C orgánico del suelo (COS, pero las especies vegetales formadoras de islas de fertilidad y de recursos amortiguan el impacto de la perturbación en el almacenamiento del C, al actuar como “hotspots” de conservación y trasformación del COS. Las biocostras también controlan la acumulación del COS, debido a su rápida respuesta a la humedad que potencia los flujos del C y la transformación de los nutrimentos en el suelo. El COS controla la estequiometría microbiana que regula la disponibilidad de otros nutrimentos en el suelo. La información sobre la dinámica del C para las regiones áridas y semiáridas de México es aún escasa y fragmentada, ya que la mayoría se limita al COS, en los primeros 30 cm del perfil, sin considerar el C inorgánico del suelo. En consecuencia, es necesario y urgente estandarizar metodologías para cuantificar los almacenes y flujos a diferentes escalas espacio-temporales en los ecosistemas áridos y semiáridos del país.

  18. Comportamiento a fractura de dos aceros de ultraalto contenido en carbono

    Directory of Open Access Journals (Sweden)

    Fernández-Vicente, A.

    2001-04-01

    Full Text Available Two ultrahigh carbon steels containing 1.3 and 1.5 pet carbon have been tested for their plane-strain (Chevron-notch fracture toughness using Barker tests. The microstructure of these two materials consisted of fine carbides dispersed in a ferrite matrix. Fracture toughness of UHC-1.3 C was twice that of UHC-1.5 C. This result can be readily explained by means of the difference in size of the carbide particles found in each microstructure. The crack growth mechanism consisted of ductile tearing at the notch tip region followed by nucleation of a brittle crack at carbides. Crack propagation in the UHC-1.3 C specimen occurred unstably and smooth crack growth behavior was observed in UHC-1.5 C. The difference in crack growth behavior was attributed to the elastic energy stored in the grips, which was higher for the UHC-1.3 C test than for the UHC-1.5 C test.

    Se ha analizado la tenacidad a la fractura de dos aceros de ultraalto contenido en carbono, UAC, conteniendo 1,3% C y 1,5% C, los cuales poseían una microestructura de carburos esferoidales finos en una matriz de ferrita. Se ha empleado el ensayo Barker para determinar el comportamiento a fractura. La tenacidad obtenida en el acero UAC-1,3 C fue doble que la del acero UAC-1,5 C. Esto se explica a partir del tamaño de los carburos presentes en cada microestructura. El mecanismo de fractura en ambos aceros consiste, inicialmente, en desgarramiento dúctil de la zona de la punta de la entalla seguido de propagación frágil de una grieta nucleada en los carburos. La propagación de la grieta en el acero UAC-1,5 C se produjo de manera estable, mientras que en el acero UAC-1,3 C la grieta se propagó catastróficamente. La diferencia de comportamientos en el crecimiento de la grieta se atribuye a la mayor energía elástica acumulada por la mordaza para el acero UAC-1,3 C que para el acero UAC-1,5 C.

  19. UTILIZAÇÃO DE LODO ANAERÓBIO COMO FONTE EXTERNA DE CARBONO NO PROCESSO DE DESNITRIFICAÇÃO DE ÁGUAS RESIDUÁRIAS

    Directory of Open Access Journals (Sweden)

    José Tavares de Sousa

    1999-04-01

    Full Text Available RESUMO O processo de desnitrificação reduz, de forma geral, nitrato a nitrogênio molecular; essa redução acontece associada ao ganho de elétrons. Na desnitrificação, as bactérias heterotróficas utilizam carbono orgânico como fonte doadora de elétrons. No caso de esgotos sanitários já tratados (tratamento secundário e como estes não dispõem de carbono orgânico suficiente exigem, portanto, uma fonte externa de carbono orgânico. Assim sendo, o objetivo desta pesquisa foi avaliar o potencial de desnitrificação de uma coluna preenchida com lodo anaeróbio sem o uso de outra fonte externa de carbono; esta coluna foi carregada pelo topo superior com lodo e, por meio de bomba peristáltica, o afluente nitrificado alimentava a coluna em fluxo ascendente. Durante 30 semanas de operação, a eficiência de remoção na coluna de desnitrificação permaneceu em torno de 72%, o lodo anaróbio se comportou como fonte externa de carbono adequada para o processo e a maior eficiência de remoção de nitrato ocorreu quando a coluna foi operada com maior concentração de sólidos suspenso voláteis (SSV; portanto, a eficiência de remoção de nitrato é função da concentração de SSV e, consequentemente, da masssa de lodo na coluna.

  20. Aplicação da técnica de ruído eletroquímico no estudo da corrosão do aço carbono em meio de bicarbonato de sódio saturado com dióxido de carbono

    OpenAIRE

    Klok, Simone Maria

    2013-01-01

    Resumo: O atual cenário da indústria petroquímica passou a envolver a perfuração de poços em condições de alta pressão e temperatura. Os campos de exploração de petróleo na camada pré-sal representam um desafio operacional, pois possuem elevada concentração de Dióxido de Carbono - CO2. O CO2 reage com a água e forma o ácido carbônico - H2CO3 que é corrosivo ao aço carbono. A corrosão por dióxido de carbono é um dos tipos de ataques mais encontrados na produção de óleo e gás e a maior parte da...

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

    Directory of Open Access Journals (Sweden)

    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.

  2. 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.

  3. 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

    OpenAIRE

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

    2012-01-01

    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 ...

  4. Susceptibility to stress corrosion in stainless steels type AISI 321 and 12X18H10T used in PWR type reactors (WWER)

    International Nuclear Information System (INIS)

    Titanium stabilized stainless steels have been utilized in sovietic pressurized water reactors (VVER) for avoid the susceptibility to Intergranular Corrosion (IGC) present in other austenitic stainless steels. However the Intergranular Corrosion resistance of this kind of materials has been questioned because of Intergranular Stress Corrosion Cracking failures (IGSCC) have been reported. This paper study the electrochemical behavior of the AISI 321 stainless steel in a H3BO3 Solution contaminated with chlorides and its susceptibility to Intergranular Corrosion.Electrochemical prediction diagrams of the stainless steels AISI 321 and 12X18H10T (sovietic) sensitized (600 Centigrade, 3 h.) were compared. Cylindrical and conical samples were used in Slow Strain Rate Tests (SSRT), to determine the susceptibility to Stress Corrosion Cracking (SCC) in AISI 321 and 12X18H10T stainless steels. The results obtained showed that the temperature of the solution is a very important factor to detect this susceptibility. Fractography studies on the fracture surfaces of the samples obtained in the SSRT at high temperature were realized. Corrosion velocities of both AISI 321 and 12X18H10T stainless steels were determined using conical samples in the CERT system at high temperature. E.D.A.X. analysis was employed in both AISI 321 and 12X18H10T stainless steels in order to explain the degree of sensitization. (Author)

  5. Simultaneous enhancement of strength and ductility in cryogenically treated AISI D2 tool steel

    International Nuclear Information System (INIS)

    In this research, the effect of cryogenic treatment on microstructural evolution and mechanical properties enhancement of AISI D2 tool steel was investigated. Cryogenic treatment down to liquid nitrogen temperature (77 K) was added to the conventional heat treatment between hardening and tempering steps. Electron microscopy investigation showed higher volume fraction of fine carbides with average diameter below 1 μm indicating effective retardation in carbide coarsening process as a results of cryogenic treatment. A modification in types of carbides was also observed after cryogenic treatment. X-ray diffraction diagrams revealed transformation of retained austenite to martensite at cryogenic temperature. Weakening or removal of carbides peak in the X-ray diagram was considered as evidence of carbides different behavior at cryogenic temperature. Mechanical testing results indicated higher ultimate tensile strength, better ductility, and higher elastic modulus after cryogenic treatment. Analysis of stress–strain diagrams revealed different strain hardening behavior for cryogenically treated alloy when compared to the conventionally heat treated one. Fractography results confirmed strain hardening behavior and showed cleavage fracture for conventionally treated alloy but mixed cleavage–ductile fracture mode for cryogenically treated alloy. The improved mechanical properties after cryogenic treatment are interpreted in terms of the influence of higher volume fraction and uniform distribution of fine carbides in reducing the average active dislocations length and enhancement of the flow stress at any given plastic strain

  6. Effect of V Notch Shape on Fatigue Life in Steel Beam Made of AISI 1037

    Directory of Open Access Journals (Sweden)

    Qasim Bader

    2014-04-01

    Full Text Available The present work encompasses effect of V notch shape with various geometries and dimensions on fatigue life behavior in steel beam made of Medium Carbon Steel AISI 1037 which has a wide application in industry. Fatigue life of notched specimens is calculated using the fatigue life obtained from the experiments for smooth specimens (reference and by use Numerical method (FEA.The fatigue experiments were carried out at room temperature, applying a fully reversed cyclic load with the frequency of (50Hz and mean stress equal to zero (R= -1, on a cantilever rotating-bending fatigue testing machine. The stress ratio was kept constant throughout the experiment. Different instruments have been used in this investigation like Chemical composition analyzer type (Spectromax ,Tensile universal testing machine type (WDW-100E ,Hardness tester type (HSV- 1000 , Fatigue testing machine model Gunt WP 140, Optical Light Microscope (OLM and Scanning Electron Microscope (SEM were employed to examine the fracture features . The results show that there is acceptable error between experimental and numerical works .

  7. Selective laser melting of Fe-Ni-Cr layer on AISI H13 tool steel

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

    An attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel was performed with selective laser melting. Fe-Ni-Cr coating was produced by experimental facilities consisting of a 200 W fiber laser which can be focused to 80 μm and atmospheric chamber which can control atmospheric pressure with N2 or Ar. Coating layer was fabricated with various process parameters such as laser power, scan rate and fill spacing. Surface quality and coating thickness were measured and analyzed. Three different surface patterns, such as typeⅠ, typeⅡand type Ⅲ, are shown with various test conditions and smooth regular pattern is obtained under the conditions as 10 μm of fill spacing, 50-350 mm/s of scan rate and 40 μm of fill spacing, 10-150 mm/s of scan rate. The maximum coating thickness is increased with power elevation or scan rate drop, and average thickness of 10 μm fill spacing is lower than that of 40 μm fill spacing.

  8. Parametric optimization during machining of AISI 304 Austenitic Stainless Steel using CVD coated DURATOMIC cutting insert

    Directory of Open Access Journals (Sweden)

    M. Kaladhar

    2012-08-01

    Full Text Available In this work, Taguchi method is applied to determine the optimum process parameters for turning of AISI 304 austenitic stainless steel on CNC lathe. A Chemical vapour deposition (CVD coated cemented carbide cutting insert is used which is produced by DuratomicTM technology of 0.4 and 0.8 mm nose radii. The tests are conducted at four levels of Cutting speed, feed and depth of cut. The influence of these parameters are investigated on the surface roughness and material removal rate (MRR. The Analysis Of Variance (ANOVA is also used to analyze the influence of cutting parameters during machining. The results revealed that cutting speed significantly (46.05% affected the machined surface roughness values followed by nose radius (23.7%. The influence of the depth of cut (61.31% in affecting material removal rate (MRR is significantly large. The cutting speed (20.40% is the next significant factor. Optimal range and optimal level of parameters are also predicted for responses.

  9. Influence of gas pressure and substrate temperature on PIII nitrocarburizing process of AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Rahman, A.M. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt) and Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany)]. E-mail: ahmedphys96@hotmail.com; El-Hossary, F.M. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt); Negm, N.Z. [Physics Department, Faculty of Science, South Valley University, Sohag Branch, Sohag (Egypt); Prokert, F. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany); Richter, E. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany); Moeller, W. [Institute of Ion Beam Physics and Material Research, FWII, Forschungszentrum Rossendorf, 01314 Dresden (Germany)

    2004-12-01

    Plasma immersion ion implantation (PIII) has been used to modify the surface properties of 304 austenitic stainless steel (AISI). The influence of working gas pressure, 0.2-1.0 Pa, and substrate temperature, 300-500 deg. C, on the microstructure, treating rate, nitrogen/carbon concentration depth profile, and surface microhardness was investigated. A gas composition of 25% C{sub 2}H{sub 2}, 75% N{sub 2}, r.f. plasma power input of 350 W, and a negatively biased potential of 30 kV were fixed during the experiment. The experimental results show that the substrate temperature and the diffusion process of nitrogen and carbon depend on the gas pressure inside the plasma chamber. The thickness of the modified layer has been found to be more than 30 {mu}m for samples were treated in the plasma for 60 min. The results show also that the values of diffusion coefficient and surface microhardness of the treated samples are high to be 3.4 x 10{sup -1} {mu}m{sup 2}/s and 1880 kg/mm{sup 2}, respectively.

  10. Influence of gas pressure and substrate temperature on PIII nitrocarburizing process of AISI 304 stainless steel

    Science.gov (United States)

    Abd El-Rahman, A. M.; El-Hossary, F. M.; Negm, N. Z.; Prokert, F.; Richter, E.; Möller, W.

    2004-12-01

    Plasma immersion ion implantation (PIII) has been used to modify the surface properties of 304 austenitic stainless steel (AISI). The influence of working gas pressure, 0.2-1.0 Pa, and substrate temperature, 300-500 °C, on the microstructure, treating rate, nitrogen/carbon concentration depth profile, and surface microhardness was investigated. A gas composition of 25% C2H2, 75% N2, r.f. plasma power input of 350 W, and a negatively biased potential of 30 kV were fixed during the experiment. The experimental results show that the substrate temperature and the diffusion process of nitrogen and carbon depend on the gas pressure inside the plasma chamber. The thickness of the modified layer has been found to be more than 30 μm for samples were treated in the plasma for 60 min. The results show also that the values of diffusion coefficient and surface microhardness of the treated samples are high to be 3.4 × 10-1 μm2/s and 1880 kg/mm2, respectively.

  11. Nitrocarburizing of AISI-304 stainless steel using high-voltage plasma immersion ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Rahman, A.M. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt)], E-mail: ahmedphys96@hotmail.com; Mohamed, S.H.; Ahmed, M.R. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); Richter, E.; Prokert, F. [Institut fuer Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden Rossendorf (Germany)

    2009-05-15

    AISI-304 austenitic stainless steel has been nitrocarburized in N{sub 2} and C{sub 2}H{sub 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 ({gamma}{sub N} and CrN) and carbide ({gamma}{sub C} and Fe{sub 3}C) 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.

  12. Effects of Cr2N Precipitation on the Antibacterial Properties of AISI 430 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Je-Kang Du

    2016-03-01

    Full Text Available Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu2+ and Ag2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr2N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr2N precipitates. When aged at a lower temperature, which resulted in nano-Cr2N precipitation, the specimen possessed the highest antibacterial activity.

  13. Effect of two synthetic lubricants on life of AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Shimski, John

    1991-01-01

    Spur-gear fatigue tests were conducted with two lubricants using a single lot of consumable-electrode vacuum-melted (CVM) AISI 9310 spur gears. The gears were case carburized and hardened to Rockwell C60. The gear pitch diameter was 8.89 cm. The lot of gears was divided into two groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-ester-based lubricants. One lubricant was 30 percent more viscous that the other. Both lubricants have similar pressure viscosity coefficients. Test conditions included a bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa at the pitch line, and a speed of 10,000 rpm. The surface fatigue life of gears tested with one lubricant was approximately 2.4 times that for gears tested with the other lubricant. The lubricant with the 30 percent higher viscosity gave a calculated elastohydrodynamic (EHD) film thickness that was 20 percent higher than the other lubricant. This increased EHD film thickness is the most probable reason for the improvement in surface fatigue life of gears tested with this lubricant over gears tested with the less viscous lubricant.

  14. Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels

    Science.gov (United States)

    Yang, Y.; Busby, J. T.

    2014-05-01

    This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors.

  15. Linking anisotropy with Fe3C distribution in AISI 1045 steel

    Institute of Scientific and Technical Information of China (English)

    Ke-chang Shen; Gui-hua Li; Yi-min Sun; Yong-gang Wang; Ying-jie Li; Guang-hui Cao; Wei-min Wang

    2015-01-01

    The anisotropy of the microstructure, thermal expansion behavior, corrosion resistance and magnetic properties of AISI 1045 steel was investigated. The distribution of Fe3C lamellae i n the investigation plane parallel to the radial directions of molds was observed to differ from that in the investigation plane perpendicular to the radial directions by transmission electron microscopy. The lattice constants a0 ofα-Fe deduced from the XRD patterns of samples prepared using a sand (S)-mold and cut parallel to the radial direction of t h e m o l d ( S∥) and using a metal (M)-mold and cut parallel to the radial direction (M∥), the corrosion resistance measured using an electrochemical work-station, and the magnetic permeability obtained by vibrating sample magnetometry also indicated the existence of anisotropy in the tested samples. The anisotropic change of corrosion potential (Ecor ), pitting potential (Epit) and magnetic permeability (µ) of the samples was ob-served to depend on the orientation factor F200 ofα-Fe in the measured samples, which is controlled by the distribution of Fe3C lamellae in the eutectoid structure.

  16. Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding

    Science.gov (United States)

    Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Yavari, R.; Arakere, A.; Yen, C.-F.; Cheeseman, B. A.

    2013-05-01

    A fully coupled (two-way), transient, thermal-mechanical finite-element procedure is developed to model conventional gas metal arc welding (GMAW) butt-joining process. Two-way thermal-mechanical coupling is achieved by making the mechanical material model of the workpiece and the weld temperature-dependent and by allowing the potential work of plastic deformation resulting from large thermal gradients to be dissipated in the form of heat. To account for the heat losses from the weld into the surroundings, heat transfer effects associated with natural convection and radiation to the environment and thermal-heat conduction to the adjacent workpiece material are considered. The procedure is next combined with the basic physical-metallurgy concepts and principles and applied to a prototypical (plain) low-carbon steel (AISI 1005) to predict the distribution of various crystalline phases within the as-welded material microstructure in different fusion zone and heat-affected zone locations, under given GMAW-process parameters. The results obtained are compared with available open-literature experimental data to provide validation/verification for the proposed GMAW modeling effort.

  17. Propagation of crevices in stainless steel AISI304L in conditions of hydrogen chemistry (HWC)

    International Nuclear Information System (INIS)

    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++ ion. CT pre cracked specimens were used and each rehearsal stayed to one constant displacement velocity of 1 x 10-9 m/s (3.6 μm/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)

  18. Effects of cold working on the pitting corrosion behavior s of AISI 304 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Kee Min; Kim, Jong Soo; Kim, Young Jun; Kwon, Houk Sang [KAIST, Daejon (Korea, Republic of)

    2015-12-15

    These microstructural changes by cold working can lead improvement of mechanical properties, however from a corrosion resistant point of view, the effects of cold working on the corrosion resistance of stainless steel have been argued. Several studies has been focused on the influence of cold working on the localized corrosion resistance of stainless steels. However, the opinions about the role of cold working on the localized corrosion resistance are highly in consistence. Some studies report that the pitting potential of austenitic stainless steels decreased with cold working level, on the other hands, other studies claimed that the pitting resistance was increased by cold working. Therefore it is necessary to verify how cold working affects pitting corrosion behavior of austenitic stainless steels. In the present work, the influence of cold working on the localized corrosion of AISI 304stainless steel in the neutral chloride solution was studied based on point defect model (PDM). The fraction of deformation-induced martensite was linearly increased with cold rolling level. Through cold rolling, the pitting potential was decreased, the metastable pitting event density was significantly increased and the repassivation potential was decreased. The overall localized corrosion resistance was decreased with cold working, however cold working level increased from 30 % to 50 %, localized corrosion resistance was recovered. The accumulated cation vacancy generates a void at metal/film interface, therefore film breakdown accelerates for cold worked alloys.

  19. CRYOGENIC AND STRESS RELIEF THERMAL TREATMENTS IN AN AISI D2 STEEL

    Directory of Open Access Journals (Sweden)

    Paula Fernanda da Silva Farina

    2012-06-01

    Full Text Available The effects of cryogenic treatments on an AISI D2 cold work tool steel using X-ray diffraction from syncronton radiation are studied. The aim of this work is to verify the effects of: i time at cryogenic temperatures (3, 10 and 30 hours; ii cryogenic temperatures (–80°C and –196°C; iii stress relief heat treatment (130°C before cryogenic treatments; iv effect of double tempering at 520°C for 2 hours each time, after cryogenic treatment at –196°C for 30 hours, with and without previous stress relief. X-ray diffraction experiments were conducted at the line D10B-XPD of the Laboratório Nacional de Luz Síncrotron and the experimental results were treated using Rietveld refining, with TOPAS Academic in conjunction with cards from the ICCD-PDF 2006 database for austenite, martensite and carbides M7C3and M2C. Tempered samples were characterized using SEM and SEM-FEG. Volume fraction of retained austenite and carbides, as well as changes in the crystal lattices of martensite and austenite are obtained from the X-ray experiments.

  20. Finite Element Simulation of Residual Stresses in Butt Welding of Two AISI 304 Stainless Steel Plates

    Directory of Open Access Journals (Sweden)

    Gurinder Singh Brar

    2013-06-01

    Full Text Available Welding is one of the most reliable and efficient permanent metal joining processes in the industry. When two plates are joined by welding, a very complex thermal cycle is applied to the weldment. Thermal energy applied results in irreversible elastic-plastic deformation and consequently gives rise to the residual stresses in and around fusion zone and heat affected zone (HAZ. It is well established fact that structural integrity of components is substantially affected by the residual stresses when subjected to thermal and structural loads. Presence of residual stresses may be beneficial or harmful for the structural components depending on the nature and magnitude of residual stresses. Using finite element based commercially available software, coupled thermal-mechanical three dimensional finite element model was developed by making an approximate geometry of the butt welded joint. Finite element analysis was performed to understand the complete nature of residual stresses in manual metal arc welded joint of AISI 304 stainless steel plate. Variation of residual stress in the plates in the heat affected zone was also being studied. The results obtained by finite element method agree well with those from X-ray diffraction method as published in literature for the prediction of residual stresses.

  1. Tribological Properties of MoSi2 Against AISI10045 Steel Under Sliding Friction

    Institute of Scientific and Technical Information of China (English)

    CHEN Ping; ZHANG Hou-an; CHEN Hua-hui

    2006-01-01

    MoSi2 samples were prepared by a self-propagating high-temperature synthesis (SHS) and a hot-press technique. The sliding friction and wear properties of intermetallic MoSi2 against AISI10045 steel under dry friction and oil lubrication conditions were investigated with a MRH-5A type ring-on-block friction and wear tester. The elemental composition, microstructure and worn surface morphology of the MoSi2 material were observed and analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The synthetic parameter pv value reflecting friction work, was used to discuss the tribological properties of MoSi2 material. The results show that 1) oil lubrication can obviously improve the tribological properties of MoSi2, 2) the bigger the pv value, the greater the antifriction and the abrasive resistance of MoSi2 under oil lubrication, 3) with an increase in the pv value, the wear mechanism of MoSi2 material under dry sliding friction is the fatigue fracture and adhesive wear and 4) under oil lubrication the wear mechanism is mainly fatigue pitting.

  2. Q-switch Nd:YAG laser welding of AISI 304 stainless steel foils

    International Nuclear Information System (INIS)

    Conventional fusion welding of stainless steel foils (<100 μm thickness) used in computer disk, precision machinery and medical device applications suffer from excessive distortion, formation of discontinuities (pore, void and hot crack), uncontrolled melting (melt-drop through) and poor aesthetics. In this work, a 15 ns pulsed, 400 mJ Nd:YAG laser beam was utilized to overcome these barriers in seam welding of 60 μm thin foil of AISI 304 stainless steel. Transmission electron microscopy was used to characterize the microstructures while hardness and tensile-shear tests were used to evaluate the strengths. Surface roughness was measured using a DekTak profilometer while porosity content was estimated using the light microscope. Results were compared against the data obtained from resistance seam welding. Laser welding, compared to resistance seam welding, required nearly three times less heat input and produced welds having 50% narrower seam, 15% less porosity, 25% stronger and improved surface aesthetics. In addition, there was no evidence of δ-ferrite in laser welds, supporting the absence of hot cracking unlike resistance welding

  3. Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling

    Science.gov (United States)

    Sudha, C.; Sivai Bharasi, N.; Anand, R.; Shaikh, H.; Dayal, R. K.; Vijayalakshmi, M.

    2010-07-01

    AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 μm width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 μm width was identified which was found to consist of M 23C 6 carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

  4. Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sudha, C. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Sivai Bharasi, N. [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Anand, R. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Shaikh, H., E-mail: hasan@igcar.gov.i [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Dayal, R.K. [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Vijayalakshmi, M. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India)

    2010-07-31

    AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 {mu}m width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 {mu}m width was identified which was found to consist of M{sub 23}C{sub 6} carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

  5. Surface Nanostructure Formations in an AISI 316L Stainless Steel Induced by Pulsed Electron Beam Treatment

    Directory of Open Access Journals (Sweden)

    Yang Cai

    2015-01-01

    Full Text Available High current pulsed electron beam (HCPEB is an efficient technique for surface modifications of metallic materials. In the present work, the formations of surface nanostructures in an AISI 316L stainless steel induced by direct HCPEB treatment and HCPEB alloying have been investigated. After HCPEB Ti alloying, the sample surface contained a mixture of the ferrite and austenite phases with an average grain size of about 90 nm, because the addition of Ti favors the formation of ferrite. In contrast, electron backscattered diffraction (EBSD analyses revealed no structural refinement on the direct HCPEB treated sample. However, transmission electron microscope (TEM observations showed that fine cells having an average size of 150 nm without misorientations, as well as nanosized carbide particles, were formed in the surface layer after the direct HCPEB treatment. The formation of nanostructures in the 316L stainless steel is therefore attributed to the rapid solidification and the generation of different phases other than the steel substrate in the melted layer.

  6. Microstructural evolution of AISI 4340 steel during Direct Metal Deposition process

    International Nuclear Information System (INIS)

    Research highlights: → 4340 steel was successfully deposited using diode laser DMD system on mild steel. → Ferrite, martensite and cementite microstructural phases were identified in the clad. → Lattice parameters of identified phases are shorter than reported lattice parameters. → Microhardness of the clad decreases down the clad layers. → Decrease in microhardness corresponds to degree of tempering of martensite phase. - Abstract: In the current investigation AISI 4340 steel was laser deposited on a rolled mild steel substrate by Direct Metal Deposition (DMD) technology. The microstructural investigation of the clad was performed using optical and electron microscopes and X-ray diffraction techniques. The microstructure consisted of ferrite, martensite and cementite phases. Two types of martensite, lathe-type and plate-type, were observed in the microstructure. Decrease in microhardness values from the top layer to the alloy layer proves that the degree of tempering of the martensite phase increases in the same direction. The lattice parameters of the identified phases were found to be shorter than those reported in literature. The reported parameters in literature are from samples processed under equilibrium conditions.

  7. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  8. Kinetics of niobium carbide coating produced on AISI 1040 steel by thermo-reactive deposition technique

    International Nuclear Information System (INIS)

    There are a lot of technologically interesting characteristics of niobium carbide coating deposited by pack method which is the production of hard, wear-resistant, oxidation and corrosion resistant coating layer on the steel substrates. In the present study, the growth kinetics of niobium carbide layer deposited by thermo-reactive diffusion techniques in a solid medium on steel samples was reported. Niobium carbide coating treatment was performed on AISI 1040 steels in the powder mixture consisting of ferro-niobium, ammonium chloride and alumina at 1073, 1173 and 1273 K for 1-4 h. The presence of NbC and Nb2C phases formed on the surface of the steel substrates was confirmed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction analyses. Niobium carbide layer thickness ranges from 3.42±0.52 to 11.78±2.29 μm depending upon the treatment time and temperature. Layer growth kinetics was analyzed by measuring the depth of niobium carbide layer as a function of time and temperature. The kinetics of niobium carbide coating by pack method shows a parabolic relationship between carbide layer thickness and treatment time, and the activation energy for the process is estimated to be 91.257 kJ mol-1. Moreover, an attempt was made to investigate the possibility of predicting the contour diagram of niobium carbide layer variation and to establish some empirical relationships between process parameters and niobium carbide layer thickness

  9. Electronic structures and nitride formation on ion-implanted AISI 304L austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chang, G.S.; Son, J.H.; Kim, S.H.; Chae, K.H.; Whang, C.N. (Yonsei Univ., Seoul (Korea, Republic of). Dept. of Physics); Menthe, E.; Rie, K.-T.; Lee, Y.P.

    1999-02-01

    A N[sub 2][sup +] implantation technique was employed to improve the surface hardness of stainless steel, and the electronic structures and nitride formation of the ion-implanted layer were investigated and compared with those produced using other techniques, including plasma nitriding. AISI 304L austenite stainless steel was irradiated by 80 keV N[sub 2][sup +] with a dosage ranging from 1.0 x 10[sup 16] to 1.0 x 10[sup 18] ions cm[sup -2] at room temperature. The formation of various nitrides was confirmed by X-ray diffraction. The quantitative hardness of the samples was measured by using a Knoop microhardness tester. X-ray photoelectron spectroscopy was also carried out to elucidate the chemical states and electronic structures of the ion-implanted layers. The measurements were repeated after post-annealing at 400 C for 1 h in a high vacuum. Changes in phase, chemical state and electronic structures were observed according to the ion dose and heat treatment. (orig.) 12 refs.

  10. Surface characterization of stainless steel AISI 316 L in contact with simulated body fluid

    International Nuclear Information System (INIS)

    Titanium and cobalt alloys, as well as some stainless steels, are often used in orthopedic surgery. In the more developed countries, stainless steel is used only for temporary implants since it does not hold up as well as other alloys to corrosion in a physiological medium. Nevertheless, stainless steel alloys are frequently used for permanent implants in developing countries. Therefore, more knowledge about its reaction to corrosion is needed as well as the characteristics of the surface layer generated in a physiological medium in order to control potential toxicity from the release of metallic ions into the organism. The surface films usually have a different composition and chemical state from the base material. The surface characterization of alloys used in orthopedic surgery should not be underestimated, since it heavily influences the behavior of the implant through the relationship of the surface film-tissue and the possible migration of metallic ions from the base metal to the surrounding tissue. This work presents a study of the surface composition and resistance to the corrosion of stainless steel AISI 316L in simulated body fluid (SBF) aired at pH 7.25 and 37oC. The resistance to the corrosion was studied with an electrochemical impedance spectroscopy (EIS) and anodic polarization curves (CW)

  11. Pengaruh Media Pendingin pada Heat Treatment Terhadap Struktur Mikro dan Sifat Mekanik Friction Wedge AISI 1340

    Directory of Open Access Journals (Sweden)

    Bayu Adie Septianto

    2013-09-01

    Full Text Available Baja AISI 1340 termasuk baja paduan rendah dengan komposisi karbon 0.38-0.43% dan Mangan 1,78%. Baja ini digunakan untuk komponen kereta api Friction Wedge yang memiliki standar kekerasan minimal 300 BHN. Untuk menambah kekerasan, salah satu cara yang digunakan adalah heat treatment. Pada penelitian ini variasi yang digunakan adalah media pendingin air, oli SAE 20W, PVA 20% dan pendinginan udara pada tempertaur austenitisasi 8400C dan waktu tahan 20 menit. Kekerasan yang dihasilkan oleh media pendingin air adalah 556,6 BHN, sedangkan quench oli dan polimer 461,8 BHN dan 416 BHN. Pada pendinginan udara dihasilkan kekerasan dibawah 300 BHN. Perbedaan media pendingin berpengaruh terhadap struktur mikro yang terbentuk. Pada pendinginan dengan media air dan oli diperoleh struktur martensit dengan bentuk kristal BCT. Sedangkan pada pendinginan udara terbentuk struktur ferrit dan perlit dengan bentuk kristal BCC. Selain berpengaruh pada sifat mekanik dan struktur mikronya, variasi media pendingin juga memberikan efek terhadap sifat termalnya dan berpengaruh terhadap elongation pada temperatur maksimum kerja. Dari hasil uji TMA, performa paling baik pada temperatur 300oC dihasilkan pada pendinginan quench oli SAE 20W, dengan pertambahan panjang sebesar 0,65%.

  12. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    Directory of Open Access Journals (Sweden)

    Chen Ying An

    2010-09-01

    Full Text Available 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 were analyzed by means of tensile tests, Vickers microhardness, metallographic tests and SEM-EDX. The strength of the joints varied with increasing friction time and the use of different pressure values. Joints were obtained with superior mechanical properties of the AA1050 aluminum, with fracture occurring in the aluminum away from the bonding interface. The analysis by EDX at the interface of the junction showed that interdiffusion occurs between the main chemical components of the materials involved. The RFW proves to be a great method for obtaining joints between dissimilar materials, which is not possible by fusion welding processes.

  13. Effect of thermal cycles on heavily cold deformed AISI 304L austenitic stainless steel

    International Nuclear Information System (INIS)

    The solution treated commercial grade AISI 304L austenitic stainless steel plate was heavily cold rolled to 90% of thickness reduction. Cold rolled specimens were annealed at various temperatures by thermal cycles and isothermal annealing. Strain-induced phase transformations and microstructure studies were carried out both in the cold rolled and annealed conditions. The X-ray diffraction and magnetic measurements were used for phase transformation studies. The transmission electron microscope characterisation revealed that the cyclic thermal process resulted in ultrafine grain austenite formation whereas, the isothermal annealing developed coarser grain size microstructure. The different microstructural evolutions by the above two processes largely influenced the development of the recrystallisation texture. The thermal cycling produced a distinct γ-fibre texture while the isothermal annealing resulted in a cube texture component along with the γ-fibre. The γ-fibre texture evolution was attributed to the over critical subgrains or nuclei and {1 0 0} cube texture to the coarser grains of micrometer size.

  14. Surface severe plastic deformation of AISI 304 via conventional shot peening, severe shot peening and repeening

    Energy Technology Data Exchange (ETDEWEB)

    Unal, Okan, E-mail: unalokan78@gmail.com [Mechanical Engineering Department, Bartın University, Bartın 74100 (Turkey); Varol, Remzi [Mechanical Engineering Department, Suleyman Demirel University, Isparta 32200 (Turkey)

    2015-10-01

    Highlights: • CSP and SSP treatments transform austenite to metastable martensite structure. • Nanograin layer thickness after CSP and SSP is 8 μm and 22 μm, respectively. • Shot peening leads to carbon segregation from coarse to nano grain layer. • Repeening is an effective way to reduce surface roughness. - Abstract: Air blast conventional shot peening (CSP), severe shot peening (SSP) and repeening (RP) as a severe plastic deformation applications on AISI 304 austenitic stainless steel is addressed. Shot peened specimens are investigated based on optical, FESEM and digital microscope. The investigations present the austenite transformation to metastable martensite via mechanical twinning due to plastic deformation with high strain rates. It is found that SSP induces thicker nanograin layer with compared to CSP. In XRD studies, the austenite peaks broaden by means of severe shot peening and FWHM increase reveals the grain size reduction below 25 nm regimes on the surface. In EDAX line analysis of CSP specimen, carbon content increase has been detected from deformed layer through the nanocrystalline layer then the content reduces. The carbon segregation takes place due to the energy level distinction between dislocations and Fe−C bonds. 3d contour digital microscope studies and roughness investigations reveal that SSP has deleterious side effect on the surface roughness and surface flatness. However, RP is an effective way to reduce the surface roughness to reasonable values.

  15. Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Lawrence O. Osoba

    2016-12-01

    Full Text Available In the current study, the influence of delta (δ ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H2SO4 and 1Molar concentration of sodium chloride (NaCl. The study was performed at ambient temperature using electrochemical technique—Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel specimen and 60% cold-worked (stainless steel specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr, the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material.

  16. Kinetic investigation of AISI 304 Stainless Steel boronized in indirect heated fluidized bed furnace

    Directory of Open Access Journals (Sweden)

    Topuz P.

    2016-01-01

    Full Text Available In this study, kinetic examinations on boronized AISI 304 Stainless Steel samples were described. Samples were boronized in indirect heated fluidized bed furnace consists of Ekabor 1™ boronizing agent at 1123, 1223 and 1323 K for 1,2 and 4 hours. Morphologically and typically examinations of borides formed on the surface of steel samples were studied by optical microscope, scanning electron microscope (SEM and X-Ray diffraction (XRD. Boride layer thickness formed on the steel X5CrNi 18-10 ranges from 12 to 176 μm. The hardness of the boride layer formed on the steel X5CrNi 18-10 varied between 1709 and 2119 Hv0,1. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature. The kinetics of the reaction has been determined with K=Ko exp (-Q/RT equation. Activation energy (Q of boronized steel X5CrNi 18-10 was determined as 244 kj/mol.

  17. Investigations on Surface Milling of Hardened AISI 4140 Steel with Pulse Jet MQL Applicator

    Science.gov (United States)

    Bashir, Mahmood Al; Mia, Mozammel; Dhar, Nikhil Ranjan

    2016-06-01

    In this article, an experimental investigation was performed in milling hardened AISI 4140 steel of hardness 40 HRC. The machining was performed in both dry and minimal quantity lubricant (MQL) conditions, as part of neat machining, to make a strong comparison of the undertaken machining environments. The MQL was impinged int the form of pulse jet, by using the specially developed pulse-jet-attachment, to ensure that the cutting fluid can be applied in different timed pulses and quantities at critical zones. The tool wear, cutting force and surface roughness were taken as the quality responses while cutting speed, table feed rate and flow rate of the pulse were considered as influential factors. The depth of cut was kept constant at 1.50 mm because of its less significant effects and the straight oil was adopted as cutting fluid in pulse-jet-MQL. The effects of different factors, on the quality responses, are analyzed using ANOVA. It is observed that MQL applicator system exhibits overall better performance when compared to dry milling by reducing surface roughness, cutting force and prolonging tool life but a flow rate of 150 ml/h has tremendous effects on the responses. This investigation and afterward results are expected to aid the industrial practitioner and researcher to adopt the pulse-MQL in high speed milling to prolong tool life, reduce tool wear, diminish cutting force generation and promote better surface finish.

  18. Multi-response optimization of Micro-EDM process parameters on AISI304 steel using TOPSIS

    Energy Technology Data Exchange (ETDEWEB)

    Manivannan, R.; Kumar, M. Pradeep [CEG, Anna University, Chennai (India)

    2016-01-15

    The Technique for order preference by similarity to ideal solution (TOPSIS) method of optimization is used to analyze the process parameters of the micro-Electrical discharge machining (micro-EDM) of an AISI 304 steel with multi-performance characteristics. The Taguchi method of experimental design L27 is performed to obtain the optimal parameters for inputs, including feed rate, current, pulse on time, and gap voltage. Several output responses, such as the material removal rate, electrode wear rate, overcut, taper angle, and circularity at entry and exit points, are analyzed for the optimal conditions. Among all the investigated parameters, feed rate exerts a greater influence on the hole quality. ANOVA is employed to identify the contribution of each experiment. The optimal level of parameter setting is maintained at a feed rate of 4 μm/s, a current of 10 A, a pulse on time of 10 μs, and a gap voltage of 10 V. Scanning electron microscope analysis is conducted to examine the hole quality. The experimental results indicate that the optimal level of the process parameter setting over the overall performance of the micro-EDM is improved through TOPSIS.

  19. Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

    Science.gov (United States)

    Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

    2015-12-01

    This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

  20. Deposition of titanium nitride on AISI-304 in a plasma focus environment

    Science.gov (United States)

    Zeb, S.; Qayyum, A.; Shafiq, M.; Zakaullah, M.

    2008-05-01

    Polycrystalline, smooth, and hard thin films of TiN are successfully deposited on AISI-304 substrates using a 1.5kJ Mather-type dense plasma focus device charged at 18kV. The purpose of this study is to investigate the structural and mechanical properties of the TiN thin films in terms of ion dose and substrate position to establish the optimum deposition conditions. The films are analyzed using XRD, SEM, electron microprobe and micro-hardness testing. XRD confirms the deposition of a polycrystalline TiN thin film together with the emergence of an iron chromium nickel phase. The surface hardness-in comparison to the unexposed substrate-is found to increase up to 250% when a film is deposited using 30 focus shots at an axial distance of 6cm. SEM micrographs show that the quality of the film is improved with an increasing number of focus shots. The constituent elements of the film are also confirmed by electron microprobe.

  1. Investigation of the influential parameters of machining of AISI 304 stainless steel

    Indian Academy of Sciences (India)

    R A Mahdavinejad; S Saeedy

    2011-12-01

    Austenitic stainless steels are hard materials to machine, due to their high strength, high ductility and low thermal conductivity. The last characteristic results in heat concentration at the tool cutting edge. This paper aims to optimize turning parameters of AISI 304 stainless steel. Turning tests have been performed in three different feed rates (0.2, 0.3, 0.4 mm/rev) at the cutting speeds of 100, 125, 150, 175 and 200 m/min with and without cutting fluid. A design of experiments (DOE) and an analysis of variance (ANOVA) have been made to determine the effects of each parameter on the tool wear and the surface roughness. It is being inferred that cutting speed has the main influence on the flank wear and as it increases to 175 m/min, the flank wear decreases. The feed rate has the most important influence on the surface roughness and as it decreases, the surface roughness also decreases. Also, the application of cutting fluid results in longer tool life and better surface finish.

  2. Metallurgical response of an AISI 4140 steel to different plasma nitriding gas mixtures

    Directory of Open Access Journals (Sweden)

    Adão Felipe Oliveira Skonieski

    2013-01-01

    Full Text Available Plasma nitriding is a surface modification process that uses glow discharge to diffuse nitrogen atoms into the metallic matrix of different materials. Among the many possible parameters of the process, the gas mixture composition plays an important role, as it impacts directly the formed layer's microstructure. In this work an AISI 4140 steel was plasma nitrided under five different gas compositions. The plasma nitriding samples were characterized using optical and scanning electron microscopy, microhardness test, X-ray diffraction and GDOES. The results showed that there are significant microstructural and morphological differences on the formed layers depending on the quantity of nitrogen and methane added to the plasma nitriding atmosphere. Thicknesses of 10, 5 and 2.5 µm were obtained when the nitrogen content of the gas mixtures were varied. The possibility to obtain a compound layer formed mainly by γ'-Fe4N nitrides was also shown. For all studied plasma nitriding conditions, the presence of a compound layer was recognized as being the responsible to hinder the decarburization on the steel surface. The highest value of surface hardness - 1277HV - were measured in the sample which were nitrided with 3vol.% of CH4.

  3. An Electrochemical Processing Strategy for Improving Tribological Performance of Aisi 316 Stainless Steel Under Grease Lubrication

    Science.gov (United States)

    Zou, Jiaojuan; Li, Maolin; Lin, Naiming; Zhang, Xiangyu; Qin, Lin; Tang, Bin

    2014-12-01

    In order to improve the tribological performance of AISI 316 stainless steel (316 SS) under grease lubrication, electrochemical processing was conducted on it to obtain a rough (surface texturing-like) surface by making use of the high sensitivity of austenitic stainless steel to pitting corrosion in Cl--rich environment. Numerous corrosion pits or micro-ditches acted as micro-reservoirs on the obtained surface. While the grease could offer consistent lubrication, and then improve the tribological performance of 316 SS. Tribological behaviors of raw 316 SS and the treated sample were measured using a reciprocating type tribometer sliding against GCr15 steel counterpart under dry and grease lubrication conditions. The results showed that the mass losses of the two samples were in the same order of magnitude, and the raw sample exhibited lower friction coefficient in dry sliding. When the tests were conducted under grease lubrication condition, the friction coefficients and mass losses of the treated sample were far lower than those of the raw 316 SS. The tribological performance of 316 SS under grease lubrication was drastically improved after electrochemical processing.

  4. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat treatment on nitrided layer

    Indian Academy of Sciences (India)

    Ravindra Kumar; J Alphonsa; Ram Prakash; K S Boob; J Ghanshyam; P A Rayjada; P M Raole; S Mukherjee

    2011-02-01

    In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific steel is that its tempering temperature (∼170–200°C) is much lower than the standard processing temperature (∼460–580°C) needed for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated. Experiments are performed on three different types of ball bearing races i.e. annealed, quenched and quench-tempered samples. Different gas compositions and process temperatures are maintained while nitriding these samples. In the quenched and quench-tempered samples, the surface hardness has decreased after plasma nitriding process. Plasma nitriding of annealed sample with argon and nitrogen gas mixture gives higher hardness in comparison to the hydrogen–nitrogen gas mixture. It is reported that the later heat treatment of the plasma nitrided annealed sample has shown improvement in the hardness of this steel. X-ray diffraction analysis shows that the dominant phases in the plasma nitrided annealed sample are (Fe2−3N) and (Fe4N), whereas in the plasma nitrided annealed sample with later heat treatment only -Fe peak occurs.

  5. Effect of Austenitizing Heat Treatment on the Microstructure and Hardness of Martensitic Stainless Steel AISI 420

    Science.gov (United States)

    Barlow, L. D.; Du Toit, M.

    2012-07-01

    The effect of austenitizing on the microstructure and hardness of two martensitic stainless steels was examined with the aim of supplying heat-treatment guidelines to the user that will ensure a martensitic structure with minimal retained austenite, evenly dispersed carbides and a hardness of between 610 and 740 HV (Vickers hardness) after quenching and tempering. The steels examined during the course of this examination conform in composition to medium-carbon AISI 420 martensitic stainless steel, except for the addition of 0.13% vanadium and 0.62% molybdenum to one of the alloys. Steel samples were austenitized at temperatures between 1000 and 1200 °C, followed by oil quenching. The as-quenched microstructures were found to range from almost fully martensitic structures to martensite with up to 35% retained austenite after quenching, with varying amounts of carbides. Optical and scanning electron microscopy was used to characterize the microstructures, and X-ray diffraction was employed to identify the carbide present in the as-quenched structures and to quantify the retained austenite contents. Hardness tests were performed to determine the effect of heat treatment on mechanical properties. As-quenched hardness values ranged from 700 to 270 HV, depending on the amount of retained austenite. Thermodynamic predictions (using the CALPHAD™ model) were employed to explain these microstructures based on the solubility of the carbide particles at various austenitizing temperatures.

  6. Dinámica del carbono en los ecosistemas de páramo de los Andes neotropicales: revisión de literatura sobre modelos y parámetros relevantes

    NARCIS (Netherlands)

    J. Sevink; F.H. Tonneijck; K. Kalbitz; L.H. Cammeraat

    2014-01-01

    Resumen Los suelos del páramo almacenan cantidades excepcionales de carbono debido a las condiciones edáficas y climáticas sobre las cuales se desarrollan. Este gran reservorio de carbono está amenazado debido a los efectos del cambio climático y las dinámicas de uso de la tierra. No obstante, el de

  7. Aportes para la estimación de la huella de carbono en los grandes asentamientos urbanos de Argentina

    Directory of Open Access Journals (Sweden)

    Rosana Ferraro

    2013-07-01

    Full Text Available El cambio climático y su efecto más inmediato, el calentamiento global, plantean desafíos para la gestión ambiental de las ciudades. Uno de ellos es estimar su huella de carbono con la finalidad de morigerar los potenciales impactos. El presente trabajo propone calcular las emisiones de CO2 producidas por las actividades antrópicas de los 15 asentamientos urbanos de Argentina de más de 300.000 habitantes. Para ello se analizaron por localidad los consumos de energía eléctrica y se calcularon las emisiones de CO2 por sector de demanda eléctrica. Los resultados muestran que Argentina, en general, y los grandes asentamientos, en particular, tienen una baja contribución de emisiones de CO2, que se asocian en orden decreciente con la actividad industrial, residencial y comercial.

  8. Aportes para la estimación de la huella de carbono en los grandes asentamientos urbanos de Argentina

    Directory of Open Access Journals (Sweden)

    Rosana Ferraro

    2013-01-01

    Full Text Available El cambio climático y su efecto más inmediato, el calentamiento global, plantean desafíos para la gestión ambiental de las ciudades. Uno de ellos es estimar su huella de carbono con la finalidad de morigerar los potenciales impactos. El presente trabajo propone calcular las emisiones de CO2 producidas por las actividades antrópicas de los 15 asentamientos urbanos de Argentina de más de 300.000 habitantes. Para ello se analizaron por localidad los consumos de energía eléctrica y se calcularon las emisiones de CO2 por sector de demanda eléctrica. Los resultados muestran que Argentina, en general, y los grandes asentamientos, en particular, tienen una baja contribución de emisiones de CO2, que se asocian en orden decreciente con la actividad industrial, residencial y comercial.

  9. Técnica alternativas de determinação "on site" de dióxido de carbono

    OpenAIRE

    Vasconcelos Segundo, Emerson Hochsteiner de

    2013-01-01

    Resumo: O presente trabalho teve como objetivo o desenvolvimento de técnicas alternativas, em campo, para determinação de dióxido de carbono em reservatórios para abastecimento de águas ou regularização de hidroelétricas. As técnicas concebidas têm aplicação tanto para o meio líquido quanto para o meio gasoso e baseiam-se na captação de sinais físicos, predominantemente no que diz respeito à espectroscopia. Foram analisadas possíveis aplicações em relação à produção de bolhas de gás pelo desl...

  10. Síntesis y caracterización de materiales híbridos basados en nanotubos de carbono

    OpenAIRE

    García Gutiérrez, Ángel Pablo

    2013-01-01

    Los nanotubos de carbono están despertando un gran interés investigativo en los últimos años debido a sus excepcionales propiedades electrónicas, mecánicas, térmicas, químicas y por sus potenciales aplicaciones en nanociencia y nanotecnología. Por otro lado, el óxido de zinc también genera un gran interés tanto científico como tecnológico debido a sus extraordinarias propiedades ópticas y eléctricas. Se trata de un material semiconductor con demostradas propiedades fotocatalíticas, que le con...

  11. ATRIBUTOS FÍSICO-HÍDRICOS E ESTOQUE DE CARBONO EM NEOSSOLO QUARTZARÊNICO SOB PLANTIO DE Eucalyptus urograndis

    Directory of Open Access Journals (Sweden)

    Allan Libanio Pelissari

    2013-11-01

    Full Text Available O objetivo  do  trabalho foi avaliar o efeito da colheita do eucalipto  nos atributos físico-hídricos e no estoque de carbono em Neossolo Quartzarênico. O estudo foi conduzido em um povoamento  de  Eucalyptus urograndis  com sete anos de idade, em Dom Aquino, MT, Brasil.  As avaliações  foram realizadas em dois períodos do ano (chuvoso e seco, e coletadas amostras de solo nas profundidades de 0–0,2; 0,2–0,4; 0,4–0,6; 0,6–0,8 e 0,8–1,0 m, antes e após a colheita semimecanizada, para a determinação da porosidade total, densidade, condutividade hidráulica saturada, conteúdo de água e estoque de carbono no solo, enquanto a resistência à penetração foi determinada até  0,8 m. O sistema semimecanizado de colheita alterou significativamente a resistência do solo à penetração e a porosidade total no período chuvoso do ano. A densidade do solo  foi inferior nas camadas superficiais, ao passo que a condutividade hidráulica saturada reduziu após a colheita. O conteúdo de água no solo foi o atributo que regulou  o impacto da colheita semimecanizada sobre o solo.  O estoque de carbono aumentou  após a colheita no período chuvoso.Palavra-chave compactação do solo, carbono orgânico, colheita de madeira.PHYSICAL-HYDRIC ATTRIBUTES AND CARBON STOCK IN TYPIC QUARTZIPISAMMENT UNDER Eucalyptus urograndis STANDS ABSTRACTThe aim of this study was to evaluate the effect of eucalyptus harvesting in the physical-hydric attributes and carbon storage in Typic Quartzipisamment. The study was conducted with seven years old Eucalyptus urograndis stand, in Dom Aquino, MT, Brazil. The evaluations were conducted in two seasons (wet and dry, with soil sampling at depths of 0-0.2, 0.2-0.4, 0.4-0.6, 0.6-0.8 and 0.8-1.0 m, before and after the semi-mechanized harvesting, for the total porosity determination, bulk density, hydraulic conductivity, water content and soil carbon stock, while the soil penetration resistance was

  12. DIÓXIDO DE CARBONO ASSOCIADO À FOSFINA NO CONTROLE DO GORGULHO-DO-MILHO (Sitophilus zeamais)

    OpenAIRE

    Talita Lacaze de Camargo Casella; Lêda Rita D'Antonino Faroni; Pedro Amorim Berbert; Paulo Roberto Cecon

    1998-01-01

    RESUMO O objetivo deste trabalho foi avaliar o efeito da utilização de fosfina, associada a atmosferas ricas em dióxido de carbono, no controle efetivo de Sitophilus zeamais, em todas as suas fases de desenvolvimento, em grãos de milho, a temperatura de 29°C e 65% de umidade relativa. Os tratamentos compreenderam a combinação de atmosfera controlada (21% de CO2 e 79% de N2) e três doses de fosfina (0,25, 0,50 e 0,75g.m-3) e atmosfera ambiente e duas doses de fosfina (0,0 e 1,0g.m-3) em três p...

  13. 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

    Directory of Open Access Journals (Sweden)

    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

  14. Use of carb counting in the dietary treatment of diabetes mellitus Utilización del contaje de hidratos de carbono en el tratamiento dietético de la diabetes mellitus

    Directory of Open Access Journals (Sweden)

    D. Lopes Souto

    2010-02-01

    Full Text Available Currently, carb counting is a nutritional strategy that has allowed a greater adherence and dietary management of patients with diabetes mellitus, because it allows the consumption of a greater variety of foods. However, also requires greater adherence by the patient to maintain an adequate blood glucose monitoring and the ability to determine the amount of carbohydrates in the meals. Since diabetes mellitus is a chronic disease, a more flexible and varied diet will allow better monitoring, taking into account their glycemic control in long-term. The objective of this study was to examine the applicability of this method to a less restrictive diet and nutritionally adequate for the patient with diabetes mellitus, as well an individual dietary adjustment that is needed to better glycemic control, identifying nutritional advantages and disadvantages of the method.En la actualidad, el contaje del contenido de hidratos de carbono es una estrategia de nutrición que ha permitido mayor adherencia al tratamiento dietético del paciente con diabetes mellitus ya que permite el consumo de una mayor diversidad de comidas. Sin embargo, también se hace necesario una mayor implicación por parte del paciente para mantener una adecuada monitorización de su glucemia, así como la capacidad para determinar la cantidad de hidratos de carbono en las ingestas. Dado que el diabetes mellitus es una enfermedad crónica, una dieta más flexible y variada permitirá un mejor seguimiento, teniendo en cuenta a su vez el control glucémico a largo plazo. El objetivo del estudio fue revisar la aplicabilidad de este método para formular una dieta menos restrictiva y nutricionalmente adecuada para el paciente con diabetes mellitus, así como el ajuste dietético individual que se hace necesario para el mejor control glucémico, identificando ventajas y desventajas nutricionales del método.

  15. Compósito cimentício reforçado com fibras de carbono para recuperação de monumentos históricos Cementicious composites made with steatite residue reinforced with carbon fiber

    Directory of Open Access Journals (Sweden)

    T. H. Panzera

    2010-12-01

    Full Text Available O intemperismo, como fenômeno natural, atinge não somente materiais produzidos pelo homem, como também construções feitas de rochas naturais. No entanto, a evolução intempérica geralmente ocorre em ritmo muito lento em relação à duração dos empreendimentos humanos. Contudo, há situações em que este se acelera, afetando as obras de engenharia, sobretudo as obras de arte, monumentos históricos e fachadas de igrejas consideradas patrimônio da humanidade. O presente trabalho investigou o efeito da adição de fibra de carbono em compósitos cimentícios de resíduos de esteatito visando à recuperação de peças confeccionadas com este mineral, popularmente conhecido como "pedra-sabão". As propriedades físico-mecânicas tais como, densidade volumétrica e resistência mecânica à flexão foram investigadas neste experimento. Concluiu-se que a adição de fibra de carbono aumenta significativamente a resistência mecânica dos compósitos além da redução de seu peso específico, permitindo o reaproveitamento de um maior percentual de resíduos de esteatito no compósito final.Weathering is a natural phenomenon that affects both the engineering materials and natural rocks used for construction. The weathering evolution generally occurs at a slow pace when compared with the overall durability of the construction elements. However, in some cases the weathering may develop much quicker, affecting the engineering constructions and also historical buildings such as monuments and churches. This work investigated the effect of carbon fibre addition into cementitious composites made with residues of steatite, a mineral, also known as soapstone, for restoration of craftwork elements. The material's properties, such as bulk density and flexural strength were investigated. It is possible to conclude that the carbon fibre addition increases the flexural strength of the composites and reduces the specific weight, allowing for the use of a

  16. Susceptibilidad y síntomas respiratorios asociados a la exposición a dióxido de carbono y dióxido de azufre provenientes del volcán Turrialba, Costa Rica

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    Marisol Yglesias-González

    2014-07-01

    Full Text Available El volcán Turrialba ha mantenido en los últimos años una actividad de desgasificación, y paulatinamente se han mostrado los efectos de este dinamismo sobre la vegetación e infraestructuras de las comunidades aledañas. Entre las sustancias que conforman esta actividad de desgasificación se encuentra el dióxido de carbono y el dióxido de azufre que se han ido incrementando y son capaces de afectar la salud respiratoria de quienes se exponen a ellas. El objetivo de esta investigación es analizar la proclividad de las poblaciones aledañas de desarrollar síntomas respiratorios ante las exposiciones vía aérea de dióxido de carbono y dióxido de azufre provenientes del volcán Turrialba. La investigación consistió en un estudio transversal, descriptivo, analítico y cuantitativo. Se trabajó con ocho comunidades, y se obtuvo una muestra de 502 personas. Las comunidades estudiadas fueron: Hacienda La Fuente, La Central, La Silvia, Miravalles, Finca El Retiro, Guayabo Arriba, Las Virtudes y La Alegría. Esta última fue la comunidad control. Los estratos con mayor riesgo de presentar molestias en la garganta cuando hay exposición a gases volcánicos fueron los niños y adultos mayores (OR=1,93, mujeres (OR=1,86, personas que emplean varios tipos de cocina (OR=2,07, individuos con ocupaciones al aire libre (OR=1,51 y personas con ingresos iguales o mayores a los USD $475 (OR=2,09. Los estratos con mayor riesgo de presentar molestias en la nariz fueron los niños y adultos mayores (OR=1,37, mujeres (OR=1,83, personas que emplean cocina eléctrica (OR=2,23, individuos con ocupaciones dentro de edificaciones (2,12 y personas con ingresos inferiores a los USD $475 (OR=2,30.

  17. Estudo da cinética de decomposição de compósitos nanoestruturados de poli (sulfeto de fenileno reforçados com nanotubos de carbono

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    Bruno Ribeiro

    2014-12-01

    Full Text Available O objetivo deste trabalho consiste na obtenção de compósitos nanoestruturados de poli (sulfeto de fenileno (PPS reforçados com nanotubos de carbono de paredes múltiplas (MWCNT por meio da técnica de mistura em fusão, e posterior caracterização de suas propriedades morfológicas e térmicas. A análise por microscopia eletrônica de transmissão foi utilizada com o intuito de avaliar a qualidade da dispersão dos MWCNTs na matriz polimérica. A partir das curvas de termogravimetria obtidas, foi observado um aumento na temperatura máxima de degradação pela adição do nanoreforço na matriz polimérica. Além disso, o modelo matemático de Ozawa-Wall-Flynn foi utilizado com o intuito de determinar os parâmetros cinéticos de degradação. Os resultados mostraram um aumento de aproximadamente 25 ºC na temperatura máxima de degradação (Tmax quando uma pequena quantidade de MWCNT (0,5 wt % foi considerada. Este fato contribuiu para o aumento da estabilidade térmica do PPS.

  18. Estimación de biomasa y carbono en dos especies de bosque mesófilo de montaña Biomass and carbon assessment in two tree species in a cloudy forest

    Directory of Open Access Journals (Sweden)

    Miguel Acosta Mireles

    2011-08-01

    Full Text Available La generación de ecuaciones alométricas es importante para determinar la biomasa y el carbono en las especies arbóreas. Esta información es útil en los estudios de cambio climático. En el presente estudio se generaron ecuaciones alométricas para dos especies de importancia ecológica en el bosque mesófilo de montaña: Clethra mexicana DC y Alnus arguta (Schltdl Spach. Las ecuaciones que se determinaron son de la forma Y= bXk; donde: Y= contenido de biomasa o de carbono (kg; y X= diámetro normal (DN en centímetros. Para estimar los valores b y k del modelo para cada especie, se realizó un muestreo de quince árboles de Clethra mexicana y 22 de Alnus arguta. En Clethra mexicana el mayor porcentaje de biomasa 45.2 % se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje estaba 36.3% y 18.6%, respectivamente. Con la biomasa y el DN de los árboles se determinaron los parámetros b y k del modelo propuesto (B= 0.4632 DN1.8168, R²= 0.946. Para Alnus arguta el mayor porcentaje de biomasa (60.6%, se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje presentó 27.4 y 12%, respectivamente. Al igual que el caso anterior con la biomasa y el DN, se obtuvieron los parámetros b y k del modelo propuesto (B= 0.1649 DN2.2755, R²= 0.968. Después de analizar el contenido de carbono en las muestra de cada especie, se ajustaron las ecuaciones para Clethra mexicana C= 22.49DN1.8168, con R²= 0.946, mientras que para Alnus arguta C= 0.0809DN2.2782 con R²= 0.968.The generation of allometric equations is important to determine biomass and carbon in tree species. This information is useful in climate change studies. In this paper, allometric equations were generated for two species of ecological importance in the cloud forest: Clethra mexicana DC and Alnus arguta (Schltdl Spach. Equations determined are of the form Y= bXk; where: Y= biomass or carbon content (kg; and X= normal diameter (ND in

  19. Oxidación óptima de alambrones de acero de bajo carbono, durante el enfriamiento a la salida de un laminador de barras

    Directory of Open Access Journals (Sweden)

    Camurri, C.

    2002-04-01

    Full Text Available The increasing environmental exigencies demand that the oxide removal of steel wire rod before drawing is carried out by mechanical means, replacing the traditional descaling, wich is polluting. In such sense the objective of the present work is to settle down the operational conditions during the cooling of low carbon steel wire rod of 5.5 mm in diameter in order to have a minimum increase in the amount of rod oxide, so that it is more easily removable by mechanical cleaning before drawing. An additional objective is to simulate by means of the explicit finite differences method the temperature distribution of these wire rod during cooling. A good correlation model-experience is obtained, with temperature differences that do not exceed 4 %. On the other hand it is found that slowing water cooling is results in an increase of the total oxide to values averaging 0.7 % in weight, as specified by the drawing industry.

    Las crecientes exigencias medioambientales exigen que la remoción de óxidos de los alambrones de acero para posterior trefilación se efectúe por medios mecánicos, reemplazando así el tradicional y contaminante decapado. En tal sentido, el objetivo del presente trabajo es determinar las condiciones operacionales en el enfriamiento a la salida del laminador de barras, tales que produzcan un pequeño aumento en la cantidad de óxido total en alambrones de acero de bajo carbono de 5,5 mm de diámetro, a valores óptimos que permitan una adecuada limpieza mecánica previa al trefilado. Adicionalmente, simular, mediante el método explícito de las diferencias finitas, la distribución de temperaturas de esos mismos alambrones, durante el enfriamiento. Se obtiene una buena correlación modelo-experiencia, con diferencias para la temperatura que no sobrepasan el 4 % entre ambos. Por otro lado, se encuentra que, retardando el enfriamiento con agua, se logra incrementar el óxido a los valores promedio exigidos del 0,7 % en peso.

  20. Huella del Carbono. Parte 2: La Visión de las Empresas, los Cuestionamientos y el Futuro Carbon Footprint: Part 2: Enterprises Viewpoint, Doubts and the Future

    Directory of Open Access Journals (Sweden)

    César Espíndola

    2012-01-01

    Full Text Available En esta segunda parte de la serie, se discute sobre la visión y posición que tienen las empresas frente al concepto de Huella del Carbono (HdC y de los métodos para cuantificarla. Se analiza los criterios de clasificación de emisiones en las principales metodologías de cálculo de la HdC y se discute sobre los principales cuestionamientos a la HdC, sobre los temas a resolver y sus alternativas de solución. Se presenta una base comparativa para los cuatro principales métodos de determinación de HdC actualmente vigentes en el mercado y se propone un método denominado Abaco para la contabilización de emisiones de CO2 equivalente , que permite identificar las características comunes de estos métodos. Todo esto puede servir de base en la toma de decisiones gerenciales para adoptar una determinada metodología. Se concluye que d e mantenerse la falta de claridad y comparabilidad en la determinación de emisiones podría provocar la pérdida de una gran oportunidad para lanzar una nueva economía medio-ambientalmente sostenible.In this second part of the series, the viewpoint of the enterprises and their position with respect to the implementation of carbon footprint (CFP quantification. The criteria for classification of emissions and the main methodologies for calculating the CFP are discussed and analyzed. The main questions and doubts about the CFP, on the subjects to be discussed and the alternatives of solution. A comparison of the main four methods currently used for determining the CFP and a method named Abacus for quantifying emissions of equivalent CO2 that allows identifying the common characteristics to all of them. All this can serve as basis for decision-making to adopt a given methodology. It is concluded that if the present situation of confusion of the different approaches to quantify the CFP continues, the companies and governments are loosing a great opportunity to arrive to a new environmentally sustainable economy.

  1. Carbono e nitrogênio de um Argissolo Vermelho sob floresta, pastagem e mata nativa Carbon and nitrogen of an Alfisol under forest, pasture and native forest

    Directory of Open Access Journals (Sweden)

    Clenio Nailto Pillon

    2011-03-01

    Full Text Available O monitoramento da matéria orgânica do solo (MOS constitui um indicador da qualidade do sistema de uso adotado. No Sul do Brasil, são escassos os trabalhos que avaliam as alterações no carbono orgânico total (COT, nitrogênio total (NT e a labilidade da MOS em sistemas de produção florestal. Diante desse contexto, este estudo teve como objetivo avaliar a concentração de COT e de NT no solo e na fração leve e livre (FLL da MOS de um Argissolo Vermelho distrófico sob eucalipto após 13 e 20 anos de implantação, adotando-se a mata nativa e um sistema com produção de pastagem como áreas de referência. Além disso, foi quantificado o estoque de COT e de NT na serrapilheira e na liteira das áreas florestais. As avaliações foram feitas, aleatoriamente, em três trincheiras por área, nas camadas de 0,00 a 0,05; 0,05 a 0,10; 0,10 a 0,20 e 0,20 a 0,40m. Maiores concentrações de COT, de NT e da FLL foram verificadas na camada superficial, sendo estas favorecidas pela adição de resíduos vegetais e pela minimização das operações de revolvimento do solo.The monitoring of soil organic matter content (MOS has been considered soil quality indicator. Few studies, in Southern Brazil, have evaluated changes in the total organic carbon (COT, total nitrogen (NT and in the lability of MOS in forestry systems. This study aimed to evaluate the COT, NT and free light fraction of MOS from 0.00 to 0.05, 0.05 to 0.10, 0.10 to 0.20 and 0.20 to 0.40m depths of the Alfisol under eucalyptus, native forest and pasture. In addition, it was quantified the stock of COT and NT in plant residues in forestry areas. The concentration of COT and NT and labile fractions of MOS increased favored by the addition of vegetables residues and by minimizing soil disturbance.

  2. Simulación de la fluencia en caliente de un acero microaleado con un contenido medio de carbono. III parte. Ecuaciones constitutivas

    Directory of Open Access Journals (Sweden)

    Cabrera, J. M.

    1997-08-01

    Full Text Available According to the part 1 of this work the constitutive equations of the hot flow behaviour of a commercial microalloyed steel have been obtained. For this purpose, the uniaxial hot compression tests described in the part 2 were employed. Tests were carried out over a range of 5 orders of magnitude in strain rate and 300 °C of temperature. Experimental results are compared with the theoretical model introduced in the first part of this study. It is concluded that deviations between experimental and theoretical curves are lower than 10 %. It is shown that the classical hiperbolic sine constitutive equation described accurately the experimental behaviour provided that stresses are normalized by the Young's modulus and strain rates by the self-diffusion coefficient. An internal stress must also be introduced in the latter equation when the initial grain size is fine enough.

    Siguiendo el planteamiento teórico efectuado en la I parte de este trabajo, se determinaron las ecuaciones constitutivas del comportamiento a la deformación en caliente de un acero comercial microaleado con un contenido medio de carbono. Para este objetivo se emplearon los ensayos de compresión uniaxial en caliente ya descritos en la II parte, los cuales se efectuaron en un rango de cinco órdenes de magnitud en velocidad de deformación y 300 °C de temperatura. Se comparan los resultados experimentales con el modelo teórico introducido en la I parte y se verifica que el error es inferior al 10 %. Se comprobó que la clásica ecuación del seno hiperbólico podía describir con precisión el comportamiento observado siempre y cuando las tensiones se normalicen por el módulo de Young, las velocidades de deformación por el coeficiente de autodifusión de la austenita, y se considere un efecto adicional sobre la tensión cuando el tamaño de grano inicial sea suficientemente fino.

  3. Residual Stress Distribution and Microstructure at a Laser Spot of AISI 304 Stainless Steel Subjected to Different Laser Shock Peening Impacts

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    Wenquan Zhang

    2015-12-01

    Full Text Available The effects of different laser shock peening (LSP impacts on the three-dimensional displayed distributions of surface and in-depth residual stress at a laser spot of AISI 304 stainless steel were investigated by X-ray diffraction technology with the sin2φ method and MATLAB 2010a software. Microstructural evolution in the top surface subjected to multiple LSP impacts was presented by means of cross-sectional optical microscopy (OM and transmission electron microscopy (TEM observations. Experimental results and analysis indicated that residual stress distribution and microstructure at a laser spot depended strongly on the number of multiple LSP impacts, and refined grain and ultra-high strain rate play an important role in the improvement of compressive residual stress of AISI 304 stainless steel. The analysis of treatment of the extended surface was presented to obtain uniform surface properties on the top surface of AISI 304 stainless steel.

  4. 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

    OpenAIRE

    Pavel Michel Almaguer‐Zaldivar; Roberto Andrés Estrada-Cingualbres

    2015-01-01

    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 ...

  5. Evaluation of Microstructure and Mechanical Properties of Laser Beam Welded AISI 409M Grade Ferritic Stainless Steel%Evaluation of Microstructure and Mechanical Properties of Laser Beam Welded AISI 409M Grade Ferritic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A K Lakshminarayanan; V Balasubramanian

    2012-01-01

    The microstructure analysis and mechanical properties evaluation of laser beam welded AISI 409M ferritic stainless steel joints are investigated. Single pass autogeneous welds free of volumetric defects were produced at a welding speed of 3 000 mm/min. The joints were subjected to optical microscope, scanning electron fractographe, microhardness, transverse and longitudinal tensile, bend and charpy impact toughness testing. The coarse ferrite grains in the base metal were changed into dendritic grains as a result of rapid solidification of laser beam welds. Tensile testing indicates overmatching of the weld metal is relative to the base metal. The joints also exhibited acceptable impact toughness and bend strength properties.

  6. 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)

  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. Comparative study of the microbiological corrosion among an AISI 304L and an API X65; Estudio comparativo de la corrosion microbiologica entre un AISI 304L y un API X65

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.; Arganis J, C.; Luna C, P.; Carapia M, L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Gonzalez F, E. [ITT, Toluca, Estado de Mexico (Mexico)

    2004-07-01

    Metallic samples of AISI 304L sensitized and API X65, were subjected to the action of an inoculated media with reductive sulphate microorganisms (SBR), carrying out electrochemical evaluations by means of the techniques of Polarization Resistance (RP), Tafel extrapolation (ET) and Electrochemical Noise (RE). The generated information was complemented with the analysis and diagnostic of the present damage in the surfaces exposed in both metals. The used electrochemical techniques allow to determine the corrosion velocities associated to each system, establishing that the uniform corrosion is not affected by the effect of the microorganisms; however, electrochemical noise, evidenced the formation of stings associated to the presence of bacteria. (Author)

  9. Characterization of passive film formed on AISI 316L stainless steel after magnetoelectropolishing in a broad range of polarization parameters

    Energy Technology Data Exchange (ETDEWEB)

    Rokosz, Krzysztof; Hryniewicz, Tadeusz [Politechnika Koszalinska, Division of Surface Electrochemistry, Raclawicka 15-17, PL 75-620 Koszalin (Poland); Raaen, Steiner [NTNU Trondheim, Institute of Physics, Trondheim (Norway)

    2012-09-15

    The aim of the paper is to present the changes in the surface film composition on AISI 316L stainless steel (SS) after electropolishing (EP) and magnetoelectropolishing (MEP) in a broad range of the process conditions. The X-ray photoelectron spectroscopy surface analyses were performed to reveal the effect of MEP. The EP process has been performed under natural convection (in a stagnant electrolyte), much above the polarization plateau. A series of experiments were carried out on AISI 316L SS samples in accordance with the five-level composite rotary statistical plan with the variables being the magnetic field intensity B (mT), and the anodic current density i (A dm{sup -2}). XP high resolution spectra have been obtained on AISI 316L SS surface concerning Fe 2p, Cr 2p, O 1s, S 2p, P 2p, and C 1s, respectively. The Cr:Fe ratio regarding both metallic M and compound X was also studied and calculated. At the end, the summary results of Cr/Fe = f(B, i) in relation to the corrosion potential, have been compared. The conclusions, concerning the selection of MEP process conditions, regarding the optimum Cr/Fe ratio and corrosion behavior, have been formulated. It was found the Cr:Fe ratio well correlates with the pitting corrosion potential. MEP process can modify not only the rate of dissolution to a determined extent, but also control the corrosion behavior and Cr:Fe ratio results. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Comparative study on structure, corrosion and hardness of Zn-Ni alloy deposition on AISI 347 steel aircraft material

    Energy Technology Data Exchange (ETDEWEB)

    Gnanamuthu, RM. [Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Gihung, Yongin, Gyeonggi 446-701 (Korea, Republic of); Mohan, S., E-mail: sanjnamohan@yahoo.com [Central Electrochemical Research Institute, (CSIR), Karaikudi 630 006, Tamilnadu (India); Saravanan, G. [Central Electrochemical Research Institute, (CSIR), Karaikudi 630 006, Tamilnadu (India); Lee, Chang Woo, E-mail: cwlee@khu.ac.kr [Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Gihung, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Electrodeposition of Zn-Ni alloy on AISI 347 steel as an aircraft material has been carried out from various baths. Black-Right-Pointing-Pointer The effect of pulse duty cycle on thickness, current efficiency and hardness reached maximum values at 40% duty cycle and for 50 Hz frequencies average current density of 4 A dm{sup -2}. Black-Right-Pointing-Pointer The XRF characterizations of 88:12% Zn-Ni alloy provided excellent corrosion resistance. Black-Right-Pointing-Pointer It is found that Zn-Ni alloy on AISI 347 aircraft material has better structure and corrosion resistance by pulse electrodeposits from electrolyte-4. - Abstract: Zn-Ni alloys were electrodeposited on AISI 347 steel aircraft materials from various electrolytes under direct current (DCD) and pulsed electrodepositing (PED) techniques. The effects of pulse duty cycle on thickness, current efficiency and hardness of electrodeposits were studied. Alloy phases of the Zn-Ni were indexed by X-ray diffraction (XRD) techniques. Microstructural morphology, topography and elemental compositions were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray fluorescence spectroscopy (XRF). The corrosion resistance properties of electrodeposited Zn-Ni alloy in 3.5% NaCl aqueous solution obtained by DCD and PED were compared using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) technique. Elemental analysis showed that 88% of Zn and 12% of Ni obtained from electrolyte-4 by PED technique at 40% duty cycle for 50 Hz frequencies having better corrosion resistance than that of deposits obtained from other electrolytes.

  11. Resistance spot welding joints of AISI 316L austenitic stainless steel sheets: Phase transformations, mechanical properties and microstructure characterizations

    International Nuclear Information System (INIS)

    Highlights: • Resistance spot welding of AISI 316L stainless steel sheets. • Microstructure prediction by the use of Schaeffler and Pseudo-binary diagrams. • Non-equilibrium phases including skeletal, acicular and lathy delta ferrite formed. • Mechanical characterization of weld nuggets including peak load and failure energy. • Different failure modes were found at various welding currents. - Abstract: In this paper, we aim to optimize welding parameters namely welding current and time in resistance spot welding (RSW) of the austenitic stainless steel sheets grade AISI 316L. Afterward, effect of optimum welding parameters on the resistance spot welding properties and microstructure of AISI 316L austenitic stainless steel sheets has been investigated. Effect of welding current at constant welding time was considered on the weld properties such as weld nugget size, tensile–shear load bearing capacity of welded materials, failure modes, failure energy, ductility, and microstructure of weld nuggets as well. Phase transformations that took place during weld thermal cycle were analyzed in more details including metallographic studies of welding of the austenitic stainless steels. Metallographic images, mechanical properties, electron microscopy photographs and micro-hardness measurements showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Backscattered electron scanning microscopic images (BE-SEM) showed various types of delta ferrite in weld nuggets. Three delta ferrite morphologies consist of skeletal, acicular and lathy delta ferrite morphologies formed in resistance spot welded regions as a result of non-equilibrium phases which can be attributed to the fast cooling rate in RSW process and consequently, prediction and explanation of the obtained morphologies based on Schaeffler, WRC-1992 and Pseudo-binary phase diagrams would be a difficult task

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

    Directory of Open Access Journals (Sweden)

    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

  13. EBSD karakterisering av et austenittisk rustfritt AISI 304 stål under in situ deformasjon ved ulike temperaturer

    OpenAIRE

    Wenn, Maia

    2014-01-01

    Denne masteroppgaven kartlegger martensittdannelsen i et austenittisk rustfritt stål som følge av ytre påkjenninger i form av temperatur og spenning. Dette er gjort ved hjelp av in situ deformasjon i skanning elektronmikroskop (SEM) i kombinasjon med diffraksjon av tilbakespredte elektroner (EBSD). Stålet som er undersøkt er AISI 304, som er et austenittisk rustfritt stål med en fullstendig austenittisk struktur. Stålet ble undersøkt ved tre forskjelli...

  14. The influence of the martensitic transformation on the fatigue of an AISI type 316 metastable stainless steel

    International Nuclear Information System (INIS)

    The influence of the martensitic transformation on the process of pulse tension fatigue of a AISI type 316 metastable stainless steel was studied at 250 and 1960c. The fatigue tests were performed on annealed and cold worked specimens in order to separate the effects of static transformation, dynamic transformation and work hardening. The fatigue limits obtained from the corresponding Wohler curves were compared for the different test conditions. The results showed that the fatigue is not affected by the dynamically induced martensite. On the other hand the static martensite, previously induced, appears to decrease the resistance to fatigue. The reasons for these effects are discussed. (Author)

  15. Effect of rare earth elements on microstructure and oxidation behaviour in TIG weldments of AISI 316L stainless steel

    International Nuclear Information System (INIS)

    The influence of rare earth addition in weld metal, on the microstructure and oxidation behaviour of AISI 316L stainless steel in dry air under isothermal condition at 973 K for 240 h is reported. Rare earth metal (REM) doped weld metal zone exhibits better oxidation resistance during isothermal holding as compared to base metal and undoped weld metal zone of 316L. Presence of both Ce and Nb in weld metal shows superior oxidation resistance than with Ce alone. TIG weld microstructures are presented by optical microscopy. The morphologies of the scales and nature of their adherence to the alloy substrates, and scale spallation have been characterized by SEM and EDAX

  16. Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa

    Energy Technology Data Exchange (ETDEWEB)

    Ellen M. Rabenberg; Brian J. Jaques; Bulent H. Sencer; Frank A. Garner; Paula D. Freyer; Taira Okita; Darryl P. Butt

    2014-05-01

    The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

  17. Effect of Cl– on the corrosive wear of AISI 321 stainless steel in H2SO4 solution

    Indian Academy of Sciences (India)

    Yanliang Huang; Xiaoxia Jiang; Sizuo Li

    2003-06-01

    The effect of Cl– on the corrosive wear behaviour of AISI 321 stainless steel in H2SO4 solution was studied via the corrosive wear rate, the load bearing capacity of passive film and the relationship between pitting and corrosive wear. There is a critical load at natural potential, below which the corrosive wear rate is slightly lowered by Cl–, while above which is increased. At natural potential there are more pits at low load than that at a higher one in the wear tracks and the pits are also deeper. The load bearing capacity is lowered by Cl– at passive region and then the corrosive wear rate increased.

  18. Formation of amorphous Ti alloy layers by excimer laser mixing of Ti on AISI 304 stainless-steel surfaces

    Science.gov (United States)

    Jervis, T. R.; Nastasi, M.; Zocco, T. G.; Martin, J. A.

    1988-07-01

    We used excimer laser radiation at 308 nm to mix thin layers of Ti into AISI 304 stainless steel. Different numbers of shots at a fluence about twice the threshold for melting varied the amount of mixing. When mixing is sufficiently complete, an amorphous surface layer is formed with Ti substituting for Fe on a one-to-one basis in the alloy. The laser mixing process, unlike Ti ion implantation, does not result in high incorporation of C in the processed layer, although some C from surface and interface contamination is incorporated into the surface layer.

  19. THE EFFECT OF THE ANNEALING TEMPERATURE ON THE CORROSION RESISTANCE OF WELD JOINT OF AISI 310 STEEL - SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Pavel Kovačócy

    2011-10-01

    Full Text Available The article presents samples of weld joint of AISI 310 austenitic steel which were subjected to solution annealing at various temperature - time exposures. The objective of the experiment was to determine the annealing temperature so that the steel should not be sensitized. Tendency to intercrystalline corrosion was analysed by means of a corrosion test in 10 % oxalic acid according to ASTM A 262. At the temperatures of 1000 and 1100°C held for 15 min. the steel was not sensitized. At the temperature of 850°C the steel was sensitized, i.e. susceptible to intercrystalline corrosion.

  20. Investigation And Optimization Of EDM Process Of AISI 4140 Alloy Steel Using Various Tool Electrodes: A Review Paper

    Directory of Open Access Journals (Sweden)

    Kishor Lal ,

    2014-11-01

    Full Text Available The purpose of this research work is to determine the optimized settings of key machining factors like pulse on time, discharge current and duty cycle for AISI 4140 alloy steel using various tool electrodes. The output responses will be measured are material removal rate (MRR,surface roughness(SR and tool wear rate(TWR. Mathematical models are proposed for the above are L27 orthogonal array. The micro structural changes in the work piece after machining process will also be examined by the use of SEM.

  1. Fatigue life improvements of the AISI 304 stainless steel ground surfaces by wire brushing

    Science.gov (United States)

    Ben Fredj, Nabil; Ben Nasr, Mohamed; Ben Rhouma, Amir; Sidhom, Habib; Braham, Chedly

    2004-10-01

    The surface and subsurface integrity of metallic ground components is usually characterized by an induced tensile residual stress, which has a detrimental effect on the fatigue life of these components. In particular, it tends to accelerate the initiation and growth of the fatigue cracks. In this investigation, to deliberately generate compressive residual stresses into the ground surfaces of the AISI 304 stainless steel (SS), wire brushing was applied. It was found that under the experimental conditions selected in this investigation, while the surface roughness was slightly improved by the brushing process, the surface residual stress shifted from a tensile stress (σ‖=+450 MPa) to a compressive stress (σ‖=-435 MPa). On the other hand, the work-hardened deformation layer was almost two times deeper after wire brushing. Concerning the fatigue life, an improvement of 26% in terms of endurance limit at 2×106 cycles was realized. Scanning electron microscope (SEM) observations of the fatigue fracture location and size were carried out to explain the fatigue life improvement. It was found that the enhancement of the fatigue strength could be correlated with the distribution and location of the fatigue fracture nucleation sites. Concerning the ground surfaces, it was seen that the fatigue cracks initiated at the bottom of the grinding grooves and were particularly long (150-200 µm). However, the fatigue cracks at the brushed surfaces were shorter (20-40 µm) and appeared to initiate sideways to the plowed material caused by the wire brushing. The results of the wire-brushed surface characterization have shown that significant advantages can be realized regarding surface integrity by the application of this low-cost process compared to shot peening.

  2. Friction Characteristics of Nitrided Layers on AISI 430 Ferritic Stainless Steel Obtained by Various Nitriding Processes

    Directory of Open Access Journals (Sweden)

    Hakan AYDIN

    2013-03-01

    Full Text Available The influence of plasma, gas and salt-bath nitriding techniques on the friction coefficient of AISI 430 ferritic stainless steel was studied in this paper. Samples were plasma nitrided in 80 % N2 + 20 % H2 atmosphere at 450 °C and 520 °C for 8 h at a pressure of 2 mbar, gas nitrided in NH3 and CO2 atmosphere at 570 °C for 13 h and salt-bath nitrided in a cyanide-cyanate salt-bath at 570 °C for 1.5 h. Characterisation of nitrided layers on the ferritic stainless steel was carried out by means of microstructure, microhardness, surface roughness and friction coefficient measurements. Friction characteristics of the nitrided layers on the 430 steel were investigated using a ball-on-disc friction-wear tester with a WC-Co ball as the counter-body under dry sliding conditions. Analysis of wear tracks was carried out by scanning electron microscopy. Maximum hardness and maximum case depth were achieved on the plasma nitrided sample at 520 ºC for 8 h. The plasma and salt-bath nitriding techniques significantly decreased the average surface roughness of the 430 ferritic stainless steel. The friction test results showed that the salt-bath nitrided layer had better friction-reducing ability than the other nitrided layers under dry sliding conditions. Furthermore, the friction characteristic of the plasma nitrided layer at 520 ºC was better than that of the plasma nitrided layer at 450 °C.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3819

  3. Determinación de carbono orgánico en materias primas cerámicas en presencia de siderita, FeCO3

    OpenAIRE

    Gazulla Barreda, María Fernanda; Gómez, Carmen M.; Rodrigo Carbonell, María Dolores; Orduña, Mónica

    2013-01-01

    La materia orgánica es una de las impurezas presentes en las materias primas utilizadas en la fabricación de pavimentos y revestimientos cerámicos. Durante el proceso de cocción, el carbono orgánico (Corgánico) puede producir la aparición de un núcleo negro conocido como “corazón negro”, que puede causar defectos en el producto final. Las materias primas cerámicas contienen Corgánico a nivel de mg·kg-1 (procedente de la materia orgánica) y carbono inorgánico (Cinorgánico) a nivel de porce...

  4. ALS - resources

    Science.gov (United States)

    Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association -- mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) Registry -- ...

  5. 冷轧AISI 304不锈钢微观组织及力学性能的变化%Evolution of the Microstructure and Mechanical Properties of AISI 304 Stainless Steels in Cold-Rolled

    Institute of Scientific and Technical Information of China (English)

    李勇峰; 蔡丽安; 马利杰; 刘贯军

    2015-01-01

    采用金相显微镜、铁素体测量仪、硬度计及力学分析等手段,研究了AISI 304不锈钢的微观组织和力学性能在冷轧过程中的演变规律.试验结果表明:冷轧变形可使AISI 304不锈钢产生形变诱发马氏体相变,试样中金属晶粒沿着轧制方向被拉扁拉长;在冷轧压下量较小时,仅有少量的奥氏体相转变为马氏体相,并且马氏体组织以板条状出现;冷轧压下量较大时,金属晶粒逐渐被拉长为纤维状;随着冷轧压下量的增大,马氏体体积分数、硬度和抗拉强度均随之增大,但延伸率逐步下降.

  6. Simulação e análise dosimétrica de protonterapia e íons de carbono no tratamento do melanoma uveal

    Directory of Open Access Journals (Sweden)

    Marília Tavares Christóvão

    2011-12-01

    Full Text Available OBJETIVO: Este artigo apresenta a avaliação dosimétrica da radioterapia por íons de carbono em comparação à protonterapia. MATERIAIS E MÉTODOS: As simulações computacionais foram elaboradas no código Geant4 (GEometry ANd Tracking. Um modelo de olho discretizado em voxels implementado no sistema Siscodes (sistema computacional para dosimetria em radioterapia foi empregado, em que perfis de dose em profundidade e curvas de isodose foram gerados e superpostos. Nas simulações com feixe de íons de carbono, distintos valores de energia do feixe foram adotados, enquanto nas simulações com feixe de prótons os dispositivos da linha de irradiação foram incluídos e diferentes espessuras do material absorvedor foram aplicadas. RESULTADOS: As saídas das simulações foram processadas e integradas ao Siscodes para gerar as distribuições espaciais de dose no modelo ocular, considerando alterações do posicionamento de entrada do feixe. Os percentuais de dose foram normalizados em função da dose máxima para um feixe em posição de entrada específica, energia da partícula incidente e número de íons de carbono e de prótons incidentes. CONCLUSÃO: Os benefícios descritos e os resultados apresentados contribuem para o desenvolvimento das aplicações clínicas e das pesquisas em radioterapia ocular por íons de carbono e prótons.

  7. Equações alométricas para estimativa de biomassa e carbono em árvores de reflorestamentos de restauração

    Directory of Open Access Journals (Sweden)

    Dirceu Lucio Carneiro de Miranda

    2011-06-01

    Full Text Available Este estudo teve como objetivos desenvolver e ajustar modelos alométricos para estimativa da biomassa seca e do carbono total em árvores plantadas em áreas de restauração florestal. Os dados dos ajustes são provenientes de 107 árvores de 44 espécies plantadas na região do Médio Vale do Paranapanema, SP, localizado nos Biomas Mata Atlântica e Cerrado. A biomassa seca e a massa de carbono foram obtidas por meio de amostragem destrutiva da parte aérea e subterrânea das árvores. Para o teste e ajuste dos modelos foi realizada a estratificação do conjunto inicial dos dados em ritmos de crescimento das espécies amostradas. Os ajustes foram feitos usando-se oito modelos lineares de cada variável dependente e dois obtidos pelo processo Stepwise-Forward. Os melhores modelos para estimativa da biomassa seca e carbono orgânico apresentaram coeficientes de determinação ajustado acima de 0,95 e erros-padrão percentuais abaixo de 32%. Os modelos baseados nos ritmos de crescimento das espécies mostraram melhores resultados estatísticos, atingindo R² = 0,985 e Syx% = 16,15 para biomassa seca das espécies de crescimento lento. Modelos provenientes do procedimento Stepwise geraram as melhores equações para as estimativas de biomassa seca e carbono total, e a estratificação dos dados dos diferentes ritmos de crescimento das espécies amostradas mostrou-se que foi adequada para melhorar o desempenho dos modelos.

  8. Wear resistance of TiAlSiN thin coatings.

    Science.gov (United States)

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions. PMID:23447962

  9. AISI304不锈钢表面硅化物渗层的制备与抗氧化性能%Preparation of silicide layer on AISI 304 stainless steel and oxidation resistance

    Institute of Scientific and Technical Information of China (English)

    安亮; 贾建刚; 马勤; 李鹏

    2011-01-01

    采用ω(NaCl)∶ω(KCl)∶ω(NaF)=2∶2∶1(摩尔比,下同)的中性熔融盐作为载体,ω(Na2SiF6)∶ω(Si)=8∶2粉末做为渗硅剂,800℃下渗硅10 h可实现在AISI 304不锈钢表面形成厚度约500μm的富含Cr、Ni合金元素的Fe3Si型硅化物渗层。采用X射线衍射仪(XRD)分析了渗硅层的物相组成,用附带能量色散谱仪(EDS)附件的扫描电子显微镜(SEM)研究了渗层截面的形貌和成分。结果表明,渗层以Fe3Si相为主,Cr在渗层中含量低于其在304不锈钢基体中含量,而Fe和Ni在%Fe3Si type silicide layer containing Cr and Ni alloying elements with a thickness of about 500 μm on AISI 304 stainless steel were formed in molten salts at 800 ℃ for 10 h using molten mixture of ω(Na2SiF6)∶ωSi=8∶2 as siliconizing agent and the molten halogenide of alkali metals of ω(NaCl)∶ω(KCl)∶ω(NaF)=2∶2∶1 as siliconizing agent carrier.The phase of the silicide layer was analyzed by X-ray diffraction.The micro structure and composition of the silicide layer were studied by scanning electron microscope(SEM) with energy dispersive X-ray spectrometer(EDS)attachment.The results show that the silicide layer mainly consists of Fe3Si.The content of Cr in silicide layer is lower than in AISI 304 steel matrix,while the same contents of Fe and Ni in the layer and in the matrix are observed.The oxidation kinetic curves of the Fe3Si type silicide layer at both 800 ℃ and 900 ℃ obey a parabolic rule.The high temperature oxidation properties of the silicide layer are a little better than that of the AISI 304 steel matrix at 800 ℃.A catastrophic failure of AISI 304 steel occurs at 900 ℃,while the high temperature oxidation properties of the silicide layer at 900 ℃ are better than that at 800 ℃.The composite oxide film containing SiO2 and Cr3O4 resuled from the uphill diffusion of Cr and Si at 900 ℃ accounts for the excellent high temperature

  10. Modelo para calculo estimación del carbono en Tipo Forestal Roble-Raulí-Coigüe en la Reserva Nacional Malleco: Chile

    Directory of Open Access Journals (Sweden)

    Norman Moreno Garcia

    2011-12-01

    Full Text Available El objetivo de este trabajo es la selección de un modelo para estimación de carbono en Tipo Forestal Roble-Raulí y Coigüe. La recolección de datos se realizo en la Reserva Nacional Malleco. Cada sitio fue representado por un grupo de 5 parcelas (cuadradas, de lado 35m, superficie 1225m2, ubicadas en un transecto según la pendiente más fuerte. Fueron estimados los volúmenes de madera con y sin corteza de la totalidad de los individuos por medio de funciones para cada especie del tipo forestal en estudio. La cantidad de carbono almacenado a nivel de fuste de las parcelas fue estimada aplicando la función universal de carbono. En cada parcela se contabilizaron los árboles por clase diamétrico de DAP, siendo definidas las clases a partir del DAP mínimo de 3 cm y con una amplitud de 5 cm. Fueron ajustados los modelos de Spurr, Meyer, Stoate, Naslund y Schumacher-Hall. El modelo Schumacher-Hall presento el mejor ajuste de acuerdo a los indicadores estadísticos considerados, además de una mejor distribución de residuales.

  11. KAPLAMASIZ SERMET TAKIMLA AISI 6150 ÇELİĞİNİN FREZELENMESİNDE KESME PARAMETRELERİNİN YÜZEY PÜRÜZLÜLÜĞÜNE ETKİSİ

    Directory of Open Access Journals (Sweden)

    Murat ÇETİN

    2011-12-01

    Full Text Available Bu çalışmada AISI 6150 (50CrV4 çeliğinin kaplamasız sermet takım ile Johnford VMC–550marka CNC dik işleme merkezinde, soğutma sıvısı kullanılmadan işlenmiştir. Beş farklı kesmehızı (220, 240, 260, 280 ve 300 m/dak ile diş başına 3 farklı ilerleme (0,10 - 0,16 ve 0,18 mm/diş ve iki farklı kesme derinliği (0,5 - 1 mm değerlerinde talaş kaldırma işlemleri gerçekleştirilerek, bu kesme parametrelerinin yüzey pürüzlülüğü üzerindeki etkileri araştırılarak optimum kesme parametreleri belirlenmeye çalışılmıştır. En iyi yüzey pürüzlülük değeri 0,5 mm talaş derinliğinde, 280 m/dak kesme hızında, 0,10 mm/diş ilerlemede 0,137 μm olarak belirlenmiştir.

  12. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    Science.gov (United States)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-09-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

  13. Irradiation creep and swelling of AISI 316 to exposures of 130 dpa at 385 to 4000C

    International Nuclear Information System (INIS)

    The creep and swelling of AISI 316 stainless steel have been studied at 385 to 4000C in EBR-II to doses of 130 dpa. Most creep capsules were operated at constant stress and temperature but mid-life changes in these variable were also made. This paper concentrates on the behavior of the 20% cold-worked condition but five other conditions were also studied. Swelling at ≤000C was found to lose the sensitivity to stress exhibited at higher temperatures while the creep rate was found to retain linear dependencies on both stress and swelling rate. The creep coefficients extracted at 4000C agree with those found in other experiments conducted at higher temperatures. In the temperature range of ≤4000C, swelling is in the recombination-dominated regime and the swelling rate falls strongly away from the ∼1%/dpa rate observed at higher temperatures. These lower rates of creep and swelling, coupled with the attainment of high damage levels without failure, encourage the use of AISI 316 in the construction of water-cooled fusion first walls operating at temperatures below 4000C. 23 refs., 8 figs

  14. Phase transformations in an AISI 410S stainless steel observed in directional and laser-induced cooling regimes

    Directory of Open Access Journals (Sweden)

    Milton Sergio Fernandes de Lima

    2012-02-01

    Full Text Available The applications of the chromium ferritic stainless steel AISI 410S have been considerably increased in the last years in many technical fields as chemical industries and oil or gas transportation. However, the phase transformation temperatures are, currently, unknown for this alloy. The aim of this work is to determine the alpha to gamma transformation temperatures of the AISI 410S alloy in different cooling conditions and to analyze them using continuous cooling theory. In order to achieve different cooling rates and thermal conditions, two complementary techniques were used: Bridgman furnace crystal growth and laser remelting technique. The measured solidification temperature was around 1730 and 1750 K. Plate-like and dendritic austenite precipitates were obtained in solid-state phase using growth rates between 5 and 10 µm/s in directional growth experiments. Only plate-like austenite phase was observed in the experiments using growth rates above 100 µm/s. The appearance of dendrites, with the consequent segregation of the elements, can be previously determined by the microstructure modeling currently proposed. Massive austenite can be produced from 0.3 to 10 mm/s rates at temperatures between 1100-1300 K. The structure might be less sensitive to corrosion because this phase is produced without microsegregation.

  15. Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

    Energy Technology Data Exchange (ETDEWEB)

    Durmaz, M., E-mail: mdurmaz@sakarya.edu.tr; Abakay, E.; Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey); Kilinc, B. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

    2015-03-30

    In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000°C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr{sub 2}N. The depth of the layer was 8.15 µm. The average hardness of the layer was 2160±15 HV{sub 0.025}. For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results.

  16. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    Science.gov (United States)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-07-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

  17. Swelling and creep observed in AISI 304 fuel pin cladding from three MOX fuel assemblies irradiated in EBR-II

    Science.gov (United States)

    Garner, F. A.; Makenas, B. J.; Chastain, S. A.

    2011-06-01

    Three 37-pin MOX-fueled experimental subassemblies were irradiated in EBR-II with fuel pin cladding constructed from annealed AISI 304 stainless steel. Analysis of the swelling and irradiation creep of the cladding showed that the terminal swelling rate of AISI 304 stainless steel appears to be ˜1%/dpa and that swelling is very reproducible for identical irradiation conditions. The swelling at a given neutron fluence is rather sensitive to both irradiation temperature and especially to the neutron flux, however, with the primary influence residing in the transient regime. As the neutron flux increases the duration of the transient regime is increased in agreement with other recent studies. The duration of the transient regime is also decreased by increasing irradiation temperature. In these assemblies swelling reached high levels rather quickly, reducing the opportunity for fuel pin cladding interaction and thereby reducing the contribution of irradiation creep to the total deformation. It also appears that in this swelling-before-creep scenario that the well-known "creep disappearance" phenomenon was operating strongly.

  18. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Science.gov (United States)

    Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 1689±85 HV0.01, and 181±7 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  19. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Energy Technology Data Exchange (ETDEWEB)

    Kilinc, B., E-mail: bkilinc@sakarya.edu.tr; Durmaz, M.; Abakay, E. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, SakaryaUniversity, Esentepe Campus, 54187Sakarya (Turkey); Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  20. Pengaruh variasi Holding Time Pada Perlakuan Panas Quench Annealing Terhadap Sifat mekanik dan Mikro Struktur Pada Baja mangan AISI 3401

    Directory of Open Access Journals (Sweden)

    Boby Endi Kurniawan

    2014-03-01

    Full Text Available 800x600 Baja mangan merupakan salah satu baja penting yang digunakan dalam industri dan memiliki aplikasi yang luas karena mempunyai wear resisten yang baik, kemampuan work hardening yang tinggi dengan ketangguhan dan keuletan yang tinggi. Tujuan dari penelitian ini adalah menganalisa pengaruh perubahan struktur mikro dan sifat mekanik pada baja mangan austenitic AISI 3401 .Penelitian baja mangan austenitk AISI 3401 ini dilakukan dengan perlakuan quench annneling pada temperature 10000C dengan empat variasi waktu tahan 30 menit, 60 menit, 120 menit yang diikuti pendinginan cepat media air, dan tanpa perlakuan. Kemudian dilakukan pengujian metalografi untuk mengetahui struktur mikro, uji kekerasan untuk mengetahui sifat mekanik dan uji XRD untuk menganalisis fasa hasil dari perlakuan quench annealing pada temperature 10000C dengan menggunakan empat variasi tersebut. Hasil penelitian diperoleh adanya pembentukan karbida dan austenit pada semua spesimen. Sedangkan hasil uji kekerasan yang didapatkan nilai yang tertinggi adalah pada waktu tahan 30 menit, yaitu 27 HRc Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4