Evaluación del grado de sensibilización en el acero inoxidable AISI

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González, O.

2003-12-01

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

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

Influencia de la soldadura sobre la rotura por tensiones en tubos de acero inoxidable austenitico del tipo 18-11NB(TP347

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Gutiérrez de Saiz-Solabarria, S.

2000-06-01

Full Text Available This work has been undertaken to study the stress cracking failure in various 18Cr11Ni [TP347 (18-11Nb, TP 321 (18-11 Ti, TP304 (18-11 and TP316 (18-11-2] types austenitic stainless steel tubes. The material used was produced hot-rolling at 76,2 mm φ (3"φ x 2,54 mm (1/10" thickness. The study was carried out at 593ºC and applied stress of 50 Ton/in2.

Se estudia el efecto de la soldadura sobre la rotura por tensiones en tubos de acero inoxidable austenítico estabilizado con Nb o Ti de los tipos 18-11Nb (TP 347 y 18-11Ti (TP 321 así como sin estabilizar del tipo 18-11 (TP 304 y con Mo del tipo 18-11-2 (TP 316. Los tubos, en todos los casos, son de dimensiones 76,2 mm (3” φ x 2,54 mm (1/10” de espesor y la tensión aplicada (σ de 10 Ton/in2, para una temperatura de servicio de 593ºC.

Stainless-Steel-Gadolinium Alloys; Alliages Acier Inoxydable-Gadolinium; Splavy iz nerzhaveyushchej stali i gadoliniya; Aleaciones de Acero Inoxidable-Gadolinio

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Copeland, M.; Kato, H. [Albany Metallurgy Research Center, Bureau Of Mines, United States Department of the Interior, Albany, OR (United States)

1964-06-15

mineures ont une grande influence sur les structures resultant de traitements equilibrants et sur les possibilites de transformation des aciers. Lorsque le gadolinium est melange a de l 'acier au chrome et au nickel, deux phases mineures, Fe{sub 9}Gd et Ni{sub 7}Gd, fondent a 1080 Degree-Sign C, ce qui impose une limite superieure aux temperatures de traitement a chaud et de transformation. Les auteurs ont pu facilement transformer des alliages comprenant jusqu'a 5 Degree-Sign Io en poids de gadolinium et determiner leurs caracteristiques mecaniques et leur resistance a la corrosion. Ils n'ont observe aucun changement dans les caracteristiques mecaniques de l'acier ou sa resistance a la corrosion par l'eau chaude, lorsqu'ils lui ont ajoute'jusqu'a 3% en poids de gadolinium. En raison des limites imposees aux temperatures de transformation des aciers au chrome et au nickel par le point de fusion des phases mineures, les auteurs ont etudie les effets du gadolinium sur des aciers au chrome. Ils ont releve une seule phase mineure qui fond a 1320 Degree-Sign C en etudiant l 'isoplethe du gadolinium a 10% en poids dans l 'alliage chrome-fer-gadolinium. Cette propriete permettrait d'equilibrer et de transformer ces aciers au gadolinium aux temperatures auxquelles on opere normalement. (author) [Spanish] En vista de la excelente resistencia a la corrosion de los aceros inoxidables y del interes que presenta el gadolinio como veneno nuclear, se han estudiado aleaciones de esos dos metales. El gadolinio fue aleado con aceros inoxidables de tipo AISI-304 y al cromo, y se estudiaron las relaciones de fase, la facilidad de trabajo y las propiedades de estas aleaciones. Se observo que en las aleaciones que contienen bajos porcentajes de gadolinio, los puntos de fusion de las fases menores ejercen un efecto muy marcado sobre las estructuras resultantes de los tratamientos de equilibracion y sobre la facilidad de trabajo de los afceros. Cuando se alea el gadolinio con acerce al cromo

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

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de Diego, G.

1998-10-01

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

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

Efecto de la Composición Química del Metal de Aporte y del Calor Aportado Sobre la Microestructura y las Propiedades Mecánicas de Juntas Soldadas de Aceros Inoxidables Dúplex

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Sebastián Zappa

Full Text Available Resumen Los aceros inoxidables dúplex poseen una microestructura dual (ferrita y austenita con contenidos aproximadamente iguales y se caracterizan por tener buena soldabilidad, buenas propiedades mecánicas y una alta resistencia a la corrosión generalizada y localizada. Gracias a estas características, estos aceros son los principales materiales a emplear en cañerías con altas exigencias, ampliamente utilizados en varias industrias, principalmente la petroquímica. Dichas propiedades están controladas por la composición química, el equilibrio microestructural y la ausencia de compuestos intermetálicos. El objetivo de este trabajo fue estudiar la influencia de la composición química del metal de aporte y el calor aportado sobre la microestructura y las propiedades mecánicas en juntas soldadas de cañerías de acero inoxidable dúplex. El metal base utilizado fue un acero inoxidable dúplex UNS S31803 de 8” de diámetro y 8,18 mm de espesor y los metales de aporte fueron dos alambres tubulares que depositan aceros inoxidables dúplex y lean dúplex (AWS A5.22: E2209T1-1 y E2209T1-G, mediante el proceso de soldadura semi-automático bajo protección gaseosa, soldados con alto y bajo calor aportado. De cada probeta se extrajeron muestras donde se determinó la composición química, se realizó la caracterización microestructural y se determinaron las propiedades mecánicas (dureza, tracción y Charpy-V.

Corrosión a alta temperatura de acero al carbono y acero inoxidable austenítico en atmósferas contaminadas por CO2

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Proy Pérez, Manuel

2014-01-01

Los efectos a veces catastróficos producidos por los procesos de corrosión a alta temperatura en atmósferas contaminadas por agentes agresivos, poseen la suficiente relevancia para ser objeto de estudio en los próximos años, debido a que en muchas ocasiones no están definidos claramente. Los aceros al carbono y los inoxidables austeníticos son materiales potencialmente utilizables en condiciones de elevada temperatura gracias a su excelente relación entre sus propiedades est...

Estudio de microestructura y composición de la oxidación en vapor a 700 y 750oC de los aceros austeníticos AISI 304, 316 y 317

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José Luddey Marulanda

2013-01-01

Full Text Available Se ha investigado la oxidación de los aceros inoxidables austeníticos AISI SAE: 304, 316 y 317; a temperaturas de 700 y 750oC, en una atmósfera próxima al 100% de vapor de agua, y de 10 a 1000h de exposición. La finalidad es comprobar la calidad de los aceros austeníticos y estudiar la morfología, composición y estructura de la fases de las capas formadas en la cascarilla del óxido de las muestras por Microscopía Electrónica de Barrido (SEM, Análisis de Rayos X por Dispersión de Energía (EDAX y Difracción de Rayos X (XRD, respectivamente. Así como también, se ha realizado a diferentes tiempos un estudio sistemático de termogravimetría de las muestras oxidadas, donde se ha observado que el acero AISI 304 presentó la menor ganancia de masa y el acero AISI 316 fue el de mayor de masa respecto a los tres aceros del trabajo. Adicionalmente fue realizado un estudio teórico de simulación termodinámica de oxidación en vapor de los tres aceros, en las mismas condiciones experimentales y mediante el programa Thermo-calc. En estos aceros oxidados se han comprobado la presencia de estructuras de fases de óxidos como: Fe2O3, espinelas protectoras Fe3O4 y Cr2NiO4, y óxidos mixtos de tipo (CrxFey2O3, (Fe,Cr,Mn3O4 y Ni6MnO8. Finalmente, se discute un posible mecanismo de la formación de las capas de óxidos de las muestras ensayadas.

Evaluación de diferentes aceros para la evolución de hidrógeno en KOH

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Falk Michel Julke

2014-05-01

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

Análisis de la resistencia a la corrosión de barras corrugadas de acero inoxidable en medios acuosos que simulan el hormigón

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Belzunce, F. J.

2004-04-01

Full Text Available The corrosion behaviour of stainless steel reinforced bars used in civil engineering was studied. Different electrochemical tests were performed using several stainless steel bars (austenitic and duplex, hot and cold rolled, in the presence of a solution, which simulates the contact with salt contaminated concrete. The corrosion rates were determined and also their behaviour against localized corrosion (pitting.

Se ha realizado un estudio sobre la resistencia a la corrosión de barras corrugadas de acero inoxidable utilizadas en construcción civil para armar el hormigón. Con este objeto se han realizado diferentes ensayos electroquímicos en presencia de un medio acuoso básico, que simula el contacto con hormigón contaminado con sal, y se ha determinado la velocidad de corrosión y la resistencia a la formación de picaduras de diferentes calidades de aceros inoxidables (austeníticos y dúplex, tanto conformadas en caliente como en frío.

Evaluación de la adherencia del biofilm sobre salivaderas dentales de acero inoxidable, cerámica y opalina

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Butler, Teresa Adela

2009-01-01

El objetivo principal de esta investigación fue estudiar el desarrollo de la biopelícula depositada sobre las salivaderas dentales de tres materiales diferentes (acero inoxidable, cerámica y opalina), de equipos odontológicos correspondientes a dos zonas diferentes del casco urbano de la ciudad de La Plata (Z1 y Z2). Para ello se realizaron 38 cortes de salivaderas dentales de los tres materiales, de cada zona En primer lugar se realizó el análisis de la microbiota planctónica y sé...

Estudio de electrodeposición de cobre sobre electrodos porosos de grafito y acero inoxidable vía SEM-DRX y análisis de imagen

OpenAIRE

Constanzo-R., Robinson; Pagliero-N., Antonio; Vergara-G., Froilán

2014-01-01

El objetivo de este trabajo fue realizar un análisis cualitativo de la distribución de un electrodepósito de cobre en el interior de electrodos porosos (EP) de acero inoxidable y carbono grafito. Para ello, se realizaron pruebas de electrodepositación de cobre a nivel de laboratorio, con un posterior análisis de cortes de muestras de acero y grafito vía Microscopía Estereoscópica, Microscopía SEM-DRX y Análisis de Imagen, los cuales mostraron que el cobre no se deposita en forma uniforme al i...

Oxidación en vapor de agua del acero inoxidable aisi 317 a 700 y 750ºc

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MARULANDA AREVALO, JOSE LUDDEY; REMOLINA MILLAN, ADULJAY; BARON, JAIRO ALBERO

2013-01-01

Se realizó la oxidación del acero inoxidable austenítico AISI SAE 317, a temperaturas de 700 y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento a la corrosión. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de Microscopia Electrónica de Barrido (SEM) y difracción de rayos X (DRX), para observar cómo se forman las capas de óxidos y discutir el posible mecanismo de oxidación en vapor de agua. Se encontró que el mecanismo de...

OXIDACIÓN EN VAPOR DE AGUA DEL ACERO INOXIDABLE AISI 317 A 700 Y 750ºC

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José Luddey Marulanda Arevalo; Aduljay Remolina Millan; Jairo Alberto Barón

2013-01-01

Se realizó la oxidación del acero inoxidable austenítico AISI SAE 317, a temperaturas de 700 y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento a la corrosión. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de Microscopia Electrónica de Barrido (SEM) y difracción de rayos X (DRX), para observar cómo se forman las capas de óxidos y discutir el posible mecanismo de oxidación en vapor de agua. Se encontró que el mecanismo de...

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

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

2009-07-01

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

Optimización topológica y fabricación aditiva de un soporte aeronáutico mediante sinterizado láser de acero inoxidable 15-5PH

OpenAIRE

Marchal Montes, Álvaro

2016-01-01

El objetivo de este trabajó será la aplicación de la optimización topológica a un soporte usado en el sector aeronáutico para reducir su masa que posteriormente se fabricará mediante fabricación aditiva con tecnología DMLS (Direct Metal Laser Sintering) en acero inoxidable 15-5PH. Para llegar a una buena optimización topológica será necesario estudiar todos los caminos de optimización posibles hasta llegar a una correcta mediante softwares adecuados además de adaptarla a la fabricación ad...

PROTECCIÓN CONTRA LA CORROSIÓN EN SALES FUNDIDAS DE UN ACERO HOT ROLLED, EN EL RANGO DE TEMPERATURAS DE 400 ºC-600 ºC, RECUBIERTO POR ROCIADO TÉRMICO CON ACERO INOXIDABLE 312

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JOSE LUDDEY MARULANDA

2009-01-01

Full Text Available Se evaluó la corrosión por sales fundidas mediante la técnica gravimétrica en un acero de bajo carbono tipo hot rolled, rociado térmicamente con una aleación de acero inoxidable tipo 312, con el equipo Rototec, en una mezcla de sal 20% Na2SO4 - 80% V2O5, entre 400ºC - 600ºC, durante tiempos de 1-7-22 horas. Los resultados mostraron una moderada protección de la capa rociada térmicamente y se presentó alta degradación en el recubrimiento a 600ºC. Se concluyó que la velocidad de corrosión aumenta con la temperatura y disminuye con el tiempo de exposición.

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

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

2005-01-01

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

Estudio de la calidad de recubrimientos de hidroxiapatita sobre acero inoxidable implantable aplicados mediante proyección térmica con plasma

OpenAIRE

Bernal Gaona, Sandra Paola

2013-01-01

El objetivo de este trabajo de investigación se basó en el estudio de los parámetros del proceso de deposición de recubrimientos de hidroxiapatita sobre substratos de acero inoxidable implantable mediante el proceso de proyección térmica con plasma atmosférico, que pueden afectar de forma significativa la calidad de los recubrimientos, en cuanto a su cristalinidad y adherencia al substrato. Como parámetros a evaluar se tomaron el tamaño de grano de la hidroxiapatita, el espesor...

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.

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

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Botella, J.

1998-05-01

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

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

Efecto de las variables del procedimiento de soldadura sobre las propiedades mecánicas y la resistencia a la corrosión en depósitos de soldadura de aceros inoxidables supermartensíticos

OpenAIRE

Zappa, Sebastián

2011-01-01

La soldadura de los aceros inoxidables martensíticos ha presentado ciertas dificultades y el uso de tratamientos térmicos es normalmente obligatorio. Las razones son diferentes para cada grado de acero, pero en general, es común obtener alta dureza y baja tenacidad en la zona afectada por el calor. Este hecho está asociado con la estructura martensítica en sí misma y el contenido de carbono. Una posible solución a este problema y para alcanzar determinadas propiedades en condición como soldad...

Efectos gammágenos del cobre en los aceros inoxidables 18Cr8Ni

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Botella, J.

1997-10-01

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

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

Correlaciones entre la microestructura y la atenuación sonora en un acero inoxidable martensítico

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Daniel Ramírez C.

2004-01-01

Full Text Available En este trabajo se exploró la relación entre la microestructura de un acero inoxidable martensítico y las variaciones en el sonido producido por un instrumento metalófono construido con dicho material. Para lograr este propósito, se hicieron copias de una de las placas de un glockenspiel y éstas fueron sometidas a diferentes tratamientos térmicos. Se construyeron montajes que permitieron producir sonidos mediante la excitación por percusión o electromagnética de las placas y se desarrollaron procedimientos para el análisis de las señales adquiridas usando programas de que permitían un análisis automático de la información. A partir de los resultados fue posible establecer correlaciones entre la microestructura obtenida con los diferentes tratamientos térmicos y características de los sonidos tales como la envolvente de atenuación y frecuencias predominantes.

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

OpenAIRE

García López, Christian Jesus

2012-01-01

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

Formación de maclas durante el enfriamiento en aceros inoxidables superferríticos envejecidos

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Salán, M. N.

2005-12-01

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

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

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

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Puchi-Cabrera, E. S.

2007-06-01

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

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

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

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Bautista, A.

2006-06-01

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

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

Oxidación en vapor de agua a 700 ºC y 750 ºC del acero inoxidable AISI 317 recubierto con aluminio por CVD-FBR.

OpenAIRE

Jose L. Marulanda; Saul I. Castañeda; Aduljay Remolina

2014-01-01

Se realizó la oxidación del acero inoxidable austenítico AISI 317 recubierto con aluminio por deposición química de vapor en lecho fluidizado, a temperaturas de 700 °C y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de SEM y difracción de rayos X, para observar la morfología de los óxidos. Se realizó la simulación termodinámica del proceso de oxidación en vapor de agua de...

Deposición electroforética de una porcelana dental sobre acero inoxidable austenítico 304

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Vargas, G.

2003-02-01

Full Text Available An alternative technique for the production of dental restorations with porcelain, is the electrophoretic deposition (EPD. In this work, deposits of dental porcelain on stainless steel were obtained by EPD using water, ethanol and isopropanol as suspension mediums. The effect of the porcelain concentration, the intensity of the electric field and the suspension medium on the quantity of deposited mass were studied. All the tests were carried out at constant voltage, using a deposition time of 3 min. The particle size of the dental porcelain was in the range between 1.5 and 2.3 μm in the suspension. The results showed that the porcelain in the aqueous medium presented the major deposition velocity, in comparison with both ethanol and isopropanol. However, due to low the low suspension stability and hydrolysis of the water problems, the best coating finishes were obtained with ethanol. These results were obtained applying voltages between 70 and 150 V, for a deposition time of 3 min. Using isopropanol heterogeneous deposits were obtained due to the low suspension stability and to electrochemical reactions problems in the working electrodes, resulted from the high voltages application.

Una técnica alternativa para la fabricación de restauraciones dentales con porcelana, es la deposición electroforética (EPD. En este trabajo depósitos de porcelana dental sobre acero inoxidable fueron obtenidos por EPD utilizando como medios de suspensión: agua, etanol e isopropanol. Se estudió el efecto de la concentración de porcelana, de la intensidad del campo eléctrico y del medio de suspensión sobre la cantidad de masa depositada. Todas las pruebas fueron realizadas a voltaje constante, utilizando un tiempo de deposición de 3 min. La porcelana dental utilizada presentó un intervalo de tamaño de partícula entre 1,5 y 2,3 μm. Los resultados mostraron que la porcelana en el medio acuoso presentó la mayor velocidad de deposición, en

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

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Ricardo Gustavo Rodríguez Cañizo

2010-07-01

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

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

OpenAIRE

Diego Pérez-Muñoz; José Luddey Marulanda-Arévalo; Juan Manuel Meza-Meza

2015-01-01

Los recubrimientos de aluminio depositados sobre el acero inoxidable austenítico AISI 317 por Deposición Química de Vapor en Lecho Fluidizado (CVD-FBR) presentan a altas temperaturas una reducción de la velocidad de corrosión de más de 80 veces. Se realizó la caracterización mecánica de los recubrimientos por medio de microdureza, nanoindentación, para conocer cómo se vieron afectas las propiedades mecánicas (en especial la dureza y el módulo de Young) del recubrimiento y del sustrato luego d...

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

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Narváez, L.

2013-04-01

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

Losas de concreto reforzadas con acero inoxidable de desecho Reinforced concrete slabs with stainless steel waste

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Jorge Alberto Pérez González

2008-08-01

Full Text Available Se muestran los resultados de un programa experimental que explora la reutilización de materiales de desecho industrial (específicamente láminas de acero inoxidable producto de la acuñación de moneda como refuerzo en losas de concreto. Para ello se elaboraron 23 especímenes tipo viga-losa a escala natural con dicho refuerzo a fin de determinar su comportamiento en términos de resistencia, ductilidad y formas de falla; el análisis experimental de modelos ensayados con diferentes cantidades de refuerzo muestra que en algunos casos, bajo ciertas condiciones de cuantías y colocación del mismo, es posible alcanzar capacidades de carga y formas de falla similares a las de especímenes de control con refuerzo tradicional. En base a estos resultados se concluye en la factibilidad de utilizar el material arriba descrito como refuerzo alternativo en elementos estructurales de concreto, tratando de encontrar alternativas más económicas en la construcción de vivienda popular.The results from an experimental program that explores the use of industrial waste materials (specifically sheets of stainless steel that result of the currency coinage as reinforcement for concrete slabs are presented. Twenty three full size beam-deck specimens were built in order to measure resistance, ductility and failure modes; the experimental analysis in models with reinforcement in different quantities shows that in some cases, under certain quantities and location, it is possible to reach similar load capacities and failure modes as specimens with traditional reinforcement. Based on these results, it is concluded the feasibility of using the material described above as alternative reinforcement in structural concrete elements, as an economic option in the construction of social housing.

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

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Miguel, V.

2010-12-01

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

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

Nitrocarburación mediante el proceso TENIFER QDQ de aceros inoxidables austeníticos estabilizados : caracterización química y estudio de su comportamiento frente al desgaste y la corrosión

OpenAIRE

Bellas Muiño, Leonardo

2016-01-01

[Resumen]La nitrocarburación en baño de sales se utiliza para mejorar las propiedades tribológicas de los aceros inoxidables. Sin embargo, la aparición de carburos y nitruros de elementos de aleación en la capa externa puede tener efectos contraproducentes para su resistencia a la corrosión. Por este motivo, el proceso TENIFER®QPQ introduce una etapa de oxidación a altas temperaturas con objeto de formar una capa de magnetita (Fe3O4) que incrementa la resistencia a la corrosión...

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

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de Damborenea, J.

1995-04-01

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

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

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

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María Elena Márquez Fernández

2007-03-01

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

Intergranular stress corrosion in soldered joints of stainless steel 304.; Corrosion intergranular bajo esfuerzo en uniones soldadas de acero inoxidable 304

Energy Technology Data Exchange (ETDEWEB)

Zamora R, L [Instituto Nacional de Investigaciones Nucleares, Mexico City (Mexico)

1994-12-31

The intergranular stress cracking of welded joints of austenitic stainless steel, AISI 304, is a serious problem in BWR type reactors. It is associated with the simultaneous presence of three factors; stress, a critical media and sensibilization (DOS). EPR technique was used in order to verify the sensibilization degree in the base metal, and the zone affected by heat and welding material. The characterization of material was done. The objective of this work is the study of microstructure and the evaluation of EPR technique used for the determination of DOS in a welded plate of austenitic stainless steel AISI 304. (Author).

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

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José Ricardo Cano Rodas

2004-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2006-07-01

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

Elasto-plastic hardening models adjustment to ferritic, austenitic and austenoferritic Rebar; Ajuste de los aceros corrugados ferríticos, austeníticos y austenoferríticos a los modelos de endurecimiento elastoplástico por deformación

Energy Technology Data Exchange (ETDEWEB)

Hortigóna, B.; Gallardo, J.M.; Nieto-García, E.J.; López, J.A.

2017-09-01

The elastoplastic behaviour of steel used for structural member fabrication has received attention to facilitate a mechanical-resistant design. New Zealand and South African standards have adopted various theoretical approaches to describe such behaviour in stainless steels. With respect to the building industry, describing the tensile behaviour of steel rebar used to produce reinforced concrete structures is of interest. Differences compared with the homogenous material described in the above mentioned standards and related literatures are discussed in this paper. Specifically, the presence of ribs and the TEMPCORE® technology used to produce carbon steel rebar may alter the elastoplastic model. Carbon steel rebar is shown to fit a Hollomon model giving hardening exponent values on the order of 0.17. Austenitic stainless steel rebar behaviour is better described using a modified Rasmussen model with a free fitted exponent of 6. Duplex stainless steel shows a poor fit to any previous model. [Spanish] Uno de los principales factores tenidos en cuenta en la fabricación de aceros estructurales es su comportamiento durante la fase elastoplástica o de endurecimiento por deformación. Normas neozelandesas y sudafricanas plantean diversas aproximaciones teóricas para describir dicho comportamiento en el caso de los aceros inoxidables. En el campo de la construcción resulta de interés la descripción del comportamiento tenso-deformacional de los aceros corrugados utilizados en las estructuras de hormigón armado. En este artículo se discuten los modelos planteados en las normas citadas anteriormente así como los existentes en la literatura tanto para los aceros corrugados inoxidables como para los aceros al carbono fabricados mediante el proceso denominado TEMPCORE® Los aceros TEMPCORE® analizados arrojan un valor del exponente de endurecimiento por deformación según el modelo de Hollomon de 0.17. Los aceros inoxidables austeníticos se ajustan mejor al modelo

A comparison of tensile, fracture and fatigue mechanical behaviour of structural reinforcing bars made with different steels

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Rodríguez, C.

2013-09-01

Full Text Available The use of austenitic stainless steels as rebar is an option increasingly used in reinforced concrete structures exposed to aggressive environments and especially those that have to work in marine environments. The same is true for duplex stainless steel rebars, although nowadays they have a lower use, mainly due to the fact that their inclusion in the reinforced concrete standards was delayed 10 years compared to austenitic stainless steel ones, and consequently their in-service behavior is not as well known. A study of the mechanical properties, including fracture toughness, fatigue behaviour and corrosion resistance in saline alkaline environments of austenitic (AISI 304LN and 316LN and duplex (D2205 stainless steel reinforcing bars was performed in this work. Bars made on a high ductility carbon steel (B500SD that are normally used to reinforce concrete were also characterized and used as a comparison. Stainless steel reinforcing bars show mechanical properties at least similar but usually higher than one of the best carbon steel re-bars (B500SD, along with a significantly higher ductility and, of course, much better corrosion behaviour in saline alkaline environments.El uso de aceros inoxidables austeníticos como armaduras de refuerzo es una opción cada vez más utilizada en estructuras de hormigón armado expuestas a ambientes agresivos y especialmente en las que han de trabajar en ambientes marinos. Lo mismo cabe decir de las armaduras de acero inoxidable dúplex, si bien su uso es menor, debido sobre todo a que su inclusión en la normativa aplicable al armado de hormigón se retrasó 10 años con respecto a los inoxidables austeníticos y, consecuentemente, su comportamiento en servicio es menos conocido. En este trabajo se analiza el comportamiento mecánico, incluyendo fractura y fatiga, así como la resistencia a la corrosión en medios que simulan un hormigón contaminado de cloruros, de armaduras fabricadas tanto con

Passivation of duplex stainless steel in solutions simulating chloride-contaminated concrete

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Takenouti, H.

2007-12-01

Full Text Available Most studies published to date on the corrosion behaviour of stainless reinforcing steel are based on austenitic steel. The market presence of corrugated duplex steel is growing, however. The present study compared passivity in 2205 type duplex and 304 type austenitic stainless steel. Polarization tests in chloride-containing Ca(OH2 solutions confirmed the exceptional performance of duplex steels. X-ray photoelectronic spectroscopy (XPS showed that the passive layer generated on duplex stainless steel in media simulating concrete pore solutions had a higher Cr content than the layer formed on steel in contact with the air. The XPS results also revealed that in duplex steel the form adopted by the passive layer Fe oxides was Fe3O4 in the solutions simulating concrete, rather than Fe2O3, as in duplex steel exposed to air. Electrochemical impedance spectroscopy (EIS can be used to monitor the transformations taking place in the passive layer and analyze the factors involved.La mayoría de los estudios publicados hasta el momento sobre el comportamiento frente a la corrosión de armaduras de acero inoxidable se basan en aceros austeníticos. Sin embargo, la presencia en el mercado de aceros corrugados dúplex es cada vez más importante. En este trabajo se analiza la pasividad de un acero inoxidable dúplex tipo 2205 en comparación con la de un inoxidable austenítico tipo 304. Los ensayos de polarización en disoluciones de Ca(OH2 con cloruros confirman el excepcional comportamiento de los aceros dúplex. La espectroscopía fotoelectrónica de rayos X (XPS informa de que la capa pasiva generada en aceros inoxidables dúplex en medios que simulan la disolución de los poros del hormigón posee mayor contenido en óxidos de Cr que la formada en aire. También se puede deducir de los resultados de XPS que los óxidos de Fe de la capa pasiva de los aceros dúplex se encuentran en forma de Fe3O4 en las disoluciones que simulan el hormigón en vez de en

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

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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)

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

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Ohanian, Mauricio

2014-06-01

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

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

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

2006-07-01

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

PROTECCIÓN CONTRA LA CORROSIÓN POR SALES FUNDIDAS DE UN ACERO AL CARBONO POR ROCIADO TERMICO

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JOSE MARULANDA; ANDRÉS GARCÍA; JOSE VITOLA

2009-01-01

Se evaluó la corrosión por sales fundidas mediante la técnica gravimétrica en un acero de bajo carbono rociado térmicamente con una aleación de acero inoxidable, en una mezcla de sal con 20% Na2SO4 - 80% V2O5, entre 700ºC - 850ºC. Los resultados de las pruebas gravimétricas mostraron una deficiente protección de la capa rociada térmicamente y se presentó alta degradación en el recubrimiento protector, debido a que las temperaturas de exposición fueron mayores que las temperaturas de fusión de...

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.

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

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Jose Luddey Marulanda-Arevalo

2015-01-01

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

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

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D. Villalobos

2010-09-01

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

Influencia de la fase sigma en la laminación en frío de los aceros inoxidables dúplex

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Fargas, G.

2004-04-01

Full Text Available One of the steps in the industrial rolling process of duplex stainless steels is the annealing heat treatment after hot rolling. If this annealing is performed in a temperature range that favours the precipitation of intermetallic phases, the mechanical properties can be modified considerably. The formation of these precipitates has a detrimental effect on the DSS ductility and toughness, so it will be a drawback for further cold rolling. In the present investigation, the effect of the sigma phase during cold rolling of a duplex stainless steel type EN 1.4462 has been studied. To simulate this process, compression tests up to a thickness reduction similar to that performed at industrial level have been done. The testing samples were studied by optical microscopy, SEM (scanning electronic microscopy and TEM (transmission electronic microscopy. Afterwards, some of the annealing conditions were selected in order to carry out cold rolling, using a laboratory scale machine, with the aim to observe if they offered a similar behaviour as that experienced in the compression tests. The results show that only the annealing condition at 975ºC during 10 minutes allows to produce sheets without rolling defects.

Una de las etapas en el proceso de fabricación industrial de los aceros inoxidables dúplex laminados es el tratamiento térmico de recocido posterior a la laminación en caliente. Si dicho recocido se efectúa en un rango de temperaturas que favorezca la formación de fases intermetálicas, las propiedades mecánicas del material pueden modificarse notablemente. La presencia en la microestructura bifásica de dichos precipitados provoca efectos muy perjudiciales sobre la ductilidad y la tenacidad del material, pudiendo llegar a hacer inviable la posterior etapa de laminación en frío. En el presente trabajo se ha estudiado el efecto sobre el proceso de laminación en frío de la presencia de fase sigma en un acero dúplex tipo E.N. 1

Zirconium oxide deposits (ZrO{sub 2}) and titanium oxide (TiO{sub 2}) on 304l stainless steel; Depositos de oxido de circonio (ZrO{sub 2}) y oxido de titanio (TiO{sub 2}) sobre acero inoxidable 304L

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Davila N, M. L.

2015-07-01

This research project aims to carry out the surface and electrochemical characterization to obtain the optimum conditions of the hydrothermal deposits of zirconium oxide ZrO{sub 2} (baddeleyite) and titanium oxide TiO{sub 2} (anatase and rutile phases) on 304l stainless steel, simulating an inhibiting protective layer. 304l steel specimens were cut, pre-oxidized in water at a temperature of 288 degrees Celsius and 8 MPa, similar to those of a typical BWR conditions. From the titanium oxide anatase crystalline phase, the rutile phase was obtained by a heat treatment at 1000 degrees Celsius. The Sigma-Aldrich pre-oxidized powders and steel 304l were characterized using techniques of X-ray diffraction, scanning electron microscopy, X-ray dispersive energy, chemical mapping and Raman spectrometry. The pre-oxidized steel has two oxide layers, an inner layer with nano metric crystals and another outer of larger crystals to 1μm, with the formation of hematite and magnetite, this predominating. The surface that contacted the sample holder has larger crystals. Hydrothermal deposits were carry out from suspensions of 10, 100 and 1000 ppm, of the crystal phases of anatase, rutile and baddeleyite, on the pre-oxidized steel at a temperature of 150 degrees Celsius for 2 and 7 days, samples were analyzed by X-ray diffraction, scanning electron microscopy, X-ray dispersive energy, Raman spectrometry and Tafel polarization. The suspension to 1000 ppm for 7 days coated surface most; the baddeleyite deposit is noticed more homogeneous than anatase and rutile. The deposit is favored when hematite and magnetite crystals are larger. The chemical mapping on deposits show that even after being immersed in water to 288 degrees Celsius during 30 days, the deposits are still present although a loss is observed. A reference electrode was assembled to conduct electrochemical tests of Tafel able to withstand a temperature of 288 degrees Celsius and pressure of 8 MPa. The baddeleyite deposit

Ductility in a new low nickel stainless steel for reinforced concrete

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Cobo, A.

2011-12-01

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

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

Caracterización de una nueva membrana cerámica de microfiltración con soporte de tejido en acero inoxidable flexible

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Palacio, L.

1999-04-01

Full Text Available In this work we present the characterization of a ceramic flexible membrane, made by SynthesechemieⓇ, with a nominal pore size of 0.45 μm. This membrane consists in an α-alúmina porous support which has an embedded stainless steel metallic network, onto what a selective layer of titanium dioxide has been deposited. Membrane characterization has been realized with the aid of several techniques as: atomic force microscopy (AFM, air-liquid displacemente porosimetry and mercury porosimetry. Each tecnique giving information on different aspects: surface characteristics, bulk pores and active pores. Although the total pore size distribution is rather broad, the active pores (those opened to flux present a narrow distribution with a mean pore size very close to the manufacturer nominal value.

En este trabajo se ha abordado la caracterización de una membrana cerámica de microfiltración flexible, fabricada por SynthesechemieⓇ con tamaño de poro nominal de 0.45 μm. Ésta consiste en un soporte poroso de α-alúmina que posee un armazón formado por una red metálica de acero inoxidable sobre el cual existe una capa selectiva de óxido de titanio. La caracterización de la membrana ha sido realizada con diversas técnicas como: microscopia de fuerza atómica (AFM, porometría de desplazamiento aire-líquido y porosimetría de mercurio. Cada técnica da información sobre aspectos diferentes: superficie, poros totales y poros activos. Si bien la distribución total de tamaños de poro es bastante ancha, los poros activos (abiertos al flujo presentan una distribución de tamaños estrecha con un valor medio muy próximo al nominal.

Efecto de la biopelícula en la corrosión de aceros inoxidables

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Bethencourt, M.

2010-02-01

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

En este trabajo se ha estudiado la influencia de las biopelículas en los procesos de corrosión de diferentes aleaciones de acero inoxidable, situadas durante 4 años en dos puntos de una estación depuradora de aguas residuales. Se caracterizó el microambiente físico-químico en el interior de las biopelículas mediante microelectrodos de O₂, H_2S y pH, y se cuantificaron las tasas de corrosión a partir del número, diámetro y profundidad de picadura. Los resultados obtenidos muestran un desarrollo más notable de las biopelículas y un número de picaduras significativamente mayor en el canal de salida de desbastes que en el canal de recirculación de fangos. Con base en las características del agua sobrenadante y en las medidas realizadas con microelectrodos, se sugiere que la biopelícula induce la corrosión a través de tres posibles mecanismos: creación de celdas de aireación diferencial, zonas con diferente pH y zonas con elevada producción de sulfuro capaz de reaccionar con iones metálicos.

Aceros aluminotérmicos. Nuevas aplicaciones

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Duart Blay, J. M.

2004-02-01

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

Influencia de la atmósfera de sinterización en las propiedades mecánicas de los aceros P/M AISI 430L

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Iglesias, F. Javier

2014-03-01

Full Text Available 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.Se ha estudiado el acero inoxidable pulvimetalúrgico AISI 430L, comparando la sinterización en dos atmósferas diferentes; en vacío, y en una atmósfera que contiene nitrógeno. Se ha desarrollado un tratamiento térmico con objeto de incrementar las propiedades mecánicas, mediante la modificación microestructural de los nitruros complejos de hierro y cromo precipitados durante la etapa de sinterización. Se han evaluado las propiedades físicas y a la vez se ha realizado un análisis microestructural con el fin de relacionar la microestructura con el incremento en las propiedades mecánicas.

EFECTO DE LA TEMPERATURA SOBRE LA RESISTENCIA A LA TRACCIÓN DE ALGUNOS REFUERZOS DE FIBRAS PARA MATRICES CERÁMICAS O POLIMÉRICAS EFEITO DA TEMPERATURA SOBRE A RESISTÊNCIA À TRAÇÃO DE ALGUNS REFORZOS DE FIBRAS PARA MATRIZES CERÁMICAS OU POLIMÉRICAS EFFECT OF TEMPERATURE ON TH E TENSILE STRENGTH OF SOME FIBER REINFORCEMENTS FOR CERAMIC OR POLYMER MATRICES

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MARYORY ASTRID GÓMEZ

2009-07-01

Full Text Available Este artículo presenta un estudio de las propiedades termomecánicas de fibras de acero de bajo carbono, de acero inoxidable ASI-SAE 304, de aramida y de carbono. Además, se analizó el aspecto superficial de refuerzos de lana mineral de roca y lana de aluminosilicatos antes y después de someterlos a tratamientos térmicos a 1000 ºC. La resistencia a la tracción de las fibras se evaluó antes y después de someterlas a tratamientos térmicos a temperaturas de 400, 600, 800 y 1000 ºC dependiendo de la degradación que mostraran. Además, se efectuó un análisis termogravimétrico a cada tipo de fibra para determinar los cambios de peso a diferentes temperaturas. Las fibras de acero inoxidable mostraron la mayor estabilidad termomecánica, mientras que las fibras de aramida con tratamientos a 400 ºC mostraron propiedades mecánicas prácticamente nulas.Este artigo apresenta um estudo das propriedades termomecánicas de fibras de aço baixo carbono, de aço inoxidável ASI-SAE 304, de aramida e de carbono. Além disso, se analisou o aspecto superficial de reforços de lã mineral de rocha e lã de aluminosilicatos antes e depois que submetê-las a tratamentos térmicos a 1000 ºC. A resistência à tração das fibras se avaliou antes e depois de submetê-las a tratamentos térmicos a temperaturas de 400, 600, 800 e 1000 ºC dependendo da degradação que mostraram. Além disso, se efetuou uma análise termogravim étrica a cada tipo de fibra para determinar as mudanças de peso a diferentes temperaturas. As fibras de aço inoxidável mostraram a maior estabilidade termomecânica, enquanto as fibras de aramida com tratamentos a 400 ºC mostraram propriedades mecânicas praticamente nulas.This paper presents a study of the thermomechanical properties of low carbon steel, AISI-SAE 304 stainless steel, aramid and carbon fibers. Moreover, surface aspect of mineral rock wool of and aluminosilicate wool reinforcements was analyzed prior and after

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

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Diego Pérez-Muñoz

2015-09-01

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

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

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Saucedo-Muñoz, M. L.

2003-10-01

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

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

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

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Jiménez, J. A.

1998-05-01

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

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

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

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Gómez de Salazar, J. M.

1998-05-01

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

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

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

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Gálvez, J. L.

2005-12-01

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

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

Evaluación electroquímica de soldaduras en tubos capilares de acero inoxidable

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Javier E. Rodríguez-Yáñez

2014-02-01

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

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

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Ohanian, M.

2011-08-01

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

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

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

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José Luddey Marulanda Arevalo

2013-12-01

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

Oxidación en vapor de agua a 700 ºC y 750 ºC del acero inoxidable AISI 317 recubierto con aluminio por CVD-FBR.

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Jose L. Marulanda

2014-01-01

Full Text Available Se realizó la oxidación del acero inoxidable austenítico AISI 317 recubierto con aluminio por deposición química de vapor en lecho fluidizado, a temperaturas de 700 °C y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de SEM y difracción de rayos X, para observar la morfología de los óxidos. Se realizó la simulación termodinámica del proceso de oxidación en vapor de agua de los substratos para conocer las posibles fases sólidas y gaseosas que se podrían formar, en presencia de una ambiente con 100% vapor de agua y una atmosfera de presión. La forma de ataque a 750 ºC es similar a 700 ºC, aunque la velocidad de oxidación es mayor, ya que la difusión de los elementos de aleación y las reacciones de oxidación son más rápidas. Los recubrimientos de aluminio tienen una buena resistencia a la oxidación en vapor de agua, ya que forman una capa superficial de Al 2 O 3 , que es compacta y adherente, la cual protege al substrato del ataque corrosivo.

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

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Cadenas, M.

2002-12-01

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

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

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

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Botella, J.

1999-06-01

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

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

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

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

2003-07-01

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

EFICACIA DE LA PREPARACIÓN BIOMECÁNICA DE CONDUCTOS RADICULARES EN EL CRECIMIENTO MICROBIOLÓGICO EN PIEZAS DENTARIAS ANTERIORES CON NECROSIS PULPAR EN PACIENTES DE LA CLÍNICA ODONTOLÓGICA UANCV. JULIACA, PUNO. 2013

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TAPIA CONDORI, RILDO PAÚL

2015-01-01

RESULTADOS TABLAS DE INFORMACIÓN GENERAL TABLAS QUE RESPONDEN A LOS OBJETIVOS MICROBIOLOGÍA ENDODÓNTICA VÍAS MICROBIANAS DE ACCESO TÚBULOS DENTINARIOS CAVIDAD ABIERTA MEMBRANA PERIODONTAL REQUERIMIENTOS PARA UN PATÓGENO ENDODÓNTICO POTENCIAL DE OXIDO-REDUCCIÓN ANTAGÓNICOS INTERMICROBIANOS NECROSIS PULPAR TIPOS DE NECROSIS PREPARACIÓN BIOMECÁNICA EN PIEZAS CON NECROSIS PULPAR INSTRUMENTOS CONVENCIONALES DE ACERO INOXIDABLE CARACTERÍSTICAS DE LAS LIMAS K DE ACERO INOXIDABLE PROPIEDADES FÍSICAS ...

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

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Marín Gallego, Enric

2012-01-01

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

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

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Múnez, C. J.

2007-08-01

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

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

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.

The Cementation of Boron to Steels by the Method of Electrolytic Deposition; Cementation Electrolytique d'Aciers par le Bore; Tsementirovanie bora v stali putem ehlektroliticheskogo osazhdeniya; Cementacion de Aceros con Boro por Deposito Electrolitico

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Kawakami, M. [Tokyo Institute of Technology (Japan)

1964-06-15

aceros al carbono, aceros inoxidables, acero de elevado contenido de cromo, etc.; todos ellos dan resultados satisfactorios. (author) [Russian] Privoditsja metod izgotovlenija upravljajushhego sterzhnja s cementirovaniem bora. Jetot process osushhestvljaetsja posredstvom jelektroliza rasplavlennogo tetrabornokislogo natrija pri temperature okolo 900 Degree-Sign S . Obrabatyvaemyj stal'noj sterzhen' sluzhit katodom, v k a chestve anoda ispol'zuetsja grafitovyj jelektrod. V processe jelektroliza bor osazhdaetsja na stal'noj sterzhen' i diffundiruet v sta l'. Pri podhodjashhih uslovijah jelektroliza legko udaetsja poluchit' stal'noj sterzhen', soderzhashhij po 20% bora. Issledovalis' sledujushhie tipy stali: uglerodistaja, nerzhavejushhie, hromistaja i t.d. , vo vseh sluchajah byli polucheny polozhitel'nye rezul'taty. (author)

DISEÑO DE UN PROTOTIPO FERMENTADOR DE LECHE SEMIAUTOMÁTICO PARA LA ELABORACIÓN DE SUERO COSTEÑO

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BASHIR YACUB B.

Full Text Available El Suero Costeño es un producto lácteo fermentado, artesanalmente en la costa atlántica colombiana. Para cumplir con las normas sanitarias el fermentador está constituido por un tanque diseñado y fabricado en acero inoxidable 304, con un volumen neto de 30 L. Se garantizó una temperatura de 35°C en la fermentación de la leche, con un sistema de enfriamiento mediante una chaqueta. La temperatura se medió con un sensor de temperatura, tipo PT-100, con el sistema microcontrolado se programó su set-point, para separar el espiche del suero se utilizó una válvula; la finalización de la fermentación se determinó con la medición del pH con un pH-metro. La cantidad de materia prima y producto se mide con un sensor de nivel y se muestra de manera continua en la pantalla LCD del panel de control.

Desarrollo de aceros reforzados con carburos primarios vía metalurgia líquida

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Agote, I.

2005-12-01

Full Text Available The steel reinforcement by means of the addition of primary carbides via liquid metallurgy needs to fulfill two essential requirements to be technically viable: the development of a solid reinforcing product which is appropriate to be mixed with the steel and the optimization of the metallurgic addition of these reinforcing particles into the liquid steel. Besides, the improvement of the reinforced alloy characteristics is directly related to the particles' nature of reinforcing particles, their homogeneous and uniform distribution in the matrix and their size and morphology. The manufacture of these carbides by SHS ('Self propagating High temperature Synthesis' and their addition before steel is poured into moulds allows achieving the above-mentioned conditions.

Para que el reforzamiento de los aceros con carburos primarios vía metalurgia líquida sea técnicamente viable se requiere del desarrollo de un tipo de producto reforzante sólido, adecuado para su incorporación al acero, así como de la optimización de dicha vía metalúrgica de adición del producto reforzante al material base en estado líquido. Además, la mejora de características de la aleación reforzada es función directa de la naturaleza de las partículas, de su homogénea y uniforme distribución en la matriz y del tamaño y morfología regular de las mismas. Estas condiciones se consiguen cuando las partículas de carburo se elaboran previamente mediante la técnica SHS (selfpropagating high temperature synthesis y se añaden al baño de acero líquido previo a su colada en moldes o lingoteras.

Cobre antimicrobiano contra patógenos intrahospitalarios en Perú

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Edwin Neciosup

2015-01-01

Full Text Available Introducción: Las infecciones intrahospitalarias (IIH constituyen un problema de salud pública que generan grandes gastos por parte de los gobiernos, debido a que los patógenos causantes de IIH presentan resistencia a fármacos y generan una mayor permanencia de los pacientes, pues la infraestructura hospitalaria constituye un reservorio favorable para los patógenos. Las superficies de cobre surgen como opción sanitaria y efectiva para controlar el crecimiento y propagación de estos patógenos. Objetivos: Evaluar la actividad bactericida de las superficies de cobre contra los principales bacterias patógenas causantes de IIH (Escherichia coli, Pseudomonas aeruginosa y Staphylococcus aureus. Diseño: Estudio experimental con muestreo no probabilístico. Lugar: Hospital Regional Docente las Mercedes (HRDLM y Hospital Provincial Docente Belén (HPDB, Lambayeque, Perú. Materiales: Nueve cepas bacterianas, 3 de E. coli , 3 de P. aeruginosa y 3 de S. aureus; superficies metálicas (1 cm² de cobre y acero inoxidable (control . Intervenciones: Las 9 cepas bacterianas fueron proporcionadas por los hospitales HRDLM (4 cepas y HPDB (5 cepas. Los análisis de ANOVA y de Tukey fueron aplicados para evaluar la actividad bactericida de las superficies de cobre y acero inoxidable contra las 9 cepas causantes de IIH, usando los programas estadísticos Minitab y Sigmaplot, respectivamente. Principales medidas de resultados: Diferencias en el crecimiento bacteriano sobre superficies de cobre o acero inoxidable, con respecto al tiempo de exposición. Resultados: Las 9 cepas -3 de P. aeruginosa, 3 de E. coli y 3 de S. aureus - expuestas a superficies de cobre fueron eliminadas en 10, 15 y 60 minutos, respectivamente. La carga bacteriana de las células expuestas en superficies de acero inoxidable permaneció constante y viable por periodos mayores a 60 minutos. Además, las superficies de cobre eliminaron más rápido a las bacterias Gram negativas (P

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

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Yusimit K. Zamora-Hernández

2015-07-01

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

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

Directory of Open Access Journals (Sweden)

Coello, J.

2012-08-01

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

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

Estudio mediante difracción de rayos X de las tensiones residuales producidas durante el depósito de películas delgadas de TiN sobre sustratos metálicos

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Mónica Monsalve

2010-01-01

Full Text Available En este trabajo se analizó la influencia que tiene el espesor de la película y el tipo de sustrato en el nivel y tipo de esfuerzos residuales generados en recubrimientos de TiN obtenidos por dos técnicas de deposición física en fase vapor: pulverización catódica con magnetrón e implantación iónica. Los sustratos utilizados fueron un acero inoxidable AISI 304 y un acero de herramientas AISI M2. Las tensiones residuales, las fases presentes y la orientación cristalográfica de las películas depositadas fueron obtenidas mediante análisis de difracción de rayos X por incidencia rasante. Se encontró que los esfuerzos residuales fueron mayores en las películas depositadas por la técnica de pulverización catódica con magnetrón que en las depositadas por la técnica de implantación iónica. En ambos casos estos esfuerzos son de compresión y disminuyen en la medida que aumenta el espesor de la película. Esto se debe a la forma como se entrega la energía, la capa en crecimiento y el momentum de las partículas ionizadas, lo que influye directamente en la microestructura y aumento o disminución de los esfuerzos residuales. En cuanto al tipo de sustrato se obtuvieron esfuerzos mayores en las películas depositadas sobre el acero AISI 304 que en las depositadas sobre el acero AISI M2, lo cual se debe posiblemente a que este último acero tiene un menor coeficiente de expansión térmica.

Tribological properties of BixTiyOz films grown via RF sputtering on 316L steel substrates

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Johanna Parra

2015-01-01

Full Text Available En este trabajo se presentan los resultados obtenidos en el análisis químico superficial, la caracterización morfológica y evaluación de las propiedades tribológicas de recubrimientos de titanato de bismuto amorfo (BixTiyOz depositados sobre sustratos de acero inoxidable 316L utilizando la técnica de pulverización catódica rf. El análisis químico elemental se realizó por medio de espectroscopia de electrones Auger (EEA, la morfología de los recubrimientos se determinó mediante microscopia de fuerza atómica (MFA. Las medidas del coeficiente de fricción y la tasa de desgaste fueron obtenidas mediante pruebas de bola sobre disco. Los análisis de EEA permitieron establecer que los primeros 10 nm de los recubrimientos están formados probablemente por óxidos de Bi4Ti3O12 y Ti2O3, las medidas de AFM indican que los recubrimientos tienen una rugosidad promedio de 22.28nm y un tamaño de grano de 50nm. Finalmente, las pruebas tribológicas establecieron que el coeficiente de fricción y la tasa de desgaste del acero recubierto tiene valores similares al acero desnudo.

Corrosion testing of type 304L stainless steel in tuff groundwater environments

International Nuclear Information System (INIS)

Westerman, R.E.; Pitman, S.G.; Haberman, J.H.

1987-11-01

The stress-corrosion cracking (SCC) resistance of Type 304L stainless steel (SS) to elevated temperatures in tuff rock and tuff groundwater environments was determined under irradiated and nonirradiated conditions using U-bend specimens and slow-strain-rate tests. The steel was tested both in the solution-annealed condition and after sensitization heat treatments. The material was found to be susceptible to SCC in both the solution-annealed and solution-annealed-and-sensitized conditions when exposed to an irradiated crushed tuff rock environment containing air and water vapor at 90 0 C. A similar exposure at 50 0 C did not result in failure after a 25-month test duration. Specimens of sensitized 304 SS conditioned with a variety of sensitization heat treatments resisted failure during a test of 1-year duration in which a nonirradiated environment of tuff rock and groundwater held at 200 0 C was allowed to boil to dryness on a cyclical basis. All specimens of sensitized 304 SS exposed to this environment failed. Slow-strain-rate studies were performed on 304L, 304, and 316L SS specimens. The 304L SS was tested in J-13 well water at 150 0 C, and the 316L SS at 95 0 C. Neither material showed evidence of SCC in these tests. Sensitized 304 SS did exhibit SCC in J-13 well water in tests conducted at 150 0 C. 12 refs., 27 figs., 13 tabs

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

Energy Technology Data Exchange (ETDEWEB)

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

2004-07-01

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

Superficial and electrochemical study of stainless steel 304l with an inhibitory protective coating (TiO{sub 2} and ZrO{sub 2}); Estudio superficial y electroquimico de acero inoxidable 304L con una capa protectora inhibidora (TiO{sub 2} y ZrO{sub 2})

Energy Technology Data Exchange (ETDEWEB)

Davila N, M. L.; Contreras R, A.; Arganis J, C. R., E-mail: aida.contreras@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2014-10-15

The degradation mechanisms in the boiling water reactors (BWR) have been an alert focus for owners, especially the cracking by stress corrosion cracking (SCC), therefore different techniques have been studied to inhibit this problem inside which is the water injection of hydrogen feeding (HWC, Hydrogen Water Chemistry), together with the noble metals injection (NMCA, Nobel Metal Chemical Addition) and the ceramic materials injection that form an inhibitory protective coating (Ipc). In this work the Ipc was simulated, for which were carried out hydro-thermals deposits starting from suspensions of 1000 ppm of zirconium oxide in its crystalline phase baddeleyite and titanium oxides in its anatase and rutile phases, on test tubes of stainless steel 304l previously rusty under simulated conditions of pressure and temperature of a BWR (288 C and 8 MPa). The superficial characterization was realized by scanning electron microscopy, energy-dispersive of X-ray and X-ray diffraction. The capacity to mitigate the corrosion was studied with the electrochemical technique of Tafel polarization (288 C and 8 MPa). The steel presents the formation of two oxide coatings formed by magnetite and hematite. The baddeleyite presents a deposit more thick and homogeneous it also presents the most negative electrochemical potential of corrosion, what indicates that it has the bigger capacity to mitigate the SCC. (Author)

Stress Corrosion Cracking Susceptibility of 304L Substrate and 308L Weld Metal Exposed to a Salt Spray

Directory of Open Access Journals (Sweden)

Chia-Hao Hsu

2017-02-01

Full Text Available 304 stainless steels (SS were considered as the materials for a dry storage canister. In this study, ER (Electrode Rod 308L was utilized as the filler metal for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. The electron backscatter diffraction (EBSD map was used to identify the inherent microstructures in distinct specimens. U-bend and weight-loss tests were conducted by testing the 304L substrates and welds in a salt spray containing 5 wt % NaCl at 80 °C to evaluate their susceptibility to stress corrosion cracking (SCC. Generally, the weight loss of the ER 308L deposit was higher than that of the 304L substrate in a salt spray in the same sample-prepared condition. The dissolution of the skeletal structure in the fusion zone (FZ was responsible for a greater weight loss of the 308L deposit, especially for the cold-rolled and sensitized specimen. Cold rolling was detrimental and sensitization after cold rolling was very harmful to the SCC resistance of the 304L substrate and 308L deposit. Overall, the SCC susceptibility of each specimen was correlated with its weight loss in each group.

Constant extension rate testing of Type 304L stainless steel in simulated waste tank environments

International Nuclear Information System (INIS)

Wiersma, B.J.

1992-01-01

New tanks for storage of low level radioactive wastes will be constructed at the Savannah River Site (SRS) of AISI Type 304L stainless steel (304L). The presence of chlorides and fluorides in the wastes may induce Stress Corrosion Cracking (SCC) in 304L. Constant Extension Rate Tests (CERT) were performed to determine the susceptibility of 304L to SCC in simulated wastes. In five of the six tests conducted thus far 304L was not susceptible to SCC in the simulated waste environments. Conflicting results were obtained in the final test and will be resolved by further tests. For comparison purposes the CERT tests were also performed with A537 carbon steel, a material similar to that utilized for the existing nuclear waste storage tanks at SRS

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

Directory of Open Access Journals (Sweden)

González-Rodríguez, G.

1995-06-01

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

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

Dynamic compressive response of wrought and additive manufactured 304L stainless steels

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Nishida Erik

2015-01-01

Full Text Available Additive manufacturing (AM technology has been developed to fabricate metal components that include complex prototype fabrication, small lot production, precision repair or feature addition, and tooling. However, the mechanical response of the AM materials is a concern to meet requirements for specific applications. Differences between AM materials as compared to wrought materials might be expected, due to possible differences in porosity (voids, grain size, and residual stress levels. When the AM materials are designed for impact applications, the dynamic mechanical properties in both compression and tension need to be fully characterized and understood for reliable designs. In this study, a 304L stainless steel was manufactured with AM technology. For comparison purposes, both the AM and wrought 304L stainless steels were dynamically characterized in compression Kolsky bar techniques. They dynamic compressive stress-strain curves were obtained and the strain rate effects were determined for both the AM and wrought 304L stainless steels. A comprehensive comparison of dynamic compressive response between the AM and wrought 304L stainless steels was performed. SAND2015-0993 C.

Simulación de la precipitación de inclusiones en diferentes etapas del procesamiento del acero líquido

Directory of Open Access Journals (Sweden)

Carreño, V.

1998-05-01

Full Text Available Steelmaking processes are continuously improved in order to attend the increasing requirements of the cleanness of the liquid metal. At the refining stages, as deoxidation and desulphuration, the formation of inclusions of oxides and sulphides is promoted, which on the other hand, are the most frequent inclusions. In this work a mathematical simulator of the precipitation and chemical composition of non-metallic inclusions at different steps of the steelmaking process is presented. To this purpose, it is assumed that inclusions formed by reoxidation can be simulated by increasing arbitrarily the oxygen levels consumed by the residual elements (aluminium, calcium, etc. and starting the chemical reaction with less powerful deoxidants (silicium and manganese. Accordingly, different operative conditions can be simulated. Numerical predictions are compared with experimental results of industrial trials, as well as results included in the bibliography.

Los procesos de fabricación de acero se mejoran constantemente en respuesta a las demandas del consumidor que exige un mayor control de limpieza del metal líquido en las diversas etapas de su elaboración. En las etapas de refinación, como son desoxidación y desulfuración, se promueve la formación de inclusiones de óxidos y sulfuros, que por otra parte son las más frecuentes en el acero líquido. En este trabajo se presenta un simulador matemático que predice la precipitación y composición de las inclusiones no metálicas que se encuentran en el acero líquido en diferentes etapas de su procesamiento, asumiendo que las inclusiones formadas por reoxidación también se pueden simular al incrementar arbitrariamente los niveles de oxígeno que deberán consumir los elementos residuales altamente oxidables (Al, Ca, y empezar la reacción con los desoxidantes menores (Si y Mn. De esta manera se simulan diferentes condiciones de operación. Las predicciones numéricas se comparan con los

Cinéticas de transformación de fases a 850 ºC de aceros inoxidables dúplex clásicos (2205 y 2507 y de uno nuevo de bajo contenido en níquel y alto en manganeso (DBNi

Directory of Open Access Journals (Sweden)

Rodríguez, M. P.

2004-04-01

Full Text Available Austenitic-ferritic stainless steels are formed by ferrite and austenite in a variable proportion between 30 % and 70 %. Their chemical composition conditions the ageing processes that can happen during heat treatments, where phases that hardens and brittles the material can be generated. Evolution of a new duplex stainless steel with lower nickel and higher nitrogen and manganese content maintained at 1123 K (critical precipitation temperature up to 8 hours compared to classical ones (2205 and 2507 is presented. The study, done by magnetic measurements, XRD, optical and scanning electron microscopy and microanalysis, revealed a roughly similar behaviour for the three steels. The new one presents a higher initial stability, probably due to the high nitrogen and manganese contents; however, it also produces the higher final transformation due to the higher initial ferrite. A fine comparative analysis was done to correctly identify any phase; an accurate microanalysis in every generated phase was performed. All the steels tested are initially made on ferrite and austenite. After the ageing treatment, 8 hours at 1123 K, in the 2205 duplex steel a strong precipitation of sigma phase is observed, austenite and some of the original ferrite are also present; ferrite completely transforms in the 2507 duplex and austenite, sigma, secondary austenite and chromium nitride can be found; regarding the new duplex steel DBNi, austenite, ferrite, sigma, chi and chromium nitrides are detected.

Los aceros dúplex austeno-ferríticos están constituidos por ferrita y austenita en proporciones variables del 30 % al 70 %. Su composición química condiciona los procesos de envejecimiento que sufren durante los tratamientos térmicos, cuando se generan fases que endurecen y fragilizan el material. Este trabajo estudia la evolución de un nuevo inoxidable dúplex con bajo contenido en níquel y alto en nitrógeno y manganeso a 1123 K (temperatura crítica de

Long-Term Effects of Temperature Exposure on SLM 304L Stainless Steel

Science.gov (United States)

Amine, Tarak; Kriewall, Caitlin S.; Newkirk, Joseph W.

2018-03-01

Austenitic stainless steel is extensively used in industries that operate at elevated temperatures. This work investigates the high-temperature microstructure stability as well as elevated-temperature properties of 304L stainless steel fabricated using the selective laser melting (SLM) process. Significant microstructural changes were seen after a 400°C aging process for as little as 25 h. This dramatic change in microstructure would not be expected based on the ferrite decomposition studied in conventional 304L materials. The as-built additively manufactured alloy has much faster kinetic response to heat treatment at 400°C. An investigation of the structures which occur, the kinetics of the various transformations, and the mechanical properties is presented. The impact of this on the application of SLM 304L is discussed.

L2 Milestone 5433: Characterization of Dynamic Behavior of AM and Conventionally Processed Stainless Steel (316L and 304L)

Energy Technology Data Exchange (ETDEWEB)

Gray, George Thompson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Livescu, Veronica [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rigg, P. A. [Washington State Univ., Pullman, WA (United States). Inst. for Shock Physics; Trujillo, Carl Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cady, Carl McElhinney [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chen, Shuh-Rong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carpenter, John S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lienert, Thomas J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fensin, Saryu Jindal [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Knapp, Cameron M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beal, Roberta Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Morrow, Benjamin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dippo, Olivia F. [Univ. of California, San Diego, CA (United States); Jones, David Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Daniel Tito [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Valdez, James Anthony [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-09-26

For additive manufacturing (AM) of metallic materials, the certification and qualification paradigm needs to evolve as there currently exists no broadly accepted “ASTM- or DIN-type” additive manufacturing certified process or AM-material produced specifications. Accordingly, design, manufacture, and thereafter implementation and insertion of AM materials to meet engineering applications requires detailed quantification of the constitutive (strength and damage) properties of these evolving materials, across the spectrum of metallic AM methods, in comparison/contrast to conventionally-manufactured metals and alloys. This report summarizes the 316L SS research results and presents initial results of the follow-on study of 304L SS. For the AM-316L SS investigation, cylindrical samples of 316L SS were produced using a LENS MR-7 laser additive manufacturing system from Optomec (Albuquerque, NM) equipped with a 1kW Yb-fiber laser. The microstructure of the AM-316L SS was characterized in both the “as-built” Additively Manufactured state and following a heat-treatment designed to obtain full recrystallization to facilitate comparison with annealed wrought 316L SS. The dynamic shock-loading-induced damage evolution and failure response of all three 316L SS materials was quantified using flyer-plate impact driven spallation experiments at peak stresses of 4.5 and 6.35 GPa. The results of these studies are reported in detail in the first section of the report. Publication of the 316L SS results in an archival journal is planned. Following on from the 316L SS completed work, initial results on a study of AM 304L SS are in progress and presented herein. Preliminary results on the structure/dynamic spallation property behavior of AM-304L SS fabricated using both the directed-energy LENS and an EOS powder-bed AM techniques in comparison to wrought 304L SS is detailed in this Level 2 Milestone report.

Cold rolled texture and microstructure in types 304 and 316L austenitic stainless steels

International Nuclear Information System (INIS)

Wasnik, D.N.; Samajdar, I.; Gopalakrishnan, I.K.; Yakhmi, J.V.; Kain, V.

2003-01-01

Two grades of austenitic stainless steel (ASS), types 304 (UNS S 30400) and 316L (UNS S 31603), were cold rolled to different reductions by unidirectional and by cross-rolling. The steels had reasonable difference in stacking fault energy (estimated respectively as 15 and 61 mJ/m 2 in types 304 and 316L) and also in starting (or pre-deformation) crystallographic texture-being relatively weak and reasonably strong in types 304 and 316L respectively. The cold rolling increased texturing in type 304, but not in type 316L ASS. The more significant effect of cold rolled texture development was in the relative increase of Brass ({011} ) against Copper ({112} ) and S ({231} ) orientations. In type 304 the increase in Brass was significant, while in type 316L the increase in Copper and S was stronger. This effect could be captured by Taylor type deformation texture simulations considering stronger twinning contributions in type 304 - for example the respective 'best-fits' (in terms of matching the changes in the volume fractions of Brass against Copper and S) were obtained by full constraint Taylor model with 1:100 and 1:10 slip:twin activities in types 304 and 316L ASS respectively. Microstructural developments during cold rolling were generalized as strain induced martensite formation and developments of dislocation substructure. The former, as estimated by vibrating sample magnetometer (VSM), increased with cold reduction, being significantly more in type 304 and was also noticeably stronger in both grades under cross-rolling. The most significant aspect of substructural developments was the formation of strain localizations. These were observed as dense dislocation walls (DDWs), micro-bands (MBs) and twin lamellar structures (TLS). The TLS contribution gained significance at higher reductions and during cross-rolling, especially in type 304. Large misorientation development and the accompanying grain splittings were always associated with such strain localizations

Assessment and comparison of oxides grown on 304l ods steel and 304l ss in water environment in supercritical conditions

International Nuclear Information System (INIS)

Mihalache, M.; Dinu, A.; Fulger, M.; Zhou, Z.; Mihalache, M.

2013-01-01

In order to fulfil superior cladding for new reactor generation G IV, the austenitic 3 04 L stainless steel was improved by oxide dispersion strengthening (ODS), using two nano-oxides: titanium and yttrium oxides. The behaviour of the new material resulted, 304 ODS, in water at supercritical temperature of about 550 O C and 25 MPa pressure, was considered. The oxidation kinetics by weigh gain measurements for both materials have been estimated and compared. The weight gain of ODS samples is higher than basic austenitic steel up to 1320 hours. The oxides developed on the ODS samples in SCPW are layered and more uniform than in 304 L SS. The protectively character of oxide films was estimated by different techniques. The morphology of oxide surface, the layering and chemical formula of oxides films were investigated by scanning electron microscopy (SEM), Energy Dispersion X-Ray Spectrometry (EDS), electrochemical impedance spectrometry (EIS) and by Small Angle X-ray Diffraction (SAXD). 1. (authors)

Comportamiento frente a la corrosión de los aceros inoxidables AISI 430L P/M

OpenAIRE

Corpas, F. A.; Iglesias, F. J.; Ruiz, J. M.; Codina, S.; Ruiz, J. M.; García, V.

2004-01-01

In this paper we have studied the resistance to corrosion of the 430L ferritic stainless steels, manufactured by powder metallurgy. We have compared the behaviour of the different series of 430L stainless steels sintered, tempered and annealing, in different corrosive environments. Finally, the microstructure of the steels was determined by means of scanning electron microscopy. The better resistance to corrosion are produced in the steel annealing to 300ºC and 600ºC.

En es...

Tensile Stress-Strain Results for 304L and 316L Stainless-Steel Plate at Temperature

International Nuclear Information System (INIS)

R. K. Blandford; D. K. Morton; S. D. Snow; T. E. Rahl

2007-01-01

The Idaho National Laboratory (INL) is conducting moderate strain rate (10 to 200 per second) research on stainless steel materials in support of the Department of Energy's (DOE) National Spent Nuclear Fuel Program (NSNFP). For this research, strain rate effects are characterized by comparison to quasi-static tensile test results. Considerable tensile testing has been conducted resulting in the generation of a large amount of basic material data expressed as engineering and true stress-strain curves. The purpose of this paper is to present the results of quasi-static tensile testing of 304/304L and 316/316L stainless steels in order to add to the existing data pool for these materials and make the data more readily available to other researchers, engineers, and interested parties. Standard tensile testing of round specimens in accordance with ASTM procedure A 370-03a were conducted on 304L and 316L stainless-steel plate materials at temperatures ranging from -20 F to 600 F. Two plate thicknesses, eight material heats, and both base and weld metal were tested. Material yield strength, Young's modulus, ultimate strength, ultimate strain, failure strength and failure strain were determined, engineering and true stress-strain curves to failure were developed, and comparisons to ASME Code minimums were made. The procedures used during testing and the typical results obtained are described in this paper

Martensitic transformation in 304L and 316L types stainless steels cathodically hydrogen charged

International Nuclear Information System (INIS)

Minkovitz, E.; Eliezer, D.

1984-01-01

This paper reports a TEM study on the role of phase transitions at the crack tip in 304L and 316L types stainless steels cathodically hydrogen charged in the absence of any eternally applied forces. The possible role of α prime and epsilon martensite phases in the fracture mechanism is discussed

Passivity and passivity breakdown of 304L stainless steel in hot and concentrated nitric acid

International Nuclear Information System (INIS)

Gillard-Tcharkhtchi, Elsa

2014-01-01

The objective of this study is to characterize the oxidation behavior of 304L stainless steel (SS) in representative conditions of spent nuclear fuel reprocessing, i.e. in hot and concentrated nitric acid. In these conditions the SS electrochemical potential is in the passive domain and its corrosion rate is low. However when the media becomes more aggressive, the potential may be shifted towards the trans-passive domain characterized with a high corrosion rate. Passivity and passivity breakdown in the trans-passive domain are of a major interest for the industry. So as to characterize these phenomenons, this work was undertaken with the following representative conditions: a 304L SS from an industrial sheet was studied, the media was hot and concentrated HNO 3 , long term tests were performed. First, the surface of an immersed 304L SS was characterized with several complementary techniques from the micro to the nanometer scale. Then oxidation kinetics was studied in the passive and in the trans-passive domain. The oxidation behavior was studied thanks to weight loss determination and surface analysis. Finally, oxidation evolution as a function of the potential was studied from the passive to the trans-passive domain. In particular, this allowed us to obtain the anodic curve of 304L SS in hot and concentrated and to define precisely the 304L SS limits of in such conditions. (author) [fr

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.

Notch Effect on Tensile Deformation Behavior of 304L and 316L Steels in Liquid Helium and Hydrogen

International Nuclear Information System (INIS)

Shibata, K.; Fujii, H.

2004-01-01

Tensile tests of type 304L and 316L steels were carried out using round bar specimens with a notch in liquid helium, hydrogen, liquid nitrogen and at ambient temperature. The obtained tensile strengths were compared with the tensile strengths of smooth specimens. For smooth specimens, tensile strength increased with a decrease in temperature and the strengths in liquid helium and hydrogen show similar values in both steels. For notched specimen of 304L steel, tensile strength (including fracture strength) increased noticeably from ambient to liquid nitrogen temperature but showed a large decrease in liquid helium and hydrogen. In liquid hydrogen and helium, the tensile strength is a little lower in liquid hydrogen than in liquid helium and both strengths are lower than tensile strengths of smooth specimens. For notched specimen of 316L steel, an increase in tensile strength from ambient to liquid nitrogen temperature was not so large and a decrease from liquid nitrogen to liquid hydrogen was small. The tensile strengths in liquid helium and hydrogen were nearly same and higher than those of smooth specimens. Different behavior of serration was observed between liquid helium and hydrogen, and between 304L and 316L steels. The reasons for these differences were discussed using computer simulation

Microstructure and mechanical properties of 304L steel fabricated by arc additive manufacturing

Directory of Open Access Journals (Sweden)

Ji Lei

2017-01-01

Full Text Available For 304L large structural parts used in nuclear power, it is hard and costly to fabricate and machine traditionally. Wire arc additive manufacturing (WAAM has low cost and high material utilization, which provides an efficient way to fabricate the large structural parts. So in this study, WAAM is used to fabricate the parts of 304L stainless steel. Through the tensile test and metallographic analysis, the mechanical properties and microstructure of the 304L stainless steel fabricated by WAAM were explored. The results indicate that with the layers depositing, the cooling rate becomes slower, the dendrites become thicker and the morphology becomes more stable. Due to the existence of dendrites, the grain boundary strengthening effect is different between the transverse direction and longitudinal direction, and resulting in anisotropy of mechanical properties. However, the mechanical properties of the parts correspond to the forged piece, which lays the foundation for future applications.

Pulse generator for bias materials in the plasma immerse ion implantation process; Generador de pulsos para polarizar materiales en el proceso de implantacion de iones inmersos en plasma

Energy Technology Data Exchange (ETDEWEB)

Lopez Callegas, Regulo; Valencia Alvarado, Raul; Munoz Castro, Arturo Eduardo; Godoy Cabrera, Oscar Gerardo [Instituto Nacional de Investigaciones Nucleares, Mexico D.F. (Mexico); Moreno Saavedra, Hilda; Gonzalez Colin, Mireya; Mariano Escamilla, Hector Fernando [Instituto Tecnologico de Toluca, Estado de Mexico (Mexico)

2003-10-15

The 0-10 kV pulse generator has been designed, with 100 {mu}s duration and 1-100 Hz frequencies ranges. The use of the pulse generator is in the plasma immersed ion implantation technique (P III). The process was realized in 304 austenitic stainless steel, the results were analyzed by: SEM, X-rays diffraction and hardness Vickers. The hardness was increased due to the efficiency of the pulse generator and P III process, the results obtained showed that the nitrogen inside the stainless steel was implanted and besides some nitrides was formed and therefore the hardness was increased. Also, the more adequate work pressure was determined to carry out the P III process. [Spanish] Se presenta el diseno de un generador de pulsos de alto voltaje con amplitudes controladas de hasta 10 kV, la duracion maxima de los pulsos es del orden de los 100 {mu}s y frecuencia de repeticion en el intervalo de 1-100 Hz. La aplicacion de este generador de pulsos es para el proceso de implantacion de iones en materiales inmersos en plasmas (PIII). Los analisis hechos a los aceros austeniticos cedula 304 mediante microscopia electronica de barrido, difraccion de rayos X y dureza Vickers, muestran la eficiencia obtenida con el generador de pulsos en el proceso PIII, debido a que en el acero inoxidable se presenta un incremento en el nitrogeno y conformacion de algunos nitruros, lo cual da lugar al incremento de la dureza. Asimismo, se determino la presion de trabajo mas adecuada para llevar a cabo el proceso PIII.

Soldabilidad del acero inoxidable austenitico

Directory of Open Access Journals (Sweden)

Pedro Pablo Torres-Medina

2002-01-01

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

Inorganic inhibitor study in the steel corrosion in the mixture of LiBr+Etilenglicol+H{sub 2}O; Estudio de inhibidores inorganicos en la corrosion de aceros en la mezcla de LiBr+Etilenglicol+H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Sarmiento Bustos, Estela

2008-07-15

develop this work. Fourth chapter is the results presentation and discussion divided in four sections: each one for material electrochemically tested in the LiBr+ etilene glycol+ H{sub 2}O solution. Also presents the results obtained for the extended study made to carbon steel under different temperature and electrochemical test conditions. This includes the EIS and electrochemical noise Hurst results analysis and simulations. Finally, the fifth chapter presents the conclusions and recommendations of this work. An appendix with the solution preparation is included. [Spanish] En esta tesis doctoral se presentan los resultados obtenidos de cinetica electroquimica de la corrosion de 4 aceros: acero al carbon, 304, 316 y 316L, en una solucion de LiBr+ etilenglicol+H{sub 2}O. Estos sistemas son utilizados en bombas de calor por absorcion para la recuperacion de calor de desecho a la salida de procesos industriales. Sin embargo, la solucion absorbente es altamente corrosiva en este tipo de equipos. Por lo anterior se evaluaron tres diferentes inhibidores inorganicos: nitrato de litio, molibdato de litio y cromato de litio los cuales son fuertes oxidantes y promueven la formacion de la capa pasiva de los aceros y se aplicaron a diferentes temperaturas: 25, 50 y 80 grados dentigrados. A traves de tecnicas electroquimicas como curvas de polarizacion, ruido electroquimico, impedancia electroquimica, resistencia a la polarizacion lineal y mediciones de potencial de corrosion a circuito abierto en el tiempo. Se determino el compuesto inhibidor mas adecuado obteniendo su eficiencia bajo las diferentes condiciones, de los tres inhibidores considerados el que presento el mejor comportamiento y eficiencia para el acero al carbon fue el nitrato de litio a 50 ppm; para el 304 el cromato de litio a 5 ppm; para el acero 316 molibdato de litio a 5 ppm y para el 316L el cromato de litio a 5 ppm. Debido a que el acero al carbon es el material mas economico y presento una mejor respuesta por

Relationship between mechanical and surface properties of a stainless steels duplex UNS S31803 (45N) nitriding at high temperature

OpenAIRE

Mesa Grajales, Dairo Hernán; Garzón Ospina, Carlos Mario; Tschiptschin, André Paulo

2008-01-01

Se estudió la relación entre dureza, resistencia a la cavitación (en sus primeras etapas), y la textura cristalográfica de un acero inoxidable duplex (UNS S31803 llamado de 45N), transformado en inoxidable austenítico por tratamiento térmoquímico de nitruración gaseosa a alta temperatura. Usando la técnica de difracción de electrones retroproyectados (Electron Backscattering Diffraction - EBSD), fue posible generar un patrón de textura del material (mapa EBSD), el cual se utilizó pa...

Irradiation-induced creep in 316 and 304L stainless steels

International Nuclear Information System (INIS)

Walters, L.C.; McVay, G.L.; Hudman, G.D.

1977-01-01

Recent results are presented from the in-reactor creep experiments that are being conducted by Argonne National Laboratory. The experiments consist of four subassemblies that contain helium-pressurized as well as unstressed capsules of 316 and 304L stainless steels in several metallurgical conditions. Experiments are being irradiated in row 7 of the EBR-II sodium-cooled fast breeder reactor. Three of the subassemblies are being irradiated at temperatures near 400 0 C, and the fourth subassembly is being irradiated at a temperature of 550 0 C. Creep and swelling strains were determined by profilometer measurements on the full length of the capsules after each irradiation cycle. The accumulated neutron dose on the 304L capsules at 385 0 C was 45 dpa; on the 316 capsules at 400 0 C, 40 dpa; and on the 316 capsules at 550 0 C, 25 dpa. It was found that the in-reactor creep rates were linearly dependent on hoop stress, with the exception being capsules of 316 stainless steel that had been given long-term carbide aging treatment and then irradiated at 550 0 C. Those capsules exhibited much higher creep and swelling rates than their unaged counterparts. For the metallurgical conditions where significant swelling was observed (solution-annealed 304L and aged 316 stainless steels), it was found that the in-reactor creep rates were readily fit to a model that related the creep rates to accumulated swelling. Additionally, it was found that the stress-normalized creep rate for 20%-cold-worked 316 stainless steel at a temperature of 550 0 C was 1.6 times that observed at 400 0 C

Multitechnique characterisation of 304L surface states oxidised at high temperature in steam and air atmospheres

Energy Technology Data Exchange (ETDEWEB)

Mamede, Anne-Sophie, E-mail: anne-sophie.mamede@ensc-lille.fr [University Lille, CNRS, ENSCL, Centrale Lille, University Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, F-59000 Lille (France); Nuns, Nicolas, E-mail: nicolas.nuns@univ-lille1.fr [University Lille, CNRS, ENSCL, Centrale Lille, University Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, F-59000 Lille (France); Cristol, Anne-Lise, E-mail: anne-lise.cristol@ec-lille.fr [University Lille, CNRS, Centrale Lille, Arts et Métiers Paris Tech, FRE 3723 – LML – Laboratoire de Mécanique de Lille, F-59000 Lille (France); Cantrel, Laurent, E-mail: laurent.cantrel@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire, PSN-RES, Cadarache, Saint Paul lez Durance, 13115 (France); Laboratoire de Recherche Commun IRSN-CNRS-Lille 1: «Cinétique Chimique, Combustion, Réactivité» (C3R), Cadarache, Saint Paul lez Durance, 13115 (France); Souvi, Sidi, E-mail: sidi.souvi@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire, PSN-RES, Cadarache, Saint Paul lez Durance, 13115 (France); Laboratoire de Recherche Commun IRSN-CNRS-Lille 1: «Cinétique Chimique, Combustion, Réactivité» (C3R), Cadarache, Saint Paul lez Durance, 13115 (France); and others

2016-04-30

Graphical abstract: - Highlights: • Mutitechnique characterisation of oxidised 304L. • Oxidation at high temperature under steam and air conditions of 304L stainless steel. • Chromium and manganese oxides formed in the outer layer. • Oxide profiles differ in air or steam atmosphere. - Abstract: In case of a severe accident occurring in a nuclear reactor, surfaces of the reactor coolant system (RCS), made of stainless steel (304L) rich in Cr (>10%) and Ni (8–12%), are oxidised. Fission products (FPs) are released from melt fuel and flow through the RCS. A part of them is deposited onto surfaces either by vapour condensation or by aerosol deposition mechanisms. To be able to understand the nature of interactions between these FPs and the RCS surfaces, a preliminary step is to characterize the RSC surface states in steam and air atmosphere at high temperatures. Pieces of 304L stainless steel have been treated in a flow reactor at two different temperatures (750 °C and 950 °C) for two different exposition times (24 h and 72 h). After surfaces analysing by a unique combination of surface analysis techniques (XPS, ToF-SIMS and LEIS), for 304L, the results show a deep oxide scale with multi layers and the outer layer is composed of chromium and manganese oxides. Oxide profiles differ in air or steam atmosphere. Fe{sub 2}O{sub 3} oxide is observed but in minor proportion and in all cases no nickel is detected near the surface. Results obtained are discussed and compared with the literature data.

Microestructura y propiedades de capas de tribaloy T-800 depositadas mediante plaqueado láser

Directory of Open Access Journals (Sweden)

Navas, C.

2004-04-01

Full Text Available The present work is based on obtaining Co based coatings (Tribaloy T-800 on plates of 18/8 stainless steel (AISI 304 by laser cladding technique. After the treatment, samples were characterized by optical and scanning electron microscopy with EDS analysis. The elemental composition of the coating was determined with a glow discharge lamp spectrometer (GDL. The study of the interface revealed a good adherence between the substrate and coating without substantial defects. For the laser cladded coatings, the microstructure was dendritic with a high degree of refinement and chemical homogeneity close to the original powder. The grain coarsening was observed in the overlapping zones due to the second heat treatment. Microhardness of the coatings reached 750 HV, a considerably higher value than the substrate hardness (200 HV. Also, the coating corrosion resistance in saline solutions had a great improvement.

El presente trabajo se centra en la obtención de capas de aleación base Cobalto (Tribaloy T-800 sobre un sustrato de acero inoxidable 18/8 (AISI 304 mediante la técnica de plaqueado láser. Tras los tratamientos, se caracterizaron las probetas mediante microscopía óptica y electrónica de barrido con microanálisis (EDS. La composición elemental del recubrimiento se determinó en un espectrómetro de emisión óptica con fuente de excitación (GDL. El estudio de la interfase reveló una perfecta adherencia entre el recubrimiento y el material base, sin defectos apreciables. La microestructura de las capas depositadas es dendrítica con un alto grado de refinamiento y una homogeneidad química a lo largo del cordón y con valores muy próximos a los del polvo de partida. En las zonas de solape entre cordones, se observó un crecimiento del grano debido al segundo tratamiento térmico recibido. La microdureza de las capas alcanza los 750 HV, valor considerablemente superior al del sustrato (200 HV. Asimismo, se obtuvo una mejora

Effect of Temperature on the Fracture Toughness of Hot Isostatically Pressed 304L Stainless Steel

OpenAIRE

Cooper, Adam J.; Sherry, Andrew

2018-01-01

Herein, we have performed J-Resistance multi-specimen fracture toughness testing of hot isostatically pressed (HIP’d) and forged 304L austenitic stainless steel, tested at elevated (300 °C) and cryogenic (− 140 °C) temperatures. The work highlights that although both materials fail in a pure ductile fashion, stainless steel manufactured by HIP displays a marked reduction in fracture toughness, defined using J0.2BL, when compared to equivalently graded forged 304L, which is relatively constant...

Identificación de aceros por espectroscopia de rompimiento inducido por láser (LIBS) y análisis de componentes principales

OpenAIRE

Contreras, U.; Meneses-Nava, M.A.; Torres-Armenta, D.; Robles-Camacho, J.; Barbosa-García, O.

2012-01-01

En la actualidad existe una producción de mas de 100 000 aceros diferentes de acuerdo a su composición química y propiedades mecánicas; sin embargo, una vez en el mercado, no existe técnica alguna capaz de identificar y clasificar cualquier acero según su clase o grado. En este trabajo se describe un método capaz de identificar y clasificar aceros a través de la determinación de su composición química. El método propuesto se basa en un análisis de espectroscopia atómica procedente de la técni...

Weld solidification cracking in 304 to 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

2010-01-01

A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

Evaluation of Mechanical Properties and Fatigue Behavior of STS 304L due to Plastic Working

Energy Technology Data Exchange (ETDEWEB)

Shim, Hyun-Bo [Yeungnam Univ., Daegu (Korea, Republic of); Kim, Young-Kyun [KOGAS Research Institute, Seoul (Korea, Republic of); Suh, Chang-Min [Kyungpook Nat’l Univ., Daegu (Korea, Republic of)

2017-07-15

The purpose of this study is to investigate the influence of the cold reduction rate and an ultrasonic fatigue test (UFT) on the fatigue behaviors of STS 304L. The tensile strength, yield strength, hardness value and fatigue limit in the UFT fatigue test linearly increased as thickness decreased from 1.5 mm to 1.1 mm, as the cold reduction rate of STS 304L increased. As a result of the UFT fatigue test (R = -1) of four specimens, the fatigue limit of the S-N curve formed a knee point in the region of 10{sup 6}, and the 2nd fatigue limit caused by giga cycle fatigue did not appeared. In the case of t = 1.1 mm, the highest fatigue limit was 345 MPa, which was 64.3% higher than the original material (t = 1.5 mm). As a result of the UFT fatigue test of STS 304L, many small surface cracks occurred, grown, coalesced while tearing.

Reciclado de las aguas de decapado

Directory of Open Access Journals (Sweden)

López, F. A.

1998-05-01

Full Text Available Pickling liquors from steel industry, listed as hazardous wastes in most industrializated countries, have been treated by means of several procedures in order to recover the iron and other metals and to obtain an environmental friendly effluent. Depending on the treatment employed, different valuable ferrous products have been obtained. Ammoniojarosite and zinc ferrite were precipitated from the previously oxidised ferrous solutions.

En la mayoría de los países industrializados, se incluyen las aguas de decapado, tanto las procedentes de los aceros al carbono como de aceros inoxidables, dentro de las listas de residuos tóxicos y peligrosos. Se presentan en este trabajo los resultados obtenidos en las investigaciones realizadas en los últimos años en los que se ha estudiado el tratamiento y recuperación de aguas de decapado de aceros comunes e inoxidables. Su tratamiento se ha enfocado hacia la consecución de dos objetivos: la recuperación del contenido total de metales y la obtención de un efluente de menor impacto ambiental. Se presentan los procedimientos estudiados para la obtención de compuestos de hierro, amoniojarosita y ferritas de zinc, con cierto valor añadido.

Dermatitis de contacto por prótesis ortopédicas Contact dermatitis for orthopaedic prostheses

Directory of Open Access Journals (Sweden)

C.A. Danielo

2007-09-01

Full Text Available Diversas aleaciones son utilizadas en la fabricación de prótesis ortopédicas (ej: titanio, vitalio, etc, dentro de las cuales la más utilizada es la de acero inoxidable. El níquel, parte importante de esta aleación, es capaz de liberarse y provocar sensibilización, desencadenando reacciones cutáneas locales y sistémicas. De los materiales que componen la aleación para formar acero inoxidable, el níquel es el que más frecuentemente se ve implicado en reacciones cutáneas por sensibilidad, en tanto que otros como el cromo y cobalto, la posibilidad de pérdida de material a partir de la prótesis es discutida. Presentamos el caso de una paciente con dermatitis alérgica al níquel con lesiones generalizadas, que aparecieron luego del implante de prótesis ortopédicas de acero inoxidable, dando positivo para níquel sulfato en las pruebas epicutáneas.Several alloys are used in the manufacture of orthopaedics prostheses (ie: titanium, vitalium. Stainless steel is the most frequently used among them. Nickel is an important component of this alloy and may release and provoke sensitivity. Arising local and systemic cutaneous reactions. Nickel is the material composing stainless steel that ordinary is implicated in cutaneous reactions of sensitivity; the role of chrome or cobalt is still uncertain. Our patient is a woman affected of nickel contact dermatitis, with generalized reactions that appear after an implant of a stainless steel orthopaedic prosthesis. Epicutaneous tests were performed, confirming a strong sensitivity to nickel sulphate.

Lubricación del contacto aluminio-acero con líquidos iónicos en atmósfera controlada

OpenAIRE

Llopis Morales, Miguel

2016-01-01

El objetivo del presente proyecto es estudiar el comportamiento tribológico de diferentes líquidos iónicos en el contacto aluminio-acero y las interacciones superficiales que se producen. Para realizar el estudio tribológico, se llevará a cabo un estudio de corrosión previo por lo que será necesario realizar ensayos de corrosión y tribológicos. En cuanto a los objetivos de los ensayos de corrosión, el objetivo que se quiere alcanzar con este ensayo es comprobar si se produce algún tipo de cor...

Influencia del acabado superficial en la permeación de hidrógeno del acero API 5L-X52

Directory of Open Access Journals (Sweden)

Réquiz, R.

2004-02-01

Full Text Available The influence of surface roughness on the corrosion and hydrogen permeation behaviour was evaluated on a type API 5L-X52 steel in deaerated 0.1 M Na₂SO₄ at pH=2. Potentiodynamic polarization curves were employed to determine the electrochemical behaviour of the steel, while the Devanathan-Stachurski technique was used to estimate the hydrogen permeation rate. Additionally, the surface roughness profiles were obtained in order to correlate the changes in the hydrogen permeation rate with different metal surface finishings. The obtained results clearly demonstrate that when the roughness parameters have larger values, the cathodic current of hydrogen evolution increases while the hydrogen entry rate decreases. This effect can be attributed to the microstructural defects induced at the steel surface, such as dislocations, which increase the catalytic activity of the atomic hydrogen favouring its recombination. Also, these defects could allow the atomic hydrogen to remain adsorbed on the steel surface. Both effects could hinder the hydrogen diffusion into the metal since the possibility for this atom of becoming absorbed has been reduced

En el presente trabajo de investigación se evalúa la influencia del acabado superficial, tanto en la corrosión generalizada como en la permeación de hidrógeno del acero API 5L-X52 en solución de Na₂SO₄ 0,1M, a pH=2. El comportamiento electroquímico del acero se estudió mediante las curvas de polarización potenciodinámicas, mientras que la susceptibilidad al daño por hidrógeno se evaluó mediante la técnica de permeación de Devanathan- Stachurski. Además, se determinaron los parámetros de rugosidad a las muestras de acero con diferentes acabados superficiales, para luego correlacionarlos con los cambios en las corrientes de permeación de hidrógeno. Los resultados obtenidos demuestran, claramente, que, cuando la rugosidad superficial del acero

Effect of Temperature on the Fracture Toughness of Hot Isostatically Pressed 304L Stainless Steel

Science.gov (United States)

Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

2018-03-01

Herein, we have performed J- Resistance multi-specimen fracture toughness testing of hot isostatically pressed (HIP'd) and forged 304L austenitic stainless steel, tested at elevated (300 °C) and cryogenic (- 140 °C) temperatures. The work highlights that although both materials fail in a pure ductile fashion, stainless steel manufactured by HIP displays a marked reduction in fracture toughness, defined using J 0.2BL, when compared to equivalently graded forged 304L, which is relatively constant across the tested temperature range.

Effect of Prior Deformation on Welding Microstructure of Steel 304L

Directory of Open Access Journals (Sweden)

WU Luo-fei

2017-01-01

Full Text Available This subject was raised by an automotive company.Based on the welding design on the curved surface,the effect of prior deformation on the weld structure was studied.Metal active-gas welding was used on the T-joint and pre-deformed plates of austenitic stainless steel 304L to find the proper welding parameters and observe the effect of prior deformation on the microstructure.The proper parameters acquired are:the speed of the torch is 4mm/s,the speed of delivery of welding wire is 2.5m/min and the voltage is 17V.In the T-joint and pre-deformed joint,the weld toes are in the zone with strain of 0% and 30%.In the pre-deformed welding specimen,it was observed that the fusion zone and partially melted zone are narrowed,carbide precipitation and ferrites are found less.In all,the microstructure in the pre-deformed weld joints on 304L is more uniform.

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...

Comportamiento a fatiga del vástago de una prótesis para cadera al caminar//Fatigue behavior stem hip prosthesis for walking

OpenAIRE

Ángel Martínez-Delfín; Javier García-de-la-Figal-Costales; Luís Manuel Rodríguez-Milián; Reynaldo Rodríguez-Pérez

2014-01-01

La prótesis de cadera consiste en sustituir la parte superior fracturada del fémur por una pieza de material biocompatible. Debido a las cargas aleatorias que sobre esta prótesis actúan al caminar la persona injertada, surge la fatiga sobre la prótesis. En este trabajo se realiza el cálculo a fatiga del vástago de una prótesis de caderas fabricada con acero inoxidable austenítico AISI 316L GrQ y de uso actual. Para ellose emplea el método de los elementos finitos, considerando la compleja geo...

Inhibidores de escaso impacto medioambiental. Sistemas basados en tierras raras

Directory of Open Access Journals (Sweden)

Aballe, A.

1997-12-01

Full Text Available Lanthanum, Cerium and Samarium chlorides have been investigated as uniform and pitting corrosion inhibitors of AISI 434 and AISI 304 stainless steels and AA 5083 Al-Mg alloy in 3.5 % NaCl aerated aqueous solutions. Their inhibitor power was evaluated by using electrochemical techniques such as Linear and Cyclic Polarisation. In each case, the highest protection degree was found in the solution dopped with 500 ppm of CeCl₃. Similar results were obtained for additions of 500 ppm of LaCl₃. Scanning Electron Microscopy and Energy Dispersive Spectroscopy allowed us to confirm the cathodic nature of the inhibition process.

Se estudia el comportamiento de los cloruros de lantano, cerio y samario como inhibidores de los procesos de corrosión uniforme y por picaduras de los aceros inoxidables AISI 434 y AISI 304 y de la aleación de aluminio AA 5083 en disoluciones aireadas de NaCl al 3,5 %. Utilizando técnicas electroquímicas como polarización lineal y cíclica, se ha podido evaluar el poder inhibidor de estas sustancias. El mejor comportamiento inhibidor se ha obtenido para una concentración de 500 ppm de CeCl₃, si bien para los aceros se obtienen resultados del mismo orden para 500 ppm de LaCl₃. Con la ayuda de microscopía electrónica de barrido y espectroscopia de dispersión de energía se ha podido confirmar el carácter catódico del mecanismo de inhibición que tiene lugar en el proceso.

An Assessment of the Ductile Fracture Behavior of Hot Isostatically Pressed and Forged 304L Stainless Steel

Science.gov (United States)

Cooper, A. J.; Smith, R. J.; Sherry, A. H.

2017-05-01

Type 300 austenitic stainless steel manufactured by hot isostatic pressing (HIP) has recently been shown to exhibit subtly different fracture behavior from that of equivalent graded forged steel, whereby the oxygen remaining in the component after HIP manifests itself in the austenite matrix as nonmetallic oxide inclusions. These inclusions facilitate fracture by acting as nucleation sites for the initiation, growth, and coalescence of microvoids in the plastically deforming austenite matrix. Here, we perform analyses based on the Rice-Tracey (RT) void growth model, supported by instrumented Charpy and J-integral fracture toughness testing at ambient temperature, to characterize the degree of void growth ahead of both a V-notch and crack in 304L stainless steel. We show that the hot isostatically pressed (HIP'd) 304L steel exhibits a lower critical void growth at the onset of fracture than that observed in forged 304L steel, which ultimately results in HIP'd steel exhibiting lower fracture toughness at initiation and impact toughness. Although the reduction in toughness of HIP'd steel is not detrimental to its use, due to the steel's sufficiently high toughness, the study does indicate that HIP'd and forged 304L steel behave as subtly different materials at a microstructural level with respect to their fracture behavior.

Funcionalización electroquímica y tribológica de películas de quitosano en fosfato tricálcico depositados en acero 316L

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Alexis Mina Escobar

2013-12-01

Full Text Available Se depositaron recubrimientos de fosfato tricálcico-β/quitosano sobre sustratos de acero 316L vía electrodeposición, a una temperatura de 60 °C, aplicando una corriente de 260 mA. Con el fin de estudiar el efecto del contenido de quitosano en la velocidad de corrosión y la respuesta tribológica de los aceros recubiertos, se utilizaron seis concentraciones de quitosano en la mezcla acuosa. Los enlaces químicos presentes en las capas fueron estudiados mediante Espectroscopia de Infrarrojo con Transformada de Fourier (FTIR; la cristalinidad de los depósitos fue examinada mediante difracción de rayos-X (DRX; la resistencia a la corrosión del TCP-β/quitosano depositado sobre los aceros se estudió mediante Espectroscopia de Impedancia Electroquímica (EIS y curvas anódicas Tafel, encontrándose una disminución del 54% en la velocidad de corrosión para la relación 50-50, con respecto a 100% TCP. La respuesta tribológica se analizó mediante pin-on-disc, evidenciando una reducción del 73% en el coeficiente de fricción con mayor concentración de quitosano.

Intergranular stress corrosion cracking of ion irradiated 304L stainless steel in PWR environment

International Nuclear Information System (INIS)

Gupta, Jyoti

2016-01-01

IASCC is irradiation - assisted enhancement of intergranular stress corrosion cracking susceptibility of austenitic stainless steel. It is a complex degrading phenomenon which can have a significant influence on maintenance time and cost of PWRs' core internals and hence, is an issue of concern. Recent studies have proposed using ion irradiation (to be specific, proton irradiation) as an alternative of neutron irradiation to improve the current understanding of the mechanism. The objective of this study was to investigate the cracking susceptibility of irradiated SA 304L and factors contributing to cracking, using two different ion irradiations; iron and proton irradiations. Both resulted in generation of point defects in the microstructure and thereby causing hardening of the SA 304L. Material (unirradiated and iron irradiated) showed no susceptibility to intergranular cracking on subjection to SSRT with a strain rate of 5 * 10 -8 s -1 up to 4 % plastic strain in inert environment. But, irradiation (iron and proton) was found to increase intergranular cracking severity of material on subjection to SSRT in simulated PWR primary water environment at 340 C. Correlation between the cracking susceptibility and degree of localization was studied. Impact of iron irradiation on bulk oxidation of SA 304L was studied as well by conducting an oxidation test for 360 h in simulated PWR environment at 340 C. The findings of this study indicate that the intergranular cracking of 304L stainless steel in PWR environment can be studied using Fe irradiation despite its small penetration depth in material. Furthermore, it has been shown that the cracking was similar in both iron and proton irradiated samples despite different degrees of localization. Lastly, on establishing iron irradiation as a successful tool, it was used to study the impact of surface finish and strain paths on intergranular cracking susceptibility of the material. (author) [fr

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

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Cervera, I.

2011-04-01

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

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

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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.

Study of copper deposit on a porous electrode of carbon and stainless steel by sem-xrd and image analysis

OpenAIRE

Constanzo-R., Robinson; Pagliero-N., Antonio; Vergara-G., Froilán

2014-01-01

El objetivo de este trabajo fue realizar un análisis cualitativ o de la distribución de un electrodepósito de cobre en el inter ior de electrodos porosos (EP) de acero inoxidable y carbono grafito. Para ello, se reali zaron pruebas de electrodepositación de cobre a nivel de labora torio, con un posterior análisis de cortes de muestras de acero y grafito vía Microscopía Estereoscópica, Microscopía SEM-DRX y Análisis de Imagen, los cuales mostraron que el cobre no se deposita en forma uniforme ...

Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación

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Castro Regal, G.

2005-06-01

Full Text Available The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions were three times smaller than those obtained without lubrication. The mechanism that controls wear behaviour under lubrication conditions is an abrasive one and the wear values obtained are almost worthless. On the other hand, mechanism controlling wear during non lubrication tests, was a combination of abrasion and adhesion

Se ha evaluado el comportamiento frente a fricción y el desgaste de distintas calidades de acero ensayadas bajo condiciones de lubricación y sin lubricación. Las calidades de acero seleccionadas son las que normalmente se emplean en los sistemas de manutención aérea de numerosos procesos de producción, como la fabricación de automóviles. Se han realizado ensayos de desgaste tipo punzón-disco mediante un punzón de acero de calidad100Cr6, empleado en los carros que circulan por las líneas de manutención aérea. Se ha observado que el valor del coeficiente de fricción obtenido bajo condiciones de lubricaciones, aproximadamente, tres veces menor que el obtenido sin lubricación. Por otro lado, el mecanismo que controla el proceso de desgaste de los aceros ensayados con lubricación es un mecanismo de desgaste abrasivo y los valores de desgaste obtenidos son prácticamente despreciables. El desgaste de los aceros ensayados sin lubricación se produjo por combinación de dos mecanismos de desgaste: abrasión y adhesión.

Efectos del tratamiento térmico en la fractura de aceros

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Héctor Hernández A.

1992-05-01

Full Text Available No obstante de los avances logrados en otros tipos de aleaciones, los aceros se siguen utilizando en forma extensiva en la construcción de elementos estructurales, porque con una adecuada selección y tratamiento técnico, los aceros permiten obtener una conveniente combinación de propiedades mecánicas ante unas exigencias específicas de servicio. La fractura en elementos de máquinas frecuentemente se encuentra asociada a una discontinuidad, la cual provoca una concentración de esfuerzo, lo que puede originar sitios de iniciación de una falla por fractura. La carga límite de fractura es afectada por parámetros geométricos, naturaleza y tipo de carga y propiedades mecánicas del material. La mayoría de fallas por fractura de elementos de máquinas son fallas por fatiga; por lo general una fractura por fatiga tiene lugar por una progresiva generación y crecimiento de grietas hasta obtenerse una condición crítica de fractura súbita de la sección residual resistente. Frecuentemente en una fractura por fatiga se observan marcas de playa, las cuales son evidencias de la posición del frente de grietas antes que se alcance la condición de fractura súbita final. En este trabajo se muestra como el tratamiento térmico de temple y revenido de los aceros afecta el esfuerzo límite de falla por fractura para carga de tracción estática y carga de fatiga uniaxial con la presencia de una entalla severa. También se estudia el efecto del tratamiento térmico en la tenacidad de fractura, propiedad que cuantifica la resistencia al crecimiento súbito de una grieta bajo carga estática.

Transferencia de calor en la colada continua de aceros. I parte. El molde

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Cicutti, C.

1997-10-01

Full Text Available The continuous casting mold plays the important role of receiving the liquid steel and allowing an uniform and defect free solidified skin to be developed. In this work, the different heat transfer mechanisms which are present from the liquid steel to the mold cooling water are reviewed. The effect of operating variables on heat extraction and the relationship between global and distributed heat flux are also analyzed.

El molde de colada continua cumple la importante función de recibir el acero líquido y permitir que se desarrolle una capa solidificada uniforme y libre de defectos. En este trabajo se revisan los distintos mecanismos implicados en el proceso de transferencia de calor, desde el acero líquido hasta el agua de refrigeración del molde. Se analiza también el efecto de las distintas variables de funcionamiento en la extracción calórica producida y la relación entre el flujo global de calor y su distribución a lo largo del molde.

Acoustic emission from hydrogen saturated Type 304L stainless steel

International Nuclear Information System (INIS)

Caskey, G.R. Jr.

1978-01-01

Acoustic emission is attributed to energy release within a material body by localized plastic deformation or failure processes. The elastic stress waves may come from slip band formation, mechanical twinning, martensite transformation, or crack propagation. Each of these processes has slightly different acoustic characteristics allowing for easy identification. Acoustic emission was monitored during tensile tests of Type 304L austenitic stainless steel to explore the applicability of the technique to hydrogen-assisted fracture

Procesos de unión y estudio de interfaces en Si3N4 y ZrO2

OpenAIRE

Polanco Rodríguez, Raquel

2007-01-01

Esta memoria se ha centrado en la obtención de uniones en dos tipos de materiales cerámicos alto interés tecnológico, como son el nitruro de silicio y el óxido de circonio. El trabajo desarrollado en esta tesis ha consistido, principalmente, en el estudio y caracterización de las interfaces metaVcerámica generadas tras el proceso de unión en estos materiales consigo mismos, o bien con piezas metálicas. En el' caso del ShN4 se utilizó acero inoxidable como lámina de unión. Por o...

Recubrimiento de acero con polidopamina

OpenAIRE

Carrasco Rodríguez, Javier

2013-01-01

Se ha obtenido recubrimientos de polidopamina en acero mecánicamente resistentes y con tiempos de obtención relativamente pequeños a través de la polimerización de la dopamina bajo diferentes condiciones.

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

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Higuera-Hidalgo, V.

2005-06-01

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

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

Estudio de la corrosión de diferentes aleaciones en sales de carbonatos fundidos con la técnica de espectroscopía de impedancia electroquímica

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Pérez, F. J.

2000-06-01

Full Text Available In the present work the corrosion behavior of different alloys (AISI 304, AISI 430 and TiAl6V in molten carbonates at 650EC are compared. By using the Electrochemical Impedance Technique different corrosion parameters such as the corrosion rate and the oxyde concentration and others features of the different layers of corrosion products are "in situ" determined. Take into account, the corrosion product characterization by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM and Electrochemical impedance Spectroscopy (EIS a corrosion mechanism for every tested alloy is proposed. In all cases, the corrosion mechanisms during the first hours are similar to a high temperature oxidation mechanism. When the equilibrium is established, the lithiation began by the formation of different double-layers on the surface of Li-metal oxydes. At the end of the corrosion process, one or two inner layers of metallic oxydes and one or two outer layers of Li-metal oxydes were formed. The corrosion mechanisms of the stainless steels (AISI 304 ans AISI 310S are a function of their chromium contents. TiAl6V alloy showed the best behavior against the corrosion of molten carbonates by the formation of a protective layer of mixed Li-Ti oxydes.

En el presente trabajo se compara el comportamiento frente a la corrosión de diferentes aleaciones (aceros inoxidables AISI 304 y AISI 310S y aleación TiAl6V en un electrolito de carbonatos fundidos a 650°C. Con la técnica de impedancia se determina “in situ” la velocidad de corrosión de las aleaciones, la resistencia del electrolito, es decir, la concentración del óxido disuelto y otras características de las capas de productos de corrosión. Teniendo en cuenta la caracterización de los productos de corrosión mediante difracción de rayos X (XRD y microscopía electrónica de barrido (SEM y los resultados de espectroscopía de impedancia (EIS, se propone un mecanismo para cada una de las aleaciones. En

Forging evaluaion of 304L stainless steel

International Nuclear Information System (INIS)

Packard, C.L.; Edstrom, C.M.

1979-01-01

The objective of this project was to evaluate and characterize the effects of various forging parameters on the metallographic structure and mechanical properties of 304L stainless steel forgings. Upset and die forgings were produced by hammer and Dynapak forging with forging temperatures ranging from 760 to 1145 0 C, upset reductions ranging from 20 to 60%, and annealing times ranging from 0 to 25 minutes at 843 0 C. The carbide precipitation behavior observed was found to be a function of forging temperature and annealing time. Higher forging temperatures were beneficial in avoiding continuous carbide precipitation and annealing at 843 0 C promoted increased carbide precipitation. The yield strength of the unannealed forgings decreased with increasing forging temperature and, with the exception of the 1145 0 C upset forgings, was significantly lowered by annealing

The effect of cysteine on the corrosion of 304L stainless steel in sulphuric acid

International Nuclear Information System (INIS)

Silva, A.B.; Agostinho, S.M.L.; Barcia, O.E.; Cordeiro, G.G.O.; D'Elia, E.

2006-01-01

The effect of cysteine on the corrosion of 304L stainless steel in 1 mol l -1 H 2 SO 4 was studied using open-circuit potential measurements, anodic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). All the electrochemical measurements obtained in the presence of low cysteine concentration (10 -6 -10 -5 mol l -1 ) presented the same behaviour as those obtained in the absence of cysteine, a passivated steel surface. However, for higher cysteine concentrations (10 -4 -10 -2 mol l -1 ), a different behaviour was observed: the corrosion potential stabilized at a more negative value; an active region was observed in the anodic polarization curves and the electrochemical impedance diagrams showed an inductive loop at lower frequencies and a much lower polarization resistance. These results show that the presence of cysteine at high concentration turns the surface of 304L stainless steel electrochemically active, probably dissolving the passivation layer and promoting the stainless steel anodic dissolution. SEM experiments performed after immersion experiments at corrosion potential were in good agreement with the electrochemical results

Biocompatibility of bismuth silicate coatings deposited on 316L stainless steel by sol-gel process

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Jorge Hernando Bautista-Ruiz

2017-01-01

Full Text Available Películas delgadas de silicato de bismuto (BSO se han fabricado mediante el proceso sol-gel. El sol estable se sintetizó utilizando nitrato de bismuto (III pentahidrato y tetraetil-ortosilicato (TEOS. Las películas fueron depositadas a 1500 rpm mediante la técnica de centrifugado. Los recubrimientos se caracterizaron por microscopía de fuerza atómica (AFM, microscopía electrónica de barrido (SEM, difracción de rayos-X (DRX y se midió el espesor de las películas. El objetivo de este estudio fue evaluar la adhesión y la proliferación en células de osteoblastos, mediante el ensayo MMT, al incubarse sobre películas BSO en sustratos de 316L. Se concluyó que el crecimiento de los osteoblastos es homogéneo en la superficie de las películas, indicando que el medio ofrecido por los recubrimientos no presenta actividad citotóxica y favorece los niveles de crecimiento celular en comparación con los resultados obtenidos para los sustratos de acero inoxidable.

Development of UO{sub 2}-Stainless Steel Fuel Plates Containing 30-50 Vol. % Oxide; Fabrication de plaques de combustible en acier inoxydable-UO{sub 2} contenant 30 a 40% d'oxyde (en volume); Razrabotka toplivnykh ehlementov iz nerzhaveyushchej stali i UO{sub 2}, soderzhashchikh 30 - 50 OB.% okisi; Elaboracion de placas de combustible de acero inoxidable UO{sub 2} conteniendo 30 a 40% de oxido (en volumen)

Energy Technology Data Exchange (ETDEWEB)

Lloyd, H. [Atomic Energy Research Establishment, Harwell (United Kingdom)

1963-11-15

lesquelles les particules de UO{sub 2} sont reparties uniformement dans la matrice en acier inoxydable, ainsi que le procede de revetement des plaques de combustible par rechargement a chaud. On a etudie des operations de laminage comprenant des deformations allant de 40% a 90%, a des temperatures allant jusqu'a 1300{sup o}C pour determiner les conditions optimums de production des noyaux de densite elevee et pour realiser une bonne cohesion entre les elements constitutifs des plaques, la fissuration des particules de UO{sub 2} etant reduite au minimum. L'auteui decrit la fabrication de grandes plaques de combustible composees de plaques a plusieurs noyaux, liees ensemble par laminage a chaud. L'auteur donne des indications sur les proprietes mecaniques de cermets UO{sub 2}-Inox contenant 30, 40 et 50% de UO{sub 2}(en volume), fabriques comme on l'a indique plus haut et essayes bruts de laminage et recuits a diverses temperatures allant jusqu'a 700{sup o}C. Il a utilise a cet effet des echantillons preleves les uns perpendiculairement, les autres parallelement au sens du laminage. Il examine en outre l'influence de la taille des particules de UO{sub 2} et de l'uniformite de leur repartition sur les proprietes mecaniques. Il a determine egalement les forces de liaison entre le noyau et la gaine pour des cermets similaires dans la meme gamme de temperatures. Le memoire contient encore les resultats d'essais de cyclage thermique entre 50 et 800{sup o}C entrepris pour determiner les effets de ce cyclage sur la structure du cermet et la stabilite de la liaison, apres 100, 500 et 1000 cycles. (author) [Spanish] La memoria expone los recientes progresos en lo relativo a la elaboracion de elementos combustibles del tipo de UO{sub 2} y acero inoxidable en placas, que contienen hasta 50% de UO{sub 2} en volumen. Describe la preparacion de particulas esfericas de UO{sub 2} sinterizado, de elevada densidad, de granulome tria comprendida entre 100 y 500, y la compactacion y sinterizacion

Oxidation behavior of 304 stainless steel exposed to steam at high temperature

Energy Technology Data Exchange (ETDEWEB)

Jeong, H.; Ryu, J. R.; Park, G. H. [Kyunghee Univ., Yongin (Korea, Republic of); Yoo, T. G. [FNC Technology, Seoul (Korea, Republic of)

2003-10-01

An experiment was conducted on 304 stainless steel(SUS304L) at the LOCA(Lost of Coolant Accident) requirement temperature, 800 .deg. C to 1100 deg. C. SUS304L was used as clothing material and structural frame of LWR. Oxidation behavior of SUS304L by temperature and time was examined after the mechanical and chemical polishing of SUS304L plate. After oxidation, change in weight showed a linear pattern for the first 20 minutes and a parabolic pattern afterwards. Then, fine structure and oxidation layer of SUS304L plate were observed through OM photographing and oxidation characteristics of SUS304L were found through hardness measurement by depth of each plate and XRD(X-Ray Diffraction) photographing.

Effect of welding process, type of electrode and electrode core diameter on the tensile property of 304L austenitic stainless steel

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Akinlabi OYETUNJI

2014-11-01

Full Text Available The effect of welding process, type of electrode and electrode core diameter on the tensile property of AISI 304L Austenitic Stainless Steel (ASS was studied. The tensile strength property of ASS welded samples was evaluated. Prepared samples of the ASS were welded under these three various variables. Tensile test was then carried out on the welded samples. It was found that the reduction in ultimate tensile strength (UTS of the butt joint samples increases with increase in core diameter of the electrode. Also, the best electrode for welding 304L ASS is 308L stainless steel-core electrode of 3.2 mm core diameter. It is recommended that the findings of this work can be applied in the chemical, food and oil industries where 304L ASS are predominantly used.

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

OpenAIRE

Victoria González Quintana; Juan Carlos Botero; Roberto Rochel; Julián Vidal; Martha Cecilia Alvarez Uribe

2005-01-01

Se presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materialA statistical analysis applied to a experimental study that determines the mechanical properties of steels produ...

XPS STRUCTURE ANALYSIS OF TiN/TiC BILAYERS PRODUCED BY PULSED VACUUM ARC DISCHARGE

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ELISABETH RESTREPO PARRA

2010-01-01

Full Text Available se crecieron bicapas de TiN/TiC sobre sustratos de acero inoxidable 304 usando un sistema de deposición física de vapor asistida por plasma en forma de arco pulsado a dos diferentes temperaturas del sustrato (50º C y150º C. Para el análisis de la composición química se empleó la técnica de la espectroscopía de fotoelectrones de rayos X (XPS. Se observó el comportamiento de las líneas Ti2p, N1s y C1s. Los análisis de energía de enlace confirmaron la conformación de TiN y TiC. Los picos C1s y Ti2p sufrieron un corrimiento a medida que se incrementó el tiempo de esputtering, revelando contaminación debido a la presencia de hidrocarburos. Además, los perfiles de profundidad de las bicapas de TiN/TiC mostraron que las películas crecidas a una temperatura de 150 ° C tienen una capa de TiN más gruesa que las muestras crecidas a 50º C. El nitrógeno se difundió en la capa de TiC y el carbón en la capa de TiN para ambas temperaturas.

Mejora de la calidad del acero obtenido por colada continua mediante influencias electrofísicas

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Shklyar, V.

1998-12-01

Full Text Available Laboratory tests with tin smelted in a crucible and industrial tests with crude steel poured in moulds had been carried out. These metals were subjected to electrophysical influences. As a result of the applied electric field, it is observed in tin that during the solidification, the crystalization temperature and the solidification time are changed. Crystal growth in the electric field direction and an increase of the fracture limit in the steel ingot are observed.

Se han realizado ensayos de laboratorio con estaño fundido en crisol y a escala industrial con acero líquido vertidos en moldes, sometiendo estos metales a influencias electrofísicas. Como resultado del campo aplicado, en el estaño se observa que durante la solidificación varía la temperatura de cristalización y el tiempo de solidificación. En el lingote de acero se observa un crecimiento de los cristales en dirección del campo eléctrico y un aumento del límite de rotura.

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

Corrosión en soldaduras de aparatos de ortodoncia

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Vázquez, S. M.

1997-10-01

Full Text Available The study of corrosion-related problems of dental materials has undergone a considerable development in recent years in order to avoid the use of materials with insufficient corrosion resistance in patients' mouth. The subject of the present work was to study a particular type of corrosion: galvanic corrosion. One of the most common case of galvanic couples in patients' mouth are the orthodontic appliances. The materials studied in the present work were stainless steel strips and silver-copper wires, isolated and welded between them. The electrochemical tests were performed in a NaCl 0.1M and Lactic Acid 0.1M solution (pH 2.3, and after test, the specimens were observed using the optical and scanning electron microscope. The results show that when stainless steel is coupled with a silver solder, the last is the anode of the galvanic couple. As a consequence of this, the silver solder undergone a severe attack. Stainless steel orthodontic appliances with silver solder are feasibly destroyed due to a severe attack on the filler metal disjoining the welded parts.

En los últimos años se ha desarrollado considerablemente el estudio de los problemas relacionados con la corrosión de aleaciones dentales a efectos de evitar la utilización de materiales con una deficiente resistencia a la corrosión en la boca de los pacientes. El objetivo del presente trabajo fue estudiar la corrosión de aparatos de ortodoncia fabricados con acero inoxidable con soldadura por punto o por aporte de aleación de plata. Los resultados obtenidos mostraron que cuando el acero inoxidable contiene aportes de soldadura de material de base plata, ésta actúa como ánodo disolviéndose preferencialmente a una velocidad considerable. Los aparatos de ortodoncia construidos con acero inoxidable soldado con aporte de material de base plata, corren el riesgo de destrucción debido a un ataque intenso en el cordón de soldadura con el consiguiente despegue de las piezas

Standard test method for electrochemical reactivation (EPR) for detecting sensitization of AISI type 304 and 304L stainless steels

CERN Document Server

American Society for Testing and Materials. Philadelphia

1994-01-01

1.1 This test method covers a laboratory procedure for conducting an electrochemical reactivation (EPR) test on AISI Type 304 and 304L (UNS No. S30400 and S30403, respectively) stainless steels. This test method can provide a nondestructive means of quantifying the degree of sensitization in these steels (1, 2, 3). This test method has found wide acceptance in studies of the effects of sensitization on intergranular corrosion and intergranular stress corrosion cracking behavior (see Terminology G15). The EPR technique has been successfully used to evaluate other stainless steels and nickel base alloys (4), but the test conditions and evaluation criteria used were modified in each case from those cited in this test method. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this...

Efecto de la imidazolina [IM-NH17] en el proceso de corrosión del acero api5l-x52 en salmueras acidificadas

OpenAIRE

Reynaud-Morales, A.G.; Casales-Díaz, M.; Chacón-Nava, J.G.; Martínez-Gómez, L.; Martínez-Villafañe, A.; González-Rodríguez, J.G.

2009-01-01

Se estudia la eficiencia de inhibición del compuesto Imidazolina Aminoetil Oleica [IM-NH17]) en la corrosión de un acero API5L-X52 en tres soluciones de salmuera acidificada a pH 3 a una temperatura de 50°C, empleando pruebas de polarización potenciodinámica y mediciones de resistencia de polarización. Bajo las condiciones de prueba, los resultados de curvas de polarización indicaron que el inhibidor se comporta como un inhibidor de tipo mixto. Los resultados de resistencia de polarización li...

Métodos electroquímicos semicuantitativos de estudio de lo corrosión por picaduras del acero para armaduras de hormigón

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Andrade Perdrix, M. C.

1977-12-01

Full Text Available El acero embebido en el hormigón se encuentra sometido a un medio de elevada alcalinidad (pH comprendido entre 12 y 13, debido a la cal libre, a los álcalis que contiene el cemento, y al Ca(0H₂ que se forma durante la hidratación de los silicatos. En esta situación, el acero se halla recubierto por una capa de óxidos e hidróxidos estables que lo mantienen pasivado, interponiendo una barrera entre él y los agentes agresivos.

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

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Garin, J. L.

2011-08-01

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

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

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

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Gaona-Tiburcio, Citlalli

2000-04-01

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

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

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

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Otero, E.

1996-04-01

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

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

Corrosion and microstructural aspects of dissimilar joints of titanium and type 304L stainless steel

International Nuclear Information System (INIS)

Mudali, U. Kamachi.; Ananda Rao, B.M.; Shanmugam, K.; Natarajan, R.; Raj, Baldev

2003-01-01

To link titanium and zirconium metal based (Ti, Zr-2, Ti-5%Ta, Ti-5%Ta-1.8Nb) dissolver vessels containing highly radioactive and concentrated corrosive nitric acid solution to other nuclear fuel reprocessing plant components made of AISI type 304L stainless steel (SS), high integrity and corrosion resistant dissimilar joints between them are necessary. Fusion welding processes produce secondary precipitates which dissolve in nitric acid, and hence solid-state processes are proposed. In this work, various dissimilar joining processes available for producing titanium-304L SS joints with adequate strength, ductility and corrosion resistance for this critical application are highlighted. Developmental efforts made at IGCAR, Kalpakkam are outlined. The possible methods and the microstructural-metallurgical properties of the joints along with corrosion results obtained with three phase (liquid, vapour, condensate) corrosion testing are discussed. Based on the results, dissimilar joint produced by the explosive joining process was adopted for plant application

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

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Gutiérrez de Saiz-Solabarría, S.

1998-05-01

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

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

Behaviour under fatigue of AISI 304-L stainless steel welded joints

International Nuclear Information System (INIS)

Scal, M.W.; Joia, C.J.B.M.; Sousa e Silva, A.S. de

1979-01-01

The fatigue behaviour at room temperature of AISI-304-L stainless steel welded joints obtained by two distinct welding methods was studied. The results obtained were compared to those characteristic of the base metal. The welded joint fatigue samples were rectified in order to eliminate the effect of the welded seam geometry. It was concluded that the mechanisms of fatigue crack start in this case is commanded by the austenitic matrix, there being no influence of the delta ferrite rate and distribution present at the melted zone. (Author) [pt

Distinguishing effect of buffing vs. grinding, milling and turning operations on the chloride induced SCC susceptibility of 304L austenitic stainless steel

International Nuclear Information System (INIS)

Kumar, Pandu Sunil; Acharyya, Swati Ghosh; Rao, S.V. Ramana; Kapoor, Komal

2017-01-01

The study compares the effect of different surface working operations like grinding, milling, turning and buffing on the Cl – induced stress corrosion cracking (SCC) susceptibility of austenitic 304L stainless steel (SS) in a chloride environment. SS 304L was subjected to four different surface working operations namely grinding, milling, turning and buffing. The residual stress distribution of the surface as a result of machining was measured by X-ray diffraction. The Cl – induced SCC susceptibility of the different surface worked samples were determined by testing in boiling magnesium chloride as per ASTM G36 for 3 h, 9 h and 72 h. The surface and cross section of the samples both pre and post exposure to the corrosive medium was characterized using optical microscopy, scanning electron microscopy (SEM). The study revealed that grinding, milling and turning operations resulted in high tensile residual stresses on the surface together with the high density of deformation bands making these surfaces highly susceptible to Cl – induced SCC. On the other hand buffing produces compressive residual stresses on the surface with minimal plastic strain, making it more resistance to Cl – induced SCC. The study highlights that the conventional machining operations on 304L SS surfaces should be invariably followed by buffing operation to make the surfaces more resistance to SCC. - Highlights: • Grinding, milling and turning lead to tensile residual stresses and plastic strain. • Buffing leads to compressive residual stresses on the surface and minimal strain. • Grinding, milling and turning make 304L SS surface susceptible to SCC. • Buffed 304L SS surface is immune to SCC. • Grinding, milling, and turning operations should be followed by buffing operation.

Distinguishing effect of buffing vs. grinding, milling and turning operations on the chloride induced SCC susceptibility of 304L austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Kumar, Pandu Sunil [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Acharyya, Swati Ghosh, E-mail: swati364@gmail.com [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Rao, S.V. Ramana; Kapoor, Komal [Nuclear Fuel Complex, Department of Atomic Energy, Government of India, Hyderabad 500062 (India)

2017-02-27

The study compares the effect of different surface working operations like grinding, milling, turning and buffing on the Cl{sup –} induced stress corrosion cracking (SCC) susceptibility of austenitic 304L stainless steel (SS) in a chloride environment. SS 304L was subjected to four different surface working operations namely grinding, milling, turning and buffing. The residual stress distribution of the surface as a result of machining was measured by X-ray diffraction. The Cl{sup –} induced SCC susceptibility of the different surface worked samples were determined by testing in boiling magnesium chloride as per ASTM G36 for 3 h, 9 h and 72 h. The surface and cross section of the samples both pre and post exposure to the corrosive medium was characterized using optical microscopy, scanning electron microscopy (SEM). The study revealed that grinding, milling and turning operations resulted in high tensile residual stresses on the surface together with the high density of deformation bands making these surfaces highly susceptible to Cl{sup –} induced SCC. On the other hand buffing produces compressive residual stresses on the surface with minimal plastic strain, making it more resistance to Cl{sup –} induced SCC. The study highlights that the conventional machining operations on 304L SS surfaces should be invariably followed by buffing operation to make the surfaces more resistance to SCC. - Highlights: • Grinding, milling and turning lead to tensile residual stresses and plastic strain. • Buffing leads to compressive residual stresses on the surface and minimal strain. • Grinding, milling and turning make 304L SS surface susceptible to SCC. • Buffed 304L SS surface is immune to SCC. • Grinding, milling, and turning operations should be followed by buffing operation.

Multi-scale analysis of behavior and fatigue life of 304L stainless under cyclic loading with pre-hardening

International Nuclear Information System (INIS)

Belattar, A.

2013-01-01

This study investigates the effects of loading history on the cyclic stress-strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension-compression tests were performed on the same specimen under controlled strain, using several loading sequences of increasing or decreasing amplitude. The results showed that fatigue life is significantly reduced by the previous loading history. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after pre-loading and their evolution during the fatigue cycles were characterized by TEM. The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction. (author)

Diseño y evaluación de un procedimiento on-line para la biorremediación de aguas radiactivas en centrales nucleares

OpenAIRE

Belinchón Vergara, Julio Angel

2016-01-01

Recientemente se ha demostrado la existencia de microorganismos en las piscinas de almacenamiento de combustible nuclear gastado en las centrales nucleares utilizando técnicas convencionales de cultivo en el laboratorio. Estudios posteriores han puesto de manifiesto que los microorganismos presentes eran capaces de colonizar las paredes de acero inoxidable de las piscinas formando biopelículas. Adicionalmente se ha observado la capacidad de estas biopelículas de retener radionúclidos, lo que ...

Behavior of stressed and unstressed 304L specimens in tuff repository environmental conditions

International Nuclear Information System (INIS)

Juhas, M.C.; McCright, R.D.; Garrison, R.E.

1984-11-01

This paper presents preliminary results of an investigation of the behavior of candidate barrier material for high-level nuclear waste storage, Type 304L stainless steel, in tuff repository environmental conditions. Tuff is a densely welded, devitrified, igneous rock common to the proposed repository site at Yucca Mountain, Nevada. The results discussed include: irradiation corrosion tests, U-bend irradiation corrosion tests, slow strain rate tests, and bent beam stress corrosion tests. Results indicate that Type 304L stainless steel shows excellent resistance to general, localized, and stress corrosion under the environmental and microstructural conditions tested so far. The environmental test conditions are 50 to 100 0 C J-13 well water (non-saline, near neutral pH, and oxic in nature) and saturated steam at 100 0 C. Microstructural conditions include solution annealed and long furnace heat treatments to provoke a sensitized structure. However, this particular type of stainless steel may be susceptible to long-term, low-temperature sensitization because of the combination of expected time at elevated temperature and residual stress in the container after emplacement in the repository. Other grades of austenitic stainless steels are reported to be more resistant to low-temperature sensitization. Future work will therefore include more extensive testing of these grades. 15 references, 5 figures, 7 tables

Procesos de conversión de acero y efecto de variables en convertidores tipo L.B.E.

Directory of Open Access Journals (Sweden)

Blanco, C.

1995-10-01

Full Text Available In order to determine control equations based on qualitative and quantitative changes of the raw materials, an analysis of the efficiency of the steel production process was carried out in converters under specified operation conditions. Empirical equations to obtain the final composition of the steel as a function of the additives, the initial concentrations of the hot metal and the blowing oxygen patterns are established. The resulting relationships depend on the considered variables and therefore could be used to determine operational strategies in order to obtain steels of a certain quality.

Se analiza la eficacia de los procesos de transformación en convertidores en condiciones de trabajo determinadas, para deducir relaciones aplicables al control basadas en la modificación de cantidades y composiciones de las materias primas. Se plantean ecuaciones empíricas para determinar la composición final del acero como función de los aditivos y de las concentraciones iniciales del arrabio tratado, así como el patrón de soplado de oxígeno. Las relaciones obtenidas establecen las dependencias entre cada una de las variables consideradas y, por tanto, permiten determinar estrategias de operación para obtener aceros con unas calidades finales dadas.

Effect of Low-Temperature Sensitization on the Corrosion Behavior of AISI Type 304L SS Weld Metal in Simulated Groundwater

Science.gov (United States)

Suresh, Girija; Nandakumar, T.; Viswanath, A.

2018-05-01

The manuscript presents the investigations carried out on the effect of low-temperature sensitization (LTS) of 304L SS weld metal on its corrosion behavior in simulated groundwater, for its application as a canister material for long-term storage of nuclear vitrified high-level waste in geological repositories. AISI type 304L SS weld pad was fabricated by multipass gas tungsten arc welding process using 308L SS filler wire. The as-welded specimens were subsequently subjected to carbide nucleation and further to LTS at 500 °C for 11 days to simulate a temperature of 300 °C for 100-year life of the canister in geological repositories. Delta ferrite ( δ-ferrite) content of the 304L SS weld metal substantially decreased on carbide nucleation treatment and further only a marginal decrease occurred on LTS treatment. The microstructure of the as-welded consisted of δ-ferrite as a minor phase distributed in austenite matrix. The δ-ferrite appeared fragmented in the carbide-nucleated and LTS-treated weld metal. The degree of sensitization measured by double-loop electrochemical potentokinetic reactivation method indicated an increase in carbide nucleation treatment when compared to the as-welded specimens, and further increase occurred on LTS treatment. Potentiodynamic anodic polarization investigations in simulated groundwater indicated a substantial decrease in the localized corrosion resistance of the carbide-nucleated and LTS 304L SS weld metals, when compared to the as-welded specimens. Post-experimental micrographs indicated pitting as the primary mode of attack in the as-welded, while pitting and intergranular corrosion (IGC) occurred in the carbide-nucleated weld metal. LTS-treated weld metal predominantly underwent IGC attack. The decrease in the localized corrosion resistance of the weld metal after LTS treatment was found to have a direct correlation with the degree of sensitization and the weld microstructure. The results are detailed in the manuscript.

Effect of Low-Temperature Sensitization on the Corrosion Behavior of AISI Type 304L SS Weld Metal in Simulated Groundwater

Science.gov (United States)

Suresh, Girija; Nandakumar, T.; Viswanath, A.

2018-04-01

The manuscript presents the investigations carried out on the effect of low-temperature sensitization (LTS) of 304L SS weld metal on its corrosion behavior in simulated groundwater, for its application as a canister material for long-term storage of nuclear vitrified high-level waste in geological repositories. AISI type 304L SS weld pad was fabricated by multipass gas tungsten arc welding process using 308L SS filler wire. The as-welded specimens were subsequently subjected to carbide nucleation and further to LTS at 500 °C for 11 days to simulate a temperature of 300 °C for 100-year life of the canister in geological repositories. Delta ferrite (δ-ferrite) content of the 304L SS weld metal substantially decreased on carbide nucleation treatment and further only a marginal decrease occurred on LTS treatment. The microstructure of the as-welded consisted of δ-ferrite as a minor phase distributed in austenite matrix. The δ-ferrite appeared fragmented in the carbide-nucleated and LTS-treated weld metal. The degree of sensitization measured by double-loop electrochemical potentokinetic reactivation method indicated an increase in carbide nucleation treatment when compared to the as-welded specimens, and further increase occurred on LTS treatment. Potentiodynamic anodic polarization investigations in simulated groundwater indicated a substantial decrease in the localized corrosion resistance of the carbide-nucleated and LTS 304L SS weld metals, when compared to the as-welded specimens. Post-experimental micrographs indicated pitting as the primary mode of attack in the as-welded, while pitting and intergranular corrosion (IGC) occurred in the carbide-nucleated weld metal. LTS-treated weld metal predominantly underwent IGC attack. The decrease in the localized corrosion resistance of the weld metal after LTS treatment was found to have a direct correlation with the degree of sensitization and the weld microstructure. The results are detailed in the manuscript.

Fatigue of welded joint in a stainless steel AISI 304 L

International Nuclear Information System (INIS)

Kuromoto, N.K.; Guimaraes, A.S.; Miranda, P.E.V. de

1986-01-01

The flexion fatigue behavior for the base metal and welded joint of an AISI 304 L stainless steel type, used in the Angra-1 reactor, was determined. An automatic welding process was used with improved procedures in order to assure better welding metallurgy. Fatigue tests samples reinforcements were done to allow the evaluation of metallurgical variables, specially the role played by delta ferrite. The resulting welded joint showed better fatigue life than the base metal. Delta ferrite was found to play an important role on the initiation and propagation processes of the fatigue cracks. (Author) [pt

Carburization behavior under the pits induced by metal dusting in 304L and 347 stainless steels

Energy Technology Data Exchange (ETDEWEB)

Chang, Chia-Hao [Department of Materials Engineering and Science, National Cheng Kung University, Tainan 701, Taiwan (China); Tsai, Wen-Ta, E-mail: wttsai@mail.ncku.edu.tw [Department of Materials Engineering and Science, National Cheng Kung University, Tainan 701, Taiwan (China)

2009-08-15

The metal dusting behavior of Type 304L and 347 stainless steels (SSs) in a flowing mixed CO/H{sub 2}/H{sub 2}O gas stream at 600 deg. C was investigated. After exposure in a 35% CO + 60% H{sub 2} + 5% H{sub 2}O gas for 500 h, large pits were formed on both steel surfaces. The aspect ratio of the pits formed in 304L SS was higher than that of the pits formed in 347 SS. The microstructures and chemical compositions of the reaction products and those of the substrate under the pits were examined by using a scanning electron microscope (SEM) combined with an energy dispersive spectrometer (EDS). A Cr-depleted zone containing voids was formed on the outer surface just beneath the pit. Massive matrix carburization and intergranular carbide precipitation were seen for both steels. The experimental results showed that niobium (Nb) could delay the ingress of carbon and retard the metal dusting reaction.

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.

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

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Victoria González Quintana

2005-04-01

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

Microstructure and mechanical properties of friction welded AISI 1040/AISI 304L steels before and after electrochemical corrosion

Energy Technology Data Exchange (ETDEWEB)

Sarsilmaz, Furkan [Firat Univ., Elazig (Turkey). Dept. of Mechatronics Engineering; Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi [Firat Univ., Elazig (Turkey)

2018-03-01

The aim of the present study is to investigate the effect of welding parameters both on the electrochemical corrosion behavior and tensile strength of pre- and post-electrochemical corrosion of friction welded dissimilar steels. The microstructural changes of AISI 1040/AISI 304L friction welded couples and also parent materials were analyzed by using scanning electron microscopy. The electrochemical behaviors of AISI1040/AISI304L joints were comparatively investigated by potentiodynamic polarization curve test and by electrochemical impedance spectra. Moreover, tensile strength experiments were carried out determining the behavior of friction welded joints of pre- and post-electrochemical corrosion and results indicated that the maximum tensile test value of the dissimilar welded pre-electrochemical corrosion was higher than those of post-electrochemical corrosion and was also very close to AISI 1040 parent material value.

INFLUENCIA DE LOS RECUBRIMIENTOS DÚPLEX SOBRE LAS PROPIEDADES MECÁNICAS Y RESISTENCIA AL DESGASTE DEL ACERO AISI 4140 BONIFICADO

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Francisco Javier Bolívar Osorio

Full Text Available El acero AISI 4140 es un acero de baja aleación al cromo/molibdeno de elevada resistencia mecánica y buena tenacidad, el cual se utiliza para la fabricación de piezas de maquinaria como piñones, cigüeñales, ejes de levas, etc. Sin embargo, su resistencia al desgaste es bastante limitada y suele ser mejorada mediante el tratamiento superficial de la nitruración. El propósito de este trabajo consistió en mejorar las propiedades mecánicas e incrementar la resistencia al desgaste del acero 4140 mediante la aplicación de un tratamiento superficial DUPLEX consistente en la nitruración líquida (conocida como Teniffer seguido del depósito de un recubrimiento duro de nitruro de titanio (TiN. La microestructura cristalina fue evaluada mediante difracción de rayos X, la morfología y la composición química fue determinada por microscopía SEM y espectroscopía de energía dispersiva de rayos X (EDS, las propiedades tribológicas fueron analizadas mediante mediciones en un tribómetro de tipo esfera sobre disco y la microdureza se determinó por el método Vickers. Las muestras tratadas con el recubrimiento dúplex mostraron una resistencia al desgaste 4 veces mayor que la muestra en estado bonificado, lo cual demuestra la aplicación potencial que tiene el acero 4140 sometido a este tratamiento dúplex.

Electrodos austeníticos inoxidables semisintéticos para la soldadura manual por arco eléctrico: Una variante económica para las pequeñas y medianas empresas (PIME. // Semi-synthetic austenitics stainless steel electrodes for shielded metal arc welding: A

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A. Paz Iglesias

2002-09-01

Full Text Available En el presente trabajo se brinda una valoración económica para la producción de electrodos austeníticos inoxidables tiposE308L, E309, E312 y E316L en las pequeñas y medianas empresas (PIME. Lo significativo de la presente valoración esque se brindan los resultados obtenidos al fabricar los electrodos de forma semisintética; es decir, utilizando un solo tipo dealambre inoxidable (308L y añadiendo las ferroaleaciones necesarias en el revestimiento. Los resultados que se muestranestán basados en las experiencias de investigación, producción y comercialización de una planta con capacidad para 200toneladas al año, a la cual le es muy difícil insertarse en el mercado utilizando los mismos procedimientos tecnológicos yfinancieros de una gran empresa con grandes capitales y recursos.Palabras claves: Electrodos austeníticos inoxidables, electrodos sintéticos, ferroaleaciones, electrodossemisintéticos, electrodos convencionales, metal depositado.___________________________________________________________________Abstract.This paper offers an economic valuation for the production of stainless electrodes type E308L, E309, E312 and E316L,for small and middle companies (PIME. The significant part of the present valuation gives the results obtained in theproduction of semi-synthetic electrodes; using just one type of stainless wire (308L and adding the ferroalloys neededin the coat. The results shown are based on investigation experiences, production and trading of companies with acapacity for 200 T/year, so it is very difficult to enter in the market using the same technological procedures of a bigcompany with higher capital and financial resources.Key words: Nonrusting austenistic electrodes, sintetic electrodes, semisintetic electrodes, iron alloy,conventional electrodes, metal deposition.

Caracterización mecánica de aceros empleados en el sector de la construcción de Almería

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Senoboua, A. J.

2003-12-01

Full Text Available Various tests have been conducted on the steel bars used in the construction of civil works in Almería (Spain during the period 18 January 2000-7 May 2001, with the aim of mechanically characterizing the different types of steel (weldable: B400S, B500S and ductile weldable: B400SD to determine whether there is a technical reason for the increase in the use of ductile weldable steel. For this, we have used a hydraulic machine to break by traction all the test samples that arrived to the laboratory, following the specifications of the UNE 7474-1:1992 and the UNE 7474-2:1992. The results indicate that only in 86 % of the cases does the steel B400SD satisfy the limits specified by the UNE 36065:1999-EX, as opposed to 95 and 94 % of the B400S and B500S steels. In addition, the ductile weldable steel registered mean values lower than those of B400S. This finding disagrees with expectations set by the specifications.

Se realizaron varios ensayos sobre las barras de acero utilizadas en la construcción de obra civil en Almería, durante el período comprendido entre 18/1/2000 y 7/05/2001, con el fin de caracterizar, mecánicamente, los diferentes tipos de aceros (soldables: B400S, B500S y soldable dúctil: B400SD y, de esta forma, determinar si existe alguna razón técnica para un incremento del consumo del acero soldable dúctil. Para ello, se ensayaron a tracción todas las muestras que llegaron al laboratorio, siguiendo las normas UNE 7474-1:1992 y UNE 7474-2:1992. Los resultados indican que el acero B400SD cumple, sólo, en un 86 % los límites especificados en la norma UNE 36065:1999 -EX, frente al 95 y 94 % de los aceros B400S y B500S. Además, el acero soldable dúctil muestra unos valores medios inferiores al B400S. Este hecho discrepa de lo que se podría esperar según la norma que lo regula.

Microestructura y propiedades mecánicas de dos aceros para herramientas con ultra alto contenido de boro

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Jiménez, J. A.

1998-05-01

Full Text Available In the present work, two selected tool steels have been modified by a boron addition of 0.5 and 1 mass %. Both steels were processed by powder metallurgy methods, including argon atomization and hot isostatic pressing. The Consolidated materials presented a microstructure consisting of a fine and homogeneous distribution borocarbides M₂₃(C,B₆ in a ferrite-martensite matrix. No changes are observed in the microstructure after deformation by compression-strain-rate-change tests at temperatures ranging from 700 to 1,100 °C. For the Fe-lB-lC steel, a stress exponent of 4.5 was obtained, that suggests that slip creep is the controlling deformation mechanism. On the other hand, a stress exponent between 2 and 3 was obtained for the Fe-0.5B-1.5C steel that suggests that grain boundary sliding is the controlling deformation mechanism. In both cases, the activation energy for creep was related to the activation energy for iron self-diffusion.

En el presente trabajo se han modificado dos aceros para herramientas convencionales por la presencia de un contenido de boro entre 0,5 y 1 % en masa. Ambos aceros se procesaron por la ruta pulvimetalúrgica, incluyendo atomización por argón y compactación isostática en caliente. El material compactado presentó una microestructura caracterizada por una distribución de partículas de borocarburos M₂₃(C,B₆ fina y homogénea en una matriz de ferrita-martensita. Esta microestructura permanece prácticamente inalterada tras los ensayos de cambios en la velocidad de deformación durante el ensayo de compresión a temperaturas entre 750 y 1.000 °C. En el caso del acero Fe-lB-lC se obtuvo un valor para el exponente de la tensión de 4,5, que sugiere que la deformación plástica está controlada por un mecanismo de fluencia por movimiento de dislocaciones. Por otro lado, para el acero Fe-0,5B-1,5C, se obtuvieron valores para el exponente de la tensión comprendidos

Mejora de la tenacidad de un acero de ultraalto contenido en carbono nnediante unión por laminación con un acero al cromo y molibdeno

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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.

Potencial de demanda energética cero en envolventes industriales: El caso de la vinificación en zonas de gran amplitud térmica.

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Alba Inés Ramos Sanz

2017-12-01

Full Text Available En el estudio presentado en este artículo se desarrolla un modelo matemático para la simulación en tiempo real de un envolvente de vinificación representativo de la tecnología de vinificación nacional -de hormigón armado-, y se lleva a cabo un seguimiento térmico tanto del vino almacenado en este interior como en uno de acero inoxidable, con el empleo de sensores de temperatura HOBO U-12. Mediante tal simulación, se contempla el efecto producido sobre la estabilidad térmica del vino y la demanda térmica originada en la convección forzada -causada por las brisas-, bajo diversas configuraciones de bodegas. Con la herramienta validada, se realiza una sencilla optimización pasiva sobre el caso representativo. Finalmente, comparando los resultados de los casos simulados optimizados y de los casos reales, se concluye una mayor eficiencia termo-energética del caso representativo, frente a los de acero inoxidable. Asimismo, se observa que la estabilidad térmica del vino con demanda cero es factible a partir del empleo de envolventes adecuadas al clima analizado; con sencillas medidas de optimización, dicha estabilidad se acerca al prototipo de demanda cero perseguida en los modelos de referencia para la gestión de la energía.

Improvement of pitting corrosion resistance of AISI 304L stainless steel by nano-pulsed laser surface melting

International Nuclear Information System (INIS)

Pacquentin, W.; Blanc, C.; Caron, N.; Thro, P.Y.; Cheniere, A.; Tabarant, M.; Moutiers, G.; Miserque, F.; Plouzennec, H.; Oltra, R.

2013-01-01

The stainless steel 304L is widely used, however, in particular conditions, it may be sensitive to pitting corrosion. Nano-pulsed laser surface melting is a surface treatment which allows improving the corrosion resistance of this steel. This treatment consists in focusing a laser beam on the surface of the material, involving its quite immediately melting through a few microns depth, then an ultra-fast solidification occurs with cooling rate about 1011 K/s. The laser parameters control the modifications of the physico-chemical properties. In particular, we studied the influence of the impacts overlap of an ytterbium laser-fiber on the corrosion resistance of a 304L stainless steel in conditions of an aerated and agitated solution of NaCl (concentration of 30 g/L). We obtained an increase of the pitting potential of 220 mV, highlighting an improvement of the corrosion resistance. The study of the chemical and structural modifications is not enough to explain the improvement of the corrosion resistance. Other phenomena must be taken into account, as the quality of the oxide layer, in terms of physico-chemical and mechanical properties. (authors)

Profundidad del surco gingival en dientes primarios restaurados con coronas de acero cromo

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Rubén Muñoz Delgado

2015-01-01

Full Text Available Objetivo: Evaluar la relación entre el ajuste marginal y la profundidad del surco gingival en dientes primarios restaurados con coronas de acero cromo. Métodos: Se midió la profundidad del surco gingival de 114 dientes primarios restaurados con coronas de acero cromo en 67 niños, ambos sexos, de 3 a 6 años de edad de la clínica de Estomatología Pediátrica de la UATx, México. La población en estudio fue dividida en tres grupos: a experimental (n=30, b control (n=8, y c control negativo (n=29. Previo consentimiento informado se tomaron los índices de placa (LöeSilness 1967 e índice gingival en seis superficies; se midió el surco gingival con sonda periodontal y las coronas de acero cromo fueron evaluadas clínica y radiográficamente según su ajuste marginal y longitud cervical. Resultados: Los índices de placa y gingival no mostraron diferencias significativas para los grupos experimental y control negativo. El 34% de las coronas mostraron buen ajuste marginal, 33% un mal ajuste, 10.5% cortas, 7.9% largas y el 14% otro tipo de mal ajuste. La profundidad del surco gingival fue estadísticamente significativa para el primer y segundo molar inferior derechos y en los caninos inferiores (p >0.05; la superficie disto-vestibular presentó la mayor profundidad del surco gingival (2.34 mm, siendo estadísticamente significativa (p>0.05. Conclusiones: La profundidad del surco gingival fue mayor en los dientes rehabilitados con coronas de acero cromo mal ajustadas y sobre contorneadas (largas. La presencia de placa bacteriana y gingivitis estuvo relacionada con las coronas de acero cromo mal ajustadas.

Hormigones de alta resistencia con nano-adiciones y fibras de acero

OpenAIRE

Alizo Mirabal, Manuel Arturo

2015-01-01

El presente Trabajo Fin de Máster consistió en determinar la influencia que pueden poseer las nano-adiciones de Sílice y Alúmina y fibras de acero en un Hormigón de Alta Resistencia. Partiendo de una dosificación de Hormigón de Alta Resistencia conocida, que contenía humo de Sílice (10%) y fibras de poliolefina (3kg/m3), se les procedió a sustituir por la incorporación de nano-adiciones de Sílice y Alúmina (7% y 3% respectivamente) y añadiendo fibras de acero en lugar de poliolefina. En el pr...

Martensitic Transformation in Ultrafine-Grained Stainless Steel AISI 304L Under Monotonic and Cyclic Loading

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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.

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

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Luis Henrique Guilherme

2014-03-01

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

Experimental investigation of Ti–6Al–4V titanium alloy and 304L stainless steel friction welded with copper interlayer

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R. Kumar

2015-03-01

Full Text Available The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical, refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Ti–6Al–4V and SS304L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Ti–6Al–4V and SS304L into which pure oxygen free copper (OFC was introduced as interlayer were investigated. Box–Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Ti–6Al–4V and SS304L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XRD analysis.

Evaluación de la susceptibilidad a la corrosión por picado del acero API 5L x42 expuesto a un ambiente con cloruros y CO2 mediante la técnica de ruido electroquímico

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Rodríguez-Vanegas, N.

2011-10-01

Full Text Available The concentration of chloride ions and the partial pressure of CO2 play an important role in the degradation of low-carbon steels used for the construction of pipelines in oil and gas industry. In order to evaluate the susceptibility of carbon steel API 5L X42 to pitting corrosion electrochemical noise and linear polarization resistance measurements were carried out in aqueous solutions containing chloride ions and CO2. The concentration of chloride ions was varied between, 10000 and 18000 ppm, and the CO2 partial pressure between 10 psi and 18 psi. Experimental results pointed out that the formation of protective layer, consisting mainly of FeCO 3, depends on the partial pressure of CO2 in the system. Nevertheless, the stability of this layer was considerably affected by increasing the concentration of chloride ions causing that localized corrosion has taken place in some areas of the surface of API 5L X42, which were detected by electrochemical noise echnique.La concentración de iones cloruro y la presión parcial de CO2, tienen un papel importante en el proceso de degradación de los aceros de bajo carbono empleados en la construcción de líneas de transporte en industrias petroleras. Con el fin de evaluar la susceptibilidad del acero al carbono API 5L X42 a la corrosión por picado, se realizaron medidas de ruido electroquímico y resistencia a la polarización lineal en soluciones acuosas de iones cloruro con concentraciones entre 10.000 y 18.000 ppm, variando la presión parcial de CO2 entre 10 psi y 18 psi. Los resultados indican que la formación de una capa protectora, constituida principalmente por FeCO3, depende de la presión parcial de CO2 del sistema. No obstante, la estabilidad de dicha capa es afectada significativamente por el aumento de la concentración de iones cloruro, que producen fenómenos de corrosión localizada en algunas áreas de la superficie del acero API 5L X42, los cuales fueron detectados por la técnica de

Moessbauer spectroscopy and X-ray diffraction study of 304 L stainless steel thin films

International Nuclear Information System (INIS)

Boubeker, B.; Eymery, J.P.; Goudeau, P.; Sayouty, E.H.

1994-01-01

304 L stainless steel films (SS) were elaborated using an ion-beam sputtering technique. The target material was a sheet of commercial grade 304 L SS. The starting material was first analysed by both conversion electron Moessbauer spectroscopy (CEMS) and X-ray diffraction. The nonmagnetic state and f.c.c. structure of this material were confirmed. The films were deposited on various substrates with thicknesses in the 175-800 nm range. The films are found to have both b.c.c. structure and ferromagnetic character. X-ray diffraction technique was also used in order to determine the residual stresses developed during the deposition process. The second stage of the work is devoted to the evolution of the film structure as a function of annealing treatments. So isochronal and isothermal kinetics at temperatures higher than 913 K have allowed to follow the alpha --> gamma phase transformation using X-ray diffraction and CEMS technique.The X-ray diffractograms reveal the existence of both b.c.c. and f.c.c. phases. Similar results can be deduced from Moessbauer spectra due to the single line coming from the non-magnetic phase and the sextet coming from the ferromagnetic phase. In addition the CEMS spectra reveal that the ferromagnetic component is split into two parts which indicates the existence of two iron sites. 1 fig., 4 refs.(author)

Análisis comparativo de la calidad del acero de refuerzo distribuido en Boyacá

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Jimmy Vergara Silva, Óscar Javier Gutiérrez Junco

2011-05-01

Full Text Available Presenta  los  resultados  del  análisis  comparativo  de barras de acero de refuerzo, según las exigencias de la Norma Técnica Colombiana NTC 2289 [1], realizado a cinco marcas diferentes distribuidas para la industria de  la  construcción  en  Boyacá.  Inicialmente  se caracterizaron  las barras de  acero mediante  ensayos, para  determinar  su  composición  química  y  sus propiedades físicas y mecánicas; las características de la fractura del acero de refuerzo se observaron con el microscopio  electrónico  de  barrido  (MEB. Adicionalmente,  se  analizaron  muestras  conmicroscopio óptico, con  técnicas de espectrometría paraobservar y determinar las características del metal base de  las probetas. Los resultados  indican que la calidad del acero de refuerzo distribuido en Boyacá cumple en un alto  porcentaje con las exigencias sismo-resistentes para construcción; sin embargo, es importante que los constructores realicen control de calidad.

Dependence of corrosion properties of AISI 304L stainless steel on the austenite grain size

Energy Technology Data Exchange (ETDEWEB)

Sabooni, Soheil; Rashtchi, Hamed; Eslami, Abdoulmajid; Karimzadeh, Fathallah; Enayati, Mohammad Hossein; Raeissi, Keyvan; Imani, Reihane Faghih [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of). Dept. of Materials Engineering; Ngan, Alfonso Hing Wan [The Univ. of Hong Kong (China). Dept. of Mechanical Engineering

2017-07-15

The corrosion resistance of austenitic stainless steels is known to be hampered by the loss of chromium available for passive surface layer formation as a result of chromium carbide precipitation at austenite grain boundaries during annealing treatments. Although high-temperature annealing can promote carbide dissolution leading to better corrosion resistance, grain coarsening also results, which would lead to poorer mechanical properties. Processing methods to achieve both good corrosion resistance and mechanical properties are thus highly desirable for austenitic stainless steels. In the present study, we show that the corrosion resistance of AISI 304L stainless steel can be improved by grain refinement into the ultrafine-grained regime. Specifically, samples with different austenite grain sizes in the range of 0.65-12 μm were studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests in a 3.5 wt.% NaCl solution. All samples showed a typical passive behavior with similar corrosion potential, but the corrosion current density decreased significantly with decreasing grain size. The results show that the sample with the finest grain size had the best corrosion resistance due to a higher resistance of the passive layer to pitting attacks. This study indicates that grain refinement which improves mechanical properties can also significantly improve the corrosion resistance of AISI 304L stainless steel.

Influencia del precalentamiento en las propiedades de uniones soldadas de acero API 5L-X80 soldadas con alambre tubular autoprotegido

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Cooper, R.

2004-08-01

Full Text Available The present work refers to the characterization of API 5L-X80 pipeline joints welded with self-shielded flux cored wire. This process was evaluated under preheating conditions, with an uniform and steady heat input. All joints were welded in flat position (IG, with the pipe turning and the torch still. Tube dimensions were 762 mm in external diameter and 16 mm in thickness. Welds were applied on single V-groove, with six weld beads, along with three levels of preheating temperatures (room temperature, 100 °C, 160 °C. These temperatures were maintained as interpass temperature. The filler metal E71T8-K6 with mechanical properties different from parent metal was used in undermatched conditions. The weld characterization is presented according to the mechanical test results of tensile strength, hardness and impact test. The mechanical tests were conducted according to API 1104, AWS and ASTM standards. API 1104 and API 51 were used as screening criteria. According to the results obtained, it was possible to remark that it is appropriate to weld API 5L-X80 steel ducts with Self-shielded Flux Cored wires, in conformance to the API standards and no preheat temperature is necessary.

Este trabajo presenta un estudio sobre la caracterización de las propiedades mecánicas de uniones soldadas con alambre tubular autoprotegido, de acero API 5L-X80. En este sentido, se evalúa la influencia de la temperatura de precalentamiento, manteniendo el aporte de calor uniforme. Todas las uniones soldadas se realizaron en la posición plana (IG, con la antorcha fíja y la tubería girando. Se utilizó un tubo de 762 mm de diámetro exterior y 16 mm de espesor. Las soldaduras se aplicaron sobre una unión de tope con bisel en V simple, utilizando 6 pasadas, con tres niveles de temperatura de precalentamiento (ambiente, 100 °C y 160 °C. Estas temperaturas se mantuvieron como temperatura entre pasadas. El metal de aporte, del tipo E71T8-K6, se utilizó en la

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

Directory of Open Access Journals (Sweden)

Danila Soares Caixeta

2012-03-01

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

Effect of SiC particle impact nano-texturing on tribological performance of 304L stainless steel

Science.gov (United States)

Lorenzo-Martin, C.; Ajayi, O. O.

2014-10-01

Topographical features on sliding contact surfaces are known to have a significant impact on friction and wear. Indeed, various forms of surface texturing are being used to improve and/or control the tribological performance of sliding surfaces. In this paper, the effect of random surface texturing produced by a mechanical impact process is studied for friction and wear behavior of 304L stainless steel (SS) under dry and marginal oil lubrication. The surface processing was applied to 304L SS flat specimens and tested under reciprocating ball-on-flat sliding contact, with a 440C stainless steel ball. Under dry contact, the impact textured surface exhibited two order of magnitude lower wear than the isotropically ground surface of the same material. After 1500 s of sliding and wearing through of the processed surface layer following occurring of scuffing, the impact textured surface underwent a transition in wear and friction behavior. Under marginal oil lubrication, however, no such transition occurred, and the wear for the impact textured surface was consistently two orders of magnitude lower than that for the ground material. Mechanisms for the tribological performance enhancement are proposed.

Ductilidad en caliente y mecanismos de fractura de un acero de construcción

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Calvo, J.

2006-02-01

Full Text Available The hot ductility of a structural steel produced from scrap recycling has been studied to determine the origin of the transverse cracks in the corners that appeared in some billets. Samples extracted both from a billet with transverse cracks and from a billet with no external damage were tested. To evaluate the influence of residual elements and inclusions, the steel was compared to another one impurity free. Reduction in area of the samples tensile tested to the fracture was taken as a measure of the hot ductility The tests were carried out at temperatures ranging from 1000ºC to 650ºC and at a strain rate of 1·10- 3 s-1. The fracture surfaces of the tested samples were observed by scanning electron microscopy in order to determine the embrittling mechanisms that could be acting. The steel with residuals and impurities exhibited lower ductility values for a wider temperature range than the clean steel. The embrittling mechanisms also changed as compared to the impurity free steel.

Se evaluó la ductilidad en caliente de un acero de construcción procedente del reciclaje de chatarra con el fin de determinar el origen de las grietas transversales que aparecen en las esquinas de algunas palanquillas. Para ello, se extrajeron probetas de dos palanquillas de una misma calidad de acero. Una de las palanquillas había presentado agrietamiento transversal al ser colada y, la otra, no. Para conocer la influencia de los elementos residuales e inclusiones en la ductilidad en caliente, otro acero, con la misma composición pero sin impurezas, se fabricó en laboratorio y fue sometido al mismo análisis que los aceros comerciales. La ductilidad en caliente se midió como la reducción del área de las probetas ensayadas a tracción hasta la rotura. Las condiciones a las que se realizaron los ensayos fueron temperaturas de 1.000 a 650 ºC y a una velocidad de deformación de 1·10-3 s-1. Las superficies de fractura de las probetas ensayadas se

Technological impact in steels degree API 5L X-70 for the manufacture of resistant ducts of 36 inches of diameter to the bitter gas; Impacto tecnologico de aceros grado API 5L X-70 para la fabricacion de ductos de 36 pulgadas de diametro resistentes al gas amargo

Energy Technology Data Exchange (ETDEWEB)

Aramburo Perez, G.; Garcia Galan, S.; Perez Campos, R.; Juarez Islas, J.A. [Facultad de Quimica, UNAM, Mexico, D.F. (Mexico)

2004-03-01

, cumplen con las propiedades del acero grado API 5L X-70, las cuales son requeridas en los tubos de acero por la industria petrolera.

Weld solidification cracking in 304 to 204L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

2010-09-15

A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

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

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Hamilton Mendes de Figueiredo

2009-09-01

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

Modeling of residual stress state in turning of 304L

International Nuclear Information System (INIS)

Valiorgue, F.; Rech, J.; Bergheau, J.M.

2010-01-01

Research presented in this paper aims to link machining parameters to residual stress state and helps understanding mechanisms responsible of machined surface properties modifications. The first presented works are based on an experimental campaign. They reproduce the finishing turning operation of 304L and allow observing the residual stress state evolution at the work piece surface and for an affected depth of 0.2 mm for such processes. Then, the finishing turning operation is simulated numerically in order to realize the same sensitivity study to cutting parameters. This simulation is based on an hybrid approach mixing experimental data and numerical simulation. This method allows getting round the classical difficulties of turning simulation by applying equivalent thermo mechanical loadings onto the work piece surface without modeling the material separation phenomena. Moreover the numerical model uses an hardening law taking into account dynamic recrystallization phenomena. (authors)

Producción electroquímica de gluconato de calcio

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Mario Grajales T.

2010-07-01

Full Text Available Se estudió experimentalmente el efecto del potencial anódico, densidad de corriente y concentración del ion bromuro en la producción electroquímica de gluconato de calcio a partir de glucosa, usando el sistema Br2 / Br' como mediador. Las condiciones de operación de la celda electroquímica con ánodo de grafito y cátodo de acero inoxidable fueron: Potencial anódico 1.3 V (vs ESC, 46 °C, densidad de corriente 26 mA / cmS y un medio acuoso compuesto por una solución de Glucosa 0.60 M -I- NaBr 0.20 M conteniendo CaCO, en suspensión (0. 30 mol / L. La eficiencia de corriente fue del 98% y la.pureza del gluconato obtenido del 99.7 %.

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

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ROBINSON TORRES GÓMEZ

2010-01-01

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

Physical characterization of austenitic stainless steels AISI 304 and AISI 348 L*

International Nuclear Information System (INIS)

Teodoro, Celso Antonio; Silva, Jose Eduardo Rosa da

2009-01-01

The study of radiation damages in metals and metallic alloys used as structural materials in nuclear reactors has a strategic meaning to the nuclear technology because it treats of performance of these materials in conditions that simulate the conditions of work in power reactors. Then it becomes necessary to know the essential physical properties of these materials, properties that are sensitive to the microstructural changes that occurred during the irradiation. The purpose of this work is to characterize, initially, some pre-irradiation properties of the stainless steels AISI 304 and AISI 348 L * , such as mechanical (stress-strain and microhardness) and electrical (resistivity). The AISI 348 L * has been studied for use as fuel cladding material. Both materials will be tested after irradiation in the IEA-R1 core and their properties will be compared with those in the pre-irradiated condition. The morphology of the fractured zones after tensile tests was observed using SEM (scanning electron microscopy). (author)

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Ho

1994-02-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H 2 O 2 played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively

Effect of H2O2 on the corrosion behavior of 304L stainless steel

International Nuclear Information System (INIS)

Song, Taek Hoh; Kim, In Sub; Noh, Sung Kee

1995-01-01

In connection with the safe storage of high level nuclear waste, effect of H 2 O 2 on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H 2 O 2 . The experimental results show that H 2 O 2 increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H 2 O 2 concentration increased, indicating that pitting resistance was decreased by the existence of H 2 O 2 in the electrolyte. These effects of H 2 O 2 on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H 2 O 2 with those of O 2 , cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H 2 O 2 on the corrosion behavior were very similar to those of O 2 such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H 2 O 2 were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively. 13 figs., 1 tabs., 17 refs. (Author)

Influencia del tamaño del cristal de cinc de láminas de acero galvanizadas en ambientes que contienen cloruros y sulfatos

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Julieth Andrea Ramírez-Jerez

2015-05-01

Full Text Available El trabajo evaluó la influencia del tamaño del cristal de cinc en el comportamiento electroquímico de láminas de acero galvanizadas por inmersión en caliente. Los ensayos se realizaron en una celda electroquímica plana en soluciones con diferentes concentraciones de NaCl y NaSO4. La velocidad y el mecanismo de corrosión, así como las características resistivas y difusivas de las láminas se evaluaron mediante técnicas electroquímicas, como espectroscopia de impedancia electroquímica (EIS, resistencia a la polarización (Rp y curvas potenciodinámicas. La composición y distribución de los productos de corrosión (FeO y algunos compuestos de cinc y el daño superficial causado por estos se determinaron por medio de DRX y SEM-EDS. Los resultados mostraron que la degradación de la capa de óxidos formada se ve afectada por la presencia de cloruros que penetran, llegan a la superficie del metal base y generan corrosión localizada.

Fragilización por hidrógeno en tuberías de acero

OpenAIRE

Gutiérrez-Solana Salcedo, Federico

2011-01-01

Se pretende analizar el comportamiento en presencia de hidrogeno de las tuberías de acero de sistemas de transporte de combustibles gaseosos en uso para ello: 1.- Se estudia la sensibilidad a la fragilización por hidrogeno del acero de estas tuberías por dos métodos diferentes: polarización catódica y ambiente de hidrogeno gaseoso diseñando y construyendo una cámara para ensayos mecánicos en hidrogeno a presión primera de su genero en España. 2.- Se determina la tenacidad a fractura kic de es...

CÁLCULO DE LA TENSIÓN DE FLUENCIA EN ACEROS DEFORMADOS EN CALIENTE

OpenAIRE

Béjar, L; Hernández, C. A

2001-01-01

Se ha desarrollado un modelo matemático para la predicción de la curva de fluencia de la austenita deformada en aceros de baja aleación. Las ecuaciones constitutivas tienen en cuenta los mecanismos gobernantes durante la deformación plástica -responsables de la forma de la curva- y emplea las variables de proceso y la composición química del acero. Para una demostración de su precisión, el modelo propuesto se ha comparado con las curvas de fluencia clásicas de Cook en condiciones hasta dos ór...

Corrosion behavior of mild steel and SS 304L in presence of dissolved nickel under aerated and deaerated conditions

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Mohd Mobin

2011-12-01

Full Text Available In dual purpose water/power co-generation plants, the presence of high concentration of Cu and Ni in the re-circulating brine/condensate as a result of condenser tubes corrosion has been attributed as one of the several causes of corrosion damage of flash chamber materials and water touched parts of the boilers. The present investigation deals with the effect of dissolved nickel in the concentration range of 10 ppb to 100 ppm on the corrosion behavior of mild steel and SS 304L in two aqueous medium namely, distilled water and artificial seawater. The effect of pH, dissolved oxygen and flow condition of aqueous medium on the corrosion behavior was also monitored. The experimental techniques include immersion test and electrochemical tests which include free corrosion potential measurements and potentiodynamic polarization measurements. The corrosion rate of mild steel and SS 304L under different experimental conditions was determined by weight loss method and spectrophotometric determination of iron ion entered into the test solution during the period of immersion. The pH of the test solution was also monitored during the entire period of immersion. The left over nickel ions present in the test solution after completion of immersion was also estimated using Atomic Absorption Spectrophotometer. The surface morphology of the corroded steel surface was also examined using scanning electron microscopy (SEM. The results of the studies show that SS 304L largely remains unaffected in both distilled water and artificial seawater under different experimental conditions. However, the effect of nickel on the corrosion behavior of mild steel is quite pronounced and follows interesting trends.

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

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Jorge N. Pecina

2016-01-01

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

Control automático con lógica difusa de la producción de cerveza artesanal en las etapas de maceración y cocción

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Mariano Luján Corro

2010-01-01

Full Text Available Se controló automáticamente con lógica difusa, el proceso de producción de cerveza artesanal en las etapas maceración y cocción de la malta; a través de diferentes actuadores y en función del tiempo y temperatura del proceso, utilizándose LabVIEW 2009. El equipo estuvo constituido principalmente de tres recipientes de acero inoxidable de 20 L de capacidad (dosificación de agua, maceración y cocción, un recipiente adicional para el lúpulo, una tarjeta de adquisición de datos (con micro controlador PIC 16F877a, tres sensores de temperatura LM35 y 11 actuadores de tipo on/off, los cuales fueron gobernados por un total de 47 reglas difusas tipo Mandani, con funciones de membresía trapezoidales, empleando para la defusificación el método del centro de área. Se controló adecuadamente en sus etapas de maceración y cocción, los actuadores: electroválvulas (5, bombas (2, calefactores (3 y un agitador; empleando un tiempo aproximado de 4 horas. La cerveza obtenida mediante el control automático con lógica difusa en las etapas de maceración y cocción, tuvo las siguientes características: densidad de 0.98 g/cm3; pH de 3.9; acidez total expresada como ácido láctico de 0.87%, grado alcohólico de 6.2 ºGL y porcentaje de CO2 de 0.91% p/v.

Effect of microstructure and chemical composition on localized corrosion resistance of a AISI 304L stainless steel after nanopulsed-laser surface melting

International Nuclear Information System (INIS)

Pacquentin, W.; Caron, N.; Oltra, R.

2015-01-01

Highlights: • Laser surface melting treatments require neither additional feedstock nor contact. • By affecting 1 μm, the pitting potential of laser treated 304L increases by 500 mV. • Surface modification of laser treated sample observed by TEM. • The physico-chemical properties of the surface are correlated to overlap rate. • AISI 304L pitting corrosion resistance strongly depends of overlap rate. - Abstract: Changes induced in the surface properties of AISI 304L stainless steel when it is treated with a nanopulsed ytterbium-doped fiber laser were investigated to determine the microscale distribution of its physico-chemical properties. A Gaussian energy distribution was created with a radius of 71 μm (1/e 2 ) at the focal point. Local investigations were carried out using transmission electron microscopy to consider the effect of overlapping individual laser impacts. The results obtained reveal that laser surface melting leads to changes in the crystallographic structure of the steel through the formation of a δ-ferritic phase. It also results in the creation of an oxide layer that increases the corrosion resistance of the steel, with the chemical composition, structure and thickness of this layer being dependent on the overlap percentage and the position along the beam radius. Measurement of the localized corrosion resistance in a 30 g L −1 NaCl solution using polarization curves found that optimal laser treatment conditions can led to an increase in the breakdown potential of more than 500 mV, which corresponds to a significant improvement in corrosion resistance.

Impact of Defects in Powder Feedstock Materials on Microstructure of 304L and 316L Stainless Steel Produced by Additive Manufacturing

Science.gov (United States)

Morrow, Benjamin M.; Lienert, Thomas J.; Knapp, Cameron M.; Sutton, Jacob O.; Brand, Michael J.; Pacheco, Robin M.; Livescu, Veronica; Carpenter, John S.; Gray, George T.

2018-05-01

Recent work in both 304L and 316L stainless steel produced by additive manufacturing (AM) has shown that in addition to the unique, characteristic microstructures formed during the process, a fine dispersion of sub-micron particles, with a chemistry different from either the powder feedstock or the expected final material, are evident in the final microstructure. Such fine-scale features can only be resolved using transmission electron microscopy (TEM) or similar techniques. The present work uses electron microscopy to study both the initial powder feedstock and microstructures in final AM parts. Special attention is paid to the chemistry and origin of these nanoscale particles in several different metal alloys, and their impact on the final build. Comparisons to traditional, wrought material will be made.

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

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Marcus Vinícius Volponi Mortean

2016-03-01

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

Swelling of AISI 304L in response to simultaneous variations in stress and displacement rate

International Nuclear Information System (INIS)

Porter, D.L.; Garner, F.A.

1984-01-01

The duration of the transient regime of neutron-induced swelling in annealed AISI 304L at 400 0 C is sensitive to both stress and displacement rate variations. The simultaneous application of both variables exerts a synergistic effect on the transient regime. The duration of this regime cannot be reduced below a required intrinsic exposure of approx. 10 dpa, however, which has been found to be characteristic of all Fe-Ni-Cr austenitic alloys. This is four times larger than that currently assumed in the stress-affected swelling equation for 20% cold-worked AISI 316

Desarrollo de un cerrojo artificial para el skin-pass en una línea de acero galvanizado por inmersión en caliente

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González-Marcos, A.

2008-02-01

Full Text Available In this paper, we present the application of data mining techniques to develop an “artificial lock” for the skin-pass in an attempt to solve a problem that can arise during the galvanising manufacturing process: the wrong labelling of the steel grade of a coil. In order to detect these errors and thus to avoid that coils with different properties than expected end up with a client, we propose neural network-based models for on-line predicting the strip elongation in the skin-pass section according to the manufacturing conditions and its chemical composition. Thus, a significant difference between estimated and measured elongation would mean that the coil must be removed from the line for further analyses.

En este trabajo se presenta la aplicación de técnicas de minería de datos en el desarrollo de un “cerrojo artificial” para el skin-pass, que permita solucionar un problema que puede presentarse en la fabricación de bobinas de acero galvanizado: el etiquetado incorrecto del grado de acero de una bobina. Para tratar de detectar estos errores y evitar así que los clientes reciban bobinas con propiedades distintas de las esperadas, se proponen modelos, basados en redes neuronales, que predicen on-line el alargamiento de las bobinas en el skin-pass en función de las variables del proceso de fabricación y de su composición química. De esta forma, si la diferencia entre el alargamiento que estima el modelo y el medido realmente es significativa, se hace necesario sacar la bobina de la línea para someterla a análisis más exhaustivos.

Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO3-HF

International Nuclear Information System (INIS)

Ondrejcin, R.S.; McLaughlin, B.D.

1980-04-01

Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO 3 -HF for dissolution, the best alloy for service at 130 0 C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130 0 C, Inconel 671 is best. At 95 0 C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr 4+ and Th 4+ ; Al 3+ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO 3 -HF used occasionally for flushing and in solutions of HNO 3 and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures

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)

Diseño y construcción de un prototipo controlado para carburización gaseosa de aceros utilizando alcoholes

OpenAIRE

Obando B, Johnny F; Castro P, Álvaro; Trujillo, Carlos Alexander

2010-01-01

En esta investigación se realizó el diseno, construcción y prueba de un equipo a escala de laboratorio para tratamientos térmicos con atmósfera controlada para el estudio de la carburización gaseosa de aceros con alcoholes. El equipo posee las siguientes caracterIsticas: producción controlada de una atmósfera gaseosa compuesta hasta por tres gases y dos lIquidos volatiles, una zona de reacción isotérmica, inerte y hermética, y una zona de analisis de gases que retiene sólidos y lIquidos cond...

Modelling of cyclic plasticity for austenitic stainless steels 304L, 316L, 316L(N)-IG

Energy Technology Data Exchange (ETDEWEB)

Dalla Palma, Mauro, E-mail: mauro.dallapalma@igi.cnr.it

2016-11-01

Highlights: • Stress-strain amplitudes of cyclic stress strain curves defined by design codes are provided as reference data. • A macroinstruction simulating cyclic plasticity and producing hardening parameters of constitutive models is developed. • Hardening parameters of the nonlinear Chaboche model are provided for stainless steels 316l-N, 316L, 304L at different temperatures. • Ratcheting is simulated by using the produced hardening parameters. - Abstract: The integrity assessment of structures subjected to cyclic loading must be verified with regard to cyclic type damage including time-independent fatigue and progressive deformation or ratcheting. Cyclic damage is verified simulating the material elastic-plastic loop and looking at the accumulated net plastic strain during each cycle at all points of the structure subjected to the complete time history of loadings. This work deals with the development of a numerical model producing the Chaboche hardening parameters starting from stress-strain data produced by testing of materials. Then, the total plastic strain can be simulated using the Chaboche inelastic constitutive model requested for finite element analyses. This is particularly demanding for pressure vessels, pressurised piping, boilers, and mechanical components of nuclear installations made of stainless steels. A design optimisation by iterative analyses is developed to approach the stress-strain test data with the Chaboche model. The parameters treated as design variables are the Chaboche parameters and the objective function to be minimised is a combination of the deviations from test data. The optimiser calls a macroinstruction simulating cyclic loading of a sample for different material temperatures. The numerical model can be used to produce hardening parameters of materials for inelastic finite element verifications of structures with complex joints like elbows subjected to a combination of steady sustained and cyclic loads.

Evolution of microstructure in laser welding of SS304L

International Nuclear Information System (INIS)

Kumar, Santosh; Kushwaha, R.P.; Viswanadham, C.S.; Dey, G.K.

2009-01-01

Laser welding is an important joining process and its application in industries is growing rapidly. One can produce laser welds over a wide range of process parameters and this offers very good opportunity for producing microstructure of different morphology and scales in the weldment. Weld beads have been produced on 5 mm thick plates of SS304L using CW Nd-YAG laser. Laser power was varied in 200 W to 1000 W range and welding speed was varied in 100 mm/mm to 1000 mm/mm. This resulted in weld beads of different morphology. Microstructure of the weld beads was examined on the cross-section as well as in the axial direction using optical microscopy and Transmission Electron Microscopy (TEM) to study evolution of the microstructure in the weldment. Microstructure was cellular and cellular-dendritic with grains growing from the fusion line towards the centerline. In the central region, cellular growth along the welding direction was observed. The cell size was found to increase with increasing laser power and decreasing welding speed. The findings are presented in this paper. (author)

Determinación de los parámetros de corrosión y desgaste del par acero/aluminio en presencia de líquidos iónicos

OpenAIRE

Jerez Mesa, Ramón

2008-01-01

El presente proyecto presenta resultados obtenidos en ensayos utilizando LI combinados con aluminio 2011 y acero F-1310, tanto en ensayos de corrosión como de tribología. Escuela Técnica Superior de Ingeniería Industrial

Effect of surface grinding on chloride induced SCC of 304L

Energy Technology Data Exchange (ETDEWEB)

Zhou, Nian, E-mail: nzh@du.se [Department of Material Science, Dalarna University, SE-79188 Falun (Sweden); KTH, SE-10044 Stockholm (Sweden); Pettersson, Rachel [KTH, SE-10044 Stockholm (Sweden); Jernkontoret, SE-11187 Stockholm (Sweden); Lin Peng, Ru [Department of Management and Engineering, Linköping University, SE-58183 Linköping (Sweden); Schönning, Mikael [Corrosion Department, Avesta Research Centre – Outokumpu Stainless AB, SE-774 22 Avesta (Sweden)

2016-03-21

The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks.

Effect of surface grinding on chloride induced SCC of 304L

International Nuclear Information System (INIS)

Zhou, Nian; Pettersson, Rachel; Lin Peng, Ru; Schönning, Mikael

2016-01-01

The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks.

Evaluation at 290 degrees Celsius and 8 MPa of the anticorrosion properties of hydrothermal ceramic nano deposits on preoxidized 304l Ss

Energy Technology Data Exchange (ETDEWEB)

Lopez G, N.; Marin A, M.; Medina A, A. L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Galicia A, G., E-mail: natali_log@hotmail.com [Universidad Veracruzana, Instituto de Ingenieria, Av. Juan Pablo II s/n, Fracc. Costa Verde, 94294 Boca del Rio, Veracruz (Mexico)

2017-09-15

In the present paper, we present the electrochemical evaluation carried out under reductive conditions (molar ratio H{sub 2}:O{sub 2} >5), at 290 degrees Celsius and 8 MPa, of preoxidized 304l Ss with hydrothermal deposits of nanoparticles of TiO{sub 2} and ZrO{sub 2}. The anticorrosion properties of the deposits were studied by Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR). After electrochemical tests, the samples were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (Sem). It was found by EIS that both, ZrO{sub 2} and TiO{sub 2} produce an increase in the charge transfer resistance (R{sub CT}) of preoxidized 304l Ss. At the same time, by LPR we observed that the studied ceramic nano deposits decrease the corrosion rate (Cr) and corrosion current density (i{sub corr}), however, in most of the cases the Electrochemical Corrosion Potential (Ecp) is slightly higher in the presence of the ceramic nano deposits that the one of preoxidized 304l Ss. After holding time at 290 degrees Celsius, when the impedance (Z) increases, the capacitance increases also, which is attributed to a surface increase due to the roughness of the oxide formed at this temperature under a reductive environment. The observed electrochemical behavior has a dependence on the homogeneity and thickness of the deposits, as has been corroborated by Sem and XRD. The best electrochemical results are obtained when two conditions are fulfilled: The bigger the effective coated area and the lower the deposit thickness. (Author)

Influencia del Calor Aportado y Metal de Aporte Sobre las Propiedades Mecánicas y la Microestructura de Juntas Soldadas por FCAW de Acero Microaleado de Alta Resistencia

Directory of Open Access Journals (Sweden)

César Marconi

2015-06-01

Full Text Available ResumenActualmente, los aceros microaleados son ampliamente utilizados en reemplazo de los aceros al C y C-Mn por sus ventajas en cuanto a propiedades mecánicas, resistencia a la corrosión y soldabilidad, permitiendo una reducción de peso de los vehículos y estructuras sin detrimento de su resistencia. Cuando estos aceros son soldados, el ciclo térmico de la soldadura provoca cambios microestructurales que modifican sus propiedades originales. El calor aportado (HI: heat input es una de las principales variables a tener en cuenta cuando se evalúan estas modificaciones. Las propiedades finales de la unión soldada también se definen por el tipo de consumible utilizado. El objetivo de este trabajo es analizar las propiedades mecánicas y la microestructura de juntas soldadas a tope de un acero microaleado con dos grados de metal de aporte y diferentes HI. Como resultado del trabajo se observó un aumento considerable de tamaño de grano en la ZAC adyacente a la línea de fusión para todas las condiciones, siendo este efecto más marcado cuando se soldó con alto HI; y un ablandamiento en la ZAC de grano fino. Prácticamente se mantuvieron los valores de resistencia a la tracción al soldar con ambos consumibles, con un mejor desempeño cuando se soldó con bajo HI. La tenacidad en la ZAC mejoró con la disminución del HI.

The application of an internal state variable model to the viscoplastic behavior of irradiated ASTM 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

McAnulty, Michael J., E-mail: mcanulmj@id.doe.gov [Department of Energy, 1955 Fremont Avenue, Idaho Falls, ID 83402 (United States); Potirniche, Gabriel P. [Mechanical Engineering Department, University of Idaho, Moscow, ID 83844 (United States); Tokuhiro, Akira [Mechanical Engineering Department, University of Idaho, Idaho Falls, ID 83402 (United States)

2012-09-15

Highlights: Black-Right-Pointing-Pointer An internal state variable approach is used to predict the plastic behavior of irradiated metals. Black-Right-Pointing-Pointer The model predicts uniaxial tensile test data for irradiated 304L stainless steel. Black-Right-Pointing-Pointer The model is implemented as a user-defined material subroutine in the finite element code ABAQUS. Black-Right-Pointing-Pointer Results are compared for the unirradiated and irradiated specimens loaded in uniaxial tension. - Abstract: Neutron irradiation of metals results in decreased fracture toughness, decreased ductility, increased yield strength and increased ductile-to-brittle transition temperature. Designers use the most limiting material properties throughout the reactor vessel lifetime to determine acceptable safety margins. To reduce analysis conservatism, a new model is proposed based on an internal state variable approach for the plastic behavior of unirradiated ductile materials to support its use for analyzing irradiated materials. The proposed modeling addresses low temperature irradiation of 304L stainless steel, and predicts uniaxial tensile test data of irradiated experimental specimens. The model was implemented as a user-defined material subroutine (UMAT) in the finite element software ABAQUS. Results are compared between the unirradiated and irradiated specimens subjected to tension tests.

Modelamiento del proceso de recubrimiento de instrumental quirúrgico con cromoduro

Directory of Open Access Journals (Sweden)

Jairo Ruiz

2003-01-01

Full Text Available En este artículo se presenta un modelo estadístico que describe el comportamiento de la variable respuesta espesor del recubrimiento de cromoduro en los portagujas quirúrgicos, de acero inoxidable martensítico, como función del tiempo de exposición, la densidad de corriente y la temperatura; el modelo fue ajustado por medio de un diseño experimental rotacional compuesto de segundo orden. El modelo tiene un poder de explicación del 75% en la variabilidad de la respuesta, que se considera muy satisfactorio dada la complejidad del proceso.

Diseño y construcción de un prototipo controlado para carburización gaseosa de aceros utilizando alcoholes

OpenAIRE

Obando B, Johnny F.; Castro P., Álvaro; Trujillo, Carlos Alexander

2006-01-01

En esta investigación se realizó el diseño, construcción y prueba de un equipo a escala de laboratorio para tratamientos térmicos con atmósfera controlada para el estudio de la carburización gaseosa de aceros con alcoholes. El equipo posee las siguientes características: producción controlada de una atmósfera gaseosa compuesta hasta por tres gases y dos líquidos volátiles, una zona de reacción isotérmica, inerte y hermética, y una zona de análisis de gases que retiene sólidos y líquidos conde...

Measurement of carbon activity in sodium by Fe-Mn 20% alloy, and by strainless austenitic steel 304L and 316L

International Nuclear Information System (INIS)

Oberlin, C.; Saint Paul, P.; Baque, P.; Champeix, L.

1980-01-01

Precise knowledge of carbon activity in sodium used as coolant in fast breeder reactors, is essential for continuous survey of carburization-decarburization processes. Carbon activity can be periodically surveyed by measuring the carbon concentration or by hot trap like metal alloy strip placed in sodium loop. In fact, in equilibrium, activity of carbon in sodium is equal to the activity in metal alloy. Thus if the relation between concentration of carbon and it activity in the alloy is known, it is possible to estimate the activity of carbon in sodium. Materials to be used should have high solubility in carbon at the needed temperature. They should quickly attain equilibrium with sodium and they should not contain impurities that can affect the results. Materials chosen according to these criteria were Fe-Mn 20%, stainless austenitic steel AISI 304L and 316L

CORROSION STUDY FOR THE EFFLUENT TREATMENT FACILITY CHROME (VI) REDUCTANT SOLUTION USING 304 AND 316L STAINLESS STEEL

Energy Technology Data Exchange (ETDEWEB)

DUNCAN JB; WYRAS RB

2007-10-08

This report documents the laboratory testing and analyses as directed under the test plan, RPP PLAN-34065, and documented in laboratory notebooks HNF 2742 and HNF-N-473-1. The purpose of this study was to evaluate and compare the electrochemical corrosion and pitting susceptibility of the 304 and 316L stainless steel in the acidified reducing solution that will be contained in either the secondary waste receiving tank or concentrate tank.

Effect of strain-path on stress corrosion cracking of AISI 304L stainless steel in PWR primary environment at 360 deg. C

International Nuclear Information System (INIS)

Couvant, T.; Vaillant, F.; Boursier, JM.; Delafosse, D.

2004-01-01

Austenitic stainless steels (ASS) are widespread in primary and auxiliary circuits of PWR. Moreover, some components suffer stress corrosion cracking (SCC) under neutron irradiation. This degradation could be the result of the increase of hardness or the modification of chemical composition at the grain boundary by irradiation. In order to avoid complex and costly corrosion facilities, the effects of irradiation on the material are commonly simulated by applying a cold work on non-irradiated material prior to stress corrosion cracking tests. Slow strain rate tests were conducted on an austenitic stainless steel (SS) AISI 304L in PWR environment (360 deg. C). Particular attention was directed towards pre-straining effects on crack growth rate (CGR) and crack growth path (CGP). Results have demonstrated that the susceptibility of 304L to SCC in high-temperature hydrogenated water was enhanced by pre-straining. It seemed that IGSCC was enhanced by complex strain paths. (authors)

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

Directory of Open Access Journals (Sweden)

LUZ S. QUINTERO

2011-01-01

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

Análise microestrutural e tenacidade ao impacto da ZAC do aço inoxidável ferrítico com 11%Cr

Directory of Open Access Journals (Sweden)

Temístocles de Sousa Luz

2013-09-01

Full Text Available O aço inoxidável ferrítico possibilita, em função de suas características, o uso em diversos campos da engenharia. Dentre esses é possível citar a industria do petróleo e gás, de celulose açucareira, de transporte, entre outras. Atualmente, o desenvolvimento de novas ligas para a substituição dos aços ao carbono no que se refere ao setor de transporte de carga, levou muitos fabricantes a adotarem a liga ferrítica com base de cromo entre 11% e 12%, implementando a tal situação, uma maior vida util. A utilização dessa nova classe de aço inoxidável ferrítico gera uma demanda no que tange à pesquisas das soldas desses aços. Neste trabalho, buscou-se analisar a região soldada de um aço inoxidável ferrítico experimental contendo 11% de cromo, realizando para tal um estudo de sua microestrutura, e tenacidade ao impacto do metal de base e da zona afetada pelo calor (ZAC. A avaliação mostrou bons resultados nas propriedades mecânicas medidas nas duas regiões analisadas. Entretanto, verificou-se uma perda acentuada da tenacidade ao impacto na ZAC em relação ao metal de base.

Aumento en la resistencia a la corrosión de un acero t91 aluminizado

OpenAIRE

QUINTERO, LUZ S.; LAVERDE, DIONISIO; ESCALANTE, HUMBERTO

2011-01-01

El acero ferrítico T91 ha sido ampliamente utilizado en plantas de generación de energía eléctrica, calderas y plantas nucleares. Sin embargo, su resistencia a la oxidación se ve gravemente afectada a temperaturas superiores a los 600ºC. En esta investigación se empleó la técnica de cementación empacada para aluminizar un acero T91 y se encontraron las condiciones óptimas para la formación de un recubrimiento libre de porosidad y con espesor uniforme (300 micras). Se evaluó la capa de óxido f...

stainless steel by SEM-XRD and image analysis

Directory of Open Access Journals (Sweden)

Robinson Constanzo-R.

2014-01-01

Full Text Available El objetivo de este trabajo fue realizar un análisis cualitativ o de la distribución de un electrodepósito de cobre en el inter ior de electrodos porosos (EP de acero inoxidable y carbono grafito. Para ello, se reali zaron pruebas de electrodepositación de cobre a nivel de labora torio, con un posterior análisis de cortes de muestras de acero y grafito vía Microscopía Estereoscópica, Microscopía SEM-DRX y Análisis de Imagen, los cuales mostraron que el cobre no se deposita en forma uniforme al interior del electrodo. En el electrodo de acero, la penetra ción del depósito en el espesor fue alrededor de 50%, mientras que para el grafito a lrededor de 90%. En forma general, se observó un aumento de la cantidad de depósito hacia el extremo frente al ánodo y con sitios de difer ente crecimiento en depósito de cobre. Esto demuestra una distr ibución de corriente y potencial, función de parámetros físicos de electrodo y de la s características fisicoquímicas e hidrodinámicos del electroli to.

Simulation of Friction Stir Processing in 304L Stainless Steel

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Miles M.P.

2016-01-01

Full Text Available A major dilemma facing the nuclear industry is repair or replacement of stainless steel reactor components that have been exposed to neutron irradiation. When conventional fusion welding is used for weld repair, the high temperatures and thermal stresses inherent in the process enhance the growth of helium bubbles, causing intergranular cracking in the heat-affected zone (HAZ. Friction stir processing (FSP has potential as a weld repair technique for irradiated stainless steel, because it operates at much lower temperatures than fusion welding, and is therefore less likely to cause cracking in the HAZ. Numerical simulation of the FSP process in 304L stainless steel was performed using an Eulerian finite element approach. Model input required flow stresses for the large range of strain rates and temperatures inherent in the FSP process. Temperature predictions in three locations adjacent to the stir zone were accurate to within 4% of experimentally measure values. Prediction of recrystallized grain size at a location about 6mm behind the tool center was less accurate, because the empirical model employed for the prediction did not account for grain growth that occurred after deformation in the experiment was halted.

Fenómenos de corrosión galvánica en las uniones aluminio y acero

OpenAIRE

Domínguez Parra, Alberto

2009-01-01

La corrosión es un proceso de degradación de un material al interactuar con el ambiente que le rodea. El presente proyecto trata de la corrosión galvánica de aceros y fundiciones, en contacto con aleaciones de aluminio. Su experimentación se ha realizado con acero AE 275 B, y fundición EN-GS 400 12. Se utilizó lingote de aluminio A356 obtenido por colada por gravedad, y dos tipos de muestras, con y sin tratamiento térmico T6, de A 356 producidas por el procedimiento de sub-liquidus casting...

STUDY AND ANALYSIS OF THE EFFECT OF WELDING PROCESS ON DISTORTION WITH 304L STAINLESS STEEL WELD JOINTS

OpenAIRE

Dhananjay Kumar*, Dharamvir mangal

2017-01-01

The effect of welding process on the distortion with 304L stainless steel 12thk weld joints made by TIG (tungsten inert gas) and SMAW (Shielded metal arc welding) welding process involving different type joint configuration have been studied. The joint configurations employed were double V-groove edge preparation for double side SMAW welding and square – butt preparation for double side TIG welding. All weld joints passed by radiographic. Distortion measurements were carried out using height ...

Mecanismos de fractura a alta temperatura en aceros eléctricos no-orientados

Directory of Open Access Journals (Sweden)

García-Sánchez, E. O.

2007-08-01

Full Text Available In this research work the effect of deformation temperature on the hot ductility of non-oriented electrical steels (0.6 % Si-0.3 Al % was studied using high temperature tensile tests. The specimens were machined from two thin slabs (50 mm thickness produced by CSP process (Compact Strip Process, one of them using 100 % sponge iron and the other using 67 % scrap and 33 % sponge iron. The tensile tests were carried out at constant strain rate (5×1010^–4 s^–1, and a temperature range from 850 to 1,200 °C. The results showed that the ductility decreased with the increment in the temperature until approximately 1,000 °C. At higher temperatures, a ductility recovery was observed only in the steel fabricated without scrap. Scanning Electron Microscopy on fracture surfaces showed that the loss of ductility is associated with intergranular cracking promoted by the austenitic transformation and AlN grain boundaries precipitation.

Se investigó el efecto de la temperatura de deformación sobre la ductilidad de aceros eléctricos de grano no-orientado (0,6 % Si-0,3 % Al mediante ensayos de tracción uniaxial. Las probetas se obtuvieron de planchones delgados (50 mm de espesor tipo CSP (Continuous Strip Processing fabricados a partir de 100 % hierro esponja y una mezcla de 67 % chatarra y 33 % de hierro esponja. El rango de temperatura de estudio fue de 850 a 1.200 °C y los ensayos se llevaron a cabo a una velocidad de deformación constante de 5×10^–4 s^–1. Los resultados experimentales demostraron que la ductilidad (% RA disminuye con el aumento en la temperatura hasta un mínimo a ~1.000 °C. A temperaturas mayores, la ductilidad del acero fabricado a partir de 100 % hierro esponja se recupera. Este efecto no fue observado en el acero fabricado a partir de chatarra. La caracterización de las superficies de fractura mediante microscopía electrónica de barrido demostró que la pérdida de

Reassessment of the swelling behavior of AISI 304 stainless steel

International Nuclear Information System (INIS)

Garner, F.A.; Porter, D.L.

1982-03-01

Published swelling data derived from EBR-II irradiations of AISI 304 and 304L have been reanalyzed in light of insights gained from irradiation of AISI 316 and Fe-15Cr-25Ni. The primary influence of temperature, displacement rate and compositional variations in the 300 series stainless steels lies in the duration of the transient regime of swelling and not in the steady-state or constant swelling rate regime

The role of martensitic transformation on bimodal grain structure in ultrafine grained AISI 304L stainless steel

International Nuclear Information System (INIS)

Sabooni, S.; Karimzadeh, F.; Enayati, M.H.; Ngan, A.H.W.

2015-01-01

In the present study, metastable AISI 304L austenitic stainless steel samples were subjected to different cold rolling reductions from 70% to 93%, followed by annealing at 700 °C for 300 min to form ultrafine grained (UFG) austenite with different grain structures. Transmission electron microscopy (TEM) and nanoindentation were used to characterize the martensitic transformation, in order to relate it to the bimodal distribution of the austenite grain size after subsequent annealing. The results showed that the martensite morphology changed from lath type in the 60% rolled sample to a mixture of lath and dislocation-cell types in the higher rolling reductions. Calculation of the Gibbs free energy change during the reversion treatment showed that the reversion mechanism is shear controlled at the annealing temperature and so the morphology of the reverted austenite is completely dependent on the morphology of the deformation induced martensite. It was found that the austenite had a bimodal grain size distribution in the 80% rolled and annealed state and this is related to the existence of different types of martensite. Increasing the rolling reduction to 93% followed by annealing caused changing of the grain structure to a monomodal like structure, which was mostly covered with small grains of around 300 nm. The existence of bimodal austenite grain size in the 80% rolled and annealed 304L stainless steel led to the improvement of ductility while maintaining a high tensile strength in comparison with the 93% rolled and annealed sample

Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Song, Taek Hoh; Kim, In Sub [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Noh, Sung Kee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-08-01

In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of {gamma}-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier`s principle respectively. 13 figs., 1 tabs., 17 refs. (Author).

Investigation of high temperature phase stability, thermal properties and evaluation of metallurgical compatibility with 304L stainless steel, of indigenously developed ferroboron alternate shielding material for fast reactor applications

Energy Technology Data Exchange (ETDEWEB)

Rai, Arun Kumar [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Raju, S., E-mail: sraju@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Jeya Ganesh, B. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Panneerselvam, G. [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Vijayalakshmi, M.; Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Raj, Baldev [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India)

2011-08-15

Highlights: > High temperature phase stability and metallurgical compatibility of indigenous Ferro boron alloy (17 wt.%) with 304L SS have been evaluated using calorimetry, metallography and X-ray diffraction. > Fe-B is stable upto 1227 deg. C without any phase transformation. > In combination with SS 304L, it develops an eutectic reaction at 1198 deg. C. > High temperature metallurgical interaction between Ferroboron and 304L SS clad has been simulated for temperatures 550-800 deg. C for reaction times up to 5000 h, using diffusion couple. > Clad penetration depth with time follows a paraobolic rate law. - Abstract: Towards the cause of serving economic power production through fast reactors, it is necessary to bring in functionally more efficient and innovative design options, which also includes exploration of cheaper material alternatives, wherever possible. In this regard, the feasibility of using a commercial grade ferroboron alloy as potential alternate shielding material in the outer subassemblies of future Indian fast reactors has been recently investigated from shielding physics point of view. The present study explores in detail the high temperature thermal stability and the metallurgical compatibility of Fe-15.4B-0.3C-0.89Si-0.17Al-0.006S-0.004P-0.003O (wt.%) alloy with SS 304L material. In addition, the high temperature specific heat and lattice thermal expansion characteristics of this alloy have also been investigated as a part of the present comprehensive characterisation program. The Fe-15 wt.%B alloy is constituted of principally of two boride phases, namely tetragonal Fe{sub 2}B and orthorhombic FeB phases, which in addition to boron also contains some amount of C and Si dissolved in solid solution form. This Fe-B alloy undergoes a series of phase transformation as a function of increasing temperature; the major ones among them are the dissolution of Fe{sub 2}B-lower boride in the matrix through a eutectic type reaction, which results in the

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-11-01

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

Fluidos iónicos en lubricación de contactos aluminio-acero : interacciones superficiales y triboquímicas

OpenAIRE

Jiménez Ballesta, Ana Eva

2009-01-01

Los líquidos iónicos (LI) son fluidos de altas prestaciones con un amplio rango de estabilidad térmica. Actualmente están siendo objeto de estudio en una gran variedad de contactos, siendo una de sus aplicaciones tribológicas más interesante la lubricación del contacto aluminio-acero. En este trabajo se estudia la influencia de la longitud de la cadena lateral del catión y de la naturaleza del anión sobre la capacidad lubricante de 6 LI derivados del catión imidazolio, un derivado de piridini...

Alternativa de protección contra la corrosión del acero AISI 310S mediante recubrimiento de aluminio bajo condiciones de platos separadores en celdas de combustible de carbonatos fundidos

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R. Orozco-Cruz

2016-01-01

Full Text Available Introducción: La celda de combustible de carbonatos fundidos (MCFC, por sus siglas en inglés convencional opera a 650°C. Consiste de un cátodo de NiO poroso y litiado, una mezcla eutéctica de carbonato de litio (Li2CO3 y carbonato de potasio (K2CO3 fundido en una matriz electrolitica de óxido de aluminio litiado (LiAlO2 y un ánodo poroso de Ni. Los platos separadores entre cada celda presentan problemas de corrosión. Ante eso, un acero inoxidable AISI 310S con recubrimiento fue estudiado en condiciones de un plato separador en una MCFC. Método: Se utilizó un acero inoxidable AISI 310S como sustrato (muestra A, aplicándole un recubrimiento de Al con (B y sin tratamiento térmico (C. Fueron expuestos en carbonatos fundidos (62 mol% Li2CO3 -38 mol% K2CO3 a 650 °C en crisoles de alúmina. El comportamiento electroquímico fue estudiado mediante la técnica de Espectroscopía de Impedancia Electroquimica (EIS. Para el análisis de los diagramas de impedancia, se utilizó el software de simulación “Boukamp Equivalent Circuit”. La sección transversal de las muestras corroídas fue caracterizada mediante Microscopía Electrónica de Barrido (SEM, por sus siglas en inglés y los productos formados por Difracción de rayos X (XRD, por sus siglas en inglés. Resultados: Los diagramas de EIS presentan aumentos y disminuciones en los semicírculos formados a altas frecuencias indicativo de disolución de la capa externa, aumento y disminución de la resistencia de esta última así como el posible rompimiento de ella. La técnica de XRD presentó fases LiFeO2, LiCrO2, -LiAlO2 y -LiAlO2 así como fases intermetálicas para las distintas condiciones de la muestra. De la misma manera, los análisis de SEM presentaron los espesores de cada una de las capas formadas. Discusión o Conclusión: En la muestra A, se formaron capas de LiFeO2 y LiCrO2 después de 200 horas de exposición. La capa de LiCrO2 aumenta por la difusión de Li hacia el

Junções de materiais dissimilares utilizando o processo de soldagem por fricção rotativa

OpenAIRE

Eder Paduan Alves

2010-01-01

O objetivo desse trabalho é o desenvolvimento de junções no estado sólido de materiais dissimilares alumínio AA 1050 e aço inoxidável AISI 304, que possam ser utilizadas nas tubulações de reservatórios de propelentes líquidos e demais tubulações dos Veículos Lançadores de Satélites. As junções foram obtidas pelo processo de soldagem por fricção rotativa convencional, que combina o calor gerado entre o atrito de duas superfícies e deformação mecânica. Foram realizados testes de soldagem com di...

Biaxial fatigue tests and crack paths for AISI 304L stainless steel

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V. Chaves

2014-10-01

Full Text Available AISI 304L stainless steel specimens have been tested in fatigue. The tests were axial, torsional and in-phase biaxial, all of them under load control and R=-1. The S-N curves were built following the ASTM E739 standard and the method of maximum likelihood proposed by Bettinelli. The fatigue limits of the biaxial tests were represented in axes σ-τ. The elliptical quadrant, appropriate for ductile materials, and the elliptical arc, appropriate for fragile materials, were included in the graph. The experimental values were better fitted with an elliptical quadrant, despite the ratio between the pure torsion and tension fatigue limits, τFL/σFL, is 0.91, close to 1, which is a typical value for fragile materials. The crack direction along the surface has been analyzed by using a microscope, with especial attention to the crack initiation zones. The crack direction during the Stage I has been compared with theoretical models.

Corrosion of type 304L stainless steel in boiling dilute neptunium nitrate solution

International Nuclear Information System (INIS)

Motooka, Takafumi; Kiuchi, Kiyoshi

2003-01-01

Corrosion of type 304L stainless steel in nitric acid solution containing neptunium was studied under immersion and heat-transfer condition. Corrosion rates of stainless steel were obtained by the weight loss measurement and the quantitative analysis of metallic ions dissolved in solution. The surface morphology was observed by scanning electron microscopy. The corrosion acceleration mechanism was investigated by polarization measurement and spectrophotometry. The corrosion rate in boiling 9M nitric acid was accelerated by addition of neptunium. The corrosion of stainless steel was promoted under heat-transfer condition compared to immersion condition. In polarization measurements, the cathodic current was increased by addition of neptunium. Spectrophotometric measurements showed the oxidization of neptunium in boiling nitric acid. It was suggested that the accelerated corrosion in nitric acid solution containing neptunium was caused by re-oxidation of neptunium. (author)

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

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Carreras, L.

1999-08-01

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

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

Desgaste por deslizamiento en seco de aceros perlíticos y bainíticos

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Cristian Camilo Viáfara Arango

2004-01-01

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

Análisis de falla en cable de acero Análisis de falla en cable de acero

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E. A. Ossa

2005-12-01

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

Análisis de productos de corrosión de acero ,zinc, cobre y aluminio formados en clima polar antártico

OpenAIRE

Chico, Belén; Fuente, Daniel de la; Morcillo, Manuel; Almeida, E.; Joseph, Günter; Rivero, S.; Rosales, B.

2002-01-01

Este artículo presenta los resultados de caracterización de los productos de corrosión formados sobre acero, zinc, cobre y aluminio expuestos en estaciones de corrosión antárticas cercanas a la línea de costa, analizándose la influencia de las características singulares de este clima sobre la formación de los mismos. Los resultados se comparan con los obtenidos en atmósferas marinas de climas tropicales y templados.

Avaliação da suscetibilidade à corrosão sob tensão da ZAC do aço inoxidável AISI 316L em ambiente de reator nuclear PWR Stress corrosion cracking of stainless steel AISI 316L HAZ in PWR Nuclear reactor environment

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Mônica Maria de Abreu Mendonça Schvartzman

2009-09-01

Full Text Available Aços carbono de baixa liga e aços inoxidáveis são amplamente utilizados nos circuitos primários de reatores nucleares do tipo PWR (Pressurized Water Reactor. Ligas de níquel são empregadas na soldagem destes materiais devido a características como elevadas resistências mecânica e à corrosão, coeficiente de expansão térmica adequado, etc. Nos últimos 30 anos, a corrosão sob tensão (CST tem sido observada principalmente nas regiões das soldas entre materiais dissimilares existentes nestes reatores. Este trabalho teve como objetivo avaliar, por comparação, a suscetibilidade à corrosão sob tensão da zona afetada pelo calor (ZAC do aço inoxidável austenítico AISI 316L quando submetida a um ambiente similar ao do circuito primário de um reator nuclear PWR nas temperaturas de 303ºC e 325ºC. Para esta avaliação empregou-se o ensaio de taxa de deformação lenta - SSRT (Slow Strain Rate Test. Os resultados indicaram que a CST é ativada termicamente e que a 325ºC pode-se observar a presença mais significativa de fratura frágil decorrente do processo de corrosão sob tensão.In pressurized water reactors (PWRs, low alloy carbon steels and stainless steel are widely used in the primary water circuits. In most cases, Ni alloys are used to joint these materials and form dissimilar welds. These alloys are known to accommodate the differences in composition and thermal expansion of the two materials. Stress corrosion cracking of metals and alloys is caused by synergistic effects of environment, material condition and stress. Over the last thirty years, CST has been observed in dissimilar metal welds. This study presents a comparative work between the CST in the HAZ (Heat Affected Zone of the AISI 316L in two different temperatures (303ºC and 325ºC. The susceptibility to stress corrosion cracking was assessed using the slow strain rate tensile (SSRT test. The results of the SSRT tests indicated that CST is a thermally

48 CFR 6103.304 - Reply to the audit division and agency responses [Rule 304].

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Reply to the audit division and agency responses [Rule 304]. 6103.304 Section 6103.304 Federal Acquisition Regulations System CIVILIAN BOARD OF CONTRACT APPEALS, GENERAL SERVICES ADMINISTRATION TRANSPORTATION RATE CASES 6103.304 Reply to the audit division and agency...

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

Energy Technology Data Exchange (ETDEWEB)

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

1999-07-01

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

Comparative study of the microbiological corrosion among an AISI 304L and an API X65

International Nuclear Information System (INIS)

Diaz S, A.; Arganis J, C.; Luna C, P.; Carapia M, L.; Gonzalez F, E.

2004-01-01

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)

Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Song, Taek Ho

1994-02-15

In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H{sub 2}O{sub 2} played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively.

EFECTO DEL PRECALENTAMIENTO Y LA SEVERIDAD DE TEMPLE SOBRE LA RESISTENCIA AL DESGASTE ADHESIVO DEL ACERO AUSTENÍTICO AL MANGANESO

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OSCAR FABIÁN HIGUERA COBOS

2010-01-01

Full Text Available En este trabajo de investigación se estudió el efecto del precalentamiento y la severidad de temple sobre la resistencia al desgaste adhesivo del acero austenítico al manganeso ASTM A 128 grado C. El material se sometió a ciclos térmicos de temple y revenido con y sin precalentamiento con el fin de evaluar su influencia sobre la resistencia al desgaste. Posteriormente el material fue sometido a prueba según norma ASTM G83 y se determinó que el acero Austenítico al manganeso, es un material que presenta una microestructura metaestable en condiciones estables y no debe ser sometido a tratamiento térmico de revenido a altas temperaturas debido que favorece la descomposición de esta a ferrita (fase blanda de los acero y por ende disminuye su resistencia al desgaste.

Mejoramiento de la resistencia a la corrosión del acero AISI 4140 utilizando multicapas de titanio/nitruro de titanio

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Faber Correa

2008-01-01

Full Text Available El acero 4140 se utiliza ampliamente en la fabricación de partes de máquinas con durezas entre 25-35 Rockwell C. Sin embargo, su vida útil se ve limitada por su baja resistencia al desgaste y a la corrosión. Con el fin de mejorar su comportamiento frente a la corrosión se depositaron multicapas de Titanio/Nitruro de Titanio (Ti/TiN sobre substratos de acero 4140 mediante un sistema multi-blanco d.c. magnetrón sputtering a partir de un blanco de Ti de alta pureza (99,99% en una atmósfera de Ar/N2. Con el objeto de estudiar el efecto del número de capas sobre la velocidad de corrosión de las películas depositadas, se crecieron multicapas con 1, 5, 10, 15, y 20 bicapas de [Ti /TiN], manteniendo un espesor total constante de 3 um en todas ellas. Las fases existentes y composición química de los recubrimientos fueron analizados mediante espectroscopía de difracción de rayos X (XRD y espectroscopía de energía dispersiva de rayos X (EDX respectivamente. Las muestras de acero sin y con recubrimiento se caracterizaron además por Espectroscopía de Impedancia Electroquímica (EIS y curvas de polarización Tafel. Se encontró que la velocidad de corrosión tuvo una disminución alrededor del 87% en el acero recubierto con 20 bicapas de Ti/TiN en comparación al acero sin recubrir y del 25% respecto a la muestra recubierta con 1 bicapa, lo cual evidencia el efecto positivo del incremento del período en las películas delgadas basadas en multicapas de Ti/TiN.

Processing of fine grained AISI 304L austenitic stainless steel by cold rolling and high-temperature short-term annealing

Science.gov (United States)

Naghizadeh, Meysam; Mirzadeh, Hamed

2018-05-01

An advanced thermomechanical process based on the formation and reversion of deformation-induced martensite was used to refine the grain size and enhance the hardness of an AISI 304L austenitic stainless steel. Both low and high reversion annealing temperatures and also the repetition of the whole thermomechanical cycle were considered. While a microstructure with average austenite grain size of a few micrometers was achieved based on cold rolling and high-temperature short-term annealing, an extreme grain refinement up to submicrometer regime was obtained by cold rolling followed by low-temperature long-term annealing. However, the required annealing time was found to be much longer, which negates its appropriateness for industrial production. While a magnificent grain refinement was achieved by one pass of the high-temperature thermomechanical process, the reduction in grain size was negligible by the repetition of the whole cycle. It was found that the hardness of the thermomechanically processed material is much higher than that of the as-received material. The results of the present work were shown to be compatible with the general trend of grain size dependence of hardness for AISI 304L stainless steel based on the Hall-Petch relationship. The results were also discussed based on the X-ray evaluation of dislocation density by modified Williamson-Hall plots.

Degradación de recubrimientos ZrO2-CaO/NiAlMo por oxidación isoterma

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Utrilla, V.

2006-12-01

Full Text Available This paper analyses the degradation of a ceramic top coating 70%ZrO2 – 30%CaO deposited onto a stainless steel AISI 304 by thermal spray, using Ni-6%Al-5%Mo as overlay coating. These thermal barrier coatings were heat treated for 48, 120 and 288 h at 800 ºC to evaluate the degradation of these materials by isothermal oxidation. The microstructure evolution during oxidation was analysed by environmental scanning electron microscopy, transmission electron microscopy, X ray microanalysis and X ray diffraction. A thermally grown oxide layer was observed between the overlay coating and the ceramic top coating after oxidation. This layer was formed by a mixed Al and Ni oxides.En este trabajo se estudia la degradación de un recubrimiento 70%ZrO2 – 30%CaO crecido por proyección térmica de oxiacetileno sobre un acero inoxidable austenítico AISI 304 y empleando una leación de Ni-6%Al-5%Mo como capa de anclaje. Los recubrimientos se trataron térmicamente en aire a 800 ºC durante 48, 120 y 288 horas para evaluar la degradación de estos materiales por oxidación isotérmica. La evolución de la microestructura de las barreras como consecuencia del proceso de oxidación se analizó mediante microscopía electrónica de barrido ambiental, microscopía electrónica de transmisión, microanálisis de rayos X (EDX y difracción de rayos X. Durante la oxidación de los recubrimientos creció una capa intermedia de óxidos (“thermally grown oxides”, TGO entre el anclaje metálico y el recubrimiento cerámico formada por una mezcla de óxidos de Al y Ni.

Zirconium oxide deposits (ZrO2) and titanium oxide (TiO2) on 304l stainless steel

International Nuclear Information System (INIS)

Davila N, M. L.

2015-01-01

This research project aims to carry out the surface and electrochemical characterization to obtain the optimum conditions of the hydrothermal deposits of zirconium oxide ZrO 2 (baddeleyite) and titanium oxide TiO 2 (anatase and rutile phases) on 304l stainless steel, simulating an inhibiting protective layer. 304l steel specimens were cut, pre-oxidized in water at a temperature of 288 degrees Celsius and 8 MPa, similar to those of a typical BWR conditions. From the titanium oxide anatase crystalline phase, the rutile phase was obtained by a heat treatment at 1000 degrees Celsius. The Sigma-Aldrich pre-oxidized powders and steel 304l were characterized using techniques of X-ray diffraction, scanning electron microscopy, X-ray dispersive energy, chemical mapping and Raman spectrometry. The pre-oxidized steel has two oxide layers, an inner layer with nano metric crystals and another outer of larger crystals to 1μm, with the formation of hematite and magnetite, this predominating. The surface that contacted the sample holder has larger crystals. Hydrothermal deposits were carry out from suspensions of 10, 100 and 1000 ppm, of the crystal phases of anatase, rutile and baddeleyite, on the pre-oxidized steel at a temperature of 150 degrees Celsius for 2 and 7 days, samples were analyzed by X-ray diffraction, scanning electron microscopy, X-ray dispersive energy, Raman spectrometry and Tafel polarization. The suspension to 1000 ppm for 7 days coated surface most; the baddeleyite deposit is noticed more homogeneous than anatase and rutile. The deposit is favored when hematite and magnetite crystals are larger. The chemical mapping on deposits show that even after being immersed in water to 288 degrees Celsius during 30 days, the deposits are still present although a loss is observed. A reference electrode was assembled to conduct electrochemical tests of Tafel able to withstand a temperature of 288 degrees Celsius and pressure of 8 MPa. The baddeleyite deposit presented

Modelos de pérdida de masa de acero por corrosión atmosférica en Colombia usando inteligencia computacional

Directory of Open Access Journals (Sweden)

Esteban Velilla

2009-01-01

Full Text Available Con el fin de clasificar la corrosividad de las diferentes atmósferas colombianas, como parte de un proyecto de investigación extenso [1], se expusieron placas de acero al carbono en 21 estaciones distribuidas a lo largo de la infraestructura eléctrica del país (líneas de transmisión y subestaciones. En estas estaciones se midieron entre otros, el tiempo de humectación y la deposición de sulfatos y cloruros durante 12 meses; además, bimensualmente se tomaban placas de acero para medir en laboratorio la pérdida de masa sufrida por estas durante el tiempo de exposición. La clasificación de las 21 estaciones se hizo en 4 grupos, considerando: el tiempo de humectación, contenidos de cloruros y sulfatos, la altura sobre el nivel del mar y el tiempo de exposición de las placas; variables consideradas linealmente independientes según la técnica de descomposición en valores singulares (SVD realizada. El criterio utilizado para la clasificación fue el de similitud de las variables utilizando la norma Euclidiana considerada en la red neuronal no supervisada tipo Kohonen. Adicionalmente, se implementaron modelos para la pérdida de masa del acero para cada uno de los grupos usando redes neuronales (RN tipo Feed-Forward, definiéndose como entradas las variables antes mencionadas y como única salida la pérdida de masa. Complementariamente se presenta una comparación entre el modelo de RN para el grupo 1, con otros modelos obtenidos usando Algoritmos Genéticos (AG y el método Simplex.

Optimización del acero usado como soporte y gancho de sujeción del acero de refuerzo en cimentaciones de concreto

OpenAIRE

Sánchez Trujillo, Bryan; Sánchez Trujillo, Bryan; Sánchez Trujillo, Bryan

2015-01-01

Para el proceso constructivo de cimentaciones de concreto se usan diversos accesorios, algunos estandarizados y otros no; uno de los no estandarizados es el acero usado como soporte y gancho de sujeción de las barras de refuerzo, (comúnmente llamado "burro", "burrito" o "silletas" de soporte), pues en los planos estructurales no se detalla la forma de colocar y sostener las barras de refuerzo y en obra las silletas se colocan de forma empírica según las experiencias previas de los encargados ...

The effect of electrode vertex angle on automatic tungsten-inert-gas welds for stainless steel 304L plates

International Nuclear Information System (INIS)

Maarek, V.; Sharir, Y.; Stern, A.

1980-03-01

The effect of electrode vertex angle on penetration depth and weld bead width, in automatic tungsten-inert-gas (TIG) dcsp bead-on-plate welding with different currents, has been studied for stainless steel 304L plates 1.5 mm and 8 mm thick. It has been found that for thin plates, wider and deeper welds are obtained when using sharper electrodes while, for thick plates, narrower and deeper welds are produced when blunt electrodes (vertex angle 180 deg) are used. An explanation of the results, based on a literature survey, is included

26 CFR 1.304-5 - Control.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Control. 1.304-5 Section 1.304-5 Internal... TAXES Effects on Recipients § 1.304-5 Control. (a) Control requirement in general. Section 304(c)(1) provides that, for purposes of section 304, control means the ownership of stock possessing at least 50...

Deposition and characterization of noble metal onto surfaces of 304l stainless steel

International Nuclear Information System (INIS)

Contreras R, A.; Arganis J, C. R.; Aguilar T, J. A.; Medina A, A. L.

2010-10-01

Noble metal chemical addition (NMCA) plus hydrogen water chemistry is an industry-wide accepted approach for potential intergranular stress corrosion cracking mitigation of BWR internals components. NMCA is a method of applying noble metal onto BWR internals surfaces using reactor water as the transport medium that causes the deposition of noble metal from the liquid onto surfaces. In this work different platinum concentration solutions were deposited onto pre-oxidized surfaces of 304l steel at 180 C during 48 hr in an autoclave. In order to simulate the zinc water conditions, deposits of Zn and Pt-Zn were also carried out. The solutions used to obtain the deposits were: sodium hexahydroxyplatinate (IV), zinc nitrate hydrate and zinc oxide. The deposits obtained were characterized by scanning electron microscopy and X-ray diffraction. Finally, the electrochemical corrosion potential of pre-oxidized samples with Pt deposit were obtained and compared with the electrochemical corrosion potential of only pre-oxidized samples. (Author)

Influence of microstructure on the microbial corrosión behaviour of stainless steels

Directory of Open Access Journals (Sweden)

Moreno, Diego Alejandro

2000-08-01

Full Text Available Several stainless steels (Types UNS S30300, S30400, S30403, S31600, S31603 and S42000 with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC. Biocorrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide -SRB metabolites- was inspected by optical and scanning electron microscopy (SEM complemented with energy-dispersive X-ray (EDX analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless Steel Type UNS S42000 was found in a- biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte.

Se han utilizado aceros inoxidables de los tipos UNS S30300, S30400, S30403, S31600, S31603 y S42000, en diferentes estados microestructurales, para estudiar la influencia de los tratamientos térmicos sobre la corrosión microbiana. Para ello, se han realizado ensayos electroquímicos y ensayos de biocorrosión, en diferentes medios microbiológicos, utilizándose dos especies de bacterias reductoras de sulfatos (SRB. La morfología de las picaduras, producidas en presencia de cloruros y en presencia de cloruros más sulfuros -metabolitos de SRB-, se ha analizado por microscopía óptica y por microscopía electrónica de barrido (SEM complementada con análisis por energía dispersiva de rayos X

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.

Influence of surface finish on the high cycle fatigue behavior of a 304L austenitic stainless steel

International Nuclear Information System (INIS)

Petitjean, S.

2003-06-01

This work has dealt with the influence of surface finish on the high cycle fatigue behavior of a 304L. The role played by roughness, surface hardening and residual stresses has been particularly described. First part of this study has consisted of the production of several surface finishes. These latter were obtained by turning, grinding, mechanical polishing and sandblasting. The obtained surfaces were then characterised in terms of roughness, hardening, microstructure and residual stresses. Fatigue tests were finally conducted under various stress ratios or mean stresses at two temperatures (25 C and 300 C). Results clearly evidenced an effect of the surface integrity on the fatigue resistance of the 304L. This influence is nevertheless more pronounced at ambient temperature and for a positive mean stress. For all explored testing conditions, the lowest endurance limit was obtained for ground specimens whereas polished samples exhibited the best fatigue strength. Results also cleared out a detrimental influence of a positive mean stress in the case of specimens having surface defaults of a great acuity. The study of the relative effect of each of the surface parameter, under a positive stress ratio and at the ambient temperature, showed that roughness profile and surface hardening are the two more influential factors. The role of the residual stresses remains negligible due to their rapid relaxation during the application of the first cycles of fatigue. The estimation of the initiation and propagation periods showed that mechanisms differed as a function of the applied stress ratio. Crack propagation is governed by the parameter DK at a positive stress ratio and by Dep/2 in the case of tension-compression tests. (author)

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.

Influencia de la transformación austenita-martensita en la estabilidad dimensional de un nuevo acero para herramientas aleado con niobio (0,08% y vanadio (0,12%

Directory of Open Access Journals (Sweden)

Conejero Ortega, Gerardo

2014-09-01

Full Text Available Austenite-martensite transformation influence on the dimensional stability of a new experimental tool steel alloyed with niobium (0.08% wt. and vanadium (0.12% wt. has been studied. The dimensional stability of this new steel was compared with the dimensional stability of commercial steel, after and before two thermal treatments, T1 (860 °C and T2 (900 °C. The thermal treatments consisted on heating and cooling, at 1 atmosphere of pressure, in N2 atmosphere furnace, fol lowing by heating in a conventional furnace at 180 °C during 1 hour. Initially, the experimental steel composition and Ac1 and Ac3 transformation temperatures were determined by glow-discharge luminescence (GDL and dilatometric tests, respectively, in order to select the austenization temperatures of T1 and T2 treatments. After hardness measurement, the microstructure of both steels was characterized by X-Ray Diffraction (XRD and optical metallography, before and after of T1 and T2 thermal treatments. Finally, longitudinal and angular dimensional stability analyses were realized for both commercial and experimental steels. After a contrastive hypothesis analysis, the results showed that the longitudinal relative variation of the experimental steel calculated was around 0.2% and the angular relative variation was not significantSe ha estudiado la influencia de la transformación de austenita a martensita en la estabilidad dimensional de un acero experimental para herramientas aleado con niobio (0,08% en peso y vanadio (0,12% en peso. La estabilidad dimensional del acero experimental fue comparada con la de un acero comercial antes y después de ser sometidos, ambos aceros, a dos tratamientos térmicos diferentes. Los tratamientos térmicos consistieron en un calentamiento y mantenimiento durante una hora a temperaturas de 860 °C (T1 y 900 °C (T2 y un enfriamiento final en horno con nitrógeno (N2 a 1 atmósfera de presión. Inicialmente, se determinaron las composiciones del

Formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo Biofilm formation by Aeromonas hydrophila and Staphylococcus aureus on stainless steel using milk and different conditions of cultivation

Directory of Open Access Journals (Sweden)

Cleube Andrade Boari

2009-12-01

Full Text Available O objetivo desta pesquisa consistiu em avaliar a formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo. As variáveis em estudo consistem no cultivo monoespécie e combinado, dos referidos microrganismos e nas temperaturas de 4, 7 e 18 °C. Recipientes contendo 1000 mL de leite, densidade populacional de 10(5 UFC.mL-1 de cada microrganismo e 10 cupons de aço inoxidável (10 × 20 mm foram lacrados e armazenados, sob agitação de 60 rpm, por um período de 10 dias. As análises ocorreram a cada 48 horas. Células sésseis de A.hydrophila e S. aureus foram enumeradas através do plaqueamento seletivo em ágar m-Aeromonas selective e Baird-Parker, respectivamente. Estudos sobre o tempo de geração, enumeração de células planctônicas e observação dos cupons através da microscopia eletrônica de varredura foram conduzidos. S. aureus, em monocultivo, formou biofilme a 18 °C e a 7 °C. Para 4 °C, foi observado um processo de adesão. A presença de A. hydrophila reduziu o desempenho de S. aureus. Nesta condição de cultivo multiespécie houve formação de biofilme a 18 °C. A. hydrophila, tanto em monocultivo quanto em presença de S. aureus, formou biofilme em todas as condições pesquisadas.The aim of this research was to verify the capability of biofilm formation on stainless steel by Aeromonas hydrophila and Staphylococcus aureus using milk and different conditions of cultivation. The variables consisted in mono and multi-species cultivation of these microorganisms and in the temperatures of 4, 7 and 18 °C. Containers containing 1000 mL of milk, population density of 10(5 CFU.mL-1 of each microorganism, and ten suspended chips of stainless steel AISI 304 (10 × 20 mm were used to seal up and storage, under 60 rpm of agitation for 10 days. The analyses were conducted every 48 hours. Sessile cells of A. hydrophila and S. aureus and were enumerated

28 CFR 24.304 - Settlement.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Settlement. 24.304 Section 24.304... DEPARTMENT OF JUSTICE ADMINISTRATIVE PROCEEDINGS Procedures for Considering Applications § 24.304 Settlement. A prevailing party and Department counsel may agree on a proposed settlement of an award before...

Gas tungsten arc welding and friction stir welding of ultrafine grained AISI 304L stainless steel: Microstructural and mechanical behavior characterization

Energy Technology Data Exchange (ETDEWEB)

Sabooni, S., E-mail: s.sabooni@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Karimzadeh, F.; Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Ngan, A.H.W. [Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Jabbari, H. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of)

2015-11-15

In the present study, an ultrafine grained (UFG) AISI 304L stainless steel with the average grain size of 650 nm was successfully welded by both gas tungsten arc welding (GTAW) and friction stir welding (FSW). GTAW was applied without any filler metal. FSW was also performed at a constant rotational speed of 630 rpm and different welding speeds from 20 to 80 mm/min. Microstructural characterization was carried out by High Resolution Scanning Electron Microscopy (HRSEM) with Electron Backscattered Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Nanoindentation, microhardness measurements and tensile tests were also performed to study the mechanical properties of the base metal and weldments. The results showed that the solidification mode in the GTAW welded sample is FA (ferrite–austenite) type with the microstructure consisting of an austenite matrix embedded with lath type and skeletal type ferrite. The nugget zone microstructure in the FSW welded samples consisted of equiaxed dynamically recrystallized austenite grains with some amount of elongated delta ferrite. Sigma phase precipitates were formed in the region ahead the rotating tool during the heating cycle of FSW, which were finally fragmented into nanometric particles and distributed in the weld nugget. Also there is a high possibility that the existing delta ferrite in the microstructure rapidly transforms into sigma phase particles during the short thermal cycle of FSW. These suggest that high strain and deformation during FSW can promote sigma phase formation. The final austenite grain size in the nugget zone was found to decrease with increasing Zener–Hollomon parameter, which was obtained quantitatively by measuring the peak temperature, calculating the strain rate during FSW and exact examination of hot deformation activation energy by considering the actual grain size before the occurrence of dynamic recrystallization. Mechanical properties observations showed that the welding

In situ AFM study of pitting corrosion and corrosion under strain on a 304L stainless steel

International Nuclear Information System (INIS)

Martin, F.A.; Cousty, J.; Masson, J-L.; Bataillon, C.

2004-01-01

Our study is centred on surface localised corrosion under strain of a standard stainless steel (304L). The interest we take in these corrosion phenomena is led by the general misunderstanding of its primary initiation steps. The goal of this study is to determine precisely the relationships between local geometrical defects (grain boundaries, dislocation lines, etc) or chemical defects (inclusions) with the preferential sites of corrosion on the strained material. By combining three techniques at the same time: Atomic Force Microscopy, an electrochemical cell and a traction plate, we can observe in situ the effect of localised stress and deformation on the sample surface exposed to a corrosive solution. We managed to build an original set-up compatible with all the requirements of these three different techniques. Furthermore, we prepared the surface of our sample as flat as possible to decrease at maximum the topographical noise in order to observe the smallest defect on the surface. By using a colloidal suspension of SiO 2 , we obtained surfaces with a typical corrugation (RMS) of about 1 A for areas of at least 1 μm 2 . Our experimental study has been organised in two primary investigations: - In situ study of the morphology evolution of the surface under a corrosive chloride solution (borate buffer with NaCl salt). The influence of time, NaCl concentration, and potential was investigated; - In situ exploration of a 304L strained surface. It revealed the first stages of the surface plastic evolutions like activation of sliding dislocations, materialized by parallel steps of about 2 nm high in the same grain. The secondary sliding plane systems were also noticeable for higher deformation rates. Recent results concerning in situ AFM observation of corroded surfaces under strain in a chloride media will be presented. (authors)

In situ AFM study of pitting corrosion and corrosion under strain on a 304L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Martin, F.A. [CEA de Saclay, DRECAM/SPCSI, 91191 Gif-sur-Yvette cedex (France); Cousty, J.; Masson, J-L. [CEA de Saclay, DRECAM/SPCSI, 91191 Gif-sur-Yvette cedex (France); Bataillon, C. [CEA de Saclay, DEN/DPC/LECA, 91191 Gif-sur-Yvette cedex (France)

2004-07-01

Our study is centred on surface localised corrosion under strain of a standard stainless steel (304L). The interest we take in these corrosion phenomena is led by the general misunderstanding of its primary initiation steps. The goal of this study is to determine precisely the relationships between local geometrical defects (grain boundaries, dislocation lines, etc) or chemical defects (inclusions) with the preferential sites of corrosion on the strained material. By combining three techniques at the same time: Atomic Force Microscopy, an electrochemical cell and a traction plate, we can observe in situ the effect of localised stress and deformation on the sample surface exposed to a corrosive solution. We managed to build an original set-up compatible with all the requirements of these three different techniques. Furthermore, we prepared the surface of our sample as flat as possible to decrease at maximum the topographical noise in order to observe the smallest defect on the surface. By using a colloidal suspension of SiO{sub 2}, we obtained surfaces with a typical corrugation (RMS) of about 1 A for areas of at least 1 {mu}m{sup 2}. Our experimental study has been organised in two primary investigations: - In situ study of the morphology evolution of the surface under a corrosive chloride solution (borate buffer with NaCl salt). The influence of time, NaCl concentration, and potential was investigated; - In situ exploration of a 304L strained surface. It revealed the first stages of the surface plastic evolutions like activation of sliding dislocations, materialized by parallel steps of about 2 nm high in the same grain. The secondary sliding plane systems were also noticeable for higher deformation rates. Recent results concerning in situ AFM observation of corroded surfaces under strain in a chloride media will be presented. (authors)

5 CFR 304.107 - Reports.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Reports. 304.107 Section 304.107 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS EXPERT AND CONSULTANT APPOINTMENTS § 304.107 Reports. As required by 5 U.S.C. 3109(e), each agency shall report to the Office of...

5 CFR 304.103 - Authority.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Authority. 304.103 Section 304.103... APPOINTMENTS § 304.103 Authority. (a) Basic authority. (1) When authorized by an appropriation or other statute... expert or consultant who works on a strictly intermittent basis may be appointed under this authority...

Análisis de la influencia del factor de solapamiento en el tratamiento térmico de superficies extensas de aceros por láser

Directory of Open Access Journals (Sweden)

García-Beltrán, A.

2007-08-01

Full Text Available On the basis of numerical models developed by the authors for the predictive analysis of transformation hardening of extended steel surfaces, the difficulties existing for the treatment of extended surfaces by overlapping cycles of laser heating are analyzed from a computational point of view. In this analysis, thermal and physical properties of the material are considered along with their temperature dependance. Some optimization guidelines for the irradiation parameters (including modifications of the spatial distribution of the laser beam energy are determined in order to obtain both the adequate material transformed depth and the required hardness profiles.

Sobre la base de modelos numéricos, desarrollados por los autores para el análisis predictivo de procesos de tratamiento térmico superficial de aceros por láser, se analiza, desde un punto de vista computacional, la influencia del factor de solapamiento en el tratamiento de superficies extensas de dichos materiales mediante ciclos parcialmente superpuestos de irradiación láser. En dichos análisis, se tienen en cuenta, explícitamente, las propiedades termofísicas de los materiales considerados así como su dependencia térmica, estableciéndose, finalmente, diversos criterios de optimización de las variables de irradiación (incluyendo posibles variaciones en la distribución espacial de la energía del haz láser con el objeto de maximizar, de forma combinada, la profundidad de material transformado y el nivel de dureza alcanzado, evitando, al mismo tiempo, el sometimiento del material a ciclos térmicos degradatorios del tratamiento original, en concreto, el revenido superficial.

Analysis of martensitic transformation and residual tension in an 304L stainless steel; Analise da transformacao martensitica e tensao residual em um aco inoxidavel 304L

Energy Technology Data Exchange (ETDEWEB)

Alves, Juciane Maria

2014-07-01

The relationship between plastic deformation and the strain induced phase transformation, that provides a practical route to the development of new engineering materials with excellent mechanical properties, characterize the TRIP effect 'Transformation Induced Plasticity'. Among the stainless steels, the metastable 304 L austenitic steel is susceptible to transformation of austenite-martensite phase from tensile tests at room temperature by increments of plastic deformation. It is of great technological and scientific interest the knowledge of the evolution of phase transformation and residual stress from different levels and rates of plastic deformation imposed to the material. It is also important to evaluate the interference of metallographic preparation in quantitative analyzes of this steel. The main techniques used in this study consisted of X-rays diffraction and Ferritoscopy for the quantitation phase, and XRD to residual stress analysis also. As observed, the phase transformation quantification has not suffered significant influence of the metallographic preparation and evolved from increments of plastic deformation due to different stop charges and strain rates, leading to a further strengthening of the austenite matrix. The evaluation of residual stress resulting from the martensitic transformation was susceptible to the metallographic preparation and increased its value on comparison to sample without metallographic preparation. It was also observed that the residual stress decreased with the increase of the fraction of transformed martensite. (author)

21 CFR 522.304 - Carprofen.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Carprofen. 522.304 Section 522.304 Food and Drugs..., AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS § 522.304 Carprofen. (a) Specifications. Each milliliter of solution contains 50 milligrams (mg) carprofen. (b) Sponsor. See No. 000069 in...

Combinación de fibras de acero de última generación para el refuerzo de hormigón autocompactante

OpenAIRE

Alberti, Marcos; Enfedaque, Alejandro; Galvez, Jaime; Cortez, Adriana

2018-01-01

[ES] Dado que la mayor desventaja mecánica del hormigón son sus propiedades en tracción, las fibras normalmente se utilizan para mejorar la respuesta frente a solicitaciones de tracción y flexión, siendo las fibras de acero las más comúnmente utilizadas. Este tipo de fibras se ha utilizado con éxito en aplicaciones estructurales en los últimos 50 años y, como consecuencia, se han desarrollado nuevas fibras de acero de última generación de las que existe una bibliografía muy lim...

EVALUACIÓN EXPERIMENTAL DE LA RESISTENCIA A LA CORROSIÓN DE UN ACERO AISI-SAE 4140 IMPLANTADO CON IONES DE NITRÓGENO

OpenAIRE

PEÑA, DARIO; FONTALVO, PAOLA; ESTUPIÑAN, HUGO; NIÑO, DANNIER; VESGA, WILSON

2009-01-01

Se estudió la resistencia a la corrosión de un acero AISI-SAE 4140 implantado con iones de Nitrógeno mediante la técnica 3DII (Implantación Iónica Tridimensional). Se evaluaron diferentes rugosidades de las muestras implantadas mediante técnicas electroquímicas de Rp, EIS y Tafel en una salmuera al 3% de NaCl, donde se obtuvo la mayor resistencia a la corrosión para el material implantado con menor rugosidad. Se produjo la formación de una posible capa protectora estable con la inmersión de l...

10 CFR 800.304 - Default.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Default. 800.304 Section 800.304 Energy DEPARTMENT OF... ASSISTANCE Loan Administration § 800.304 Default. (a) In the event that the borrower fails to perform the terms and conditions of the loan, the borrower shall be in default and the Secretary shall have the...

Establishing precursor events for stress corrosion cracking initiation in type 304L stainless steel

International Nuclear Information System (INIS)

Khan, M.U.F.; Raja, V.S.; Roychowdhury, S.; Kain, V.

2015-01-01

The present study attempts to establish slip band emergence, due to localized deformation, as a precursor event for SCC initiation in type 304L SS. The unidirectional tensile loading was used for straining flat tensile specimen, less than 10% strain, in air, 0.5 M NaCl + 0.5 M H 2 SO 4 and boiling water reactor (BWR) simulated environment (288 C. degrees, 10 MPa). The surface features were characterized using optical microscopy, scanning electron microscopy (including electron backscattered diffraction-EBSD) and atomic force microscopy. The study shows that with increase in strain level, during unidirectional slow strain rate test (SSRT), average slip band height increases in air and the attack on slip lines occurs in acidified chloride environment. In BWR simulated environment, preferential oxidation on slip lines and initiation of a few cracks on some of the slip lines are observed. Based on the observation, the study suggests slip bands, formed due to localized deformation, to act as a precursor for SCC initiation. (authors)

5 CFR 179.304 - Notification procedures.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Notification procedures. 179.304 Section 179.304 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CLAIMS COLLECTION STANDARDS Administrative Offset § 179.304 Notification procedures. Before collecting any debt...

Investigation of thin film deposition on stainless steel 304 substrates under different operating conditions

International Nuclear Information System (INIS)

Chowdhury, M A; Nuruzzaman, D M

2016-01-01

In recent times, friction and wear in relation to the deposited carbon films on the steel substrates are important issues for industrial applications. In this research study, solid thin films were deposited on the stainless steel 304 (SS 304) substrates under different operating conditions. In the experiments, natural gas (97.14% methane) was used as a precursor gas in a hot filament thermal chemical vapor deposition (CVD) reactor. Deposition rates on SS 304 substrates were investigated under gas flow rates 0.5 - 3.0 l/min, pressure 20 - 50 torr, gap between activation heater and substrate 3.0 - 6.0 mm and deposition duration 30 - 120 minutes. The obtained results show that there are significant effects of these parameters on the deposition rates on SS 304 within the observed range. Friction coefficient of SS 304 sliding against SS 314 was also investigated under normal loads 5 - 10 N and sliding velocities 0.5 - m/s before and after deposition. The experimental results reveal that in general, frictional values are lower after deposition than that of before deposition. (paper)

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

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JOSÉ TRISTANCHO

2007-01-01

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

Surface decontamination of Type 304L stainless steel with electrolytically generated hydrogen: Design and operation of the electrolyzer

International Nuclear Information System (INIS)

Bellanger, G.

1993-01-01

The surface of tritiated Type 304L stainless steel is decontaminated by isotopic exchange with the hydrogen generated in an electrolyzer. This steel had previously been exposed to tritium in a tritium gas facility for several years. The electrolyzer for the decontamination uses a conducting solid polymer electrolyte made of a Nafion membrane. The cathode where the hydrogen is formed is nickel deposited on one of the polymer surfaces. This cathode is placed next to the region of the steel to be decontaminated. The decontamination involves, essentially, the tritiated oxide layers of which the initial radioactivity is ∼ 5 kBq/cm 2 . After treatment for 1 h, the decontamination factor is 8. 9 refs., 16 figs., 2 tabs

Comparación de la microestructura y propiedades de impacto de dos materiales compuestos laminados de acero de ultraalto contenido de carbono

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Pozuelo, M.

2004-04-01

Full Text Available Two ferrous laminated composites containing six layers have been processed by roll bonding. One of them consists of three layers of an ultrahigh carbon steel (1.3%C UHCS interlayered with other three layers of a microalloyed steel. The other composite consists of three layers of UHCS and three layers of a mild steel. Microstructure, Vickers hardness and impact properties have been studied. The absorbed energy values of the two laminated composites were higher than that of the UHCS.

Se procesaron mediante laminación en caliente dos materiales compuestos laminados de acero de ultraalto contenido de carbono (AUAC, 1,3%C de seis capas cada uno: El primero está compuesto por tres capas de AUAC alternadas con tres capas de un acero microaleado, y el segundo con tres del mismo AUAC alternadas con tres de un acero suave. Se ha realizado un estudio de sus microestructuras, dureza Vickers y propiedades de impacto. Se han mejorado los valores de energía absorbida de los dos materiales compuestos laminados respecto al del AUAC.

20 CFR 638.304 - Historical preservation.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Historical preservation. 638.304 Section 638.304 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR JOB CORPS PROGRAM... § 638.304 Historical preservation. The Job Corps Director shall review the “National Register of...

S-N Curves of high resistance steels in the gigacyclic regime; Curvas S-N de aceros de alta resistencia dentro del regimen gigaciclico

Energy Technology Data Exchange (ETDEWEB)

Marinez G, I [Conservatoire National des Arts et Metiers-Institut des Technologies et des Materiaux Avances (CNAM-ITMA), Paris (France); Dominguez A, G [Instituto Tecnologico de Celaya, Guanajuato (Mexico); Bathias, C [Conservatoire National des Arts et Metiers-Institut des Technologies et des Materiaux Avances (CNAM-ITMA), Paris (France)

2004-04-15

In this paper, the fatigue behavior of high strength steel used for mechanical parts has been investigated in the gigacycle fatigue regime. An experimental study has been carried out with both: R = 0.1 (perlitic-ferritic steel) and R = -1 (perlitic-ferritic steel, bainitic steel, martensitic steels) loads, at a high frequency of 20 khz up to 1010 cycles, to determine the S-N curves when fatigue life is more than 107 cycles. Comparison of experimental results at frequencies of 20 khz and 30 Hz with R = -1, shows that the S-N curve has a good agreement between 105 and 107 cycles for the high strength steels, Furthermore, fracture surface observations are made by SEM; the transition of crack initiation site is described. The generalization of gigacycle fatigue behavior is analyzed. More often initiation of fatigue crack at 109 cycles is a bulk phenomenon with an important effect of stress concentration due to mineral inclusions or perlitic platelets. Thus, the Murakami model is efficient when we can measure the defects associated with fracture, but it can not take into account the microstructure effect related to platelets phenomenon. [Spanish] En este trabajo se investigo el comportamiento en fatiga gigaciclica de varios aceros de alta resistencia utilizados en la industria automotriz. El estudio experimental se llevo a cabo utilizando dos diferentes valores de carga: R = 0.1 (acero perlitoferritico) y R = -1 (acero perlito-ferritico, acero bainitico, aceros martensiticos), a una frecuencia de ensayo de 20 kHz y hasta 1010 ciclos, para determinar las curvas S-N arriba de 107 ciclos. La comparacion de resultados experimentales obtenidos utilizando frecuencias de ensayo de 20 kHz y 30 Hz con la relacion de carga R = - 1, muestran la continuidad de las curvas S-N entre 105 y 107 ciclos para estos aceros de alta resistencia. Por otro lado, observaciones de la superficie de fractura se efectuaron utilizando el microscopio electronico de barrido; se describe la transicion

DESGASTE POR ABRASIÓN DEL ACERO API 5L X65 REVESTIDO CON NIOBIO POR ASPERSIÓN TÉRMICA A PLASMA Y CON INCONEL 625 POR SOLDADURA

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JOSE MATOS

2012-01-01

Full Text Available El objetivo de este trabajo fue evaluar y caracterizar el comportamiento mecánico en desgaste del acero API 5L X65, revestido con niobio en comparación al desempeño del revestimiento de la aleación de inconel 625 empleados en la industria de petróleo y gas. El revestimiento de niobio fue obtenido por el proceso de aspersión térmica a plasma de arco no transferido y el revestimiento inconel 625 por soldadura con electrodo revestido. La resistencia al desgaste por abrasión fue evaluada según la norma Petrobras N-2568, en un tribómetro CTER, la rugosidad y el volumen de material desgastado se determinó a través de perfilometría y la dureza de los revestimientos por microscopia Vickers. Los revestimientos obtenidos fueron caracterizados respecto a su morfología por microscopia electrónica de barrido (MEB y microscopía óptica (MO. La mayor dureza del revestimiento con niobio obtenido puede haber contribuido a reducir la tasa de desgaste en comparación con el revestimiento de inconel 625.

47 CFR 65.304 - Capital structure.

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2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Capital structure. 65.304 Section 65.304... OF RETURN PRESCRIPTION PROCEDURES AND METHODOLOGIES Exchange Carriers § 65.304 Capital structure. The proportion of each cost of capital component in the capital structure is equal to: Proportion in the capital...

Dislocation structure evolution in 304L stainless steel and weld joint during cyclic plastic deformation

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao; Jing, Hongyang; Zhao, Lei; Han, Yongdian; Lv, Xiaoqing [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072 (China); Xu, Lianyong, E-mail: xulianyong@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072 (China)

2017-04-06

Dislocation structures and their evolution of 304L stainless steel and weld metal made with ER308L stainless steel welding wire subjected to uniaxial symmetric strain-controlled loading and stress-controlled ratcheting loading were observed by transmission electron microscopy (TEM). The correlation between the cyclic response and the dislocation structure has been studied. The experiment results show that the cyclic behaviour of base metal and weld metal are different. The cyclic behaviour of the base metal consists of primary hardening, slight softening and secondary hardening, while the weld metal shows a short hardening within several cycles followed by the cyclic softening behaviour. The microscopic observations indicate that in base metal, the dislocation structures evolve from low density patterns to those with higher dislocation density during both strain cycling and ratcheting deformation. However, the dislocation structures of weld metal change oppositely form initial complicated structures to simple patterns and the dislocation density gradually decrease. The dislocation evolution presented during the strain cycling and ratcheting deformation is summarized, which can qualitatively explain the cyclic behaviour and the uniaxial ratcheting behaviour of two materials. Moreover, the dislocation evolution in the two types of tests is compared, which shows that the mean stress has an effect on the rate of dislocation evolution during the cyclic loading.

Effect of martensitic transformation on springback behavior of 304L austenitic stainless steel

Science.gov (United States)

Fathi, H.; Mohammadian Semnani, H. R.; Emadoddin, E.; Sadeghi, B. Mohammad

2017-09-01

The present paper studies the effect of martensitic transformation on the springback behavior of 304L austenitic stainless steel. Martensite volume fraction was determined at the bent portion under various strain rates after bending test. Martensitic transformation has a significant effect on the springback behavior of this material. The findings of this study indicated that the amount of springback was reduced under a situation of low strain rate, while a higher amount of springback was obtained with a higher strain rate. The reason for this phenomenon is that higher work hardening occurs during the forming process with the low strain rate due to the higher martensite volume fraction, therefore the formability of the sheet is enhanced and it leads to a decreased amount of springback after the bending test. Dependency of the springback on the martensite volume fraction and strain rate was expressed as formulas from the results of the experimental tests and simulation method. Bending tests were simulated using LS-DYNA software and utilizing MAT_TRIP to determine the martensite volume fraction and strain under various strain rates. Experimental result reveals good agreement with the simulation method.

34 CFR 304.21 - Allowable costs.

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2010-07-01

... 34 Education 2 2010-07-01 2010-07-01 false Allowable costs. 304.21 Section 304.21 Education... Grantee § 304.21 Allowable costs. In addition to the allowable costs established in the Education... allowable expenditures by projects funded under the program: (a) Cost of attendance, as defined in Title IV...

14 CFR 1203.304 - Internal effect.

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2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Internal effect. 1203.304 Section 1203.304... Classification Principles and Considerations § 1203.304 Internal effect. The effect of security protection on... effects and added costs inherent in a security classification must be assessed in light of the detrimental...

24 CFR 291.304 - Bidding process.

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2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Bidding process. 291.304 Section 291.304 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued... Family Mortgage Loans § 291.304 Bidding process. (a) Submission of bids. All bids must be submitted to...

34 CFR 685.304 - Counseling borrowers.

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2010-07-01

... 34 Education 3 2010-07-01 2010-07-01 false Counseling borrowers. 685.304 Section 685.304 Education... Direct Loan Program Schools § 685.304 Counseling borrowers. (a) Entrance counseling. (1) Except as provided in paragraph (a)(8) of this section, a school must ensure that entrance counseling is conducted...

20 CFR 801.304 - Business hours.

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2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Business hours. 801.304 Section 801.304 Employees' Benefits BENEFITS REVIEW BOARD, DEPARTMENT OF LABOR ESTABLISHMENT AND OPERATION OF THE BOARD Action by the Board § 801.304 Business hours. The office of the Clerk of the Board at Washington, DC...

Effect of pre-hardening on the lifetime of type 304L austenitic stainless steels

International Nuclear Information System (INIS)

Kpodekon, C.

2010-01-01

This study deals with the effect of the loading history on the cyclic behavior and the fatigue life of two kinds (THYSSEN and CLI) of 304L stainless steel at room temperature. The experiments have been performed using two specimens' categories. The first one (virgin) has been submitted to only classical fatigue tests while in the second category, prior to the fatigue test, the specimen is subjected to a pre-hardening process under either monotonic or cyclic strain control. Cyclic softening followed by cyclic hardening are observed for the virgin specimens while only cyclic softening is exhibited by the pre-hardened specimens. The obtained results show that fatigue life is strongly influenced by the pre-hardening: it seems beneficial under stress control but detrimental under strain control, even in the presence of a compressive mean stress. The results are discussed regarding the cyclic evolution of the elastic modulus as well as the isotropic and kinematic parts of the strain hardening, and strain energy density per cycle, in different configurations: with or without prehardening,stress or strain control. (author)

GEL DE ALOE-VERA COMO POTENCIAL INHIBIDOR DE LA CORROSIÓN DEL ACERO DE REFUERZO ESTRUCTURAL

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Héctor Herrera-Hernández

2015-01-01

Full Text Available En el presente trabajo se estudiaelectroquímicamente un GELextracto de las hojas de ALOE VERAcomo un posible inhibidor de la corrosión del acero de refuerzo estructuraldel concreto.Los estudiosde corrosiónse llevaron a cabo en 1M de HCl y utilizando la técnica de espectroscopia de impedancia electroquímica (EISse evaluó la resistencia a la corrosión en presencia y ausencia del GEL.Los diagramas de impedancia mostraronque la adición en diferentes proporcionesdel GELinhibe notablemente el proceso de la corrosión del acero inmerso en la solución ácida. También se determinó que las moléculas del GEL obedecena un mecanismo de fisisorciónsobre la superficie del metal de acuerdo con el modelo de isoterma de Langmuircon unG°adsde alrededor de 14.17 kJ/mol. El GEL se clasificócomo un inhibidor orgánico del tipo mixto.

Influencia de la termodependencia de las propiedades físicas del acero en la simulación por elementos finitos del proceso de soldadura

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Félix Ramos Morales

2009-01-01

Full Text Available En el presente trabajo se desarrolló un modelo de elementos finitos para simular la unión a tope, con electrodo E 7018 de 3,2 mm de diámetro, de dos placas de acero con bajo contenido de carbono y baja aleación. Adicionalmente, se estudia la influencia sobre la distribución de temperaturas en la placa al considerar la termo-dependencia de diferentes propiedades físicas del acero (conductividad térmica y calor específico.

Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

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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.

Soldadura de aceros dual phase en chapa fina: GMAW, PAW y RSW

OpenAIRE

Svoboda,Hernán; Lorusso,Hernán N.; Burgueño,Alejandro

2011-01-01

Los aceros Dual Phase (DP) han encontrado recientemente una fuerte aplicación en elementos estructurales en la industria automotriz, debido a la necesidad de disminuir peso. La soldadura de estos materiales cobra particular importancia considerando su aplicación estructural y los procesos relacionados en su fabricación. En particular la soldadura de resistencia por punto (RSW) y semiautomática con alambre macizo y protección gaseosa (GMAW) son ampliamente utilizados en la industria automotriz...

Conformado por vía coloidal de recubrimientos en la cara interna de un tubo de acero

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Ferrari, B.

2004-04-01

Full Text Available The development of new coating processes has important limitations related to the films thickness and the geometry of the coating substrates. In this work, two colloidal forming processes are proposed for manufacturing ceramic and metallic coatings on the inner surface of a steel pipe. Ceramic coatings of CaCO3 have been formed by electrophoretic deposition (EPD. Aqueous stable suspensions were prepared and a electrophoretic cell was designed, in which the steel tube to be coated acted simultaneously as container and working electrode. Nickel films were prepared by filling the pipe with the suspension and rotating to fully wet the steel surface. Nickel suspensions were formulated focusing an improved wettability and adherence to the steel surface by using binders. From these processes, ceramic and metallic coatings with 300- 350 μm in thickness, homogeneous and strongly adhered to the inner surface of the steel pipe have been obtained.

El desarrollo de las tecnologías de fabricación de recubrimientos presenta importantes limitaciones relativas a los espesores de las capas fabricadas y a la geometría de los substratos a recubrir. En este trabajo se proponen dos procesos de conformado coloidal de revestimientos cerámicos y metálicos en la cara interna de un tubo de acero. El revestimiento cerámico (CaCO3 se ha conformado por deposición electroforética (EPD. Para ello se han preparado suspensiones estables de CaCO3 en agua, y se ha diseñado una célula electroforética en la que el tubo es a la vez el contenedor y el electrodo de trabajo. El revestimiento metálico (níquel se ha fabricado por vertido de una suspensión estable sobre el propio tubo de acero. Para ello se han acondicionado las suspensiones con el objetivo de mejorar el mojado y la adherencia sobre el acero. A partir de los procesos de EPD y vertido se han obtenido revestimientos cerámicos y metálicos, respectivamente, con espesores de 300-350 μm, homogéneos y

Plasma spot welding of ferritic stainless steels

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Lešnjak, A.

2002-06-01

Full Text Available Plasma spot welding of ferritic stainless steels is studied. The study was focused on welding parameters, plasma and shielding gases and the optimum welding equipment. Plasma-spot welded overlap joints on a 0.8 mm thick ferritic stainless steel sheet were subjected to a visual examination and mechanical testing in terms of tension-shear strength. Several macro specimens were prepared. Plasma spot welding is suitable to use the same gas as shielding gas and as plasma gas, i.e., a 98 % Ar/2 % H ₂ gas mixture. Tension-shear strength of plasma-spot welded joints was compared to that of resistance-spot welded joints. It was found that the resistance welded joints withstand a somewhat stronger load than the plasma welded joints due to a larger weld spot diameter of the former. Strength of both types of welded joints is approximately the same.

El artículo describe el proceso de soldeo de aceros inoxidables ferríticos por puntos con plasma. La investigación se centró en el establecimiento de los parámetros óptimos de la soldadura, la definición del gas de plasma y de protección más adecuado, así como del equipo óptimo para la realización de la soldadura. Las uniones de láminas de aceros inoxidables ferríticos de 0,8 mm de espesor, soldadas a solape por puntos con plasma, se inspeccionaron visualmente y se ensayaron mecánicamente mediante el ensayo de cizalladura por tracción. Se realizaron macro pulidos. Los resultados de la investigación demostraron que la solución más adecuada para el soldeo por puntos con plasma es elegir el mismo gas de plasma que de protección. Es decir, una mezcla de 98 % de argón y 2 % de hidrógeno. La resistencia a la cizalladura por tracción de las uniones soldadas por puntos con plasma fue comparada con la resistencia de las uniones soldadas por resistencia por puntos. Se llegó a la conclusión de que las uniones soldadas por resistencia soportan una carga algo mayor que la uniones

Tests on mechanical behavior of 304 L stainless steel under constant stress associated with cyclic strain

International Nuclear Information System (INIS)

Lebey, J.; Roche, R.

1979-01-01

Mechanical analyses of structures, to be efficient, must incorporate materials behavior data. Among the mechanisms liable to cause collapse, progressive distortion (or ratcheting) has been the subject of only a few basic experiments, most of the investigations being theoretical. In order to get meaningful results to characterize materials behavior, an experimental study on ratcheting of austenitic steels has been undertaken at the C.E.A. This paper gives the first results of tests at room temperature on thin tubes of 304L steel submitted to an axial constant stress (primary stress) to which is added a cyclic shearing strain (secondary stress). The tests cover a large combination of the two loading modes. The main results consist of curves of cumulative iso-deformation in the primary and secondary stress field (Bree type diagrams). Results are given for plastic deformations ranging from 0.1 to 2.5% up to N=100 cycles

Evaluación experimental de la resistencia a la corrosión de un acero aisi-sae 4140 implantado con iones de nitrógeno

OpenAIRE

PEÑA, DARIO; FONTALVO, PAOLA; ESTUPIÑAN, HUGO; NIÑO, DANNIER; VESGA, WILSON

2010-01-01

Se estudió la resistencia a la corrosión de un acero AISI-SAE 4140 implantado con iones de Nitrógeno mediante la técnica 3DII (Implantación Iónica Tridimensional). Se evaluaron diferentes rugosidades de las muestras implantadas mediante técnicas electroquímicas de Rp, EIS y Tafel en una salmuera al 3% de NaCl, donde se obtuvo la mayor resistencia a la corrosión para el material implantado con menor rugosidad. Se produjo la formación de una posible capa protectora estable con la inmersión de l...

Evaluación del trabajo esencial de fractura en chapa de un acero de alta resistencia de fase dual

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Gutiérrez, D.

2013-02-01

Full Text Available Fracture toughness of advanced high strength steels (AHSS, can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets.

La tenacidad de fractura de aceros de alta resistencia (AHSS, es una propiedad interesante para optimizar el comportamiento a impacto, pero su caracterización experimental en chapas metálicas es compleja debido a su espesor. En este trabajo se plantea el método del Trabajo Esencial de Fractura (TEF, como alternativa al cálculo de la tenacidad. Este método ya ha sido utilizado con éxito en polímeros y aceros dúctiles, aunque la información sobre su aplicación en AHSS es escasa. Se ha evaluado la tenacidad en un acero de fase dual de 800 MPa de resistencia y se ha comparado con la de un acero de embutición. Los resultados muestran que se cumplen los requisitos del método y ponen en evidencia la influencia del radio de entalla en el valor obtenido de TEF, especialmente para AHSS. Con todo ello, el método TEF se puede usar para caracterizar la tenacidad de AHSS en formato chapa.

Low cycle fatigue: high cycle fatigue damage accumulation in a 304L austenitic stainless steel; Endommagement et cumul de dommage en fatigue dans le domaine de l'endurance limitee d'un acier inoxydable austenitique 304L

Energy Technology Data Exchange (ETDEWEB)

Lehericy, Y

2007-05-15

The aim of this study was to evaluate the consequences of a Low Cycle Fatigue pre-damage on the subsequent fatigue limit of a 304L stainless steel. The effects of hardening and severe roughness (grinding) have also been investigated. In a first set of tests, the evolution of the surface damage induced by the different LCF pre-cycling was characterized. This has permitted to identify mechanisms and kinetics of damage in the plastic domain for different surface conditions. Then, pre-damaged samples were tested in the High Cycle Fatigue domain in order to establish the fatigue limits associated with each level of pre-damage. Results evidence that, in the case of polished samples, an important number of cycles is required to initiate surface cracks ant then to affect the fatigue limit of the material but, in the case of ground samples, a few number of cycles is sufficient to initiate cracks and to critically decrease the fatigue limit. The fatigue limit of pre-damaged samples can be estimated using the stress intensity factor threshold. Moreover, this detrimental effect of severe surface conditions is enhanced when fatigue tests are performed under a positive mean stress (author)

28 CFR 301.304 - Representation of claimant.

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2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Representation of claimant. 301.304 Section 301.304 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death § 301.304 Representation...

Multi-Wavelength Variability in PKS 2155-304 Y. G. Zheng1,2, L ...

Indian Academy of Sciences (India)

2009), we attempt to model the multi-wavelength variability in PKS 2155-304. We assume that the acceleration process is a stochastic process and we describe it as the diffusion of the particle momentum. Throughout the paper, we assume the. Hubble constant H0 = 70 km s−1. Mpc. −1. , the matter energy density M = 0.27,.

AES depth profiles in Mo-coated 304L stainless steel achieved by RF-magnetron sputtering and influence of Mo on the corrosion in 3.5% NaCl solution

Energy Technology Data Exchange (ETDEWEB)

Saidi, D. [Département de métallurgie, Division de Technologie du Combustible, Centre de Recherche Nucléaire de Draria CRND, BP. 43 Draria, Alger (Algeria); Zaid, B., E-mail: zaidbachir@yahoo.com [Département de métallurgie, Division de Technologie du Combustible, Centre de Recherche Nucléaire de Draria CRND, BP. 43 Draria, Alger (Algeria); Souami, N. [Centre de Recherche Nucléaire d’Alger CRNA, 2 Bd. Frantz Fanon, Alger (Algeria); Saoula, N. [Division des Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées CDTA, Cité du 20 août 1956, Baba Hassan, BP n 17, Alger (Algeria); Siad, M. [Centre de Recherche Nucléaire d’Alger CRNA, 2 Bd. Frantz Fanon, Alger (Algeria); Si Ahmed, A. [Im2np, UMR 7334 CNRS, Aix-Marseille Université, 13397 Marseille Cedex 20 (France); Biberian, J.P. [CINaM, UMR 7525 CNRS, Aix Marseille Université, 13288 Marseille Cedex 9 (France)

2015-10-05

Highlights: • Mo coating of 304L stainless steel is achieved via RF-magnetron sputtering. • The AES depth profiles before and after annealing in air (at 973 K) are analyzed. • The corrosions in NaCl solution of bare and Mo-coated samples are compared. • Mo-coated steels exhibit better corrosion behaviors. • The positive action of Mo oxide via its semi-conducting properties is deduced. - Abstract: Molybdenum-coated 304L stainless steel samples, fabricated by RF-magnetron sputtering, are characterized by Auger Electron Spectroscopy (AES) before and after annealing in air at 973 K. The electrochemical parameters of bare and coated materials, in NaCl 3.5% water solution at 298 K, are derived from the potentiodynamic polarization curves. The corrosion current of Mo-coated samples (before and after annealing) is significantly lower than that of its bare counterpart. The information gained from the AES depth profiles leads us to infer that the positive action of molybdenum on the corrosion behavior may be attributed to the changes induced by the semi-conducting properties of Mo oxide in the passive film.

48 CFR 9901.304 - Membership.

Science.gov (United States)

2010-10-01

... Administrator. (d) An individual who is particularly knowledgeable about cost accounting problems and systems... Section 9901.304 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET ADMINISTRATION RULES AND PROCEDURES 9901.304 Membership...

Protocolo para evaluar y comparar la respuesta al contacto por indentación esférica de un sistema integrado por un recubrimiento cerámico depositado sobre un acero de herramienta

OpenAIRE

Cordier, Delphine

2009-01-01

En aplicaciones como el conformado en frío donde las herramientas están sometidas a diversas cargas, se usan materiales para herramientas como aceros rápidos y metales duros recubiertos. En estas aplicaciones, los impactos sucesivos inducen presiones que pueden ocasionar el fallo por fatiga. Por ello, es necesario establecer las condiciones límite de trabajo de los materiales para optimizar la vida útil de las herramientas. En este trabajo, el sistema sustrato/recubrimiento ana...

Modelado de Control de Nivel en Molde para Vaciado Continuo de Palanquillas de Acero

Directory of Open Access Journals (Sweden)

Guillermo González Yero

2014-01-01

Full Text Available Resumen: Este trabajo presenta un modelo del sistema de control de nivel en molde de una máquina de vaciado continuo de palanquillas de acero. El objetivo fue realizar el modelado de cada elemento del sistema incluyendo las perturbaciones y transformaciones de la planta que más afectan la calidad del control. Se obtuvo y validó un modelo aproximado, utilizando leyes físicas, la identificación experimental mediante señales especiales e identificación paramétrica fuera de línea. En el modelo se incluyen de forma explícita los fenómenos de obstrucción y erosión en la válvula, que tienen una incidencia significativa en el funcionamiento de la planta. Para el servosistema hidráulico de la instalación se logró un modelo de caja gris que contribuye a un mejor entendimiento del comportamiento del proceso y a evaluar la incidencia de una implementación multifrecuencia bajo esquema convencional. Con el modelo obtenido es posible estudiar la operación del sistema a escala de simulación y la efectividad de soluciones de control avanzadas. El trabajo desarrollado es parte de un proceso de I+D que en el transcurso de más de 10 años ha contribuido a que en la acería donde se realiza la investigación, exista un sistema de control de nivel en molde que tiene impacto positivo sobre la calidad del acero producido. Abstract: This paper presents a model of system for the mould level control in a continuous casting machine for steel billets. The objective was to carry out the modeling of each element of the system including disturbances and transformations of the plant that affect the quality of control in the installation study object. It was obtained and validated an approximate model of the control system using physical laws governing the same one, experimental identification by special signals and parametric identification off- line. The model explicitly includes the phenomena of obstruction and erosion of the valve which have a

Caracterización de los aceros sinterizados obtenidos a partir de polvos prealeados Fe-1,5% Mo

Directory of Open Access Journals (Sweden)

Torralba, J. M.

1995-02-01

Full Text Available Sintered molybdenum-, copper-, nickel- alloyed steels, have been studied through the influence of the Chemical composition on different mechanical and physical properties. In all the studied steels, a constant percentage of carbon has been used, as well Fe-Mo prealloyed powders, with a 1,5% Mo content. Selected sintering conditions were close to those used in the P/M industry, potential consumer of the studied steels.

Se estudian los aceros aleados sinterizados con molibdeno, cobre, níquel y grafito, a partir de la influencia de su composición sobre distintas propiedades mecánicas y físicas. En todos los aceros, se utilizó una composición de carbono constante, así como polvos prealeados de Fe-Mo, con 1,5% Mo. Las condiciones de sinterización elegidas han sido las más próximas a las utilizadas en la industria pulvimetalúrgica, que es el usuario potencial de los materiales estudiados.

41 CFR 105-54.304 - Cost guidelines.

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Cost guidelines. 105-54.304 Section 105-54.304 Public Contracts and Property Management Federal Property Management... Administration 54-ADVISORY COMMITTEE MANAGEMENT 54.3-Advisory Committee Procedures § 105-54.304 Cost guidelines...

Solid state crack repair by friction stir processing in 304L stainless steel

Institute of Scientific and Technical Information of China (English)

C.Gunter; M.P.Miles; F.C.Liu; T.W Nelson

2018-01-01

Friction stir processing (FSP) was investigated as a method of repairing cracks in 12mm thick 304L stainless steel plate.Healing feasibility was demonstrated by processing a tapered crack using a PCBN/WRe tool with a 25 mm diameter shoulder and a pin length of 6.4 mm.The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm.Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal.Grain refinement in some specimens resulted in much higher stir zone hardness,compared to base metal.A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness,as expected from the HallPetch relationship.Corrosion testing was carried out in order to evaluate the effect of FSP on potential sensitization of the stir zone.After 1000h of intermittent immersion in 3.5％ saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.

Crack propagation in stainless steel AISI 304L in Hydrogen Chemistry conditions (HWC)

International Nuclear Information System (INIS)

Diaz S, A.; Fuentes C, P.; Merino C, F.; Castano M, V.

2006-01-01

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

5 CFR 9901.304 - Definitions.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Definitions. 9901.304 Section 9901.304 Administrative Personnel DEPARTMENT OF DEFENSE HUMAN RESOURCES MANAGEMENT AND LABOR RELATIONS SYSTEMS (DEPARTMENT... supplement established to address recruitment or retention difficulties or for other appropriate reasons and...

48 CFR 9.304 - Exceptions.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Exceptions. 9.304 Section... CONTRACTOR QUALIFICATIONS First Article Testing and Approval 9.304 Exceptions. Normally, testing and approval is not required in contracts for— (a) Research or development; (b) Products requiring qualification...

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-09-01

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

304 Concretion Facility Closure Plan

International Nuclear Information System (INIS)

1991-10-01

The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium with Zircaloy-2 and copper silicon allo , uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets (7.5-gal containers) in the 304 Concretion Facility (304 Facility), located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA) and the Washington Administrative Code (WAC) Dangerous Waste Regulations, WAC 173-303-040 (Ecology 1991). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Facility. The strategy for closure of the 304 Facility is presented in Section 6.0

304 Concretion facility closure plan

International Nuclear Information System (INIS)

1990-04-01

The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium Zircaloy-2 and copper silicon alloy, uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets in the 304 Concretion Facility, located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Concretion Facility (304 Facility). Clean closure of the 304 Facility is the proposed method for closure of the facility. Justification for this proposal is presented. 15 refs., 22 figs., 4 tabs

MODIFICACIÓN DEL SISTEMA CONCRETO-ACERO DE REFUERZO MEDIANTE LA ADICIÓN DE FIBRAS DE BAGAZO DE CAÑA PARA FACILITAR SU PROTECCIÓN ANTICORROSIVA.

OpenAIRE

GARCIA DELGADO, AMERICA

2015-01-01

Los sistemas concreto-acero de refuerzo son considerados estructuras durables y resistentes; sin embargo, con el paso del tiempo se ven afectados por problemas de corrosión, la cual, se desarrolla cuando los cloruros se encuentran más allá de un cierto nivel umbral, en el que se inicia la despasivación o la ruptura la capa pasiva que protege al acero de refuerzo. Para contrarrestar los daños ocasionados por la corrosión, se han propuestos varios métodos para disminuir y/o preve...

Some aspects of thermomechanical fatigue of AISI 304L stainless steel: Part I. creep- fatigue damage

Science.gov (United States)

Zauter, R.; Christ, H. J.; Mughrabi, H.

1994-02-01

Thermomechanical fatigue (TMF) tests on the austenitic stainless steel AISI 304L have been conducted under “true≓ plastic-strain control in vacuum. This report considers the damage oc-curring during TMF loading. It is shown how the temperature interval and the phasing (in-phase, out-of-phase) determine the mechanical response and the lifetime of the specimens. If creep-fatigue interaction takes place during in-phase cycling, the damage occurs inside the ma-terial, leading to intergranular cracks which reduce the lifetime considerably. Out-of-phase cy-cling inhibits creep-induced damage, and no lifetime reduction occurs, even if the material is exposed periodically to temperatures in the creep regime. A formula is proposed which allows prediction of the failure mode, depending on whether creep-fatigue damage occurs or not. At a given strain rate, the formula is able to estimate the temperature of transition between pure fatigue and creep-fatigue damage.

Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

International Nuclear Information System (INIS)

Magnier-Monin, L.

2007-12-01

This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)

Influence of low-temperature nitriding on the strain-induced martensite and laser-quenched austenite in a magnetic encoder made from 304L stainless steel

Science.gov (United States)

Leskovšek, Vojteh; Godec, Matjaž; Kogej, Peter

2016-01-01

We have investigated the possibility of producing a magnetic encoder by an innovative process. Instead of turning grooves in the encoder bar for precise positioning, we incorporated the information in 304L stainless steel by transforming the austenite to martensite after bar extrusion in liquid nitrogen and marking it with a laser, which caused a local transformation of martensite back into austenite. 304L has an excellent corrosion resistance, but a low hardness and poor wear resistance, which limits its range of applications. However, nitriding is a very promising way to enhance the mechanical and magnetic properties. After low-temperature nitriding at 400 °C it is clear that both ε- and α′-martensite are present in the deformed microstructure, indicating the simultaneous stress-induced and strain-induced transformations of the austenite. The effects of a laser surface treatment and the consequent appearance of a non-magnetic phase due to the α′ → γ transformation were investigated. The EDS maps show a high concentration of nitrogen in the alternating hard surface layers of γN and α′N (expanded austenite and martensite), but no significantly higher concentration of chromium or iron was detected. The high surface hardness of this nitride layer will lead to steels and encoders with better wear and corrosion resistance. PMID:27492862

Comparative study in the induced corrosion by sulfate reducing microorganisms, in a stainless steel 304L sensitized and a carbon steel API X65

International Nuclear Information System (INIS)

Diaz S, A.; Gonzalez F, E.; Arganis J, C.; Luna C, P.; Carapia M, L.

2004-01-01

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)

El acero que nunca se fundió. Una reseña sobre Stalin

Directory of Open Access Journals (Sweden)

Iñaki Oneca Agurruza

2004-02-01

Full Text Available Era el 5 de marzo de 1953 cuando murió el fetiche, el gurú, el símbolo. Stalin significa “acero”, y precisamente una de las cosas que se reprochó al joven revolucionario, tras la adopción de este apodo, era que el acero era duro pero también frío. Así iniciamos esta breve nota sobre la figura de uno de los personajes clave del siglo XX.

Comportamiento a la Corrosión del Acero API X70 Soldado por el Proceso de Doble Arco Sumergido Inmerso en Diferentes Medios Corrosivos

OpenAIRE

Montes, Omar Francisco; Garcés, Rocío Saldaña; Reyes, Felipe A. Reyes; Robledo, Patricia del Carmen Zambrano; López, Francisco H. Estupiñán; Calderón, Facundo Almeraya

2016-01-01

Resumen Los aceros API X70 son aplicados en fabricación y construcción de tuberías para el transporte de hidrocarburos, sin embargo, a un lapso de tiempo se degradan debido al medio ambiente al cual están expuestos; influyendo en la velocidad y tipo de corrosión sobre las superficies del metal base (MB), zona afectada por el calor (ZAC) y zona de fusión (ZF). A fin de conocer y evaluar la susceptibilidad a la corrosión en uniones del acero API X70 sometido a diferentes medios corrosivos, vari...

COMPORTAMIENTO DEL CONCRETO REFORZADO CON FIBRAS DE ACERO ZP-306 SOMETIDO A ESFUERZOS DE COMPRESIÓN

Directory of Open Access Journals (Sweden)

Lina P. Gallo-Arciniegas

2013-01-01

Full Text Available En Colombia, el uso del concreto reforzado con fibras de acero (CRFA es muy limitado, debido a que en el país no existe suficiente evidencia experimental y requisitos reglamentarios al respecto. En el artículo se presentan los resultados de una investigación experimental y analítica sobre el comportamiento del CRFA elaborado con fibras ZP-306, sometidas a esfuerzos de compresión. El estudio involucra la revisión y discusión de los modelos disponibles en la literatura, así como un programa experimental que incluye el ensayo de 48 especímenes. A partir de un análisis de regresión de los datos medidos, se proponen ecuaciones para estimar las principales propiedades mecánicas del CRFA, tales como resistencia a compresión, módulo de elasticidad y relación de Poisson. Las ecuaciones correlacionan las propiedades mecánicas con las principales características de las fibras de acero, tales como dosificación y relación de aspecto.

Fuego y acero

Directory of Open Access Journals (Sweden)

Sfintesco, D.

1965-03-01

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

Corrosión microbiológica en aceros de bajo carbono

OpenAIRE

Medina-Custodio, O; Ortiz-Prado, A; Jacobo-Armendáriz, V.H.; Schouwenaars-Franssens, R

2009-01-01

La corrosión microbiológica es un tipo común 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 tuberías de trasporte de hidrocarburos es favorecida por microorganismos. Las reacciones químicas que sustentan éstos, generan transferencia de iones, lo que justifica el empleo de técnicas electroquímicas para su análisis. En este trabajo, se estudiaron probetas de acero de bajo carbono SAE 1018, sumergidas en un medio n...

Oligo-cyclic damage and behaviour of a 304 L austenitic stainless steel according to environment (vacuum, air, PWR primary water) at 300 C

International Nuclear Information System (INIS)

De Baglion, L.

2011-01-01

Nowadays, for nuclear power plants licensing or operating life extensions, various safety authorities require the consideration of the primary water environment effect on the fatigue life of Pressurized Water Reactor (PWR) components. Thus, this work focused on the study of low cycle fatigue damage kinetics and mechanisms, of a type 304L austenitic stainless steel. Several parameters effects such as temperature, strain rate or strain amplitude were investigated in air as in PWR water. Thanks to targeted in-vacuum tests, the intrinsic influence of these parameters and environments on the fatigue behaviour of the material was studied. It appears that compared with vacuum, air is already an active environment which is responsible for a strong decrease in fatigue lifetime of this steel, especially at 300 C and low strain amplitude. The PWR water coolant environment is more active than air and leads to increased damage kinetics, without any modifications of the initiation sites or propagation modes. Moreover, the decreased fatigue life in PWR water is essentially attributed to an enhancement of both initiation and micropropagation of 'short cracks'. Finally, the deleterious influence of low strain rates on the 304L austenitic stainless steel fatigue lifetime was observed in PWR water environment, in air and also in vacuum without any environmental effects. This intrinsic strain rate effect is attributed to the occurrence of the Dynamic Strain Aging phenomenon which is responsible for a change in deformation modes and for an enhancement of cracks initiation. (author)

12 CFR 304.3 - Reports.

Science.gov (United States)

2010-01-01

... assessments and monitor the condition, performance, and risk profile of individual banks and the banking... insured branches and the banking industry. Insured branches must also submit annually such information on... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Reports. 304.3 Section 304.3 Banks and Banking...

Influence of Size on the Microstructure and Mechanical Properties of an AISI 304L Stainless Steel—A Comparison between Bulk and Fibers

Directory of Open Access Journals (Sweden)

Francisco J. Baldenebro-Lopez

2015-01-01

Full Text Available In this work, the mechanical properties and microstructural features of an AISI 304L stainless steel in two presentations, bulk and fibers, were systematically studied in order to establish the relationship among microstructure, mechanical properties, manufacturing process and effect on sample size. The microstructure was analyzed by XRD, SEM and TEM techniques. The strength, Young’s modulus and elongation of the samples were determined by tensile tests, while the hardness was measured by Vickers microhardness and nanoindentation tests. The materials have been observed to possess different mechanical and microstructural properties, which are compared and discussed.

Ecuaciones constitutivas de la fluencia en caliente de aceros microaleados

Directory of Open Access Journals (Sweden)

Cabrera, J. M.

1998-05-01

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

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

Corrosion testing of a degraded moderator: L-Area Tuff Tanks

International Nuclear Information System (INIS)

Mickalonis, J.I.

2000-01-01

Based on test results, storage of the degraded moderator in 55-gallon 304L drums (0.065 inches thick) would not cause failure by general corrosion for up to 5 plus years storage. Acidic degraded moderator was temporarily stored in Tuff Tanks located in L-area. The moderator characteristics included a D 2 O content of 5.02--5.33%, a pH of 1.25--1.31, a conductivity of 29,300--31,200 m mhos/cm, tritium activity of 114--141 m Ci/mL, and levels of approximately 6,000 ppm for chloride and 500 ppm for chromium. The compatibility of the degraded with AISI Type 304L stainless steel (304L) was investigated in this study. Following ASTM standard practice, coupon immersion tests were conducted in both treated and untreated moderator. Treatment included the addition of either a 40 wt % NaOH solution, distilled water to serially dilute the chloride, or concentrated nitric acid to increase the nitrate concentration. Type 304L stainless steel exposed to the Tuff Tank moderator was found from these tests to: have a general corrosion rate of less than 5 mils per year (mpy) for 304L plate, which bounds that of the 304L storage drum, passivate at chloride concentrations up to 5,000 ppm for 304L sheet, resist corrosion for nitrate/chloride ratios ranging from 0.1 to 1,000, and be susceptible to crevice corrosion. Based on these test results, storage of the degraded moderator in 55-gallon 304L drums (0.065 inch thick) would not cause failure by general corrosion for up to 5+ years storage. The chloride concentration, [Cl], in the degraded moderator has been measured up to 6000 ppm. The potential or risk for aggressive localized attack of 304L increases with [Cl] concentration. A qualitative range is as follows: [Cl minus ] minus ] minus ] < 600 ppm, reasonable resistance, medium risk. The degraded moderator should be treated to reduce the chloride concentration to reduce the potential for localized corrosion and the risk for a leakage failure of the drum. A good practice would be to

Estudio de inteligencia de mercados para la importación de tubería de acero carbón para PSA Colombia S.A.S.

OpenAIRE

2012-01-01

Estudio de inteligencia de mercados para la importación de tuberia de acero carbon para PSA Colombia S.A.S, SCH 40 de 2" revisar la viabilidad de la compra local versus la compra en el exterior analizando tres proveedores Estados Unidos, China y Brasil. En el presente trabajo se estudian los mercados para la importación de tubería de Acero Carbón SCH40, se realiza el análisis de cada área del proceso de comercialización y se establece en términos técnicos, comerciales, financieros, logísticos...

ESTUDIO DE LA PROTECCIÓN ANTICORROSIVA SOBRE ACERO DE BAJO CARBONO MEDIANTE TRATAMIENTO DE CONVERSIÓN QUÍMICA BASE CERIO COMO PREPARACIÓN DE SUPERFICIE

OpenAIRE

MATA GALLARDO, LUIS JAIME

2014-01-01

En este trabajo, se propone un tratamiento de conversión química base cerio sobre acero de bajo carbono para obtener un incremento en las propiedades de protección y ser utilizado como una preparación de superficie para un pintado posterior. El nitrato de cerio fue elegido como precursor y se utilizaron tres métodos para la obtención de películas sobre la superficie de acero al carbono. Las películas son formadas utilizando o no el H2O2, sin embargo, el papel del H2O2 es el de ...

48 CFR 47.304 - Determination of delivery terms.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Determination of delivery terms. 47.304 Section 47.304 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.304 Determination of delivery...

Study of inclusions and segregation in metals by autoradiography; Etude autoradiographic des inclusions et de la segregation dans les metaux; Izuchenie primesej i usadki metalla s pomoshch'yu avtoradiografii; Estudio autoradiografico de las inclusiones y de la segregacion en los metales

Energy Technology Data Exchange (ETDEWEB)

Makin, S M [Wantage Research Laboratory, Wantage, Berks (United Kingdom)

1962-01-15

Three applications of radioisotope techniques to metallurgy are described. During the course of this work, new autoradiographic techniques are developed. These include the irradiation and autoradiography of extraction replicas, similar to those used in electron microscopy, and a two-colour dye-transfer process in which colour prints of autoradiographs are shown with the corresponding micrographs superposed. These methods are applied to the study of inclusions in steel and uranium and to an investigation of the segregation of sulphur and phosphorus in welds in stainless steel. (author) [French] Le memoire decrit trois applications des radioisotopes en metallurgie. Au cours de ces travaux, l'auteur a mis au point de nouvelles techniques d'autoradiographie. Celles-ci comportent l'irradiation d'empreintes pour autoradiographie et d'empreintes d'extraction, semblables a celles qui sont employees dans la microscopie electronique, et font appel a un procede de transfert en deux couleurs dans lequel on superpose des autoradiographies en couleur et les microphotographies correspondantes. Ces methodes sont appliquees a l'etude des inclusions dans l'acier et l'uranium ainsi qu'aux recherches sur la segregation du soufre et du phosphore dans les pieces soudees en acier inoxydable. (author) [Spanish] Se describen tres aplicaciones de las tecnicas de los radioisotopes en la metalurgia. En el curso de los experimentos se han perfeccionado nuevas tecnicas autorradiograficas, que comprenden la irradiacion de replicas de autorradiografia y extraccion, analogas a las utilizadas en la microscopia electronica y un procedimiento de impresion a dos colores que permite obtener autorradiografias superpuestas a las correspondientes micrografias. Estos metodos se aplican al estudio de inclusiones en el acero y el uranio y a una investigacion de la segregacion del azufre y del fosforo en soldaduras hechas en acero inoxidable. (author) [Russian] Daetsya opisanie trekh sposobov primeneniya

Correlation of radiation-induced changes in microstructure/microchemistry, density and thermo-electric power of type 304L and 316 stainless steels irradiated in the Phénix reactor

Energy Technology Data Exchange (ETDEWEB)

Renault Laborne, Alexandra, E-mail: alexandra.renault@cea.fr [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France); Gavoille, Pierre [CEA, DEN, SEMI, F-91191 Gif-sur-Yvette (France); Malaplate, Joël [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France); Pokor, Cédric [EDF R& D, MMC, Site des Renardières, F-77818 Morêt-sur-Loing cedex (France); Tanguy, Benoît [CEA, DEN, SEMI, F-91191 Gif-sur-Yvette (France)

2015-05-15

Annealed specimens of type 304L and 316 stainless steel and cold-worked 316 specimens were irradiated in the Phénix reactor in the temperature range 381–394 °C and to different damage doses up to 39 dpa. The microstructure and microchemistry of both 304L and 316 have been examined using the combination of the different techniques of TEM to establish the void swelling and precipitation behavior under neutron irradiation. TEM observations are compared with results of measurements of immersion density and thermo-electric power obtained on the same irradiated stainless steels. The similarities and differences in their behavior on different scales are used to understand the factors in terms of the chemical composition and metallurgical state of steels, affecting the precipitation under irradiation and the swelling behavior. Irradiation induces the formation of some precipitate phases (e.g., M{sub 6}C and M{sub 23}C{sub 6}-type carbides, and γ’- and G-phases), Frank loops and cavities. According to the metallurgical state and chemical composition of the steel, the amount of each type of radiation-induced defects is not the same, affecting their density and thermo-electric power.

Correlation of radiation-induced changes in microstructure/microchemistry, density and thermo-electric power of type 304L and 316 stainless steels irradiated in the Phénix reactor

Science.gov (United States)

Renault Laborne, Alexandra; Gavoille, Pierre; Malaplate, Joël; Pokor, Cédric; Tanguy, Benoît

2015-05-01

Annealed specimens of type 304L and 316 stainless steel and cold-worked 316 specimens were irradiated in the Phénix reactor in the temperature range 381-394 °C and to different damage doses up to 39 dpa. The microstructure and microchemistry of both 304L and 316 have been examined using the combination of the different techniques of TEM to establish the void swelling and precipitation behavior under neutron irradiation. TEM observations are compared with results of measurements of immersion density and thermo-electric power obtained on the same irradiated stainless steels. The similarities and differences in their behavior on different scales are used to understand the factors in terms of the chemical composition and metallurgical state of steels, affecting the precipitation under irradiation and the swelling behavior. Irradiation induces the formation of some precipitate phases (e.g., M6C and M23C6-type carbides, and γ'- and G-phases), Frank loops and cavities. According to the metallurgical state and chemical composition of the steel, the amount of each type of radiation-induced defects is not the same, affecting their density and thermo-electric power.

Correlation of radiation-induced changes in microstructure/microchemistry, density and thermo-electric power of type 304L and 316 stainless steels irradiated in the Phénix reactor

International Nuclear Information System (INIS)

Renault Laborne, Alexandra; Gavoille, Pierre; Malaplate, Joël; Pokor, Cédric; Tanguy, Benoît

2015-01-01

Annealed specimens of type 304L and 316 stainless steel and cold-worked 316 specimens were irradiated in the Phénix reactor in the temperature range 381–394 °C and to different damage doses up to 39 dpa. The microstructure and microchemistry of both 304L and 316 have been examined using the combination of the different techniques of TEM to establish the void swelling and precipitation behavior under neutron irradiation. TEM observations are compared with results of measurements of immersion density and thermo-electric power obtained on the same irradiated stainless steels. The similarities and differences in their behavior on different scales are used to understand the factors in terms of the chemical composition and metallurgical state of steels, affecting the precipitation under irradiation and the swelling behavior. Irradiation induces the formation of some precipitate phases (e.g., M 6 C and M 23 C 6 -type carbides, and γ’- and G-phases), Frank loops and cavities. According to the metallurgical state and chemical composition of the steel, the amount of each type of radiation-induced defects is not the same, affecting their density and thermo-electric power

Producción de aceros al carbono en hornos de arco eléctrico en condiciones de mineral de manganeso.

Directory of Open Access Journals (Sweden)

E. E. Navas Medina

2007-05-01

Full Text Available El presente trabajo constituye una segunda etapa de investigación relacionada con la producción de acero en hornos de arco eléctrico con revestimiento básico en condiciones de utilización de mineral de manganeso como sustituto del ferro-manganeso. En la investigación se caracteriza el acero producido utilizando el mineral de manganeso en dos variantes tecnológicas diferentes y se determinan parámetros importantes, tales como la estructura del acero obtenido, la influencia de la composición química y la temperatura en la reducción del Mn. Adicionalmente, se determina la composición química de la escoria, su basicidad e influencia en el aprovechamiento del Mn del mineral, así como, lo que significa la sustitución del FeMn en la problemática medioambiental. This present work constitutes the second stage of investigation in relation with the steel production by means of electric arc furnaces in the condition of use of manganese ores as a substitute of the ferromanganese. In the investigation, the steel manufactured is analyzed the manganese ore in two different technological variants and some important parameters are determined such as: the chemical composition's structure of the steel, the influence of temperature in the reduction of Mn. Moreover, an analysis of the chemical composition of the slag and the influence in the environmental is realized.

Estudio de la resistencia a la abrasión de capas vitrocerámicas depositadas sobre acero

Directory of Open Access Journals (Sweden)

Gómez de Salazar, J. M.

2002-12-01

Full Text Available Wear test has been completed on two types of layered materials: a non-reinforced enamel plate and a ceramic reinforced enamel plate. The latter has been tested in two forms: with 10 wt. % and 20 wt. % ceramic particles reinforcement. For comparison the same test has also been completed on polished steel. Wear resistance was measure using a tribometer, equipped with a chromium steel sphere of 6 mm diameter. The sphere-plate surface contact area increases with distance covered, which in the polished steel provokes exponential increments in wear values. This exponential behaviour was not observed in the enamel plates due to their greater wear resistance. The reinforcement of the enamel plates with ceramic particles increases the wear resistance. A higher percentage of ceramic reinforcement results in a greater wear resistance of the plates.

Se han realizado ensayos de desgaste, tanto en placas esmaltadas sin refuerzo como en esmaltes con distinto porcentaje de carga cerámica (10 y 20% en peso, y se han comparado frente al del acero base pulido. Las medidas de resistencia a la abrasión se han obtenido utilizado un tribómetro con bola de acero al cromo de 6 mm de diámetro. El aumento de la superficie de contacto bola-placa a medida que aumenta la distancia recorrida, provoca aumentos exponenciales en los desgastes en el caso del acero pulido. Sin embargo, en el caso de las chapas esmaltadas no se observa este comportamiento, debido a la mayor resistencia al desgaste de las mismas. Cuando las capas esmaltadas están reforzadas con cargas cerámicas, la resistencia al desgaste aumenta con el porcentaje de refuerzo cerámico.

Analysis of martensitic transformation and residual tension in an 304L stainless steel

International Nuclear Information System (INIS)

Alves, Juciane Maria

2014-01-01

The relationship between plastic deformation and the strain induced phase transformation, that provides a practical route to the development of new engineering materials with excellent mechanical properties, characterize the TRIP effect 'Transformation Induced Plasticity'. Among the stainless steels, the metastable 304 L austenitic steel is susceptible to transformation of austenite-martensite phase from tensile tests at room temperature by increments of plastic deformation. It is of great technological and scientific interest the knowledge of the evolution of phase transformation and residual stress from different levels and rates of plastic deformation imposed to the material. It is also important to evaluate the interference of metallographic preparation in quantitative analyzes of this steel. The main techniques used in this study consisted of X-rays diffraction and Ferritoscopy for the quantitation phase, and XRD to residual stress analysis also. As observed, the phase transformation quantification has not suffered significant influence of the metallographic preparation and evolved from increments of plastic deformation due to different stop charges and strain rates, leading to a further strengthening of the austenite matrix. The evaluation of residual stress resulting from the martensitic transformation was susceptible to the metallographic preparation and increased its value on comparison to sample without metallographic preparation. It was also observed that the residual stress decreased with the increase of the fraction of transformed martensite. (author)

7 CFR 22.304 - Multiyear planning and programming.

Science.gov (United States)

2010-01-01

... 7 Agriculture 1 2010-01-01 2010-01-01 false Multiyear planning and programming. 22.304 Section 22.304 Agriculture Office of the Secretary of Agriculture RURAL DEVELOPMENT COORDINATION Roles and Responsibilities of State Governments § 22.304 Multiyear planning and programming. State and multicounty...

48 CFR 11.304 - Contract clause.

Science.gov (United States)

2010-10-01

... Section 11.304 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Acceptable Material 11.304 Contract clause. Insert the clause at 52.211-5, Material Requirements, in solicitations and contracts for supplies that are not commercial items. ...

Estudio del daño por hidrógeno en uniones soldadas de un acero API 5L X52

Directory of Open Access Journals (Sweden)

Réquiz, R.

2008-04-01

Full Text Available The main objective of the present investigation was to study the susceptibility to hydrogen damage on a type API 5L X52 steel welded by electrical resistance. Several techniques, such as hydrogen permeation and cathodic charging were used. The metallic material was characterized using SEM and TEM. The base metal microstructure was very similar to that one corresponding to the welded area. This microstructure was mainly comprised by ferrite and perlite, differing only in the grain size. Therefore, the susceptibility to hydrogen damage was similar in both cases. It is worth mentioning that the welded area has very small dimensions. Indeed, the fusion zone is only 5 mm wide while the heat affected zone is 1 mm wide. The hydrogen damage observed was mainly in the form of blisters, which were associated to the presence of aluminum rich inclusions. Also, it was noticed partial inclusion dissolution and some matrix attack adjacent to the inclusions.

En la presente investigación se estudió la susceptibilidad al daño por hidrógeno en un acero API 5L X52 soldado por resistencia eléctrica. Para ello, se emplearon técnicas de permeación y de carga catódica de hidrógeno. El material fue caracterizado mediante microscopía electrónica de barrido y de transmisión. La susceptibilidad al daño por hidrógeno fue similar tanto en el metal base como en el cordón de soldadura. Este comportamiento se vincula a la microestructura homogénea constituida por perlita y ferrita, que presentan ambos, aun cuando existen diferencias en el tamaño de grano. El cordón de soldadura tenía dimensiones muy pequeñas, donde la zona de fusión y la afectada por el calor poseen espesores de 5 mm y 1 mm, respectivamente. El daño inducido por hidrógeno se presentó en forma de ampollas en la superficie del material, asociado, principalmente, a la presencia de inclusiones globulares y semiglobulares ricas en aluminio. Además, se manifestó una disoluci

Comportamiento termomecánico de un acero microaleado al Nb-V

OpenAIRE

Cartaya, E. A.; Varela, G.; Cabrera Marrero, José M.; Prado Pozuelo, José Manuel

2012-01-01

Empleando ensayos de compresión simple en ca- liente y relajación de tensiones después de la de - formación en un dilatómetro modelo DIL805T, se obtuvieron las curvas de fluencia y relajación de dos aceros, el primero de ellos al C – Mn y otro HS- LA con idéntica composición química base, micro- aleado con Nb – V. Los ensayos de compresión simple fueron efectua- dos a temperaturas en el rango austenítico, desde 900 – 1.200 ºC y velocidades de deformación de 0....

Response to annealing and reirradiation of AISI 304L stainless steel following initial high-dose neutron irradiation in EBR-II

International Nuclear Information System (INIS)

Porter, D.L.; McVay, G.L.; Walters, L.C.

1980-01-01

The object of this study was to measure the stability of irradiation-induced microstructure upon annealing and, by selectively annealing out some of these features and reirradiating the material, it was expected that information could be gained concerning the role of microstructural changes in the void swelling process. Transmission electron microscopic examinations of isochronally annealed (200 to 1050 0 C) AISI 304L stainless steel, which had been irradiated at approximately 415 0 C to a fast (E > 0.1 MeV) neutron fluence of approximately 5.1 x 10 26 n/m 2 , verified that the two-stage hardness recovery with temperatures was related to a low temperature annealing of dislocation structures and a higher temperature annealing of voids and solute redistribution

Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments.

Science.gov (United States)

Sun, C; Zheng, S; Wei, C C; Wu, Y; Shao, L; Yang, Y; Hartwig, K T; Maloy, S A; Zinkle, S J; Allen, T R; Wang, H; Zhang, X

2015-01-15

Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304 L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500 °C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M(23)C(6) precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

Low cycle fatigue: high cycle fatigue damage accumulation in a 304L austenitic stainless steel

International Nuclear Information System (INIS)

Lehericy, Y.

2007-05-01

The aim of this study was to evaluate the consequences of a Low Cycle Fatigue pre-damage on the subsequent fatigue limit of a 304L stainless steel. The effects of hardening and severe roughness (grinding) have also been investigated. In a first set of tests, the evolution of the surface damage induced by the different LCF pre-cycling was characterized. This has permitted to identify mechanisms and kinetics of damage in the plastic domain for different surface conditions. Then, pre-damaged samples were tested in the High Cycle Fatigue domain in order to establish the fatigue limits associated with each level of pre-damage. Results evidence that, in the case of polished samples, an important number of cycles is required to initiate surface cracks ant then to affect the fatigue limit of the material but, in the case of ground samples, a few number of cycles is sufficient to initiate cracks and to critically decrease the fatigue limit. The fatigue limit of pre-damaged samples can be estimated using the stress intensity factor threshold. Moreover, this detrimental effect of severe surface conditions is enhanced when fatigue tests are performed under a positive mean stress (author)

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

International Nuclear Information System (INIS)

Diaz S, A.; Fuentes C, P.; Merino C, F.; Castano M, V.

2006-01-01

Crevice growth velocities in samples of AISI 304L stainless steel thermally welded and sensitized were obtained by the Rising displacement method or of growing displacement. It was used a recirculation circuit in where the operation conditions of a BWR type reactor were simulated (temperature of 288 C and a pressure of 8 MPa) with the chemistry modified by the addition of hydrogen with and without the addition of impurities of a powerful oxidizer like the Cu ++ 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)

Aceros para embutido profundo: fabricación, caracterización, microestructura y texturas

Directory of Open Access Journals (Sweden)

Sipos, K.

2005-12-01

las curvas de deformación límite permite a las empresas que producen piezas de diseños particulares evaluar sus diseños y la conveniencia o no del uso de diferentes tipos de aceros para su fabricación. Se muestra como ejemplo el caso de cubiertas de enceradoras.

13 CFR 304.4 - Performance evaluations.

Science.gov (United States)

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Performance evaluations. 304.4... ECONOMIC DEVELOPMENT DISTRICTS § 304.4 Performance evaluations. (a) EDA shall evaluate the management... of at least one (1) other District Organization in the performance evaluation on a cost-reimbursement...

48 CFR 1427.304-1 - General.

Science.gov (United States)

2010-10-01

... Solicitor for the General Law Division shall issue a final determination, after consideration of any further... Section 1427.304-1 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Patent Rights Under Government Contracts. 1427.304-1 General. (a)(1...

9 CFR 319.304 - Meat stews.

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2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Meat stews. 319.304 Section 319.304... ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Canned, Frozen, or Dehydrated Meat Food...

5 CFR 845.304 - Financial hardship.

Science.gov (United States)

2010-01-01

...) Considerations. Some pertinent considerations in determining whether recovery would cause financial hardship are... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Financial hardship. 845.304 Section 845....304 Financial hardship. Financial hardship may be deemed to exist in, but not limited to, those...

5 CFR 304.104 - Determining rate of pay.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Determining rate of pay. 304.104 Section... CONSULTANT APPOINTMENTS § 304.104 Determining rate of pay. (a) The rate of basic pay for experts and... appropriate rate of basic pay on an hourly or daily basis, subject to the limitations described in section 304...

Corrosion study of stainless steel SS304L in molten molybdates

Energy Technology Data Exchange (ETDEWEB)

Usami, T., E-mail: tusami@criepi.denken.or.jp [Central Research Institute of Electric Power Industry, Iwadokita2-11-1, Komae-shi, Tokyo 201-8511 (Japan); Uruga, K.; Tsukada, T. [Central Research Institute of Electric Power Industry, Iwadokita2-11-1, Komae-shi, Tokyo 201-8511 (Japan); Miura, Y.; Komamine, S.; Ochi, E. [Japan Nuclear Fuel Limited, 4-108, Aza Okitsuke, Oaza Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan)

2016-04-01

Depending on operating conditions of the vitrification process of high-level liquid waste, molten salt mainly composed of sodium and molybdenum can be generated, and poured into stainless steel canisters. In this work, the possible reaction between the molten molybdate and stainless steel was investigated using multi-component molybdate and simple Na{sub 2}MoO{sub 4} – MoO{sub 3} molybdate. In the experiments using multi-component molybdates, no significant reaction is observed between the mixed molybdates and the stainless steel specimens at 700 °C in 4 h. The reaction rate of the stainless steel with the multi-component molybdate increases in proportion to exp(-1/T). The depth of the most reacted area is about 300 μm even at 1000 °C, and was much smaller than the 6 mm thickness of the canister. In the simple Na{sub 2}MoO{sub 4} – MoO{sub 3} molybdate, the reaction rate was proportional to the MoO{sub 3} concentration. The essence of the reaction is oxidation of metals by Mo{sup 6+} - > Mo{sup 4+}. Part of the reaction product mainly composed of Fe is dissolved into the molybdate, while the other part mainly composed of Cr sloughs and forms a banded layer. - Highlights: • The reaction yield of SS304L with molten molybdate was negligible at 700 °C in 4 h. • The corrosion rate increased in proportion to exp (-1/T). • The corrosion rate was proportional to MoO{sub 3} concentration in Na{sub 2}MoO{sub 4}–MoO{sub 3} mixture. • The essence of the reaction was oxidation of metals by Mo{sup 6+} –> Mo{sup 4+}.

31 CFR 596.304 - Financial transaction.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Financial transaction. 596.304 Section 596.304 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... term includes: (a) A transaction which in any way or degree affects interstate or foreign commerce; (1...

17 CFR 229.304 - (Item 304) Changes in and disagreements with accountants on accounting and financial disclosure.

Science.gov (United States)

2010-04-01

... disagreements with accountants on accounting and financial disclosure. 229.304 Section 229.304 Commodity and... accounting and financial disclosure. (a)(1) If during the registrant's two most recent fiscal years or any... any matter of accounting principles or practices, financial statement disclosure, or auditing scope or...

Acero de alto silicio producido por inmersión en Al-Si y recocido de difusión

Directory of Open Access Journals (Sweden)

Ros-Yáñez, Tanya

2000-10-01

Full Text Available It is difficult to process steel sheet with a high Si content (>3.5%Si, mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a "hot-dip simulator" using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that:

• intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram
• with a double dipping primary silicon crystals are formed in the surface layer
• the ordered DO₃ structure is present if the dipping and/or diffusion time is long enough
• homogeneous silicon gradients in the whole substrate thickness have not yet been achieved
• theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour

Estudio para la optimización de la composición de un HACFRA (hormigón autocompactante reforzado con fibras de acero estructural

Directory of Open Access Journals (Sweden)

Orbe, A.

2015-03-01

Full Text Available The interest of HACFRA (self compacting concrete reinforced with steel fibers, is the combination of the residual strength increase and cracking decrease compared to plain concrete by the introduction of steel fibers in the mass with the advantages of the self-compacting. The paper presents an analysis of the influence of different components of the HACRFA and provides their selection, refered to the granular skeleton and to different steel fiber types and amount, in order to obtain an optimization of its features and structural behavior.El interés de un HACFRA (Hormigón autocompactante reforzado con fibras de acero, radica en la combinación del incremento de capacidad resistente con respecto al hormigón y disminución de la fisuración, aportada por la introducción de fibras de acero, con las ventajas de la puesta en obra que supone la autocompactación. El artículo analiza la influencia de los diferentes componentes que integran el HACRFA, proponiendo una selección de los mismos, referidos tanto al esqueleto granular como a los diferentes tipos y densidades de fibras de acero, en base a la obtención de sus características y de un comportamiento estructural optimizado.

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-07-01

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

Influence of surface conditions on fatigue strength through the numerical simulation of microstructure; Etude par simulation numerique de la microstructure de l'influence de l'etat de surface sur la resistance a la fatigue d'un acier 304L

Energy Technology Data Exchange (ETDEWEB)

Le Pecheur, A.; Clavel, M.; Rey, C.; Bompard, P. [Laboratoire MSSMat, UMR 8579 CNRS, Ecole Centrale Paris (France); Le Pecheur, A.; Curtit, F.; Stephan, J.M. [Departement MMC, EDF RD, Site des Renardieres (France)

2010-11-15

A thermal fatigue test (INTHERPOL) was developed by EDF in order to study the initiation of cracks. These tests are carried out on tubular specimens under various thermal loadings and surface finish qualities in order to give an account of these parameters on crack initiation. The main topic of this study is to test the sensitivity of different fatigue criteria to surface conditions using a micro/macro modelling approach. Therefore a 304L polycrystalline aggregate, used for cyclic plasticity based FE modelling, have been considered as a Representative Volume Element located at the surface and subsurface of the test tube. This aggregate has been cyclically strained according to the results issued from FE simulation of INTHERPOL thermal fatigue experiment. Different surface parameters have been numerically simulated: effects of local microstructure and of grains orientation, effects of machining: metallurgical prehardening, residual stress gradient, and surface roughness. Three different fatigue criteria (Manson Coffin, Fatemi Socie and dissipated energy types), previously fitted at a macro-scale for thermal fatigue of 304L, have been computed at a meso scale, in order to show the surface 'hot spots' features and test the sensitivity of these three criteria to different surface conditions. Results show that grain orientation and neighbouring play an important role on the location of hot spots, and also that the positive effect of pre-straining and the negative effect of roughness on fatigue life are not all similarly predicted by these different fatigue criteria. (authors)

47 CFR 80.304 - Watch requirement during silence periods.

Science.gov (United States)

2010-10-01

....304 Section 80.304 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Safety Watch Requirements and Procedures Ship Station Safety Watches § 80.304 Watch requirement during silence periods. Each ship station operating on...

Modificación superficial de aceros y hierros fundidos mediante láser de Nd: YAG. // Steels and cast irons superficial modification by means of laser Nd: YAG.

Directory of Open Access Journals (Sweden)

R. Sagaró Z.

2001-10-01

Full Text Available Se presentan los resultados de los autores en el tratamiento térmico superficial con técnica láser (TTSL. Con el empleo deun láser de Nd: YAG se procedió al endurecimiento superficial de los aceros AISI 1045, W1, W112 y hierros fundidos detipo laminar y nodular. Los autores prestan atención a las rutas de endurecimiento superficial atendiendo a los parámetrosoperacionales del láser: potencia incidente en la zona de interacción (P y la velocidad de barrido del haz de láser (V. Deigual forma se establecen valoraciones acerca de las estructuras metalográficas obtenidas. En todos los casos se reportanvalores de microdureza Vickers que oscilan entre los 500-900 HV (incrementos de 3-4 veces respecto al substratooriginal. Los resultados obtenidos permiten establecer en todos los casos experimentados que el incremento de lavelocidad de barrido provocó una disminución de la profundidad de la capa endurecida. Las experiencias del TTSL en losaceros ensayados muestran una tendencia a la disminución de la profundidad del endurecimiento con el incremento delcontenido de carbono.Palabras claves: Endurecimiento superficial, parámetros de operación de láser., microdureza, profundidadde capa endurecida, de fallo, vibraciones.____________________________________________________________________________AbstractThis paper expose the experiences of researchers on the laser surface heat treatment. The hardening of AISI 1045, W1,W112 steels and cast irons flake and nodular was carried out by using a Nd: YAG laser. Operation parameters of laser, likebeam power (P and traverse speed of the laser spot (V are closely with hardening depth . Authors present some analysesabout metallographic studies. In all cases are reported Vickers microhardness about 500-900 HV (three or four times higherthan original substrates. Relations between microhardness and depth of hardening are presented for the processedmaterials. Experimental results showed that the increased

“Corrosión Inducida por Bacterias Sulfato Reductoras Termófilas de 60°C en la Unión Soldada del Acero API 5L- X60.”

OpenAIRE

Romero Romero, Justo Román

2012-01-01

En esta investigación se estudio el efecto de la corrosión inducida por Bacterias Sulfato Reductoras (BSR) termófilas a 60oC en el metal base (MB) y la unión soldada (US) del acero API X-60. Las bacterias sulfato reductoras fueron aisladas en el medio sólido postgate con la técnica de estriado, y fueron resembradas hasta obtener la misma morfología. El medio postgate fue seleccionado entre otros medios de cultivo, por el óptimo crecimiento que presento la BSR. Se preparar...

La fatiga en las barras de acero corrugado para refuerzo de hormigón

OpenAIRE

Avila Kildal, Francisco

2003-01-01

Para conseguir aprovechar los recursos que la sociedad invierte en infraestructuras de manera óptima es imprescindible, para la ingeniería civil, un buen conocimiento de los materiales y de sus propiedades. Partiendo de esta premisa, el objetivo de esta tesina es aportar conocimiento a la caracterización de las barras de acero corrugado para refuerzo de hormigón en su funcionamiento frente a la fatiga. Definimos fatiga como la alteración mecánica de los materiales bajo el ef...

Influence of substrate bias voltage on the properties of TiO2 deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

International Nuclear Information System (INIS)

Bait, L.; Azzouz, L.; Madaoui, N.; Saoula, N.

2017-01-01

Highlights: • TiO 2 films were deposited on stainless steel 304L RF magnetron sputtering at different substrate bias. • The hardness of TiO 2 coated 304L are higher than those obtained for uncoated substrate. • TiO 2 films provide good protection for stainless steel against corrosion in Ringer solution. - Abstract: The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to −100 V, on the structure and properties of the TiO 2 thin films for biomaterials applications. The TiO 2 films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O 2 gas mixture. The variation of substrate bias voltage from 0 to −100 V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO 2 films sliding against alumina ball in air were investigated. Experimental results showed that the thickness increases for non-biased substrate voltage to Vs = −100 V from 820 nm to 1936 nm respectively. The roughness is in the range of 50 nm and 14 nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0–50 V). The hardness significantly increased from 2.2 to 6.4 GPa when the bias voltage was increased from 0 to 75 V and then slightly decrease to 5.1 GPa as further increased to 100 V. At the same time, the results indicate that TiO 2 films deposited at −100 V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH = 6.3), thermostatically controlled at 37 °C, was used as the electrolyte for the study of the electrochemical properties

40 CFR 63.304 - Standards for compliance date extension.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for compliance date extension. 63.304 Section 63.304 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... National Emission Standards for Coke Oven Batteries § 63.304 Standards for compliance date extension. (a...

42 CFR 495.304 - Medicaid provider scope and eligibility.

Science.gov (United States)

2010-10-01

... 42 Public Health 5 2010-10-01 2010-10-01 false Medicaid provider scope and eligibility. 495.304 Section 495.304 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... INCENTIVE PROGRAM Requirements Specific to the Medicaid Program § 495.304 Medicaid provider scope and...

Investigation of high temperature corrosion behavior on 304L austenite stainless steel in corrosive environments

Energy Technology Data Exchange (ETDEWEB)

Sahri, M. I.; Othman, N. K.; Samsu, Z.; Daud, A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia)

2014-09-03

In this work, 304L stainless steel samples were exposed at 700 °C for 10hrs in different corrosive environments; dry oxygen, molten salt, and molten salt + dry oxygen. The corrosion behavior of samples was analyzed using weight change measurement technique, optical microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The existence phases of corroded sample were determined using X-ray Diffraction (XRD). The lowest corrosion rate was recorded in dry oxygen while the highest was in molten salt + dry oxygen environments with the value of 0.0062 mg/cm{sup 2} and −13.5225 mg/cm{sup 2} respectively. The surface morphology of sample in presence of salt mixture showed scale spallation. Oxide scales of Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3} were the main phases developed and detected by XRD technique. Cr{sub 2}O{sub 3} was not developed in every sample as protective layers but chromate-rich oxide was developed. The cross-section analysis found the oxide scales were in porous, thick and non-adherent that would not an effective barrier to prevent from further degradation of alloy. EDX analysis also showed the Cr-element was low compared to Fe-element at the oxide scale region.

Iodine-131 production by a dry method using reactor-irradiated elementary tellurium. Part 1 - Conditions for obtaining iodine emanation and its capture. Part 2 - comparative study of preparation conditions using Pyrex, stainless steel and alumina equipment. Part 3 - production on a semi-industrial scale; Production de l'iode 131 par voie seche a partir de tellure elementaire irradie a la pile. 1ere partie - Etudes des conditions pour obtenir l'emanation de l'iode et le capter. 2eme partie - Etude comparee des conditions pour effectuer cette preparation avec des appareils en Pyrex, en acier inoxydable et en alumine. 3eme partie - production a l'echelle semi-industrielle

Energy Technology Data Exchange (ETDEWEB)

Bardy, A; Beydon, J; Murthy, T S; Doyen, J B; Lefrancois, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-04-15

A previous report has described how iodine 131 can be prepared from elementary tellurium by a dry method which consists in treating irradiated tellurium at 400 degrees in argon. The possibility of carrying out this treatment in a stainless steel or alumina apparatus has been considered. The behavior of gaseous iodine 131 towards these materials has thus been studied. If the adsorption of iodine on stainless steel is superficial desorption is rapid at 250 degrees in oxygen or 400 degrees in argon. If the adsorption is chemical in nature it becomes necessary to heat to higher temperatures. Adsorption of iodine on alumina is very weak and the iodine can be desorbed rapidly. With these materials tests have been carried out on 300 gms of tellurium containing 41 curies of iodine 131; the yields were very satisfactory ( 98 per cent). (author) [French] La methode de preparation de l iode 131 par voie seche a partir de tellure elementaire decrite dans un precedent rapport consiste a traiter le tellure irradie a 400 degres sous argon. Nous avons examine la possibilite d effectuer ce traitement dans un appareil en acier inoxidable ou en alumine. Le comportement de l iode 131 gazeux vis a vis de ces materiaux a donc ete etudie. Si l adsorption de l iode sur l acier inoxidable est superficielle la desorption est rapide a 250 degres sous oxygene ou 400 degres sous argon. Si la fixation est de nature chimique il est necessaire de chauffer a des temperatures plus elevees. L adsorption de l iode sur l alumine est res faible et l iode peut etre desorbe rapideemnt. En employant ces materiaux des essais ont ete obtenus sur 300 g de tellure contenant 41 curies d iode 131 avec un bon rendement (98 pour cent). (auteur00.

41 CFR 101-26.304 - Substitution policy.

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Substitution policy. 101-26.304 Section 101-26.304 Public Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 26-PROCUREMENT SOURCES AND...

Design, Fabrication and Performance of Boron-Carbide Control Elements; Conception, Fabrication et Comportement de Lames de Commande en Carbure de Bore; Raschety, izgotovlenie i kharakteristiki reguliruyushchikh sterzhnej. Iz karbida Bora; Proyecto, Elaboracion y Rendimiento de Elementos de Control de Carburo de Boro

Energy Technology Data Exchange (ETDEWEB)

Brammer, H. A.; Jacobson, J. [General Electric Company, San Jose, CA (United States)

1964-06-15

compartiments independants par tassement sur des supports spheriques situes a l'interieur des tubes. Les auteurs etudient la mise au point et l'utilisation des lames de commande en carbure de bore sous les cinq rubriques suivantes: 1. Apercu de l'experience acquise avec l'acier au bore et raisons de son remplacement par du carbure de bore. 2. Etudes de la lame en carbure de bore depuis le debut des experiences de mise au point, y compris les premieres mesures effectuees dans le cadre du ' Programme de mise au point de materiaux pour barres de controle' de la CEA au Laboratoire atomique de Vallecitos, et description de la configuration definitive de la lame de controle. 3. Fabrication des lames et methodes de controle de la qualite. 4. Resultats des essais confirmatoires avant mise en service (essais mecaniques et essais de reactivites). 5. Experience apres mise en service, y compris les resultats d'essais mecaniques et d'essais'de reactivites effectues apres deux annees d'utilisation dans le reacteur. (author) [Spanish] En abril de 1961 se comenzo a utilizar en los reactores de agua hirviente un nuevo modelo de elemento de control de carburo de boro (B{sub 4}C) en tubos de acero inoxidable. Desde entonces, este elemento se ha convertido en el elemento de control normal de referencia en los reactores de agua hirviente de la General Electric, y ha sustituido a las placas de acero inoxidable con 2% de boro que se utilizaban con anterioridad. Los nuevos elementos consisten en pequenos tubos verticales de acero inoxidable, dispuestos de manera cruciforme,, con un revestimiento, que estan llenos de polvo de carburo de boro compactado. El polvo de carburo de boro queda confinado longitudinalmente en varios compartimentos independientes estampandolo sobre bolas de acero de cojinetes situadas en el interior de los tubos. La memoria discute en cinco fases el perfeccionamiento, y el empleo de las barras de control de carburo de boro. 1. Resumen de los experimentos realizados con placas de

Um novo fio de aço inoxidável para aplicações ortodônticas A new stainless steel wire for orthodontic purposes

Directory of Open Access Journals (Sweden)

André Itman Filho

2011-08-01

Full Text Available OBJETIVO: desenvolver uma metodologia para fabricação de fios ortodônticos de aço inoxidável austeno-ferrítico SEW 410 Nr. 14517 por meio dos processos convencionais de laminação e trefilação. MÉTODOS: o aço austeno-ferrítico foi elaborado em um forno elétrico de indução. A qualidade dos fios foi avaliada por ensaios de tração e medidas de microdureza. A ductilidade e a manuseabilidade foram analisadas por meio da confecção de componentes ortodônticos. RESULTADOS E CONCLUSÕES: os valores encontrados mostraram que os fios de aço inoxidável austeno-ferrítico atenderam às normas BS 3507:1976 e ISO 5832-1, e apresentaram ótima ductilidade para confecção de componentes ortodônticos com dobras complexas.OBJECTIVE: To develop a method to manufacture austenitic-ferritic stainless steel orthodontic wires (SEW 410 Nr. 14517 using conventional rolling and wiredrawing processes. METHODS: Austenitic-ferritic steel was produced in an induction furnace. Traction trials and microhardness measurements were used to evaluate wire quality. Orthodontic parts were fabricated to assess ductility and malleability. RESULTS AND CONCLUSIONS: Austenitic-ferritic stainless steel wires meet the BS 3507:1976 and ISO 5832-1 norms and have excellent ductility for the fabrication of orthodontic parts with complex folds.

Effect of sensitization on the mechanical properties of type 304 L stainless steel

International Nuclear Information System (INIS)

Vargas Mendoza, L.F.

1990-01-01

The sensitization is a corrosion cause that it has studied broadly in the austenitic steels; however its relations don't knowed very well, into the sensitization and the steel's mechanical properties. Wherefore, the objectives of this work was to study the mechanical properties, in tension of austenitic steel with different levels of sensitization. The material utilized was a 304 L steel of standard composition AISI. The samples were sensitized at 450, 650 and 850 Centigrade degree, by short expositions, following by a temper in water. After this treatment, the tension test tubes were carried to rupture at low deformation velocity. The sensitization was evaluated by the method of Akashi EPR cyclic polarization. The sensitization distribution was analyzed by optical metallography in color and the fracture surface were studied by sweeping electronic microscopy. The distribution and length of the carbides were the factor that control the mechanic behavior of materials. At 450 Centigrade, the border of the grain its founded free of carbides, also for the longest times of exposition, but the particles are presented as fine precipitates in the grain interior, with this is increased the mechanical properties by the internal interactions of hardness or oldness types. At 650 Centigrade the frontiers show a dense distribution of fine carbides. These precipitates are interacting with the borders grain, increasing lightly the mechanical properties of steel. At 850 Centigrade, were formed discontinued carbides that not affect the mechanical behavior, but whether the fracture; the resistance is reduced and the ductility is increased although to impose the thermic effect of treatment. (Author)

Compressibility of 304 Stainless Steel Powder Metallurgy Materials Reinforced with 304 Short Stainless Steel Fibers.

Science.gov (United States)

Yao, Bibo; Zhou, Zhaoyao; Duan, Liuyang; Xiao, Zhiyu

2016-03-04

Powder metallurgy (P/M) technique is usually used for manufacturing porous metal materials. However, some P/M materials are limitedly used in engineering for their performance deficiency. A novel 304 stainless steel P/M material was produced by a solid-state sintering of 304 stainless steel powders and 304 short stainless steel fibers, which were alternately laid in layers according to mass ratio. In this paper, the compressive properties of the P/M materials were characterized by a series of uniaxial compression tests. The effects of fiber content, compaction pressure and high temperature nitriding on compressive properties were investigated. The results indicated that, without nitriding, the samples changed from cuboid to cydariform without damage in the process of compression. The compressive stress was enhanced with increasing fiber content ranging from 0 to 8 wt.%. For compaction pressure from 55 to 75 MPa, greater compaction pressure improved compressive stress. Moreover, high temperature nitriding was able to significantly improve the yield stress, but collapse failure eventually occurred.

Optimización de los Parámetros de Soldadura por Arco Sumergido en Acero HSLA: una Aplicación para Manufactura de Tuberías de Conducción de Hidrocarburos

OpenAIRE

Costa,Patricia Sheilla; Reyes-Valdés,Felipe Arturo; Saldaña-Garcés,Rocio; González-González,David Salvador; Delgado-Albavera,Erick Rafael

2015-01-01

Resumen El acero HSLA (High Strength Low Alloy) API 5L X70 es utilizado para fabricación de tuberías para transporte de hidrocarburos. La construcción de tuberías de este material involucra alta cantidad de soldadura, donde los parámetros empleados influyen directamente en las estructuras metalúrgicas y en las propiedades mecánicas del mismo cuando soldado. Así, para estudiar el impacto de los parámetros de soldadura por arco sumergido en la resistencia mecánica y dureza de la Zona Afectada p...

Subcooled boiling heat transfer in a short vertical SUS304-tube at liquid Reynolds number range 5.19 x 104 to 7.43 x 105

International Nuclear Information System (INIS)

Hata, Koichi; Masuzaki, Suguru

2009-01-01

The subcooled boiling heat transfer and the steady-state critical heat fluxes (CHFs) in a short vertical SUS304-tube for the flow velocities (u = 17.28-40.20 m/s), the inlet liquid temperatures (T in = 293.30-362.49 K), the inlet pressures (P in = 842.90-1467.93 kPa) and the exponentially increasing heat input (Q = Q 0 exp(t/τ), τ = 8.5 s) are systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tubes of inner diameters (d = 3 and 6 mm), heated lengths (L = 33 and 59.5 mm), effective lengths (L eff = 23.3 and 49.1 mm), L/d (=11 and 9.92), L eff /d (=7.77 and 8.18), and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.18 μm) are used in this work. The inner surface temperature and the heat flux from non-boiling to CHF are clarified. The subcooled boiling heat transfer for SUS304 test tube is compared with our Platinum test tube data and the values calculated by other workers' correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details and the widely and precisely predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical SUS304-tube is given based on the experimental data. The correlation can describe the subcooled boiling heat transfer obtained in this work within 15% difference. Nucleate boiling surface superheats for the SUS304 test tube become very high. Those at the high flow velocity are close to the lower limit of Heterogeneous Spontaneous Nucleation Temperature. The dominant mechanisms of the flow boiling CHF in a short vertical SUS304-tube are discussed.

5 CFR 2634.304 - Gifts and reimbursements.

Science.gov (United States)

2010-01-01

... manners: (1) If the gift has been newly purchased or is readily available in the market, the value shall... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Gifts and reimbursements. 2634.304....304 Gifts and reimbursements. (a) Gifts. Except as indicated in § 2634.308(b), each financial...

32 CFR 700.304 - Recommendations to Congress.

Science.gov (United States)

2010-07-01

... 32 National Defense 5 2010-07-01 2010-07-01 false Recommendations to Congress. 700.304 Section 700... The Secretary of the Navy § 700.304 Recommendations to Congress. After first informing the Secretary of Defense, the Secretary of the Navy may make such recommendations to Congress relating to the...

9 CFR 318.304 - Operations in the thermal processing area.

Science.gov (United States)

2010-01-01

... area. 318.304 Section 318.304 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION... PREPARATION OF PRODUCTS Canning and Canned Products § 318.304 Operations in the thermal processing area. (a...

Diseño de puesto de trabajo para la fabricación de eslingas de cable de acero

Directory of Open Access Journals (Sweden)

Téllez Chavarro Luz Ángela

2015-04-01

Full Text Available Introducción: Para la realización de eslingas se demanda alto nivel físico y adopción de diferentes posturas en largas jornadas laborales. Los desórdenes músculo esqueléticos relacionados con el trabajo son comunes, potencialmente discapacitantes y evitables. Objetivos: Proponer un diseño de puesto de trabajo que facilite la tarea de armado de eslingas de cable de acero bajo condiciones ergonómicas para el trabajador, luego identificar las características sociodemográficas, determinar las condiciones de salud de los trabajadores, establecer las dimensiones antropométricas de los trabajadores y del puesto de trabajo y evaluar el riesgo ergonómico del puesto actual. Metodología: Estudio cuali-cuantitativo, transversal descriptivo con dos trabajadores que fabricaban eslingas de cable de acero. Criterios de inclusión: desarrollo de su labor diaria únicamente en área, más de 12 meses trabajando con la empresa. La recolección de datos se hizo a través de videos, entrevistas y fotografías. Para la evaluación del riesgo ergonómico se aplicó el método REBA (Rapid Entire Body Assessment y la herramienta antropométrica "Dimensiones de Puesto de Trabajo". Este fue validado por expertos. Posteriormente se realizó la propuesta del diseño de puesto de trabajo en AutoCad®. Resultados: La puntuación total de REBA para el grupo A fue 9, del grupo B fue 9, para una puntuación final de 11. Conclusiones: La manipulación del cable de acero es un factor de riesgo mecánico. Para la implementación del puesto de trabajo se debería realizar: definición del modelo de prueba, documentación del proceso productivo, capacitación a los trabajadores, seguimiento permanente y ajustes al proceso.

Relationship between oxide film structures and corrosion resistance of SUS 304 L stainless steel in high temperature pure water

International Nuclear Information System (INIS)

Yamanaka, Kazuo; Matsuda, Yasushi.

1990-01-01

The effect of various oxidation conditions on metal release of SUS304L stainless steels in deaerated pure water at 488 K was investigated. The behavior of metal release was also discussed in relation to the surface films which were formed by various oxidation treatments. The results obtained are as follows: (1) The oxidation treatment in high purity argon gas at high temperatures for short time such as 1273 K - 2 min (120S) was effective to decrease the metal dissolution, and the oxide films primarily consisted of spinel type double oxide layer containing high concentration of Mn and Cr. (2) The oxidation treatments in non-deaerated pure water at 561 K for 24∼336 h (86.4∼1209.6 ks) were furthermore effective to decrease the metal dissolution. (3) It may be concluded that the key factors controlling the metal release are thickness, structure and compactness together with compositions of surface oxide films. (author)

40 CFR 304.30 - Filing of pleadings.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 27 2010-07-01 2010-07-01 false Filing of pleadings. 304.30 Section... CLAIMS Hearings Before the Arbitrator § 304.30 Filing of pleadings. (a) Discovery shall be in accordance... nature of the substances contributed to the facility by each identified PRP, and a ranking by volume of...

Selección automatizada de electrodos para la soldadura manual de los aceros al carbono

Directory of Open Access Journals (Sweden)

Alexander Velázquez Font

2008-01-01

Full Text Available Se aborda lo relativo a un sistema para la selección automatizada de electrodos en la soldadura de los aceros al carbono. Se inicia con una breve revisión de los problemas que presentan estos en su soldabilidad y los factores concernientes a la selección correcta del electrodo en los mismos. En el mismo se expone el fundamento teórico sobre el diseño del sistema el cual da solución a lo anteriormente expuesto. En la elaboración del software se tiene en cuenta los siguientes principios: propiedades mecánicas de la unión soldada, tipo de revestimiento, posición de la soldadura, etc. Se tienen en cuenta en el trabajo diferentes firmas y normas de fabricantes de electrodos y países que mas se utilizan en la industria mecánica en Cuba. El software tiene la ventaja de ser sencillo, rápido y seguro, garantizando la selección correcta de los electrodos para cada caso y situación. El software supone que el usuario no tenga que tener conocimientos profundos de soldadura, debido a que el sistema se encarga de la mayor parte de las decisiones para la selección del electrodo, procedimiento que con métodos convencionales, exigen del usuario una determinada experiencia en la selección de estos materiales para la soldadura de los aceros al carbono.

Migración de hierro y níquel, y estabilidad oxidativa del aceite refinado de soja calentado en utensilios culinarios de diversos materiales

Directory of Open Access Journals (Sweden)

Almeyda Haj-Isa, Niurka Maritza

2007-12-01

Full Text Available Cookware may release some inorganic components into foods during cooking, some of which have undesirable consequences. In fried foods, for instance, oil oxidation is favored by metals. The present study evaluated oxidative stability (AOCS method and iron and nickel migration (inductively coupled plasma-optical emission spectrometry into refined soybean oil in four cycles, with intervals of 24 hours. The cookware materials were glass, aluminum, stainless steel, iron and soapstone. The results demonstrated that the lowest metal migration occurred from glass and aluminum pans while the oil heated in these pans showed the highest oxidative stability. The highest migration of Fe and Ni into the oil occurred from the soapstone and iron pots (3.94 and 3.21 mg _ kg-1, respectively.Nevertheless, increasing loss of oxidative stability was evident in the oils heated in the soapstone, stainless steel and iron cookware, in this order. Since iron migration was lower from glass and aluminum pans, these were considered the best type of materials for fryingDurante la elaboración de alimentos los utensilios culinarios pueden liberar componentes inorgánicos ocasionalmente no deseables. La oxidación del aceite es durante la fritura es favorecida por la presencia de metales. Fue evaluada la migración de hierro y níquel (espectrometría de emisión óptica y la estabilidad oxidativa (método AOCS del aceite de soja sometido a cuatro calentamientos con intervalos de 24 horas en cazuelas de vidrio, aluminio, acero inoxidable, hierro y piedra-jabón. La mayor migración de hierro al aceite ocurrió en las cazuelas de hierro (3,94 mg•kg–1 y piedra (3,21 mg _ kg–1, sin diferencia estadística entre ellas. La pérdida progresiva de estabilidad oxidativa fue acentuada en los aceites calentados en utensilios de piedra, acero inoxidable e hierro, en tal orden. Vidrio y aluminio fueron considerados los mejores materiales para la fabricación de cazuelas

Prototipo autotérmico móvil para producción de biocarbón con biomasa de esquilmos de aguacate

Directory of Open Access Journals (Sweden)

Lenin Ejecatl Medina Orozco

2018-04-01

Full Text Available El estado de Michoacán, México, es el principal productor mundial de aguacate, con un impacto social y económico en función de la superficie cultivada. Productos secundarios de esta actividad, son los esquilmos agrícolas derivados de las podas de mantenimiento de los árboles. El biocarbón (biochar de subproductos de aguacate, se vislumbra como una alternativa económica, ambiental y socialmente viable, para producir biocarbón en grandes volúmenes, sin extracción de maderas de bosque y selvas prístinas. El objetivo del presente estudio, fue construir y evaluar el desempeño en condiciones de campo, de un prototipo de biocarbón-pirólisis autotérmico y móvil, con volumen útil de 1.7 m3 de biomasa triturada. El equipo fue construido de acero inoxidable, para darle un periodo de vida útil de 7 años bajo condiciones intensivas de uso, con movilidad dentro de los campos agrícolas y auto térmico para no depender de una fuente de calor externa. El equipo fue de bajo costo comparado con equipos comerciales ($ 700 000.00 pesos MN y con un potencial futuro en la cogeneración de energía. La principal variable en el costo de fabricación es el precio del acero inoxidable en el mercado. El equipo reportó una tasa de conversión de biomasa a biocarbón, en condiciones de campo, de entre 300 y 400 kg por día, con una tasa promedio de recuperación del 16% en biocarbón. Las principales variables en la transformación de la biomasa a biocarbón fueron: humedad, el tamaño de la astilla y condiciones atmosféricas. Se encontró una Capacidad de Intercambio Catiónico (CIC de 46 Cmolc kg-1 y pH 10.25. El equipo transformó satisfactoriamente la biomasa de aguacate y el biocarbón presentó características adecuadas para su uso en suelos volcánicos.

16 CFR 304.4 - Application of other law or regulation.

Science.gov (United States)

2010-01-01

... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Application of other law or regulation. 304.4 Section 304.4 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS RULES AND REGULATIONS UNDER THE HOBBY PROTECTION ACT § 304.4 Application of other law or...

Comportamiento a fatiga del acero sae 4140 usando alta rugosidad superficial y ambiente corrosivo

OpenAIRE

CEBALLOS, WILSON FERNANDO; GÓMEZ, ADOLFO LEÓN; CORONADO, JOHN JAIRO

2010-01-01

En este artículo se presenta el estudio del comportamiento a fatiga del acero SAE 4140 en condiciones diferentes: superficie pulida (acabado espejo), ambiente corrosivo (jugo de caña de azúcar), alta rugosidad superficial (superficie equivalente a la encontrada típicamente en los ejes de molino de caña) y una condición que involucra la combinación de las dos últimas. Las anteriores condiciones están presentes en los ejes de maza de molino de caña de azúcar durante el proceso de molienda. Se r...

COMPORTAMIENTO A FATIGA DEL ACERO SAE 4140 USANDO ALTA RUGOSIDAD SUPERFICIAL Y AMBIENTE CORROSIVO

OpenAIRE

CEBALLOS, WILSON FERNANDO; GÓMEZ, ADOLFO LEÓN; CORONADO, JOHN JAIRO

2010-01-01

En este artículo se presenta el estudio del comportamiento a fatiga del acero SAE 4140 en condiciones diferentes: superficie pulida (acabado espejo), ambiente corrosivo (jugo de caña de azúcar), alta rugosidad superficial (superficie equivalente a la encontrada típicamente en los ejes de molino de caña) y una condición que involucra la combinación de las dos últimas. Las anteriores condiciones están presentes en los ejes de maza de molino de caña de azúcar durante el proceso de molienda. Se r...

Deformation and failure response of 304L stainless steel SMAW joint under dynamic shear loading

International Nuclear Information System (INIS)

Lee, Woei-Shyan; Cheng, J.-I.; Lin, C.-F.

2004-01-01

The dynamic shear deformation behavior and fracture characteristics of 304L stainless steel shielded metal arc welding (SMAW) joint are studied experimentally with regard to the relations between mechanical properties and strain rate. Thin-wall tubular specimens are deformed at room temperature under strain rates in the range of 8 x 10 2 to 2.8 x 10 3 s -1 using a torsional split-Hopkinson bar. The results indicate that the strain rate has a significant influence on the mechanical properties and fracture response of the tested SMAW joints. It is found that the flow stress, total shear strain to failure, work hardening rate and strain rate sensitivity all increase with increasing strain rate, but that the activation volume decreases. The observed dynamic shear deformation behavior is modeled using the Kobayashi-Dodd constitutive law, and it is shown that the predicted results are in good agreement with the experimental data. Fractographic analysis using scanning electron microscopy reveals that the tested specimens all fracture within their fusion zones, and that the primary failure mechanism is one of the extensive localized shearing. The fracture surfaces are characterized by the presence of many dimples. A higher strain rate tends to reduce the size of the dimples and to increase their density. The observed fracture features are closely related to the preceding flow behavior

Compressibility of 304 Stainless Steel Powder Metallurgy Materials Reinforced with 304 Short Stainless Steel Fibers

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Bibo Yao

2016-03-01

Full Text Available Powder metallurgy (P/M technique is usually used for manufacturing porous metal materials. However, some P/M materials are limitedly used in engineering for their performance deficiency. A novel 304 stainless steel P/M material was produced by a solid-state sintering of 304 stainless steel powders and 304 short stainless steel fibers, which were alternately laid in layers according to mass ratio. In this paper, the compressive properties of the P/M materials were characterized by a series of uniaxial compression tests. The effects of fiber content, compaction pressure and high temperature nitriding on compressive properties were investigated. The results indicated that, without nitriding, the samples changed from cuboid to cydariform without damage in the process of compression. The compressive stress was enhanced with increasing fiber content ranging from 0 to 8 wt.%. For compaction pressure from 55 to 75 MPa, greater compaction pressure improved compressive stress. Moreover, high temperature nitriding was able to significantly improve the yield stress, but collapse failure eventually occurred.

Técnicas para revelar el borde de grano austenítico en aceros microaleados

Directory of Open Access Journals (Sweden)

García de Andrés, Carlos

2001-08-01

Full Text Available The prior austenite grain size (PAGS exerts an important influence on the microstructures forged by continuous cooling in the steel and on their mechanical properties. Since microalloyed steels have received considerable attention in the last years and enormous difficulties have been repetitively to reveal the austenite grain boundaries in these steels, this work analyzes the different techniques effective in that sense, which enable thus an accurate determination of the PAGS. This paper presents results obtained applying different conventional techniques such us chemical etching of quenched microstructures, the application of thermal cycles that enable the formation of phases around the prior austenite grain boundaries or oxidation etching which reveals the austenite grain boundaries by the preferential accumulation of oxides. Finally, an innovative and effective technique to reveal the prior austenite grain boundaries is presented. This technique is based on the preferential transfer of matter from the grain boundaries to the surrounding austenite by complicated mechanisms such as evaporation-condensation and volume and surface diffusion of atoms.

El tamaño de grano austenítico (TGA tiene una gran influencia sobre la microestructura final y sobre las propiedades mecánicas de los productos obtenidos por transformación anisotérmica del acero. Debido a la considerable atención que se está prestando a los aceros microaleados en los últimos años y a las dificultades que se encuentran en muchos casos para poder revelar los bordes de grano austenítico de estos aceros, en este trabajo se han analizado las técnicas que lo hacen posible, permitiendo así la determinación fiable del TGA. En este sentido, se presentan los resultados obtenidos al aplicar aislada y combinadamente distintas técnicas tradicionales, como el ataque químico de microestructuras obtenidas directamente por temple, la aplicación de diferentes tipos de ciclos t

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

24 CFR 982.304 - Illegal discrimination: PHA assistance to family.

Science.gov (United States)

2010-04-01

... assistance to family. 982.304 Section 982.304 Housing and Urban Development Regulations Relating to Housing... Leasing a Unit § 982.304 Illegal discrimination: PHA assistance to family. A family may claim that illegal... prevents the family from finding or leasing a suitable unit with assistance under the program. The PHA must...

Martensite phase reversion-induced nano/ ultrafine grained AISI 304L stainless steel with magnificent mechanical properties

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Mohammad Shirdel

2015-06-01

Full Text Available Austenitic stainless steels are extensively used in various applications requiring good corrosion resistance and formability. In the current study, the formation of nano/ ultrafine grained austenitic microstructure in a microalloyed AISI 304L stainless steel was investigated by the advanced thermomechanical process of reversion of strain-induced martensite. For this purpose, samples were subjected to heavy cold rolling to produce a nearly complete martensitic structure. Subsequently, a wide range of annealing temperatures (600 to 800°C and times (1 to 240 min were employed to assess the reversion behavior and to find the best annealing condition for the production of the nano/ultrafine grained austenitic microstructure. Microstructural characterizations have been performed using X-ray diffraction (XRD, scanning electron microscopy (SEM, and magnetic measurement, whereas the mechanical properties were assessed by tensile and hardness tests. After thermomechanical treatment, a very fine austenitic structure was obtained, which was composed of nano sized grains of ~ 85 nm in an ultrafine grained matrix with an average grain size of 480 nm. This microstructure exhibited superior mechanical properties: high tensile strength of about 1280 MPa with a desirable elongation of about 41%, which can pave the way for the application of these sheets in the automotive industry.

Condiciones térmicas de un dispositivo electrónico en caso de incendio Primera parte: estudio experimental

Directory of Open Access Journals (Sweden)

Bruno Chine

2007-11-01

Full Text Available En este trabajo se presentan los resultados de un estudio experimental para determinar las condiciones térmicas a la cual un sistema electrónico, usado para radiocomunicaciones en túneles, podría estar sujeto en caso de incendio. El sistema se compone de un dispositivo electrónico contenido en una caja metálica de acero inoxidable 316, un cable coaxial interno y un cable coaxial externo de cobre. Sobre el sistema, que se alberga en una cámara de polímero concreto, ha sido realizada una prueba al fuego con registro experimental de los valores de temperatura en diferentes puntos del sistema mismo. El trabajo experimental ha permitido analizar eficazmente la respuesta del dispositivo electrónico y de los distintos materiales que lo componen a las severas condiciones térmicas de prueba.

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

Directory of Open Access Journals (Sweden)

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.

13 CFR 304.3 - District modification and termination.

Science.gov (United States)

2010-01-01

... Organization (e.g., natural disaster, plant closure, overall economic downturn, sudden and severe economic... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false District modification and termination. 304.3 Section 304.3 Business Credit and Assistance ECONOMIC DEVELOPMENT ADMINISTRATION...

Modelación de fenómenos metalúrgicos en laminación en caliente de acero

Directory of Open Access Journals (Sweden)

Zambrano, P.

2008-02-01

Full Text Available Modelling of hot rolling of steel strip involves metallurgical phenomena such as restoration of deformed structures, transformation to ferrite and growth of the oxide layer on top of the steel strip. The effect of composition is taken into account when restoration and phase transformation is considered, whereas it is assumed that the chemical composition of the steel substrate does not affect the oxide crust, being common place to consider the oxide just as a thermal barrier and to assume sticking conditions within the roll-gap. Observations indicate that elements such as silicon and manganese, more susceptible to oxidize than iron, affect the growth kinetics, adhesion and the behaviour during deformation of the oxide layer. This work deals with the way used to model various superficial and metallurgical phenomena, and how this knowledge is used to simulate hot rolling of steel strip.

La modelación del proceso de laminación en caliente de acero incorpora fenómenos metalúrgicos como son la restauración de la estructura deformada, la trasformación de fase y el crecimiento de la capa de óxido sobre la superficie del acero. Se reconoce el efecto de la composición química sobre la transformación de fase y la restauración, sin embargo se considera que el crecimiento del óxido no es afectado por la presencia de elementos aleantes en el acero y es común que se maneje a la costra de óxido como una barrera térmica y que se supongan condiciones de fricción adhesivas en el entrehierro. Determinadas observaciones indican que elementos como el silicio y el manganeso, más susceptibles a oxidarse que el hierro, afectan la cinética de crecimiento, la adhesión y el comportamiento de la costra al ser deformada. En este trabajo se presenta la forma en que diversos fenómenos metalúrgicos y de superficie se modelan y se utilizan para simular el proceso de laminación en caliente.

22 CFR 304.9 - Referral to the Department of Justice.

Science.gov (United States)

2010-04-01

... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Referral to the Department of Justice. 304.9... Procedures § 304.9 Referral to the Department of Justice. When Department of Justice approval or consultation is required under § 304.8, the referral or request shall be transmitted to the Department of Justice...

48 CFR 32.304-6 - Other collateral security.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Other collateral security. 32.304-6 Section 32.304-6 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION... collateral security. The following are examples of other forms of security that, although seldom invoked...

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-07-01

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

13 CFR 304.1 - Designation of Economic Development Districts: Regional eligibility.

Science.gov (United States)

2010-01-01

... Development Districts: Regional eligibility. 304.1 Section 304.1 Business Credit and Assistance ECONOMIC DEVELOPMENT ADMINISTRATION, DEPARTMENT OF COMMERCE ECONOMIC DEVELOPMENT DISTRICTS § 304.1 Designation of Economic Development Districts: Regional eligibility. Upon the request of a District Organization (as...

The possibilities for reuse of steel scrap in order to obtain blades for knives; Posibilidades de reutilización de la chatarra de acero para la obtención de cuchillas para cortar

Energy Technology Data Exchange (ETDEWEB)

Štrbaca, N.; Markovića, I.; Mitovskia, A.; Balanovića, L.; Živkovića, D.; Grekulović, V.

2017-09-01

The purpose of this study is to determine fracture toughness of Resistance Spot Welded (RSW) Dual Phase (DP) steels. RSW of galvanized and ungalvanized DP 450 steel sheets was carried out on spot welding machine. Fracture toughness of RSW joints of galvanized and ungalvanized DP 450 steel sheets was calculated from tensile-shear tests. New empirical equations were developed using Least Squares Method (LSM) between energy release rate, fracture toughness and critical crack size depending on the relationship between hardness and fracture toughness values. Results indicated that fracture toughness of joints welded by using RSW increased exponentially while the hardness decreased. In addition, fracture toughness and energy release rate of RSW galvanized DP 450 steel sheets were lower compared to RSW ungalvanized DP 450 steel sheets which had approximately the same hardness. [Spanish] El trabajo presenta los resultados de la caracterización de diversos tipos de aceros que han llegado al final de su ciclo de vida útil, y de los que se desconocía su composición química, propiedades mecánicas y tratamiento termomecánico aplicado previamente. El estudio se realizó con el objetivo de analizar las posibilidades de reutilización de algunos de estos materiales en aplicaciones agrícolas e industriales, obteniendo hojas de corte. Las formas exigidas a las hojas de corte se consiguieron aplicando diversos tipos de tratamientos termomecánicos. El análisis químico de la chatarra de acero de acero se realizó utilizando Energías Dispersivas de Rayos X. La microestructura se estudió utilizando Microscopía Óptica y Microscopía Electrónica de Barrido. La dureza de la chatarra de acero y de las cuchillas obtenidas se midió utilizando la escala Rockwell C. Los valores de dureza de las cuchillas obtenidas indican una buena selección de los productos finales de acero.

Modelización de las transformaciones de fase en el proceso de endurecimiento de aceros con láser de CO₂

Directory of Open Access Journals (Sweden)

Amado, J. M.

2004-10-01

Full Text Available Hardening processes of steel are very dependent on the heating and cooling rates, in both cases high rates are needed. In the laser hardening the power density of the laser beam is responsible of the fast heating of the material; fast cooling is achieved due to the heat conduction from the region being treated to the bulk of the workpiece. Within this work thermal cycles are determined with a Finite Element Model which computes the temperature of the material during the laser treatment. For the prediction of the hardening IT diagrams are applied, isothermal steps are connected with constant volume fraction steps; the content of each phase is computed in the framework of the Johnson-Mehl and Avrami law. During the cooling process, a similar procedure is applied but now using TTT diagrams. Model validation is done comparing, on a local basis, microhardness measurement on a treated workpiece with the martensite concentration extracted from the model.

Los procesos de endurecimiento superficial de aceros dependen de los ritmos de calentamiento y enfriamiento del material, que han de ser rápidos. En el endurecimiento por láser, el rápido calentamiento viene asegurado por la elevada densidad de potencia del haz láser incidiendo sobre un pequeño volumen de la pieza, mientras que el flujo de calor por conducción hacia el resto del material ayuda a producir un rápido ritmo de enfriamiento. En este artículo, los ciclos térmicos se determinan con la ayuda de un modelo de elementos finitos que calcula la evolución de la temperatura en los diferentes puntos del material durante el proceso de tratamiento con láser. Para la predicción del endurecimiento son necesarios los diagramas de calentamiento isotermo (IT para su aplicación durante el calentamiento; la cuantificación de las transformaciones se realiza en una serie de pasos isotermos conectados con otros de fracción de volumen constante; el porcentaje de cada fase se calcula

GEL DE ALOE-VERA COMO POTENCIAL INHIBIDOR DE LA CORROSIÓN DEL ACERO DE REFUERZO ESTRUCTURAL

OpenAIRE

Héctor Herrera-Hernández

2015-01-01

En el presente trabajo se estudiaelectroquímicamente un GELextracto de las hojas de ALOE VERAcomo un posible inhibidor de la corrosión del acero de refuerzo estructuraldel concreto.Los estudiosde corrosiónse llevaron a cabo en 1M de HCl y utilizando la técnica de espectroscopia de impedancia electroquímica (EIS)se evaluó la resistencia a la corrosión en presencia y ausencia del GEL.Los diagramas de impedancia mostraronque la adición en diferentes proporciones...

Influencia de la ductilidad de las armaduras de acero en el comportamiento y la seguridad de losas de hormigón armado

Directory of Open Access Journals (Sweden)

Ortega, H.

1999-10-01

Full Text Available This work is based on the results and basic conclusions of author's doctoral thesis, directed by Professor José Calavera. On the one hand, a new form to measure the ductility of those steels used like reinforcement of concrete, is proposed, in order to be compared and classified in accordance with this one. On the other hand it has been studied the results of the tests on 12 continuous slabs of two equal spans, reinforced with four different steel types chosen so that, in the more requested section the steel will reach, in first place, its collapse (situation in the 2 domain, A pivot. The reinforcement to allow the mentioned extent, is provided with same nominal resistance steels and same diameter, but with - different ductility. The results of this experimental study, reveals the importance of the steel ductility concerning the behaviour and real security of the structure in front of the collapse, and furnish a group of conclusions and proposals concerning this interesting subject.

Este trabajo se basa en los resultados y conclusiones básicas de la tesis doctoral del autor, dirigida por el Profesor D. José Calavera. Se propone, por un lado, una forma de medir mediante un único parámetro la ductilidad de los aceros utilizados como armaduras para hormigón armado, de forma que se puedan comparar y clasificar con arreglo al mismo. Por otro, se estudian los resultados de los ensayos sobre 12 losas continuas de dos vanos, de sección maciza, armadas con cuatro cuantías diferentes elegidas de forma que, en la sección más solicitada, sea el acero el que alcance, en primer lugar, su agotamiento (situación en el dominio 2, pivote A . El armado para conseguir las citadas cuantías se realiza con aceros de la misma resistencia nominal y del mismo diámetro, pero con distinta ductilidad. Los resultados de este estudio experimental, ponen de manifiesto la importancia de la ductilidad del acero en relación con el comportamiento, as

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

Directory of Open Access Journals (Sweden)

Busquets, D.

2010-08-01

microscopia óptica, microscopía electrónica de barrido (MEB y difracción de electrones retrodispersados (EBSD. El objetivo del trabajo es relacionar los parámetros del proceso de recubrimiento por láser (potencia, velocidad, caudal de polvo con las transformaciones metalúrgicas producidas en el acero de herramienta AISI D2, con el fin de optimizar las condiciones de operación durante la reparación. Los resultados muestran que los parámetros influyen en gran medida en la geometría del cordón y en la formación de la microestructura. Aunque es sencillo obtener deposiciones geométricamente aceptables (forma y tamaño adecuado, ausencia de porosidad, en muchos casos aparecen fenómenos perjudiciales como la dilución de carburos y la aparición de fases metaestables que modifican las propiedades mecánicas del recubrimiento. En concreto, la presencia de austenita retenida en el recubrimiento, relacionada con la temperatura máxima alcanzada y la velocidad de enfriamiento, produce una fuerte disminución en la dureza, que debe evitarse. Además, para una misma composición y acabado superficial, el estado metalúrgico inicial del sustrato tiene una gran influencia sobre el resultado. Sustratos en estado de temple implican una mayor absorción del láser y la acumulación de calor que produce mayores zonas afectadas por el calor (ZAC. Por ese motivo, deben optimizarse los parámetros del proceso para cada operación de manera que se mejore el comportamiento en servicio del componente.

42 CFR 3.304 - Principles for achieving compliance.

Science.gov (United States)

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Principles for achieving compliance. 3.304 Section 3.304 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... Principles for achieving compliance. (a) Cooperation. The Secretary will, to the extent practicable, seek the...

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.

Influence of substrate bias voltage on the properties of TiO{sub 2} deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

Energy Technology Data Exchange (ETDEWEB)

Bait, L. [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria); Azzouz, L. [Université de Amar Telidji, Laghouat (Algeria); Madaoui, N. [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria); Saoula, N., E-mail: nsaoula@cdta.dz [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria)

2017-02-15

Highlights: • TiO{sub 2} films were deposited on stainless steel 304L RF magnetron sputtering at different substrate bias. • The hardness of TiO{sub 2} coated 304L are higher than those obtained for uncoated substrate. • TiO{sub 2} films provide good protection for stainless steel against corrosion in Ringer solution. - Abstract: The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to −100 V, on the structure and properties of the TiO{sub 2} thin films for biomaterials applications. The TiO{sub 2} films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O{sub 2} gas mixture. The variation of substrate bias voltage from 0 to −100 V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO{sub 2} films sliding against alumina ball in air were investigated. Experimental results showed that the thickness increases for non-biased substrate voltage to Vs = −100 V from 820 nm to 1936 nm respectively. The roughness is in the range of 50 nm and 14 nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0–50 V). The hardness significantly increased from 2.2 to 6.4 GPa when the bias voltage was increased from 0 to 75 V and then slightly decrease to 5.1 GPa as further increased to 100 V. At the same time, the results indicate that TiO{sub 2} films deposited at −100 V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH = 6.3), thermostatically controlled at 37 °C, was used as the electrolyte for the

Plasticity-induced martensitic transformation in austenitic stainless steels SUS 304 and SUS 316 L at room and liquid nitrogen temperatures. Quantitative measurement using X-ray diffraction method

International Nuclear Information System (INIS)

Iwasaki, Yoshifumi; Nakasone, Yuji; Shimizu, Tetsu; Kobayashi, Noboru

2006-01-01

The present study investigates plasticity-induced martensitic transformation in two types of austenitic stainless steels SUS 304 and 316 L subjected to uniform tensile stresses at room and liquid nitrogen temperatures. The X-ray diffraction method was used in order to measure volume fractions of transformed α' and ε' martensitic phases and to obtain the dependence of the volume fractions of these phases on the applied strain level ε. The difficulty in the measurement of the martensitic phases by the X-ray diffraction method caused by the preferred orientation which had been introduced during the rolling process and during the tensile tests was overcome by the help of Arnell's Method. Two types of target materials, i.e. Cu and Mo for the X-ray source were used to verify the accuracy and reproducibility of the present X-ray diffraction analyses. The results were also compared with those obtained by the saturation magnetization method using VSM, or vibrating-sample magnetometer reported elsewhere. It was revealed that α' was transformed in SUS 304 both at 297 and 77 K whereas in SUS 316L only at 77 K. Another type of martensitic phase, i.e., ε was transformed in the both steels only at 77 K. Almost the same values of the volume fractions of α' and ε' phases were obtained by the two types of target materials. The plots of α' volume fraction obtained by the X-ray diffraction methods vs. that by VSM showed a good linear correlation. (author)

"Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

Science.gov (United States)

Martinez Mateo, Isidoro Jose

fabricacion del molde, tienen una gran influencia sobre su comportamiento en servicio a lo largo de la vida util del molde. En la primera parte del presente estudio, a partir de ensayos punzon sobre disco, se ha determinado la relacion entre la resistencia al desgaste y la dureza de aceros para moldes obtenidos a partir de bloques de gran espesor, estudiando los principales mecanismos de desgaste que tienen lugar. A continuacion, con el fin de determinar el dano superficial que sufren los aceros para moldes en condiciones reales de inyeccion, se han estudiado distintos tipos de aceros utilizados comercialmente en moldes de inyeccion de polimeros y materiales compuestos, seleccionando las condiciones de operacion para determinar la variacion de la rugosidad superficial del acero en funcion del material inyectado, del numero de operaciones sucesivas de inyeccion y de la orientacion del flujo de inyeccion, mediante tecnicas de perfilometria optica y microscopia electronica de barrido. Ademas del dano superficial sufrido por el acero con el numero de piezas inyectadas, tambien se ha determinado la evolucion de la rugosidad superficial de los materiales inyectados, polibutilentereftalato (PBT) puro y materiales compuestos derivados de PBT por adicion de un 20 o un 50% en peso de fibra de vidrio. En el caso de las piezas inyectadas, se ha caracterizado su microestructura en funcion del flujo de inyeccion y de la densidad de fibra, se han determinado sus propiedades termicas y dinamico-mecanicas, asi como la variacion de la rugosidad superficial de las piezas inyectadas con el numero de operaciones de inyeccion y con la geometria de las distintas secciones de las piezas. Finalmente, se ha evaluado la resistencia a la abrasion de PBT reforzado con un 50% de fibra, en funcion del numero de piezas inyectadas y de la direccion de rayado con respecto a la orientacion del flujo de inyeccion.

INTEGRAL hard X-ray detection of HMXB GX 304-1 and H1417-624

DEFF Research Database (Denmark)

Manousakis, A.; Beckmann, V.; Bianchin, V.

2008-01-01

We report on the first detection of the Be star HMXBs GX 304-1 and H1417-624 above 20 keV with the IBIS/ISGRI X-ray imager on board INTEGRAL. From 2008-06-24 to 2008-07-09, INTEGRAL performed monitoring observations of the Galactic plane around l=305 degrees for a total exposure time of 352 ksec....

Microestructuras producidas en la soldadura de unión de aceros para tuberías de gran diámetro

Directory of Open Access Journals (Sweden)

Salazar, M.

1998-12-01

Full Text Available This is an evaluation of the microstructure in the heat affected zone (HAZ of steel weldings used in pipe lines. The welding was made by shielding metal are welding. This is a welding process with multiple run and low heat input, however local brittle zones are present in the HAZ. These are originated by a complex mechanism that is influenced by welding parameters and chemical composition of the steel. The welding sequences that help to eliminate the local brittle zones are studied.

En este trabajo se estudian las microestructuras producidas en la zona afectada por el calor (HAZ de la soldadura de unión en aceros utilizados en la construcción de poliductos. Se analizan las juntas obtenidas mediante soldadura manual con electrodo revestido. A pesar de que este es un proceso de soldadura con un bajo aporte térmico, se encuentran zonas frágiles locales que se originan por un mecanismo complejo influido por parámetros de soldadura y composición química del acero. Se analizan secuencias de soldaduras que ayuden a la desaparición de las mismas.

27 CFR 70.304 - Place for filing documents other than returns.

Science.gov (United States)

2010-04-01

...: Members of the taxpayer's family, an employee of the taxpayer, the taxpayer's attorney, accountant, or tax... other than returns. 70.304 Section 70.304 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX... ADMINISTRATION Collection of Excise and Special (Occupational) Tax Miscellaneous Provisions § 70.304 Place for...

Producción de aceros al carbono en hornos de arco eléctrico en condiciones de mineral de manganeso. // Steel production in electric arc furnaces in the condition of use of manganese.

Directory of Open Access Journals (Sweden)

E. E. Navas Medina

2007-05-01

Full Text Available El presente trabajo constituye una segunda etapa de investigación relacionada con la producción de acero en hornos de arcoeléctrico con revestimiento básico en condiciones de utilización de mineral de manganeso como sustituto del ferromanganeso.En la investigación se caracteriza el acero producido utilizando el mineral de manganeso en dos variantes tecnológicasdiferentes y se determinan parámetros importantes, tales como la estructura del acero obtenido, la influencia de lacomposición química y la temperatura en la reducción del Mn. Adicionalmente, se determina la composición química de laescoria, su basicidad e influencia en el aprovechamiento del Mn del mineral, así como, lo que significa la sustitución delFeMn en la problemática medioambiental.Palabras claves: Producción de aceros al carbono, hornos de arco eléctricos, mineral de manganeso.______________________________________________________________________________Abstract:This present work constitutes the second stage of investigation in relation with the steel production bymeans of electric arc furnaces in the condition of use of manganese ores as a substitute of theferromanganese. In the investigation, the steel manufactured is analyzed the manganese ore in twodifferent technological variants and some important parameters are determined such as: the chemicalcomposition's structure of the steel, the influence of temperature in the reduction of Mn. Moreover, ananalysis of the chemical composition of the slag and the influence in the environmental is realized.Key words: Carbon steel production, electric arc furnaces, manganese mineral.

Oxidation behavior of TiC particle-reinforced 304 stainless steel

International Nuclear Information System (INIS)

Wu Qianlin; Zhang Jianqiang; Sun Yangshan

2010-01-01

TiC particle-reinforced 304 stainless steels were prepared using a new developed in situ technology and exhibited the uniform distribution of TiC particles in the matrix. The oxidation behavior of 304SS-2TiC and 304SS-6TiC (all in weight percentage) was compared with that of 304SS at 850 deg. C in air for 96 h using thermogravimetry analysis. For 304SS, the rate of weight gain was very slow initially, but accelerated suddenly to a very high level, forming breakaway oxidation. The addition of TiC particles to 304SS resulted in no breakaway oxidation and maintained a low oxidation rate in the whole reaction time investigated. Examination of oxide scale morphology and cross-section analysis by scanning electron microscopy and optical microscopy showed a significant scale spallation and a deep oxide penetration in the case of 304SS, but a rather continuous, dense and adherent oxide layer formed on the surface of TiC particle-reinforced alloys. XRD analysis revealed the presence of Cr 2 O 3 together with spinel-type oxides in the oxide scale. For TiC-containing alloys, fine TiO 2 was also found on the surface and the amount of this oxide increased with TiC addition. The TiC addition developed finer matrix structure before oxidation, which accelerates chromium diffusion. As a result, scale adherence was improved and oxidation resistance was increased.

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.

High temperature oxidation behavior of AISI 304L stainless steel—Effect of surface working operations

International Nuclear Information System (INIS)

Ghosh, Swati; Kumar, M. Kiran; Kain, Vivekanand

2013-01-01

Highlights: ► Surface working resulted in thinner oxide on the surface. ► Oxides on machined/ground surfaces richer in Cr, higher in specific resistivity. ► Additional ionic transport process at the metal-oxide for ground sample established. ► Presence of fragmented grains and martensite influenced oxide nature/morphology. - Abstract: The oxidation behavior of grade 304L stainless steel (SS) subjected to different surface finishing (machining and grinding) operations was followed in situ by contact electric resistance (CER) and electrochemical impedance spectroscopy (EIS) measurements using controlled distance electrochemistry (CDE) technique in high purity water (conductivity −1 ) at 300 °C and 10 MPa in an autoclave connected to a recirculation loop system. The results highlight the distinct differences in the oxidation behavior of surface worked material as compared to solution annealed material in terms of specific resistivity and low frequency Warburg impedance. The resultant oxide layer was characterized for (a) elemental analyses by glow discharge optical emission spectroscopy (GDOES) and (b) morphology by scanning electron microscopy (SEM). Oxide layers with higher specific resistivity and chromium content were formed in case of machined and ground conditions. Presence of an additional ionic transport process has also been identified for the ground condition at the metal/oxide interface. These differences in electrochemical properties and distinct morphological features of the oxide layer as a result of surface working were attributed to the prevalence of heavily fragmented grain structure and presence of martensite.

Study of interaction of fatigue damage and ratcheting. Effect of a tensile primary load on torsion fatigue resistance of stainless steel 304 L at ambient temperature

International Nuclear Information System (INIS)

Hakem, N.S.

1987-01-01

Effect of ratcheting on fatigue resistance of a stainless steel 304 L, used for reactor vessels, is studied experimentally. Lifetime of samples is reduced if a static constant tensile load (primary loading) is superimposed to cyclic torsion deformations (secondary loading). An equivalent deformation concept is developed to express a criterion of fatigue rupture under primary loading. No effect is noted on the curve of cyclic strain hardening. This fatigue analysis gives no information on cumulated axial deformation. Progressive elongation, observed during testing, is dependent of primary and secondary loading. Rupture is produced by fatigue because cumulated axial deformation is limited ( 4 cycles at rupture cumulated deformation is [fr

Influencia de las adiciones de TaC y NbC en las propiedades de los aceros rápidos pulvimetalúrgicos M3/2

Directory of Open Access Journals (Sweden)

Gordo, E.

2002-04-01

Full Text Available Metal matrix composites based on M3/2 high speed steel and reinforced with different percentages of NbC and TaC were manufactured following a conventional powder metallurgy route: mixing, compacting and sintering. Graphite, to compensate carbon losses during sintering, and copper-phosphorous, to promote liquid phase sintering, were added to M3/2 powders to constitute the base material. Carbide and base material powders were dry mixed and uniaxially compacted at 700 MPa. After this, vacuum sintering was carried out at two temperatures: 1190 °C and 1230 °C. The mechanical properties and wear behaviour of all sintered materials were examined, and their characterisation was completed with a broad microstructural study

Este trabajo plantea la fabricación de materiales compuestos de matriz metálica, basados en el acero rápido M3/2 y reforzados con distintas cantidades de NbC y TaC, mediante técnicas convencionales pulvimetalúrgicas (P/M: mezcla, compactación y sinterización. Al acero rápido se añadió grafito para compensar las pérdidas de carbono durante la sinterización y cupro-fósforo para promover sinterización en fase líquida, constituyendo esta mezcla el material base. Los polvos de carburos y de material base fueron mezclados en seco y compactados uniaxialmente a 700 MPa. Tras esta etapa, se realizó la sinterización en vacío a dos temperaturas: 1.190 °C y 1.230 °C. Todos los materiales sinterizados fueron caracterizados mediante el estudio de las propiedades mecánicas, el comportamiento a desgaste y un amplio análisis microestructural.

Thermal fatigue of a 304L austenitic stainless steel: simulation of the initiation and of the propagation of the short cracks in isothermal and aniso-thermal fatigue; Fatigue thermique d'un acier inoxydable austenitique 304L: simulation de l'amorcage et de la croissance des fissures courtes en fatigue isotherme et anisotherme

Energy Technology Data Exchange (ETDEWEB)

Haddar, N

2003-04-01

The elbow pipes of thermal plants cooling systems are submitted to thermal variations of short range and of variable frequency. These variations bound to temperature changes of the fluids present a risk of cracks and leakages. In order to solve this problem, EDF has started the 'CRECO RNE 808' plan: 'thermal fatigue of 304L austenitic stainless steels' to study experimentally on a volume part, the initiation and the beginning of the propagation of cracks in thermal fatigue on austenitic stainless steels. The aim of this study is more particularly to compare the behaviour and the damage of the material in mechanic-thermal fatigue (cycling in temperature and cycling in deformation) and in isothermal fatigue (the utmost conditions have been determined by EDF for the metal: Tmax = 165 degrees C and Tmin = 90 degrees C; the frequency of the thermal variations can reach a Hertz). A lot of experimental results are given. A model of lifetime is introduced and validated. (O.M.)

Phosphate coating on stainless steel 304 sensitized

International Nuclear Information System (INIS)

Cruz V, J. P.; Vite T, J.; Castillo S, M.; Vite T, M.

2009-01-01

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

5 CFR 530.304 - Establishing or increasing special rates.

Science.gov (United States)

2010-01-01

... involved (including exposure to toxic substances or other occupational hazards); or (4) Any other... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Establishing or increasing special rates. 530.304 Section 530.304 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE...

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

Directory of Open Access Journals (Sweden)

Nádia Nara BATISTA

2014-01-01

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

Estudio de la viabilidad de fabricación de un sistema codo (fundición inoxidable ferrítica, GX 260 Cr27-tubo composite (Incolloy 800 HT+Stal 2465 solidario por fusión

Directory of Open Access Journals (Sweden)

Gutiérrez de Solabarría, S.

1995-10-01

Full Text Available Flying ashes captured by ciclones in the experimental plant for combustion in pressure fluid bed, in Escatrón Power Plant (Zaragoza, Spain, circulate through the gas cleaning system and are evacuated by means of pneumatic transport. The temperature of these ashes is aprox. 800 °C and the relative pressure is up to 8 negative bars relating the outdoor pressure of the transport pipe. The configuration of the pneumatic transport lines is Incolloy 800 HT quality composite tubes lined with Stal 2465 in straight stretches. Regarding direction changes, ferritic stainless casting, quality GX 260 Cr 27 elbows are used. The aim of this work is to study the possibility of manufacturing a solidary system by means of melting between the ferritic stainless casting elbow and the composite pipe.

Las cenizas volantes captadas por ciclones en la planta experimental de combustión en lecho fluido a presión, de la central térmica de Escatrón (Zaragoza, circulan por el sistema de depuración de gases y son evacuadas mediante transporte neumático. Estas cenizas se encuentran a una temperatura aproximada de 800 °C y a una presión relativa de hasta 8 bares negativos con respecto a la presión en el exterior de la tubería de transporte. Para configurar las líneas de transporte neumático, se utilizan en los tramos rectos tubos composite de calidad Incolloy 800 HT recubiertos interiormente de material Stal 2465. Para los cambios de dirección, se utilizan codos de fundición inoxidable ferrítica de calidad GX 260 Cr 27. El objetivo del presente trabajo es estudiar la viabilidad de fabricación de un sistema solidario por fusión entre el codo de fundición inoxidable ferrítica y la tubería composite.

Wear studies in the shearing process by means of irradiated tools; Etudes d'usure dans les operations de cisaillement, au moyen d'outils irradies; Issledovaniya problemy iznosa v protsesse skalyvaniya posredstvom obluchennykh instrumentov; Estudios de desgaste en las operaciones de cizallamiento, realizados con ayuda de herramientas irradiadas

Energy Technology Data Exchange (ETDEWEB)

Sata, Toshio; Abe, Kunio; Nakajima, Kiyoshi [Institute of Physical and Chemical Research, Komagome, Bunkyo-Ku, Tokyo (Japan)

1962-01-15

pastilles, tandis que la radioactivite des trous variait a peine. Cela montre que l'usure de la matrice peut etre mesuree d'apres la radioactivite des pastilles, et celle du poincon d'apres la radioactivite des trous. On a eu recours a cette methode pour suivre le processus d'usure du poincon et de la matrice en employant differents lubrifiants et differentes toles, ce qui a permis de faire les constatations suivantes: 1. Au debut du poinconnage, le taux d'usure du poincon et celui de la matrice sont tres eleves mais diminuent rapidement, pour devenir finalement stationnaires apres decoupage d'environ 4 a 500 pieces. 2. L'usure du poincon est d'environ 20 % plus forte que celle de la matrice. 3. Les lubrifiants contenant des additifs qui resistent aux pressions extremes, tels que le chlore, le phosphore ou le soufre, reduisent l'usure des outils, tandis que les huiles minerales raffinees n'apportent guere d'amelioration. 4. La plus forte usure des outils se produit lors du poinconnage des toles les plus dures. Cette usure est environ trois fois plus forte pour l'acier inoxydable et environ six fois plus forte pour l'acier riche en silicium que pour l'acier pauvre en carbone. (author) [Spanish] Se ha estudiado el desgaste de las herramientas utilizadas en el corte de laminas metalicas con punzones y matrices de acero rapido irradiados en un reactor. Se recortaron a punzon discos de 10 mm de diametro en laminas de acero pobre en carbono, acero inoxidable y acero al silicio de 0,5 mm de espesor en estado seco y lubricado. Despues del punzonamiento, se midio la radiactividad de los discos y de los orificios. Al reemplazar la matriz radiactiva por otra no irradiada, se detecto escasa actividad en los discos, mientras que la radiactividad de los orificios apenas sufrio variacion. Ello demuestra que el desgaste de la matriz y del punzon pueden medirse en funcion de la radiactividad de los discos y de los orificios, respectivamente. Con ayuda de este metodo, se estudio el desgaste

Aplicabilidad de un concreto de escoria activada alcalinamente como material protector del acero de refuerzo

OpenAIRE

Robinson de Jesús Torres Gómez, William A. Aperador Ch., Enrique Vera López,Rubi Mejía de Gutiérrez

2011-01-01

Se presentan los resultados del análisis electroquímico de las  barras  de  acero  embebidas  en  un  concreto  no convencional usado internacionalmente para reparación de estructuras. Este concreto utiliza materiales de desecho de otros procesos; en este caso específico se empleó escoria siderúrgica de  la empresa Acerías Paz del Río S.A. Se estudio el comportamiento frente a la corrosión generada por  los iones cloruro, con el uso de la técnica de resistencia lineal a la polarización LPR y ...

45 CFR 73.735-304 - Use of government property.

Science.gov (United States)

2010-10-01

.... (Exception for employee welfare and recreation associations is stated in Chapter 25-10, General... 45 Public Welfare 1 2010-10-01 2010-10-01 false Use of government property. 73.735-304 Section 73.735-304 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION STANDARDS OF...

PengaruhKorosiAir LautpadaKekuatanTarik SambunganLas KombinasiStainless Steel 304-201

Directory of Open Access Journals (Sweden)

Tjokorda Gde Tirta Nindhia

2016-07-01

Full Text Available Abstrak: Instalasi konstruksi yang dibangun dengan bahan stainless steel merupakan pilihan pertama dari daftar lis yang akan digunakan untuk konstruksi dekat laut. Dengan ditemukannya teknologi tungsten inert gas (TIG belakangan ini maka kontruksi dengan bahan stainles steel dapat direalisasikan. Dalam beberapa kasus sampungan las stainless steel dilakukan dengan menyambung dengan stainless steel dari jenis yang berbeda tanpa peduli dengan kekuatan yang dihasilkan khusunya jika mengalami korosi dalam hal ini korosi akibat air laut. Dalam penelitian ini kekuatan tarik sambungan kombinasi stainles steel dari jenis 304- 201 diuji dan dibandingkan dengan sambungan sejenis dari jenis 304-304 dan 201-201 Pengerauh korosi air laut terhadap kekuatan tarik sambungan stainless steel tersebut juga diteliti. Penelitian menemukan bahwa kekuatan tarik paling tinggi dimiliki oleh sambungan sejenis 304-304 diikuti oleh samnbungan kombinasi 304-201 dan yang terendah adalah sambungan 201-201. Pengaruh korosi airlaut diketahui menurunkan kekuatan dari semua jenis sambungan Kata Kunci : Stainless steel, las, air laut, korosi, kekuatan tarik Abstract: Installation of construction made from stainless steel is in the first list to be selected for location near the sea. The construction is by recent technology is much realize by using welding technology especially tungsten inert gas (TIG. In some case the welded joint of stainless steel are realized by joining 2 different type of stainless steel such as between type of 304 and 201 without any concern to the strength that will be achieved especially after exposure to the sea water. In this research the tensile strength of a combination of welding between stainless steel of 304- 201 is tested and compare to the welded of 304-304 and welded of 201-201. The effect of sea water corrosion in 30 days to the strength of the welded joint is observed . It is found that the tensile strength of welded 304-304 is found the highest

Simulation and experimental comparison of the thermo-mechanical history and 3D microstructure evolution of 304L stainless steel tubes manufactured using LENS

Science.gov (United States)

Johnson, Kyle L.; Rodgers, Theron M.; Underwood, Olivia D.; Madison, Jonathan D.; Ford, Kurtis R.; Whetten, Shaun R.; Dagel, Daryl J.; Bishop, Joseph E.

2017-12-01

Additive manufacturing enables the production of previously unachievable designs in conjunction with time and cost savings. However, spatially and temporally fluctuating thermal histories can lead to residual stress states and microstructural variations that challenge conventional assumptions used to predict part performance. Numerical simulations offer a viable way to explore the root causes of these characteristics, and can provide insight into methods of controlling them. Here, the thermal history of a 304L stainless steel cylinder produced using the Laser Engineered Net Shape process is simulated using finite element analysis (FEA). The resultant thermal history is coupled to both a solid mechanics FEA simulation to predict residual stress and a kinetic Monte Carlo model to predict the three-dimensional grain structure evolution. Experimental EBSD measurements of grain structure and in-process infrared thermal data are compared to the predictions.

Simulation and experimental comparison of the thermo-mechanical history and 3D microstructure evolution of 304L stainless steel tubes manufactured using LENS

Science.gov (United States)

Johnson, Kyle L.; Rodgers, Theron M.; Underwood, Olivia D.; Madison, Jonathan D.; Ford, Kurtis R.; Whetten, Shaun R.; Dagel, Daryl J.; Bishop, Joseph E.

2018-05-01

Additive manufacturing enables the production of previously unachievable designs in conjunction with time and cost savings. However, spatially and temporally fluctuating thermal histories can lead to residual stress states and microstructural variations that challenge conventional assumptions used to predict part performance. Numerical simulations offer a viable way to explore the root causes of these characteristics, and can provide insight into methods of controlling them. Here, the thermal history of a 304L stainless steel cylinder produced using the Laser Engineered Net Shape process is simulated using finite element analysis (FEA). The resultant thermal history is coupled to both a solid mechanics FEA simulation to predict residual stress and a kinetic Monte Carlo model to predict the three-dimensional grain structure evolution. Experimental EBSD measurements of grain structure and in-process infrared thermal data are compared to the predictions.

Electrical conductivity of air under the action of a shock wave; Conductivite electrique de l'air sous l'action d'une onde de choc

Energy Technology Data Exchange (ETDEWEB)

Thouvenin, Jacques [Commissariat a l' energie atomique et aux energies alternatives - CEA (France)

1960-07-01

A method is described for the measurement of the electrical conductivity of a shock wave in air. The results reveal the preponderant part played by the NO molecule. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 302-304, sitting of 11 January 1960 [French] On decrit un procede de mesure de la conductivite electrique d'une onde de choc dans l'air. Les resultats font apparaitre le role preponderant joue par la molecule NO. Reproduction d'un article publie dans les Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 302-304, seance du 11 janvier 1960.

Brasagem dos aços inoxidáveis duplex 'baixa liga' UNS S32101, UNS S32304 e superduplex UNS S32750 com metal de adição AWS A5.3 tipo BNi-7 (Ni-Cr-P

Directory of Open Access Journals (Sweden)

Dany Michell Andrade Centeno

2013-12-01

Full Text Available Os aços inoxidáveis duplex, devido à sua resistência à corrosão, têm uma grande aplicação em diversos segmentos industriais, onde a resistência à corrosão é uma propriedade requerida. Por terem resistência mecânica superior aos aços inoxidáveis ferríticos e austeníticos convencionais, podem produzir equipamentos mais leves. Quando ciclados termicamente, estes aços podem ter suas propriedades alteradas, principalmente quando se emprega processos de junção, como a brasagem, e quando ocorre o desbalanceamento da fração volumétrica ferrita/austenita. O objetivo deste trabalho é caracterizar a brasagem de aços inoxidáveis duplex 'baixa liga' e superduplex, verificando o efeito da folga e do tempo de brasagem na formação de intermetálicos contínuos no interior da junta brasada. Neste trabalho foram brasados, em forno continuo com atmosfera de hidrogênio, corpos-de-prova de aço inoxidável duplex UNS S32101, UNS S32304 e UNS S32750 com a adição para brasagem BNi-7 (Ni-Cr-P, na temperatura de 1100ºC, por tempos de 12 min e 32 min, utilizando-se folgas das juntas de 0,0 e 0,3 mm, seguidos de resfriamento em forno. Os corpos de prova foram caracterizados utilizando-se microscópio óptico, microscópio eletrônico de varredura com EDS e difração de raios X. Os resultados mostraram que a melhor condição para a brasagem em forno empregado foi a brasagem com a folga de 0,0 mm. Ambas as folgas apresentaram microestruturas variadas, porém a folga de 0,0 mm mostrou a presença de uma fase contínua CFC (cúbica de face centrada, rica em níquel, que é denominada, frequentemente, de γ-Ni. Para folgas de 0,3 mm, forma-se uma região eutética contínua no centro da junta, que pode prejudicar as propriedades mecânicas da mesma. Esta região é composta de fases intermetálicas ricas em fósforo. Foram observadas precipitações de fase sigma no metal de base no AID UNS S35750, nas condições de brasagem estudadas.

29 CFR 541.304 - Practice of law or medicine.

Science.gov (United States)

2010-07-01

... 29 Labor 3 2010-07-01 2010-07-01 false Practice of law or medicine. 541.304 Section 541.304 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS DEFINING AND DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Professional Employees §...

Resultados de ensayos de soldadura a tope y por solape, con electrodo, de barras de aceros estirados en frío

Directory of Open Access Journals (Sweden)

Calavera Ruiz, José

1969-03-01

Full Text Available The authors report on a series of tests carried out in the welding of reinforced concrete bars. The tested bars were cold drawn, with elastic limits of 4,200 and 5,000 kg/cm2. The tests included butt and overlap welding, involving excentric and axial overlaps, with joint reinforcements. Results of these experiments show that if the indicated method is adopted, including an average standard of workmanship, the weld attains 100 % of the bar strength.Los autores dan cuenta de una serie de ensayos realizados sobre soldadura de barras para hormigón armado. Las barras ensayadas son de acero estirado en frío con límites elásticos de 4.200 y 5.000 kp/cm2. Los ensayos abarcaron la soldadura a tope y la soldadura por solape, con sus variantes de solape excéntrico y solape centrado con cubrejuntas. Los resultados de los ensayos demuestran que siguiendo la técnica indicada, y con una calidad normal de ejecución, la soldadura presenta el 100 % de la resistencia de la barra.

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

Directory of Open Access Journals (Sweden)

L. Dumitrescu

2010-01-01

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

Designing of CK45 carbon steel and AISI 304 stainless steel dissimilar welds

OpenAIRE

Pouraliakbar,Hesam; Hamedi,Mohsen; Kokabi,Amir Hossein; Nazari,Ali

2014-01-01

Gas tungsten arc welding of CK45 and AISI304 stainless steel was performed through preparation of different types of samples using ER308L and ERNi-1 wires. Welded samples were studied by different techniques including optical metallography, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction, hardness measurements and impact test. It was observed that in the buttered specimen, the structure of the weld metal was completely austenitic wh...

Analysis of AISI 304 Tensile Strength as an Anchor Chain of Mooring System

Science.gov (United States)

Hamidah, I.; Wati, R.; Hamdani, R. A.

2018-05-01

The background of this research is the use of mild steel (i.e., St37) as anchor chain that works on the corrosive environment of seawater which is possible to decrease its tensile strength. The longer soaked in seawater, the more significant the lowering of its tensile strength. Anchor chain needs to be designed by considering its tensile strength and corrosion resistance, so it’s able to support mooring system well. The primary purpose of this research is obtaining the decreasing of stainless steel 304 (AISI 304) tensile strength which is corroded by seawater as anchor chain of the mooring system. It is also essential to obtain the lifetime of AISI304 and St37 as anchor chain with the same load, the corrosion rate of AISI 304, and St 37 in seawater. The method which was employed in this research is an experiment with four pieces of stainless steel AISI 304, and of St 37 corrosion testing samples, six pieces of stainless steel 304, and six pieces of St 37 for tensile testing samples. The result of this research shows that seawater caused stainless steel AISI 304 as anchor chain has decreased of tensile strength about 1.68 % during four weeks. Also, it indicates that AISI 304 as anchor chain has a lifetime about 130 times longer than St 37. Further, we found that the corrosion rate of stainless steel 304 in seawater is 0.2042 mpy in outstanding category, while the St 37 samples reached up to 27.0247 mpy ranked as fair category. This result recommends that AISI 304 more excellence than St 37 as anchor chain of the mooring system.