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Sample records for acero inoxidable 316l

  1. “ESTUDIO DEL COMPORTAMIENTO DE LOS ACEROS INOXIDABLES AUSTENITICOS 316 Y 316L, EN LA ZONA AFECTADA TERMICAMENTE, UNIDO POR SOLDADURA MIG, CON APLICACION DE INTERACCION ELECTROMAGNETICA DE BAJA INTENSIDAD”

    Estrella García, Salvador

    2012-01-01

    En el presente capítulo, se presenta un contenido breve acerca del tema a estudiar, es decir, de la influencia de la interacción de dos campos magnéticos de baja intensidad durante el proceso de soldadura MIG, en los aceros inoxidables austeníticos 316 y 316L, así como también los principales problemas que presentan dichos aceros inoxidables y de una manera simplificada el resumen de los objetivos planteados y la forma en que se desarrollarán. Los aceros inoxidables, son ino...

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

    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

  3. Aplicación y caracterización físico-química de varios tratamientos superficiales realizados al acero inoxidable 316L para aplicaciones biomédicas

    Mañá, M.; Valentí, J.; Mestre Vinardell, Aleix; Gil Mur, Francisco Javier

    2008-01-01

    La biocompatibilidad de los metales utilizados en implantología está íntimamente relacionada con las características superficiales de los implantes tanto desde un punto de vista químico como topográfico. El objetivo de este trabajo es aplicar varios tratamientos superficiales al acero inoxidable 316 L y caracterizar, posteriormente, la superficie físico-químicamente. La superficie pulida de varios discos de acero 316 L fue tratada mediante los procesos de: granallado, variando el tamaño y la...

  4. Aplicación y caracterización físico-química de varios tratamientos superficiales realizados al acero inoxidable 316 L para aplicacions biomédicas

    Mañá, M.; Valentí, J.; Mestre Vinardell, Aleix; Gil Mur, Francisco Javier

    2008-01-01

    La biocompatibilidad de los metales utilizados en implantología está íntimamente relacionada con las características superficiales de los implantes tanto desde un punto de vista químico como topográfico. El objetivo de este trabajo es aplicar varios tratamientos superficiales al acero inoxidable 316 L y caracterizar, posteriormente, la superficie físico-químicamente. La superficie pulida de varios discos de acero 316 L fue tratada mediante los procesos de: granallado, variando el tamaño y l...

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

    Gómez, P. P.

    2005-12-01

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

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

    Ricardo Gustavo Rodríguez Cañizo

    2010-10-01

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

  7. 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

    María Elena Márquez Fernández; Pablo Jesús Abad Mejía; Claudia Patricia García García; Andrés Pareja López

    2007-01-01

    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 i...

  8. 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

    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

  9. Sinterabilidad y propiedades del acero pulvimetalúrgico HCx diluido con aceros inoxidables

    Gordo, E.

    2005-12-01

    Full Text Available HCx is a powder metallurgy steel developed to combine the corrosion resistance of stainless steel with the wear resistance of tool steels. Therefore, HCx appears to be a suitable material for wear applications in aggressive environments, as valve seat inserts in automotive engines. In this work dilution of HCx with two stainless steels, one ferritic (430 and another austenitic (316L, in percentages up to 15 % in mass, has been studied to improve process conditions, especially compressibility. The sinterability of diluted materials was studied through vacuum sintering at temperatures from 1.200 °C to 1.260 °C. Finally, properties of sintered materials were determined. The results are discussed in relation to the microstructure evolution.

    El acero pulvimetalúrgico HCx ha sido desarrollado para combinar la resistencia a corrosión de los aceros inoxidables con la resistencia al desgaste de los aceros de herramientas. Aparece así como un material adecuado para componentes sometidos a desgaste en un ambiente agresivo, como los asientos de válvulas en motores de automóviles. En este trabajo se estudia la dilución del HCx con dos aceros inoxidables, uno ferrítico (430 y otro austenítico (316L, en porcentajes hasta 15 % en masa, para mejorar las condiciones de procesado, especialmente la compresibilidad. La sinterabilidad de los materiales diluidos se ha estudiado mediante sinterización en vacío, a temperaturas entre 1.200 °C y 1.260 °C, y se han determinado las propiedades de los materiales sinterizados. Los resultados se discuten en relación a la evolución microestructural.

  10. Soldabilidad de un acero de blindaje con electrodos de acero inoxidable austenitico

    GIRALDO BARRADA, JORGE ENRIQUE

    2005-01-01

    Se evaluaron las propiedades mecánicas y la microestructura de las soldaduras obtenidas con diferentes electrodos para unir platinas de un acero, templado y revenido, de alta dureza y baja aleación producido bajo la especificación MIL A46100, el cual es usado en la fabricación de estructuras blindadas. Se determinó el efecto que tiene el material de aporte (aceros inoxidables austeníticos, E307 y E308Mo, y dúplex, E312 y Eutectic 680),aplicado con proceso de soldadura al arco con electr...

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

    Marcelo Senatore

    2007-03-01

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

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

    Velasco, F.

    1997-04-01

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

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

  13. Estudio del fenómeno de Strain Ageing en el acero inoxidable metaestable 301 LN

    Hevin, Lucas

    2014-01-01

    Un acero inoxidable metaestable es una aleación que presenta el efecto TRIP: Transformation Induced Plasticity. El acero estudiado, EN 1.4318/AISI 301 LN, tiene una estructura austenítica que puede transformarse en martensita por deformación. Tiene una buena resistencia a corrosión, buena conformabilidad, y una combinación de límite elástico y de deformación máxima muy superior a otros aceros. Con dicha transformación martensítica se puede aumentar el límite elástico y la resistencia a tracci...

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

    José Luddey Marulanda Arevalo

    2013-12-01

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

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

    Carlos Eduardo Pinedo

    2013-06-01

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

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

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

    2004-01-01

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

  17. Comportamiento frente a corrosión bajo tensión en ambiente marino de armaduras de acero inoxidable dúplex

    Fernández Robles, José Jaime

    2015-01-01

    La utilización de barras corrugadas de acero inoxidable en estructuras de hormigón armado, se está mostrando como una alternativa con gran futuro en estructuras expuestas a ambientes muy agresivos o que requieran vidas en servicio muy elevadas. Estos aceros inoxidables cuentan con similares propiedades mecánicas que los aceros al carbono pero un comportamiento muy mejorado frente a la corrosión, especialmente frente a cloruros. Dentro de los aceros inoxidables, los del tipo dúplex tienen ...

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

    Marcelo Senatore; Leandro Finzetto; Eduardo Perea

    2007-01-01

    Os aços inoxidáveis dúplex ferríticos-austeníticos fazem parte de uma classe de materiais com microestrutura bifásica, composta por uma matriz ferrítica e ilhas de austenita, com frações volumétricas aproximadamente iguais dessas fases. Essa classe de materiais é caracterizada por apresentar interessante combinação de elevadas propriedades mecânicas e de resistência à corrosão e, por isso, é considerada bastante versátil. Os aços inoxidáveis dúplex são, freqüentemente, utilizados nas indústri...

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

    Martínez, M.; Suwardjo, W.; Aragón, B.; García, L.; Formoso, A.; Cortés, A.

    2001-01-01

    En el trabajo se trata el desarrollo de la tecnología de obtención de polvos microporosos de acero inoxidable mediante atomización y recocido de descarburación. La esencia del proceso consiste en recarburar el metal en estado líquido y, posteriormente, descarburar el polvo en estado sólido mediante recocido en hidrógeno o amoniaco disociado. Con esta tecnología se logra la formación de una microporosidad interna en la partícula, que aligera el material y mejora los procesos de conformación, y...

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

    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 %.

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

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

    2012-01-01

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

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

    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.

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

    Fosca, C.

    1996-08-01

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

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

  4. Desarrollo de un modelo predictivo de la degradación de lacas colaminadas sobre aceros inoxidables

    Peña de la Mora, Eduardo

    2007-01-01

    En ese trabajo anterior se desarrollaron dos modelos acelerados de prueba que predicen la degradación de lacas con base de dos componentes de poliuretano aplicados sobre acero inoxidable 304 del tipo austenítico. Sin embargo, dichos modelos son de tipo particular. Es decir, específicos para las características particulares de las lacas estudiadas. En síntesis, no se cuenta ni con un procedimiento de prueba general, ni con un modelo general de pruebas aceleradas que permita predecir el envejec...

  5. Recubrimientos por sol-gel sobre sustratos de acero inoxidable, revisión del estado del arte

    EMIGDIO MENDOZA; CLAUDIA GARCÍA

    2008-01-01

    En este trabajo se presenta una recopilación bibliográfica de los recubrimientos inorgánicos, híbridos, con partículas dispersas, depositados sobre aleaciones de acero inoxidable por medio de la técnica sol-gel. A partir de estos recubrimientos es posible la modificación de las propiedades superficiales de estas aleaciones metálicas, en busca de mejorar su resistencia química, además del grado de biocompatibilidad cuando están expuestas a ambientes fisiológicos.

  6. Recubrimientos por sol-gel sobre sustratos de acero inoxidable, revisión del estado del arte

    EMIGDIO MENDOZA

    2007-01-01

    Full Text Available En este trabajo se presenta una recopilación bibliográfica de los recubrimientos inorgánicos, híbridos, con partículas dispersas, depositados sobre aleaciones de acero inoxidable por medio de la técnica sol-gel. A partir de estos recubrimientos es posible la modificación de las propiedades superficiales de estas aleaciones metálicas, en busca de mejorar su resistencia química, además del grado de biocompatibilidad cuando están expuestas a ambientes fisiológicos

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

    José D.B de Mello

    2006-01-01

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

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

    Carlos Eduardo Pinedo; André Paulo Tschiptschin

    2013-01-01

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

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

    Ruiz-Prieto, J. M.

    2005-12-01

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

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

    Amigó, V.

    2005-04-01

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

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

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

    Bethencourt, M.

    2010-02-01

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

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

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

    González, O.

    2003-12-01

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

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

  13. Efecto de la predeformación en la vida a fatiga de un acero inoxidable austenítico metaestable

    Durán Avilés, Ana María

    2009-01-01

    Los aceros de tipo 301LN son aceros inoxidables austeníticos metaestables de baja aleación que pueden transformar a martensita por deformación. Esta transformación tiene lugar por mecanismos cristalográficos, al producirse un movimiento colectivo de átomos por cizalladura. El desplazamiento de los átomos es inferior a las distancias interatómicas, de manera que aunque los mecanismos de difusión no intervienen se observa un cambio de volumen. La cantidad de austenita transfor...

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

    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.

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

    Gironès, A.

    2001-04-01

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

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

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

    Vargas Morales, Karla Odette

    2012-01-01

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

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

    Ruiz-Prieto, J. M.; G. Cambronero, L. E.; Iglesias, F. J; Corpas, F.; Ruiz-Román, J. M.

    2005-01-01

    In this Work the influence of sintering AISI 430L stainless steel in N2-H2 atmosphere on its properties and microstructure have been studied. The presence of nitrogen in the sintering atmosphere leads to complex nitrides formation the AISI 430L sintered steel microstructure. A subsequent heat treatment was applied to modify this microstructure in order to improve the mechanical properties and corrosion resistance of these ferritic stainless steels.Los aceros inoxidables ferríticos, son aceros...

  18. Estudio del efecto de la irradiación en aceros inoxidables 316 (Study of irradiation effect on the stainless steels type 316)

    Yagüe Martín-Lunas, César

    2011-01-01

    Los cambios en la microestructura inducidas por la radiación neutrónica contribuyen de manera importante en el comportamiento de los componentes internos bajo operación de los reactores nucleares. La radiación neutrónica induce defectos en la microestructura en forma de bucles de dislocación y también la redistribución de átomos de soluto e impurezas. En la serie 300, los aceros inoxidables austeníticos, materiales estructurales comunes usados en los componentes del núcleo de los reactores de...

  19. Influencia de la composición y el conformado en el comportamiento frente a la corrosión de los corrugados de acero inoxidable

    Álvarez Arboleda, Sandra Milena

    2014-01-01

    En la presente Tesis Doctoral se evalúa el comportamiento frente a la corrosión de barras corrugadas de aceros inoxidables (que pueden ser utilizadas como refuerzo en las partes más expuestas de las estructuras de hormigón) y se analizan en profundidad diversos factores que pueden influir en su durabilidad. El estudio de la influencia de la composición química de las barras ha demostrado el gran interés de los nuevos grados 2001 y el 2304 (dúplex de baja aleación), que ofrecen excelentes resu...

  20. Comportamiento frente a la corrosión de nuevos tipos de armaduras de acero inoxidable para estructuras de hormigón armado

    Blanco Rodríguez, Gema

    2009-01-01

    En la presente Tesis Doctoral se ha realizado un profundo estudio sobre el comportamiento frente a la corrosión de nuevos tipos de armaduras de acero inoxidable para su empleo en estructuras de hormigón armado. Las estructuras de hormigón armado suelen presentar graves problemas de corrosión en medios con cloruros o cuando el hormigón se carbonata. Las alternativas tradicionales para aumentar su durabilidad (protección catódica, galvanizados, resinas epoxi, adición de inhibidores, etc.) han d...

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

    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...

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

    Oñoro, J.

    2006-02-01

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

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

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

    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.

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

    Moratilla, B.Y.; J.I. Linares; Portolés, A.

    2005-01-01

    Se realiza un estudio simple de tensiones considerando dos materiales, acero inoxidable y acero de baja aleación. El estudio es motivado porque en la industria petroquímica es práctica habitual, para reducir costes de materiales, utilizar recargues de inoxidable sobre una pared de acero de baja aleación para la construcción de la pared de reactores. Se determina el coeficiente de dilatación térmica y su evolución a lo largo del espesor de la zona afectada térmicamente, usando una probeta extr...

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

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

    2013-01-01

    Los recubrimientos de aluminio-silicio fueron depositados sobre el acero inoxidable AISI 316 mediante deposición química de vapor en lecho fluidizado (CVD-FBR), en el rango de temperaturas de 540 a 560 ºC, utilizando un lecho formado por 2,5 g de silicio y 7,5 g de aluminio en polvo, y 90 g de lecho inerte (Alúmina), el cual se hizo fluidizar con Ar. Como gases activadores se usó una mezcla de HCl/H2, en relaciones de 1/10 a 1/16. Además, se varió el tiempo de deposición de los recubrimientos...

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

    Fargas, G.

    2004-06-01

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

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

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

    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

  8. Evaluación de la resistencia a la corrosión de recubrimientos de ZrOxNy sobre acero inoxidable y/o silicio mediante técnicas electroquímicas

    Cubillos González, Gloria Ivonne

    2013-01-01

    Se hicieron crecer películas de oxinitruro de zirconio ZrOxNy sobre tres sustratos diferentes: acero inoxidable, Si (100) y vidrio, empleando tres técnicas distintas: spray pirólisis-nitruración (UPS-N), sputtering con radiofrecuencia (RF) y sputtering DC con magnetrón desbalanceado. Para cada una de ellas se optimizó las condiciones de depósito y se estudió la influencia de las mismas en las características estructurales y morfológicas del recubrimiento. Adicionalmente, se realizó la evaluac...

  9. Corrosión de aceros inoxidables martensíticos 13CrNiMo de bajo contenido de carbono en las industrias de gas y petróleo

    Méndez, Claudia Marcela

    2013-01-01

    Los aceros inoxidables 13CrNiMo con bajo contenido de carbono, surgen como alternativa para el reemplazo de materiales más caros en el uso como sistemas de transporte de fluidos de las industrias de gas y petróleo, con concentraciones importantes de cloruros, pCO2, pH2S y temperatura elevadas. El bajo contenido en carbono permite salvar algunos problemas vinculados a la operación de soldadura. Con el fin de obtener una alta tenacidad, se realizan tratamientos térmicos de precalentamiento y de...

  10. Identificación y cuantificación de fases en acero inoxidable ASTM A743 grado CA6NM mediante la técnica de difracción de rayos x

    Rojas Marín, Jessika Viviana

    2009-01-01

    La técnica de difracción de rayos X a altas temperaturas fue aplicada al estudio de las transformaciones de fase en el acero inoxidable martensítico ASTM A743 grado CA6NM, material ampliamente usado en la fabricación de componentes hidráulicos por las excelentes propiedades mecánicas que ofrece. Mediante la técnica de difracción de rayos X y en el intervalo de temperaturas entre 25-860°C se estudió la dilatación térmica del acero durante el calentamiento, se identificaron las temperaturas de ...

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

    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

  12. Influencia del tamaño del grano en las propiedades mecánicas de los aceros inoxidables austeníticos

    Martínez, M. A.

    2005-12-01

    Full Text Available The goal of this work is to study the influence of the grain size on mechanical properties of austenitic stainless steels. The study covers both, stable stainless steels and metastable steels. A relevant topic is to identify the differences in the behaviour of both types of steels. First of all, several steel taps are taken into account and by this way the average of results are derived. A sorted collection of them show its behaviour. Several rules are identified, like straight relationship between the number of grain size (ASTM and the 0.2 % proof stress and the tensile strength and inverse relationship with the elongation. Specific studies analyzing the relevance of nickel are performed. Finally main conclusions and valuations are presented and some statistic results of mechanics properties and steel taps are performed in order to get better prediction of their behaviour.

    En el presente trabajo se lleva a cabo un análisis de la influencia del tamaño del grano de aceros inoxidables austeníticos sobre algunas propiedades mecánicas de interés en estos materiales. Se han estudiado tanto aceros estables como metaestables para valorar las diferencias de comportamiento, considerando varias coladas de cada material para promediar los resultados y obtener un comportamiento más robusto de los estimadores. Se ha procedido a una preparación y adecuación de las probetas, previa a su ensayo en laboratorio. Se han observado los comportamientos habituales de modo que, a mayor número de tamaño de grano según norma ASTM, mayor límite elástico y resistencia a la tracción y menor alargamiento; llevándose a cabo estudios de detalle de valores de las tendencias de crecimiento, comportamiento comparado de estables y metaestables y valorándose cuidadosamente la influencia del níquel presente en el material. Finalmente se presentan las principales conclusiones y valoraciones, y un estudio estadístico de las propiedades mecánicas y de las

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

    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.

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

    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.

  15. Estrutura e propriedades do aço inoxidável austenítico AISI 316L Grau ASTM F138 nitretado sob plasma à baixa temperatura Structure and properties of an austenitic stainless steel AISI 316L grade ASTM F138 after low temperature plasma nitriding

    André Paulo Tschiptschin

    2010-03-01

    Full Text Available Os aços inoxidáveis austeníticos possuem restrições para a nitretação nas temperaturas convencionais, próximas de 550ºC, devido à precipitação intensa de nitretos de cromo na zona de difusão. Essa precipitação eleva a dureza, mas deteriora as propriedades de corrosão. O uso do processo de nitretação sob plasma permite introduzir nitrogênio em temperaturas inferiores a 450ºC, levando à formação de uma fina camada de austenita expandida pelo nitrogênio (gN. Essa fase possui uma estrutura cristalina mais bem representada pelo reticulado triclínico, com elevada concentração de nitrogênio em solução sólida supersaturada, a qual promove um estado de tensões residuais de compressão capaz de elevar a dureza do substrato de 4 GPa para valores próximos de 14 GPa. O Módulo de Elasticidade mantém-se próximo de 200 GPa após a nitretação.Austenitic stainless steels cannot be conventionally nitrided at temperatures near 550°C due to the intense precipitation of chromium nitrides in the diffusion zone. The precipitation of chromium nitrides increases the hardness but severely impairs corrosion resistance. Plasma nitriding allows introducing nitrogen in the steel at temperatures below 450°C, forming pre-dominantly expanded austenite (gN, with a crystalline structure best represented by a special triclinic lattice, with a very high nitrogen atomic concentration promoting high compressive residual stresses at the surface, increasing substrate hardness from 4 GPa up to 14 GPa on the nitrided case.

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

    Iza-Mendia, A.

    1998-05-01

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

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

  17. Efecto del silicio como posible elemento reactivo en la protección frente a la oxidación a elevada temperatura del acero inoxidable AISI 304

    Otero, E.

    1998-05-01

    Full Text Available The influence of silicon incorporated into the alloy by means of ion implantation of 1 x 1015 ions/cm2 at 150 keV on the protective scale development based upon Cr1,3Fe0,7O3 and manganese-enriched spinels, Mn1,5Cr1,5O4 after oxidation of an austenitic AISI 304 stainless steel at 1,173 K and atmospheric pressure of air for 144 h has been studied. The presence of small quantities of silicon at the outermost layers of the alloy promotes transport of chromium during the early stages of oxidation. Further, ion implantation seems to play a beneficial role against decarburization of the alloy.

    Se estudia la influencia de silicio incorporado a la aleación mediante implantación iónica de 1 x 1015 iones/cm2 a 150 keV en el crecimiento de la capa protectora de oxidación basada en Cr1,3Fe0,7O3 y en espinelas enriquecidas en manganeso, Mn1,5Cr1,5O4, tras someter a un acero inoxidable austenítico AISI 304 a oxidación a 1.173 K y presión atmosférica de aire durante 144 h. La presencia de pequeñas cantidades de silicio en las capas más externas del material promueve el transporte de cromo durante los primeros estadios de la oxidación. Además, la implantación iónica parece ejercer un efecto beneficioso contra la descarburación de la aleación.

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

    Coello, J.

    2008-12-01

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

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

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

    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.

  20. Soldabilidad del acero inoxidable austenitico

    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.

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

    Gallegos, A.

    2012-12-01

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

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

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

    Medina, E.

    2012-12-01

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

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

  3. Transformaciones de inequilibrio producidas por ciclos anisotérmicos en aceros inoxidables martensíticos tipo 13Cr y 14CrMoV

    Álvarez Moreno, Luisa Fernanda

    1991-01-01

    Diversas investigaciones en el campo de las transformaciones de inequilibrio en estado sólido han intentado buscar explicación a ciertos comportamientos atípicos observados en el desarrollo de la transformación martensítica de aceros aleados con elementos carburíqenos, tales como el cromo, molibdeno, vanadio y wolframio. En estos aceros aleados, la transformación anisotérmica de la austenita en rnartensita no se realiza de forma continua durante el enfriamiento en un intervalo determinado de ...

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

    Diego Pérez-Muñoz

    2015-09-01

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

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

    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.

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

    Gutiérrez de Saiz-Solabarría, S.; San Juan, J. M.; Valea, A.

    1998-01-01

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

    Se estudia el comportamiento de un mismo acero moldeado inoxidable dúplex austeno-ferrítico (48-52 %) del tipo 2...

  7. 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

    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

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

    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...

  9. Susceptibilidad a la Fractura Inducida por Hidrógeno de Soldadura de Placa Clad de Acero Inoxidable 12% Cr Hydrogen Induced Cracking Susceptibility of 12% Cr Stainless Steel Clad Plate Weld

    Víctor M Sánchez

    2006-01-01

    Full Text Available En este trabajo se evalúa la susceptibilidad a la fractura inducida por hidrógeno (FIH en cordones aplicados sobre placa clad 1¼ Cr-½Mo + Acero Inoxidable ferrítico/martensítico 12% Cr. Para ello se ha desarrollado un sistema basado en la prueba del implante propuesta por Granjon, con el proceso de soldadura GMAW y diferentes niveles de hidrógeno en el gas de protección. Se presentan resultados de análisis fractográfico con microscopía electrónica de barrido, metalografía, perfil de dureza y correlación a través de modelos de regresión del esfuerzo critico de fractura versus hidrógeno difusible, carbono equivalente, y tiempo de enfriamiento. Los resultados del modelado son satisfactorios al compararlos con los resultados experimentales.The aim of the work was to evaluate the hydrogen induced cracking (HIC susceptibility of weld beads applied on 1¼ Cr-½Mo + ferritic/martensitic stainless steel 12% Cr clad plate. For this, a system was developed based on the implant test proposed by Granjon, with the GMAW welding process and different hydrogen levels in the shielding gas. The results of this research included SEM fractographic analysis, metallography, hardness profile and correlation through a mathematical regression model of the critical fracture stress versus diffusible hydrogen, carbon equivalent, and cooling time. The results of the modeling are found to be satisfactory when compared with experimental data.

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

    Almeraya-Calderón, F.

    2012-04-01

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

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

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

    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

  12. 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

    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.

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

    Coello, J.

    2009-10-01

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

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

  14. Ion nitriding in 316=L stainless steel

    Ion nitriding is a glow discharge process that is used to induce surface modification in metals. It has been applied to 316-L austenitic stainless steel looking for similar benefits already obtained in other steels. An austenitic stainless steel was selected because is not hardenable by heat treatment and is not easy to nitride by gas nitriding. The samples were plastically deformed to 10, 20, 40, 50 AND 70% of their original thickness in order to obtain bulk hardening and to observe nitrogen penetration dependence on it. The results were: an increase of one to two rockwell hardness number (except in 70% deformed sample because of its thickness); an increase of even several hundreds per cent in microhardness knoop number in nitrided surface. The later surely modifies waste resistance which would be worth to quantify in further studies. Microhardness measured in an internal transversal face to nitrided surface had a gradual diminish in its value with depth. Auger microanalysis showed a higher relative concentration rate CN/CFe near the surface giving evidence of nitrogen presence till 250 microns deep. The color metallography etchant used, produced faster corrosion in nitrited regions. Therefore, corrosion studies have to be done before using ion nitrited 316-L under these chemicals. (Author)

  15. Evaluación del comportamiento mecánico, estructural y frente a la corrosión, de una nueva armadura de acero inoxidable dúplex bajo en níquel

    Medina Sanchez, Eduardo

    2012-01-01

    La durabilidad de las estructuras de hormigón armado no es ilimitada, en especial en determinados ambientes. El ingreso de agentes agresivos en el hormigón, fundamentalmente dióxido de carbono e iones cloruros, rebasando el espesor del recubrimiento y alcanzando las armaduras, reducen el alto pH del hormigón hasta alcanzar un umbral crítico, por debajo del cual, el acero queda despasivado. Posteriormente, si existe el suficiente aporte de humedad y oxígeno, el acero se corroe, lo que supone d...

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

    Gutiérrez de Saiz-Solabarría, S.

    1998-05-01

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

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

  17. Study of Ce-modified antibacterial 316L stainless steel

    Yuan Junping

    2012-11-01

    Full Text Available 316L stainless steel is widely used for fashion jewelry, but it can carry a large number of bacteria and bring the risk of infection since the steel has no antimicrobial performance. In this paper, the effects of Ce on the antibacterial property, corrosion resistance and processability of 316L were studied by microscopic observation, thin-film adhering quantitative bacteriostasis, and electrochemical and mechanical tests. The results show that a trace of Ce can distribute uniformly in the matrix of 316L and slightly improve its corrosion resistance in artificial sweat. With an increase in Ce content, the Ce is prone to form clustering, which degrades the corrosion resistance and the processability. The Ce-containing 316L exhibits Hormesis effect against S. aureus. A small Ce addition stimulates the growth of S. aureus. As the Ce content increases, the modified 316L exhibits an improved antibacterial efficacy. The more Ce is added, the better antibacterial capability is achieved. Overall, if the 316L is modified with Ce alone, it is difficult to obtain the optimal combination of corrosion resistance, antibacterial performance and processability. In spite of that, 0.15 wt.%-0.20 wt.% Ce around is inferred to be the best trade-off.

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

    Molleja, Javier García

    2014-01-01

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

  19. 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

    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.

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

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

    2008-07-01

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

  1. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    Kruszewski, Kristen M; Nistico, Laura; Mark J Longwell; Hynes, Matthew J; Maurer, Joshua A; Hall-Stoodley, Luanne; Gawalt, Ellen S.

    2013-01-01

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with lo...

  2. 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

    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.

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

    Botella, J.

    1998-05-01

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

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

  4. Biomaterial Studies on AISI 316L Stainless Steel after Magnetoelectropolishing

    Massimiliano Filippi

    2009-03-01

    Full Text Available The polarisation characteristics of the electropolishing process in a magnetic field (MEP – magnetoelectropolishing, in comparison with those obtained under standard/conventional process (EP conditions, have been obtained. The occurrence of an EP plateau has been observed in view of the optimization of MEP process. Up-to-date stainless steel surface studies always indicated some amount of free-metal atoms apart from the detected oxides and hydroxides. Such a morphology of the surface film usually affects the thermodynamic stability and corrosion resistance of surface oxide layer and is one of the most important features of stainless steels. With this new MEP process we can improve metal surface properties by making the stainless steel more resistant to halides encountered in a variety of environments. Furthermore, in this paper the stainless steel surface film study results have been presented. The results of the corrosion research carried out by the authors on the behaviour of the most commonly used material - medical grade AISI 316L stainless steel both in Ringer’s body fluid and in aqueous 3% NaCl solution have been investigated and presented earlier elsewhere, though some of these results, concerning the EIS Nyquist plots and polarization curves are also revealed herein. In this paper an attempt to explain this peculiar performance of 316L stainless steel has been undertaken. The SEM studies, Auger electron spectroscopy (AES and X-ray photoelectron spectroscopy (XPS were performed on 316L samples after three treatments: MP – abrasive polishing (800 grit size, EP – conventional electrolytic polishing, and MEP – magnetoelectropolishing. It has been found that the proposed magnetoelectropolishing (MEP process considerably modifies the morphology and the composition of the surface film, thus leading to improved corrosion resistance of the studied 316L SS.

  5. Study of hydroxyapatite behaviour during sintering of 316L steel

    A. Szewczyk-Nykiel; M. Nykiel

    2010-01-01

    316L stainless steel – hydroxyapatite composite biomaterials with different hydroxyapatite weight fraction in the composite wereinvestigated. Hydroxyapatite (HAp – Ca10(PO4)6(OH)2) is well known biomaterial. HAp reveals excellent chemical and biological affinitywith bony tissues. On the other hand hydroxyapatite shows low mechanical properties. The combination of very good biocompatibility of hydroxyapatite and high mechanical properties of stainless steel seems to be a good solution. In pres...

  6. Linear friction welding of AISI 316L stainless steel

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

  7. Emission of deuterium from SS 316L after plasma bombardment

    The understanding of the recycling (particle re-emission) behaviour of hydrogen isotopes from the first wall structures to the plasma of a fusion reactor is a crucial issue in plasma-wall interaction research, because the plasma performance will strongly depend on the time-scale and magnitude of this phenomenon. Deuterium recycling measurements from AISI 316L austenitic stainless steel surfaces have been performed in an experimental facility capable of reproducing particle flux densities and ion energies similar to those of ITER. The recycling flux has been evaluated. It is strongly dependent upon the impinging particle flux while target temperature and particle energy do not play a significant role. From these measurements a recombination coefficient for the system deuterium-AISI 316L has been calculated. The values are quite low, hence indicating that the AISI 316L sample target used was covered by an oxide layer that inhibits recombination. Moreover, the chemical composition of the recycling flux is pure molecular deuterium. ((orig.))

  8. Study of hydroxyapatite behaviour during sintering of 316L steel

    A. Szewczyk-Nykiel

    2010-07-01

    Full Text Available 316L stainless steel – hydroxyapatite composite biomaterials with different hydroxyapatite weight fraction in the composite wereinvestigated. Hydroxyapatite (HAp – Ca10(PO46(OH2 is well known biomaterial. HAp reveals excellent chemical and biological affinitywith bony tissues. On the other hand hydroxyapatite shows low mechanical properties. The combination of very good biocompatibility of hydroxyapatite and high mechanical properties of stainless steel seems to be a good solution. In presented research natural originhydroxyapatite and 316L austenitic stainless steel were used. In this work, metal-ceramics composites were fabricated by the powdermetallurgy technology (involving pressing and sintering process. Sintering was carried out at 1250oC in hydrogen atmosphere. Thedensity, porosity and hardness were investigated. Metallographic microscope and SEM were carried out in order to investigate themicrostructure. The horizontal NETZSCH DIL 402E dilatometer was used to evaluate the dimensional changes and phenomena occurringduring sintering. The research displayed that physical properties of sintered 316L-HAp composites decrease with increase ofhydroxyapatite content. Microstructure of investigated composites consists of austenitic and probably inclusions of hydroxyapatite andheterogeneous eutectic occurring on the grain boundaries. It was shown that amount of hydroxyapatite in the powder mixtures influencethe dimensional changes occurring during sintering.

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

    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

  10. Surface modification of investment cast-316L implants: microstructure effects.

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase. PMID:25579929

  11. Corrosion of 316L stainless steels MAVL wastes containers

    The long lived and medium activity wastes are conditioned or could be re-conditioned in primary drums of 316L stainless steels. In the framework of wastes storage, these drums will be placed in concrete containers; each containers would contain one or more drums. This document recalls global information on the corrosion of stainless steels, analyzes specific conditions bond to the drums conditioning in concrete containers and the nature of the wastes, and details the consequences on the possible risks of external and internal corrosion of the drums. (A.L.B.)

  12. Hydrogen embrittlement of 316L type stainless steel

    Hydrogen embrittlement tests on type 316L stainless steel are performed including cathodic charging during slow strain rate tests. Brittle multiple cracking is observed and relationships between crack growth rate and diffusion are analysed. The influence of hydrogen on the morphology of ductile fracture is found after fractographic examination. Two aspects of ductile failure are observed in accordance with the hydrogen content of the sample; a reduced density of microvoids for higher hydrogen contents and brittle secondary cracking in addition to ductile fracture surfaces for lower hydrogen contents. (orig.)

  13. In pile AISI 316L. Low cycle fatigue. Final report

    In pile testing of the effect of neutron irradiation on the fatigue life of the reference material AISI 316L was performed in the framework of the European fusion technology program. The overall programme, carried out at SCK CEN (Mol,Belgium), exists of two instrumented rigs for low cycle fatigue testing, which were consecutively loaded in the BR-2 reactor during periods Jan (94) June (94) and Aug (94)-Dec(94). In each experiment, two identical samples were loaded by means of a pneumatically driven system. The samples were instrumented with thermocouples, strain gages, linear variable displacement transducers, and activation monitors. The experimental conditions are given. Type of fatigue test: load controlled, symmetric, uniaxial, triangular wave shape; stress range: about 580 MPa; sample shape: hourglass, diameter 3.2 mm, radius 12.5 mm; environment: NaK (peritectic); temperature: 250 C; maximum dpa value up to fracture: 1.7. Two of four samples were broken (one in each experiment) after having experienced 17 419 respectively 11 870 stress cycles. These new data points confirm earlier results from pile fatigue tests: irradiation causes no degradation of fatigue life of AISI 316L steel, at least for the parameters corresponding to these experiments

  14. Microstructural characterization of pulsed plasma nitrided 316L stainless steel

    Highlights: → The low temperature pulsed plasma nitrided layer of 316 SS was studied. → The plastic deformation induced in the austenite due to nitriding is characterized by EBSD at different depths (i.e., nitrogen concentration). → Nanomechanical properties of the nitride layer was investigated by nanoindentation at different depths (i.e., nitrogen concentration). → High hardness, high nitrogen concentration and high dislocation density is detected in the nitride layer. → The hardness and nitrogen concentration decreased sharply beyond the nitride layer. - Abstract: Pulsed plasma nitriding (PPN) treatment is one of the new processes to improve the surface hardness and tribology behavior of austenitic stainless steels. Through low temperature treatment (<440 deg. C), it is possible to obtain unique combinations of wear and corrosion properties. Such a combination is achieved through the formation of a so-called 'extended austenite phase'. These surface layers are often also referred to as S-phase, m-phase or γ-phase. In this work, nitrided layers on austenitic stainless steels AISI 316L (SS316L) were examined by means of a nanoindentation method at different loads. Additionally, the mechanical properties of the S-phase at different depths were studied. Electron back-scatter diffraction (EBSD) examination of the layer showed a high amount of plasticity induced in the layer during its formation. XRD results confirmed the formation of the S-phase, and no deleterious CrN phase was detected.

  15. Microstructural characterization of pulsed plasma nitrided 316L stainless steel

    Asgari, M. [Norwegian University of Science and Technology, Trondheim (Norway); Barnoush, A., E-mail: a.barnoush@matsci.uni-sb.de [Saarland University, Saarbruecken (Germany); Johnsen, R. [Norwegian University of Science and Technology, Trondheim (Norway); Hoel, R. [MOTecH Plasma Company, Oslo (Norway)

    2011-11-25

    Highlights: {yields} The low temperature pulsed plasma nitrided layer of 316 SS was studied. {yields} The plastic deformation induced in the austenite due to nitriding is characterized by EBSD at different depths (i.e., nitrogen concentration). {yields} Nanomechanical properties of the nitride layer was investigated by nanoindentation at different depths (i.e., nitrogen concentration). {yields} High hardness, high nitrogen concentration and high dislocation density is detected in the nitride layer. {yields} The hardness and nitrogen concentration decreased sharply beyond the nitride layer. - Abstract: Pulsed plasma nitriding (PPN) treatment is one of the new processes to improve the surface hardness and tribology behavior of austenitic stainless steels. Through low temperature treatment (<440 deg. C), it is possible to obtain unique combinations of wear and corrosion properties. Such a combination is achieved through the formation of a so-called 'extended austenite phase'. These surface layers are often also referred to as S-phase, m-phase or {gamma}-phase. In this work, nitrided layers on austenitic stainless steels AISI 316L (SS316L) were examined by means of a nanoindentation method at different loads. Additionally, the mechanical properties of the S-phase at different depths were studied. Electron back-scatter diffraction (EBSD) examination of the layer showed a high amount of plasticity induced in the layer during its formation. XRD results confirmed the formation of the S-phase, and no deleterious CrN phase was detected.

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

    Miguel, V.

    2013-06-01

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

  17. A Study on Stainless Steel 316L Annealed Ultrasonic Consolidation and Linear Welding Density Estimation

    Gonzalez, Raelvim

    2010-01-01

    Ultrasonic Consolidation of stainless steel structures is being investigated for potential applications. This study investigates the suitability of Stainless Steel 316L annealed (SS316L annealed) as a building material for Ultrasonic Consolidation (UC), including research on Linear Welding Density (LWD) estimation on micrographs of samples. Experiment results are presented that include the effect of UC process parameters on SS316L annealed UC, optimum levels of these parameters, and bond qual...

  18. Perfluorocarbon thin films and polymer brushes on stainless steel 316L for control of interfacial properties

    Kruszewski, Kristen M; Gawalt, Ellen S.

    2011-01-01

    Perfluorocarbon thin films and polymer brushes were formed on stainless steel 316L (SS316L) to control the surface properties of the metal oxide. Substrates modified with the films were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), contact angle analysis, atomic force microscopy (AFM), and cyclic voltammetry (CV). Perfluorooctadecanoic acid (PFOA) was used to form thin films by self-assembly on the surface of SS316L. Polypentafluorostyrene (PFS) poly...

  19. The behavior of diffusion and permeation of tritium through 316L stainless steel

    Results on diffusivity, solubility coefficient and permeability of tritium through palladium-plated 316 L stainless steel are described. An empirical formula for the diffusivity, the solubility coefficient and the permeability of tritium through palladium-plated 316 L stainless steel at various temperatures is presented. The influence of tritium pressure on the permeability, and the isotope effect of diffusivity of hydrogen and tritium in 316 L stainless steel is discussed. (orig.)

  20. Literature study - Sigma phase in 316L and 304L

    A literature survey of the existence, formation and kinetics of the sigma phase has been made. It was early realised that the precipitation of the sigma phase and that of 23-carbide were intimately coupled, why both are treated. The mechanical properties of both 304L and 316L are highly affected by the presence of sigma phase. The dominating features are: Yield strength is reduced, due to reduced solution hardening, Deformation hardening increases, Ultimate tensile stress increases, due to the presence of a hard phase, Impact strength is generally decreased. This is however dependant on the microstructure and processing. There are conditions where the impact strength can increase due to crack deflection, Ductility is significantly reduced. An additional conclusion is that the Huey test is too a blunt and conservative instrument to identify sensitization, caused by sigma phase. In a material that contains ferrite in some form, before aging, 23-carbide will precipitate in all welded 304L and 316L steels according to the literature. It is also clear that the first carbide to form is very fine and is precipitated before the sigma phase. This has the consequence that welded and annealed weldments will show some sensitization from 23-carbide. It is also clear that the amount of 23-carbide reduces as the amount of sigma phase increases. The time to the start of the dissolution, which could decrease the level of sensitization, depends on temperature. This could for instance explain why there are examples of sensitized 30L steel that showed excellent corrosion resistance. Direct corrosion of the sigma phase is highly pH-dependant. The sμμma phase has little resistance against oxidizing acids. It is thus important to understand the coupling between the sensitization caused by the 23-carbide and the change in ductility caused by the 23-carbide with sigma phase present. This is in turn primarily depending on the carbon content and the ferrite content after welding

  1. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS. PMID:23475060

  2. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH3) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L

  3. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    Kruszewski, Kristen M., E-mail: kruszewskik@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States); Nistico, Laura, E-mail: lnistico@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Longwell, Mark J., E-mail: mlongwel@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Hynes, Matthew J., E-mail: mjhynes@go.wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Maurer, Joshua A., E-mail: maurer@wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Hall-Stoodley, Luanne, E-mail: L.Hall-Stoodley@soton.ac.uk [Southampton Wellcome Trust Clinical Research Facility/NIHR Respiratory BRU, University of Southampton Faculty of Medicine, Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD (United Kingdom); Gawalt, Ellen S., E-mail: gawalte@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, McGowan Institute for Regenerative Medicine, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States)

    2013-05-01

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH{sub 3}) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L.

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

    Luciana Iglésias Lourenço Lima

    2010-06-01

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

  5. Susceptibility of 316L stainless steel to crevice corrosion in submersible solenoid valve

    Cai, B.P.; Liu, Y.H.; Tian, X.J.; Li, H.; Ji, R.J.; Wang, F.; Zhang, Y.Z. [School of Mechanical and Electronic Engineering, China University of Petroleum, Dongying, Shandong, 257061 (China)

    2011-08-15

    The susceptibility of 316L stainless steel to crevice corrosion was investigated by using immersion test and electrochemical test. Three kinds of crevices including 316L-to-polytetrafluoroethylene (PTFE) crevice, 316L-to-fluoroelastomeric (FKM) crevice and 316L-to-316L crevice were tested in artificial seawater at 50 C. The results indicate that 316L stainless steel specimen is the most susceptible to crevice corrosion when it is coupled to 316L stainless steel crevice former, while it is the least susceptible when it is coupled to FKM crevice former. It suggests that during submersible solenoid valve design, the crevice of metal-to-metal should be moderately large so that crevice corrosion can not initiate and propagate, and FKM O-ring rather than PTFE O-ring should be selected as obturating ring. The corroded surface morphology was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Three regions including passive region, active region and variable region can be observed on crevice corrosion sites. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting

    Zhong, Yuan; Liu, Leifeng; Wikman, Stefan; Cui, Daqing; Shen, Zhijian

    2016-03-01

    A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 °C and 250 °C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.

  7. Synthesis and electrochemical characterization of porous niobium oxide coated 316L SS for orthopedic applications

    Niobium oxide was prepared using sol-gel process and coated on 316L stainless steel (SS) substrate via dip-coating technique. The surface characterization results after a thermal treatment revealed that the coated surface was porous, uniform and well crystalline on the substrate. The corrosion resistance and bioactivity of the porous niobium oxide coated 316L SS in simulated body fluid (SBF) solution was evaluated. The in vitro test revealed a layer of carbonate-containing apatite formation over the coated porous surface. The results indicated that the porous niobium oxide coated 316L SS exhibited a high corrosion resistance and an enhanced biocompatibility in SBF solution.

  8. Surface hardening of stainless steel 316L with RF-plasma nitrocarburizing device

    Surface hardening on stainless steel 316L with RF-plasma nitrocarburizing device made by BATAN have been investigated. Some samples was nitrocarburized at 400°C for 2-6 hours. The results show that the hardness of the untreated sample of SS 316L was 230,7 Kgf/mm2 . The hardness increased up to 299,4 Kgf/mm2 for nitrocarburizing at 400°C for 6 hours. Furthermore, the maximum depth of carbon and nitrogen atoms diffused in SS 316L was 73,1 micrometer. Microstructure observation shows that the sample that was nitrocarburized at 400°C for 6 hours produced a very clear image indicating N and C atoms layers in SS 316L. The un-treated sample and the sample that was nitrocarburized at 400°C (t = 6 hours) have the same matrixes, i.e. δ-ferrite and pearlite. (author)

  9. Fractographic studies of hydrogen embrittlement of AISI 316L austenitic stainless steel

    This paper concerns a fractographic examination of hydrogen embrittlement of a stable AISI 316L type austenitic stainless steel. The objective is a better understanding of the possible role of hydrogen in stress corrosion cracking processes. (author)

  10. Improvement in the Corrosion Resistance of Austenitic Stainless Steel 316L by Ion Implantation

    Cai, Xun; Feng, Kai

    In the present work, austenitic stainless steel 316L (SS316L) samples were implanted with Ni and Ni-Cr. A nickel-rich layer about 100 nm in thickness and a Ni-Cr enriched layer about 60 nm thick are formed on the surface of SS316L. The effects of ion implantation on the corrosion performance of SS316L are investigated in a 0.5 M H2SO4 with 2 ppm HF solution at 80°C by open circuit potential (OCP), potentiodynamic and potentiostatic tests. The samples after the potentiostatic test are analyzed by XPS. The results indicate that the composition of the passive film change from a mixture of Fe oxides and Cr oxide to a Cr oxide dominated passive film after the potentiostatic test. The solutions after the potentiostatic test are analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results reveal that Fe is selectively dissolved in all cases and a proper Ni and Ni-Cr implant fluence can greatly improve the corrosion resistance of SS316L in the simulated polymer electrolyte membrane fuel cells (PEMFCS) environment. They are in agreement with the electrochemical test results that the bare SS316L has the highest dissolution rate in both cathode and anode environments and the Ni and Ni-Cr implantation reduce markedly the dissolution rate. After the potentiostatic test the interfacial contact resistance (ICR) values are also measured. Ni and Ni-Cr are enriched in the passive film formed in the simulated PEMFC cathode environment after ion implantation thereby providing better conductivity than that formed in the anode one. A significant improvement of ICR is achieved for the SS316L implanted with Ni and Ni-Cr as compared to the bare SS316L, which is attributed to the reduction in passive layer thickness caused by Ni and Ni-Cr implantation. The ICR values for implanted specimens increase with increasing dose.

  11. Microstructure of 316L austenite stainless steel after charging with deuterium and tritium

    The microstructure of 316L austenite stainless steel after charging with deuterium and tritium for 6 years at room temperature is studied. The results indicate that the morphology of fracture surface after blasting is ductile rupture with dimple, stress produced by blasting of high pressure leads to the martensite transformation. The deuterium and tritium improve the ε martensite transformation of austenite and reduce the fault energy, which reduce the hydrogen-resistant properties of 316L stainless steel

  12. Electrochemical polishing as a 316L stainless steel surface treatment method: Towards the improvement of biocompatibility

    Highlights: • Electropolishing of 316L stainless steel increases its corrosion resistance. • New electropolishing electrolyte composition is suggested. • Larger thickness and chromium enrichment of the passive film is obtained. • Electropolishing improves the surface biocompatibility and hemocompatibility. - Abstract: A 316L stainless steel (316L-SS) surface was electrochemically polished (EP) in an electrolyte of a new chemical composition at different cell voltages, with the aim of improving its corrosion resistance and biocompatibility. X-ray photoelectron spectroscopy results revealed that the EP-formed oxide films were characterized by a significantly higher atomic Cr/Fe ratio and film thickness, in comparison to the naturally-grown passive oxide film formed on the untreated (control) 316L-SS surface. As a result of the increase in the oxide film thickness and relative Cr enrichment, the EP-treated 316L-SS surfaces offered a notable improvement in general corrosion resistance and pitting potential. In addition, the attachment of endothelial cells (ECs) and smooth muscle cells (SMCs) to the 316L-SS surfaces revealed a positive effect of electropolishing on the preferential attachment of ECs, thus indicating that the EP surfaces could be endothelialized faster than the control (unmodified) 316L-SS surface. Furthermore, the EP surfaces showed a much lower degree of thrombogenicity in experiments with the platelet-rich plasma. Therefore, the use of the electrochemical polishing technique in treating a 316L-SS surface, under the conditions presented in this paper, indicates a significant improvement in the surface’s performance as an implant material

  13. Functional properties of a spark plasma sintered ultrafine-grained 316L steel

    Highlights: • A ultrafine-grained 316L stainless steel was densified by SPS. • Forming process does not induce any internal strain gradients in sintered samples. • An enhancement of hardness up to twice the value of as cast 316L is obtained. • Fully dense samples display an enhanced passive corrosion state in chloride media. - Abstract: A micrometric austenitic stainless steel 316L powder was densified by spark plasma sintering. The process parameters were varied over wide ranges and the impact of such variations on sintered materials was studied through the characterization of their microstructures, densities, hardness and corrosion resistance. For comparison with the properties of traditionally cast 316L, all these investigations were also systematically carried out on as cast samples. The sintered stainless steel produced this way was highly densified, with grains of a micrometric size and the forming process did not induce any residual strain gradients as shown by transmission electronic microscopy analysis. The investigation of the corresponding mechanical properties reveals an enhancement of hardness up to twice the value measured on one sample of as cast 316L. This result is in good agreement with the Hall–Petch formalism. Additionally, in the matter of corrosion behavior, fully dense samples display an enhanced passive state in chloride media compared to as cast material. Spark plasma sintering appears to be an interesting alternative elaboration way of ultrafine 316L stainless steel giving materials with high stress resistance, without strain gradients through the volume, and promising functional properties concerning corrosion behavior

  14. New route to form micro-pores on 316L stainless steel surface

    Ma Xinxin [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001 (China)], E-mail: maxin@hit.edu.cn; Wang Yujiang; Tang Guangze [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001 (China); Chen Qingfu [Jiangyin Fasten-PLT Materials Science Co., Ltd (Peier), 998 Changjiang Donglu, Jiangyin, 214434 (China)

    2008-11-15

    In order to seek an effective way for preventing restenosis after coronary stent implantation, a proposal of increasing the amount of loaded drug without changing the size of struts was given. Thereafter, a process of fabricating in-situ formed sub-micro-pores on 316L stainless steel (316L SS) was demonstrated. An aluminum thin film was deposited by magnetron sputtering on a 316L substrate. The aluminum film was then anodized in different acids (0.3 M oxalic and 10 vol.% sulfuric) by regulating direct current power supply. Through an appropriate chemical dissolution, the anodic alumina film was removed and the underlying porous 316L was obtained. The morphology of the porous 316L surface was examined by scanning electron microscope and the composition of the pores was investigated by energy dispersive X-ray analysis. The corrosion behavior of the porous 316L was evaluated by the polarization measurement. The results indicate that the shape and size of pores could be affected evidently by the acids used in anodization. The pores density is found to change with variation of the applied voltage in anodization. The corrosion current of the anodized specimens decrease and the corrosion voltage increase, compared with the untreated specimens.

  15. Metalurgia de uniones soldadas de aceros disímiles (astm a240-a537) y comportamiento mecánico ante cargas monotónica y cíclica Metallurgy of dissimilar steels welded unions (astm a240-a537) and mechanical behavior under monotonic and cyclic loads

    Andrés García; Rafael Salas; Leiry Centeno; Alberto Velázquez del Rosario

    2012-01-01

    En el presente estudio se caracterizaron las propiedades mecánicas en uniones soldadas de aceros disímiles: un acero estructural (ASTM A537/A537M:95) soldado a tope con un acero inoxidable austenítico 304L (ASTM A240/A240M:01) mediante proceso por arco eléctrico con protección inerte de gas argón (GMAW) y un acero inoxidable austenítico ER- 308L como material aporte (ANSI/AWS A5.9/A5.9M:2006). Las muestras se ensayaron en condición sin soldadura, con el objeto de caracterizar los materiales i...

  16. Improved CuCrZr / 316L Transition for Plasma Facing Components

    Plasma Facing Components used in all advanced nuclear fusion experiments and in particular for ITER consist of heat sinks made of the precipitation hardened CuCrZr alloy. This material has been selected due to the requirements regarding thermal and mechanical properties with and without the presence of neutrons. The divertor parts which are highly heat loaded are actively cooled and are assembled onto weld stainless steel pressure vessels of grade 316L. Therefore these plasma facing parts need a transition in the cooling pipes from CuCrZr to 316L which withstands the internal pressure, the fatigue loads and remains leak tight during operation. As direct fusion welding of CuCrZr with 316L is regarded as critical due to metallurgical issues, the current design uses a transition of Ni - sleeve which is welded onto the CuCrZr and 316L, respectively. However, there is still some concern for the mechanically constraint region of the inlet coolant that this intermediate adapter is the weakest point and could fail due to strongly localised plasticity. The aim of this project is to investigate alternative solutions for the transition of CuCrZr / 316L, to down-select the most promising candidate and finally qualify a new improved tubular transition system. Basic EB welding experiments have been carried out on CuCrZr / 316L tubular samples using different adapter and filler materials. The adapter materials, e.g. Inconel 625 and Monel K500, were chosen due to their high temperature strength and good weldability with respect to Cu - alloys and austenitic steels. In case of the investigated filler metals Ni and Ti the intention was to control the dilution and to produce a fine grained weld zone with no formation of detrimental phases. As a further option the use of an explosively welded CuCrZr/316L adapter was evaluated. The application of such an adapter would simplify the issue to the welding of CuCrZr / CuCrZr and 316L / 316L respectively. In the characterisation programme

  17. Weldability of dissimilar joint between F82H and SUS316L under fiber laser welding

    Serizawa, Hisashi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Mori, Daiki; Shirai, Yuma; Ogiwara, Hiroyuki; Mori, Hiroaki [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-10-15

    Highlights: • The microstructure of F82H/SUS316L dissimilar joint can be divided into four regions. • In the case without beam position shift, hardness of WM cannot be reduced by PWHT. • The fiber laser welding would be applicable for constructing the dissimilar joint. -- Abstract: As one of the high beam quality heat sources, 4 kW fiber laser was applied for joining between reduced activation ferritic/martensitic steel, F82H and SUS316L austenitic stainless steel, and the microstructural analyses and Vickers hardness measurements were carried out before and after post-weld heat treatment (PWHT). The microstructure of joint can be divided into four regions which are base metal of F82H, heat affected zone (HAZ) in F82H, weld metal (WM) and base metal of SUS316L. Also, it is revealed that the high-power fiber laser can be employed for constructing butt joint between F82H and SUS316L by applying PWHT and shifting the laser beam position to SUS316L, where the distance between the contact face and beam should be set as a range from radius to diameter of laser beam.

  18. Structure/property (constitutive and dynamic strength/damage) characterization of additively manufactured 316L SS

    Gray, G. T., III; Livescu, V.; Rigg, P. A.; Trujillo, C. P.; Cady, C. M.; Chen, S. R.; Carpenter, J. S.; Lienert, T. J.; Fensin, S.

    2015-09-01

    For additive manufacturing (AM), the certification and qualification paradigm needs to evolve as there exists no "ASTM-type" additive manufacturing certified process or AM-material produced specifications. Accordingly, utilization of AM materials to meet engineering applications requires quantification of the constitutive properties of these evolving materials in comparison to conventionally-manufactured metals and alloys. Cylinders 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 is detailed in both the as-built condition and following heat-treatments designed to obtain full recrystallization. The constitutive behavior as a function of strain rate and temperature is presented and compared to that of nominal annealed wrought 316L SS plate. The dynamic damage evolution and failure response of all three materials was probed using flyer-plate impact driven spallation experiments at a peak stress of 4.5 GPa to examine incipient spallation response. The spall strength of AM-produced 316L SS was found to be very similar for the peak shock stress studied to that of annealed wrought or AM-316L SS following recrystallization. The damage evolution as a function of microstructure was characterized using optical metallography.

  19. Structure/property (constitutive and dynamic strength/damage characterization of additively manufactured 316L SS

    Gray III G.T.

    2015-01-01

    Full Text Available For additive manufacturing (AM, the certification and qualification paradigm needs to evolve as there exists no “ASTM-type” additive manufacturing certified process or AM-material produced specifications. Accordingly, utilization of AM materials to meet engineering applications requires quantification of the constitutive properties of these evolving materials in comparison to conventionally-manufactured metals and alloys. Cylinders 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 is detailed in both the as-built condition and following heat-treatments designed to obtain full recrystallization. The constitutive behavior as a function of strain rate and temperature is presented and compared to that of nominal annealed wrought 316L SS plate. The dynamic damage evolution and failure response of all three materials was probed using flyer-plate impact driven spallation experiments at a peak stress of 4.5 GPa to examine incipient spallation response. The spall strength of AM-produced 316L SS was found to be very similar for the peak shock stress studied to that of annealed wrought or AM-316L SS following recrystallization. The damage evolution as a function of microstructure was characterized using optical metallography.

  20. Effect of multiple film on the tritium permeation property in 316L stainless steel

    The films of TiN + TiC + TiN and TiN + TiC + SiO2 were deposited on the surface of 316L stainless steel by physical vapor deposition technology. The characteristics of films are tested by SEM technology, it shows that the films are compact, thermal shock-resistant, oxidation-resistant and have good compatibility with bulk. the SIMS and IR analysis results show that the tritium permeation barrier is formed when TiC and SiO2 films are annealed in hydrogen above 300 degree C. The tritium permeability in 316L with film is measured at various temperature, the results show that the tritium permeability in 316L with TiN + TiC + SiO2 film is 4-6 orders of magnitude lower, and that in 316L with TiN + TiC + TiN film is 4-5 orders of magnitude lower than that in 316L with Pd film at about 200-600 degree C. These films may be used as the surface coating of the first wall, tritium blanket and heat exchanger in fusion reactor

  1. Metallurgical factors affecting the toughness of 316L SMA weldments at cryogenic temperatures

    The effects of delta ferrite content, ferrite morphology, carbon content, and sensitization on the fracture toughness and tensile properties of AWS/E316L and E316 shielded metal arc (SMA) weldments at 295, 76, and 40K are reported. The SMA test welds were evaluated, eight made with E316L and two with E316 electrodes. All of the weldments had excellent toughness at room temperature. At 760K, only the E316L weld with low ferrite had acceptable (to ASME Standards) toughness. Large decreases in toughness at 760K and 40K were related to increasing ferrite content. Decreases in Charpy impact energy at 760K were also related to coarsened ferrite morphology caused by reduced cooling rates, to increased carbon content and to the sensitization heat treatment. The tensile-yield strength increased with ferrite content, especially at 40K. Ferrite content generally effected the ultimate tensile strength or ductility only in a minor way

  2. Pitting Corrosion of 316L Stainless Steel under Low Stress below Yield Strength

    L(U) Shengjie; CHENG Xuequn; LI Xiaogang

    2012-01-01

    Pitting corrosion of 316L stainless steel (316L SS) under various stress was studied by potentiodynamic polarization,electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis in 3.5% NaCl solution.The results of polarization curves show that,with the increase of the stress,the pitting potentials and the passive current density markedly decrease firstly (180 MPa),and then increase greatly (200 MPa).The corresponding surface morphologies of the samples after the polarization test well correspond to the results.Mott-Schottky analysis proved the least Cl- adsorbed to the surface of passive film with more positive flat potential,indicating that a moderate stress could increase the pitting corrosion resistance of 316L SS in 3.5% NaCl solution.

  3. Wear and Corrosion Study of Sputtered Zirconium thin films on SS316L for Windmill Application

    Arunkumar N

    2015-05-01

    Full Text Available The Aim of this study is to observe the Wear and Corrosion behavior of Zirconium coated 316L stainless steel. After polishing, SS316L was coated with Zirconium employing DC sputtering process (a technique of physical vapor deposition.Structure characterization techniques including Scanning Electron Microscope (SEM and X-Ray Diffraction (XRD were utilized to investigate the microstructure and crystallinity of the coating. Salt spray test was performed by spraying Sodium chloride in order to determine corrosion resistance behavior of the coated sample. Pin on disc wear test was performed by hardened and tempered EN31 steel pin in order to determine and compare the Wear resistance behavior of Coated and uncoated samples. The Objective is to recommend the zirconium coated Stainless steel SS316L can be a choice for Off-shore wind mills where the shafts undergo Wear and corrosion problems.

  4. Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

    SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process

  5. Corrosion fatigue of 316L stainless steel in hot LiOH solution

    The corrosion fatigue behavior of AlSl 316L (UNS S31603) stainless steel was tested in concentrated aqueous lithium hydroxide solutions at elevated temperature. Fatigue tests were conducted in a 10 g LiOH/100cc H2O solution at 95 C at controlled electrochemical potentials. Experimental conditions met requirements of the aqueous Li salt blanket option for the international and European nuclear fusion reactor programs of the International Thermonuclear Experimental Reactor (ITER) and Next European Torus (NET). Results indicated 316L stainless steel was susceptible to corrosion fatigue in a narrow potential range of approximately 100 mV (vs SCE). Tests at lower or higher potentials (e.g., -80 and 200 mV), however, did not show susceptibility to corrosion fatigue cracking. Results were compared with the stress corrosion cracking behavior of 316L in the same environment

  6. Resistance of superhydrophobic and oleophobic surfaces to varied temperature applications on 316L SS

    Shams, Hamza; Basit, Kanza; Saleem, Sajid; Siddiqui, Bilal A.

    316L SS also called Marine Stainless Steel is an important material for structural and marine applications. When superhydrophobic and oleophobic coatings are applied on 316L SS it shows significant resistance to wear and corrosion. This paper aims to validate the coatings manufacturer's information on optimal temperature range and test the viability of coating against multiple oil based cleaning agents. 316L SS was coated with multiple superhydrophic and oleohobic coatings and observed under SEM for validity of adhesion and thickness and then scanned under FFM to validate the tribological information. The samples were then dipped into multiple cleaning agents maintained at the range of operating temperatures specified by the manufacturer. Coating was observed for deterioration over a fixed time intervals through SEM and FFM. A comparison was drawn to validate the most critical cleaning agent and the most critical temperature at which the coating fails to leave the base substrate exposed to the environment.

  7. Processing and mechanical properties of porous 316L stainless steel for biomedical applications

    Montasser M.DEWIDAR; Khalil A.KHALIL; J. K. LIM

    2007-01-01

    Highly porous 316L stainless steel parts were produced by using a powder metallurgy process, which includes the selective laser sintering(SLS) and traditional sintering. Porous 316L stainless steel suitable for medical applications was successfully fabricated in the porosity range of 40%-50% (volume fraction) by controlling the SLS parameters and sintering behaviour. The porosity of the sintered compacts was investigated as a function of the SLS parameters and the furnace cycle. Compressive stress and elastic modulus of the 316L stainless steel material were determined. The compressive strength was found to be ranging from 21 to 32 MPa and corresponding elastic modulus ranging from 26 to 43 GPa. The present parts are promising for biomedical applications since the optimal porosity of implant materials for ingrowths of new-bone tissues is in the range of 20%-59% (volume fraction) and mechanical properties are matching with human bone.

  8. Processing and properties of sinters prepared from 316L steel nanopowders

    J. Paduch; R. Molenda; D. Kolesnikow; H. Krztoń

    2007-01-01

    Purpose: The results of the research work on processing the sinters obtained from nanocrystalline powders of 316L steel are presented.Design/methodology/approach: The 316L steel powder has been mechanically alloyed from a set of elementary powders with use of Fritsch Vario-Planetary Mill Pulverisette 4. The time of 12 hours of milling has been needed for producing the powder. The X-ray diffraction has been used for controlling of the mechanical alloying process. The Rietveld method has been u...

  9. Short-term low-temperature glow discharge nitriding of 316L austenitic steel

    T. Frączek

    2011-07-01

    Full Text Available The AISI 316L austenitic steel after glow discharge nitriding at temperature of T = 673 K and duration of τ=14,4 ks, for two different variants of specimen arrangement in the glow-discharge chamber was investigated. In order to assess the effectiveness of nitriding process, the surface layers profile analysis examination, surface hardness and hardness profile examination, the analysis of surface layer structures and corrosion resistance tests were performed. It has been found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel surface, what results in the surface layer thickness escalation.

  10. An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures

    Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.

    2003-01-01

    Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.

  11. An integrated approach to the modelling of hydrogen assisted failure in 316L steel

    An integrated approach to the modelling of hydrogen assisted failure in 316L steel is presented. The approach includes experimental, fractographic, numerical and theoretical analysis of the phenomenon. The physical adequacy of the mechanical models of hydrogen embrittlement (notch extension model and notch cracking model) is discussed by comparing the virtual damage depth (theoretical) predicted by the models with the embrittled zone (microphysical) measured in the fractographic analysis by scanning electron microscopy. In addition, a numerical modelling of hydrogen diffusion is performed, concluding that bulk diffusion is not important in hydrogen embrittlement of 316L steel, so that hydrogen transport accelerated by the microdamage itself should be taken into account. (orig.)

  12. Microstructure and Corrosion Resistance of Laser Additively Manufactured 316L Stainless Steel

    Trelewicz, Jason R.; Halada, Gary P.; Donaldson, Olivia K.; Manogharan, Guha

    2016-03-01

    Additive manufacturing (AM) of metal alloys to produce complex part designs via powder bed fusion methods such as laser melting promises to be a transformative technology for advanced materials processing. However, effective implementation of AM processes requires a clear understanding of the processing-structure-properties-performance relationships in fabricated components. In this study, we report on the formation of micro and nanoscale structures in 316L stainless steel samples printed by laser AM and their implications for general corrosion resistance. A variety of techniques including x-ray diffraction, optical, scanning and transmission electron microscopy, x-ray fluorescence, and energy dispersive x-ray spectroscopy were employed to characterize the microstructure and chemistry of the laser additively manufactured 316L stainless steel, which are compared with wrought 316L coupons via electrochemical polarization. Apparent segregation of Mo has been found to contribute to a loss of passivity and an increased anodic current density. While porosity will also likely impact the environmental performance (e.g., facilitating crevice corrosion) of AM alloys, this work demonstrates the critical influence of microstructure and heterogeneous solute distributions on the corrosion resistance of laser additively manufactured 316L stainless steel.

  13. Electrochemical behavior of SUS316L stainless steel after surface modification

    梁成浩; 郭亮; 陈婉; 刘敬肖

    2003-01-01

    The surface modification for SUS316L stainless steel was carried out by electroplating Rh, ion beam assisted deposition Ta2O5 and sol-gel-derived TiO2. In Tyrodes stimulated body fluid, the surface modified samples were investigated with electrochemical techniques. The results indicate that the electrochemical stability and dissolution are improved significantly after surface modification. Moreover, as to ion beam assisted deposition Ta2O5 and sol-gel-derived TiO2 film, the metals d orbit electron holes filled up by the oxygen electrons make against the adsorption of hydrogen. Thus the cathode process, which is controlled by the hydrogen reduction, is held back. X-ray diffraction analysis of SUS316L stainless steel after surface modification reveal that each method forms the uniform and compact film on SUS316L stainless steel. These films prevent the dissolving of elements and improve passivation property of the SUS316L stainless steel.

  14. Development of nanostructured SUS316L-2%TiC with superior tensile properties

    Sakamoto, T.; Kurishita, H.; Matsuo, S.; Arakawa, H.; Takahashi, S.; Tsuchida, M.; Kobayashi, S.; Nakai, K.; Terasawa, M.; Yamasaki, T.; Kawai, M.

    2015-11-01

    Structural materials used in radiation environments require radiation tolerance and sufficient mechanical properties in the controlled state. In order to offer SUS316L austenitic stainless steel with the assumed requirements, nanostructured SUS316L with TiC addition of 2% (SUS316L-2TiC) that is capable of exhibiting enhanced tensile ductility and flow strength sufficient for structural applications was fabricated by advanced powder metallurgical methods. The methods include MA (Mechanical Alloying), HIP (Hot Isostatic Pressing), GSMM (Grain boundary Sliding Microstructural Modification) for ductility enhancement, cold rolling at temperatures below Md (the temperature where the martensite phase occurs by plastic deformation) for phase transformation from austenite to martensite and heat treatment for reverse transformation from martensite to austenite. It is shown that the developed SUS316L-2TiC exhibits ultrafine grains with sizes of 90-270 nm, accompanied by TiC precipitates with 20-50 nm in grain interior and 70-110 nm at grain boundaries, yield strengths of 1850 to 900 MPa, tensile strengths of 1920 to 1100 MPa and uniform elongations of 0.6-21%, respectively, depending on the heat treatment temperature after rolling at -196 °C.

  15. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Dundeková, S.; Hadzima, B.; Fintová, Stanislava

    2015-01-01

    Roč. 22, č. 2 (2015), s. 77-84. ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * EIS * Corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/167/278

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

    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

  17. In vitro biocompatibility of plasma-aided surface-modified 316L stainless steel for intracoronary stents

    Bayram, Cem; Denkbas, Emir Baki [Nanotechnology and Nanomedicine Division, The Institute For Graduate Studies in Science and Engineering, Hacettepe University, 06800, Ankara (Turkey); Mizrak, Alpay Koray [Institute of Materials Science and Nanotechnology, Bilkent University, UNAM, 06800, Ankara (Turkey); Aktuerk, Selcuk [Department of Physics, Mugla University, 48000 Koetekli, Mugla (Turkey); Kursaklioglu, Hurkan; Iyisoy, Atila [Department of Cardiology, School of Medicine, Gulhane Military Medicine Academy, 06018, Ankara (Turkey); Ifran, Ahmet, E-mail: denkbas@hacettepe.edu.t [Department of Hematology, School of Medicine, Gulhane Military Medicine Academy, 06018, Ankara (Turkey)

    2010-10-01

    316L-type stainless steel is a raw material mostly used for manufacturing metallic coronary stents. The purpose of this study was to examine the chemical, wettability, cytotoxic and haemocompatibility properties of 316L stainless steel stents which were modified by plasma polymerization. Six different polymeric compounds, polyethylene glycol, 2-hydroxyethyl methacrylate, ethylenediamine, acrylic acid, hexamethyldisilane and hexamethyldisiloxane, were used in a radio frequency glow discharge plasma polymerization system. As a model antiproliferative drug, mitomycin-C was chosen for covalent coupling onto the stent surface. Modified SS 316L stents were characterized by water contact angle measurements (goniometer) and x-ray photoelectron spectroscopy. C1s binding energies showed a good correlation with the literature. Haemocompatibility tests of coated SS 316L stents showed significant latency (t-test, p < 0.05) with respect to SS 316L and control groups in each test.

  18. Aceros aluminotérmicos. Nuevas aplicaciones

    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.

  19. Grain boundary character distribution in a hot rolled 316 L stainless steel; Distribuicao de tipos de contornos de grao em um aco inoxidavel 316L laminado a quente

    Lopes, L.C.R. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. de Metalurgia; Thomson, C.B. [Wales Univ., Swansea (United Kingdom)

    1995-12-31

    The texture and the grain boundary character distribution of a 316 L stainless steel under hot rolled condition have been studied. Electron back-scatter diffraction technique associated to the scanning electron microscopy is used to determine the crystallographic orientation of grains individually. The material presented a random texture. However, the misorientation axis distribution represented by an inverse pole figure showed a non-random distribution with a high proportion <111> misorientation axis. The disorientation angle distribution indicates a proportion of about 60% of boundaries with 60 deg C misorientation angle. A 25% proportion of CSL interfaces of {Sigma} = 3 type was found 17 refs., 9 figs., 2 tabs.

  20. AISI 316L under electron radiolysis at high temperature and pressure in PWR modelling conditions

    temperature (HT), 280-320 deg. C, and high pressure (HP), 15.5 MPa. Very few data are available in the literature on the role of HTHP water radiolysis on the corrosion of metallic reactor components. The present approach use electron beam to control the production of radiolytic species at a AISI 316L/PWR solution interface in a high temperature and high pressure (HTHP) electrochemical cell working at the range [25 deg. C, 1 bar] - [300 deg. C, 90 bar]. The cell is designed to record the free corrosion potential of the AISI 316L/PWR solution interface mounted on line at the SIRIUS pelletron delivering the electron beam (LSI, Ecole Polytechnique, France). The PWR primary solutions are simulated by aqueous solutions prepared at room temperature by adding boric acid and lithium hydroxide to high purity water and, in some cases, purged with Ar/H2 flow. At the AISI 316L/PWR solution interfaces irradiated between 25 deg. C/ 1 bar and 300 deg. C/ 90 bar, electrons emerge at ∼0.6 MeV and the flux varies from ∼1010 to 1012 e-.cm-2.s-1. The results clearly show that the response of the free potential between the AISI316L/water interface and a pseudo-reference electrode, i.e. a platinum wire during the irradiation (from electron beam switch-on until cut-off) depends on many parameters: the energy of the electron beam, the temperature and pressure, the concentration of hydrogen in the solution, the ageing of the disc electrode, the growth conditions of the initial oxide passive layers, etc... These results can be compared with those which have obtained by using the proton beam (CEMHTI, CNRS Orleans, France). Surface characterization experiments (XPS, SEM, Raman spectroscopy, photoluminescence...) on the oxide layer of AISI316L which are formed under the irradiation could also bring new information about the irradiation influence on the AISI316L. (authors)

  1. Experimental Study on Uniaxial and Multiaxial Strain Cyclic Characteristics and Ratcheting of 316L Stainless Steel

    2001-01-01

    An experimental study was carried out on the strain cycliccharacteristics and ratcheting of 316Lstainless steel subjected to uniaxial and multiaxial cyclic loading. The strain cyclic characteristics were researched under the strain-controlled uniaxial tension-compression and multiaxial circular paths of loading. The ratcheting tests were conducted for the stress-controlled uniaxial tensioncompression and multiaxial circular, rhombic and linear paths of loading with different mean stresses, stress amplitudes and histories. The experiment results show that 316L stainless steel features the cyclic hardening, and its strain cyclic characteristics depend on the strain amplitude and its history apparently. The ratcheting of 316L stainless steel depends greatly on the values of mean stress, stress amplitude and their histories. In the meantime, the shape of load path and its history also apparently influence the ratcheting.

  2. Effect of in site strain on passivated property of the 316L stainless steels.

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Ting, Guo

    2016-04-01

    The effect of the strain of 316L stainless steel on its corrosion resistance in borate buffer solution was investigated by in site tensile test and the electrochemical impedance spectroscopy measurements. It was found that the corrosion resistance of the 316L stainless steel decreased with the increasing of in site strain. The lower corrosion resistance of the stainless steel during in site strain was mainly attributed to the higher doping concentration in passive film. Especially, with the increasing of in site strain, the concentrations of acceptor (i.e., cation vacancies) in the passive films significantly increased. More acceptor concentrations reduced the compactness of the passive film and its corrosion resistance. Moreover, two exponential relationships were found between in site strain and the charge transfer resistance of the passive film and between in site strain and total doping concentrations in passive film, respectively. PMID:26838820

  3. Effect of Surface Treatment on the Surface Characteristics of AISI 316L Stainless Steel

    Trigwell, Steve; Selvaduray, Guna

    2005-01-01

    The ability of 316L stainless steel to maintain biocompatibility, which is dependent upon the surface characteristics, is critical to its effectiveness as an implant material. The surfaces of mechanically polished (MP), electropolished (EP) and plasma treated 316L stainless steel coupons were characterized by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) for chemical composition, Atomic Force Microscopy for surface roughness, and contact angle measurements for critical surface tension. All surfaces had a Ni concentration that was significantly lower than the bulk concentration of -43%. The Cr content of the surface was increased significantly by electropolishing. The surface roughness was also improved significantly by electropolishing. Plasma treatment had the reverse effect - the surface Cr content was decreased. It was also found that the Cr and Fe in the surface exist in both the oxide and hydroxide states, with the ratios varying according to surface treatment.

  4. Nanosized controlled surface pretreatment of biometallic alloy 316L stainless steel.

    Abdel-Fattah, Tarek M; Loftis, Derek; Mahapatro, Anil

    2011-12-01

    Stainless steel (AISI 316L) is a medical grade stainless steel alloy used extensively in medical devices and in the biomedical field. 316L stainless steel was successfully electropolished via an ecologically friendly and biocompatible ionic liquid (IL) medium based on Vitamin B4 (NB4) and resulting in nanosized surface roughness and topography. Voltammetry and chronoamperometry tests determined optimum polishing conditions for the stainless steel alloy while atomic force microscopy (AFM) and scanning electron microscopy (SEM) provided surface morphology comparisons to benchmark success of each electropolishing condition. Energy dispersive X-ray analysis (EDX) combined with SEM revealed significantly smoother surfaces for each alloy surface while indicating that the constituent metals comprising each alloy effectively electropolished at uniform rates. PMID:22416578

  5. Evaluation of the austenitic alloys 304L, 316L, and alloy 825 under Tuff repository conditions

    Austenitic alloys 304L and 316L and stainless steel 825 were investigated as candidate materials for containers for waste disposal in the relatively benign conditions of the Yucca Mountain site. In this vault there will be very little water, and what there is will contain small amounts of chlorides, nitrates, sulphates and carbonates. The radiation fields will be 104 rad/h initially, but will decay to low levels by the end of the containment period. The initial temperature will be around 250 C, and it will remain above the boiling point of water for the containment period (approximately 300 years). There will be no lithostatic or hydrostatic pressure. Type 304L stainless steel is a base case material used in comparisons with other candidates. Type 316L stainless steel possesses enhanced resistance to sensitization and localized corrosion; alloy 825 is stabilized to have a much better resistance to sensitization and localized corrosion and performs better in chloride environments

  6. EVALUATION OF MECHANICAL PROPERTIES OF SS 316 L WELDMENTS USING TUNGSTEN INERT GAS WELDING

    S.V. ABINESH KUMAR

    2012-05-01

    Full Text Available This work aims at joining of similar grades of stainless steel by TIG welding with the various parameters like current, bevel angle and gas flow rate. The SS 316L is selected over other grades due to its lesser carbon content it is used in pressure vessels for corrosive liquids etc. The rod of SS 316L of 25 mm diameter and 75 mm lengthwas used as the base material for this experiment. The rod was machined in accordance to ASTM-A-370 standards for finding the echanical behaviour like Tensile strength, micro hardness and micro structure. Higher tensile strength achieved with a current of 110A, bevel angle of 600 and a gas flow rate of 0.7 LPM. Non-destructive tests like radiographic tests were performed to find the defects in the joints. The defect incurred was lack of penetration and it was observed in the sample D and sample G.

  7. Damage mechanism at different transpassive potentials of solution-annealed 316 and 316l stainless steels

    Morshed Behbahani, K.; Pakshir, M.; Abbasi, Z.; Najafisayar, P.

    2015-01-01

    Electrochemical impedance spectroscopy (EIS), anodic polarization and scanning electron microscopy techniques were used to investigate the damage mechanism in the transpassive potential region of AISI 316 and AISI 316L solution-annealed stainless steels (SS) with different degrees of sensitization. Depending on the DC potential applied during EIS tests, the AC responses in the transpassive region included three different regions: the first one associated with anodic dissolution of the passive layer, the second one contributed to the dissolution at the area near grain boundaries, and the last one attributed to pitting corrosion. In addition, the fitting results to experimental data showed that as the DC bias during the EIS test increases the charge transfer resistance ( R ct) decreases. Moreover, the R ct values decreased as the sensitization temperature increases but the AISI 316L SS samples exhibited a higher resistance to intergranular corrosion than 316 SS samples.

  8. Corrosion resistance of the welded AISI 316L after various surface treatments

    Tatiana Liptáková

    2014-01-01

    Full Text Available The main aim of this work is to monitor the surface treatment impact on the corrosion resistance of the welded stainless steel AISI 316L to local corrosion forms. The excellent corrosion resistance of austenitic stainless steel is caused by the existence of stable, thin and well adhering passive layer which quality is strongly influenced by welding. Therefore surface treatment of stainless steel is very important with regard to its local corrosion susceptibility Surfaces of welded stainless steel were treated by various mechanical methods (grinding, garnet blasting. Surface properties were studied by SEM, corrosion resistance was evaluated after exposition tests in chlorides environment using weight and metalographic analysis. The experimental outcomes confirmed that the mechanical finishing has a significant effect on the corrosion behavior of welded stainless steel AISI 316L.

  9. Effects of Admixed Titanium on Densification of 316L Stainless Steel Powder during Sintering

    Aslam Muhammad

    2014-07-01

    Full Text Available Effects of admixed titanium on powder water atomized (PWA and powder gas atomized (PGA 316L stainless steel (SS have been investigated in terms of densification. PGA and PWA powders, having different shapes and sizes, were cold pressed and sintered in argon atmosphere at 1300°C. The admixed titanium compacts of PGA and PWA have shown significant effect on densification through formation of intermetallic compound and reducing porosity during sintering process. PWA, having particle size 8 μm, blended with 1wt% titanium has exhibited higher sintered density and shrinkage as compared to gas atomized powder compacts. Improved densification of titanium blended PGA and PWA 316L SS at sintering temperature 1300°C is probably due to enhanced diffusion kinetics resulting from stresses induced by concentration gradient in powder compacts.

  10. Oxide Formation In Metal Injection Molding Of 316L Stainless Steel

    Jang Jin Man

    2015-06-01

    Full Text Available The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.

  11. Hydrogen transport and solubility in 316L and 1.4914 steels for fusion reactor applications

    Equations are given which describe the permeation rate, diffusivity and solubility of hydrogen over the range 250-6000C at pressures up to 105 Pa for the 316L stainless and modified 1.4914 martensitic candidate steels proposed for the construction of the Next European Torus (NET). For heat-treated 316L steel, the permeation rates measured agreed well with previous work and did not vary significantly from specimen to specimen or from batch to batch. Measurements of the permeation rate of hydrogen and deuterium through the modified 1.4914 steel, believed to be the first made, show that the martensitic steel is significantly more permeable than the austenitic steel, by an order of magnitude at 2500C and a factor of five at 6000C. This difference could make it necessary to use permeation barriers on critical components made from the martensitic steel in order to reduce the tritium permeation rate to acceptable levels. (orig.)

  12. The effect of hydrogen/helium implantation on the microstructure of 316L stainless steel

    Type 316L stainless steel has been used for first wall material of NET (Next European TOKAMAK). The 316L stainless steel was implanted with helium and hydrogen to investigate the irradiation behavior in the temperature range 120-420 deg C. The strength of implanted material increased at 120, 220 deg C while elongation decreased. At 420 deg C, abrupt decrease in strength and elongation occured due to helium bubbles. Slip bands were well developed during tensile test like channel deformation. Dislocations were along the (111) planes and cell structure was also generated at higher temperature. With 500 appm hydrogen implantation, microstructure did not change much but contained small amount of dislocations and stacking faults. (Author)

  13. Corrosion and low-cycle fatigue properties of AISI 316L in flowing Pb-17Li

    Corrosion and low-cycle fatigue (LCF) tests were performed on AISI 316L steel specimens in a flowing lithium lead environment. The LCF and corrosion tests were conducted simultaneously in the ''LIFUS 2'' forced convection loop, at a temperature of 723 K and a flow velocity of approximately 0.01 m/s. The LCF tests, which had a strain amplitude ranging from 0.008 to 0.016, were compared with reference tests performed in an inert argon atmosphere. The results show that liquid Pb-17Li has no detrimental effect on the LCF behaviour of 316L at the test temperature of 723 K. The corrosion tests extended from 650 to 1600 h with intermediate steps. Metallographic and SEM-EDAX analyses indicated the presence of an irregular porous ferritic layer. The results are discussed in terms of ferrite growth rate and the effect of corrosion phenomena on LCF behaviour. ((orig.))

  14. Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder

    Jeon Byoungjun; Sohn Seong Ho; Lee Wonsik; Han Chulwoong; Kim Young Do; Choi Hanshin

    2015-01-01

    316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present st...

  15. Stability of austenitic 316L steel against martensite formation during cyclic straining

    Man, Jiří; Obrtlík, Karel; Petrenec, Martin; Beran, Přemysl; Smaga, M.; Weidner, A.; Dluhoš, J.; Kruml, Tomáš; Biermann, H.; Eifler, D.; Polák, Jaroslav

    2011-01-01

    Roč. 10, - (2011), s. 1279-1284. ISSN 1877-7058. [ICM11 -International Conference on The Mechanical Behavior of Materials /11./. Lake Como, 05.06.2011-09.06.2011] R&D Projects: GA ČR GAP108/10/2371 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z20410507 Keywords : low cycle fatigue * 316L austenitic stainless steel * deformation-induced martensite Subject RIV: JL - Materials Fatigue, Friction Mechanics

  16. Surface Relief Evolution in 316L Steel Fatigued at Depressed and Elevated Temperatures

    Man, Jiří; Petrenec, Martin; Klapetek, P.; Obrtlík, Karel; Polák, Jaroslav

    Ottawa : NRCan - CANMET, 2009, s. 1-10. ISBN N. [International Conference on Fracture /12./. Ottawa (CA), 12.07.2009-17.07.2009] R&D Projects: GA AV ČR 1QS200410502; GA ČR GA106/06/1096; GA ČR GA101/07/1500 Institutional research plan: CEZ:AV0Z20410507 Keywords : 316L steel * persistent slip marking (PSM) * atomic force microscopy (AFM) Subject RIV: JL - Materials Fatigue, Friction Mechanics

  17. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

    Jones, John Eric; Chen, Meng; Yu, Qingsong

    2014-01-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH3/O2 plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC...

  18. Weld process study for 316L stainless steel weld metal for liquid helium service

    This study was conducted to determine the effects of welding process choice on the cryogenic properties of 316L stainless steel welds. Six weldments were impact tested down to 77 K and tensile and fracture toughness tested down to 4 K. The best properties obtained were from a GTA weld, followed by GMA welds; SA welds had the poorest properties. This variation in properties was attributed to the cleanliness of the weld metal, which is dependent on the welding process and parameters selected

  19. Short-term low-temperature glow discharge nitriding of 316L austenitic steel

    T. Frączek; Olejnik, M.; Jasiñski, J.; Skuza, Z.

    2011-01-01

    The AISI 316L austenitic steel after glow discharge nitriding at temperature of T = 673 K and duration of τ=14,4 ks, for two different variants of specimen arrangement in the glow-discharge chamber was investigated. In order to assess the effectiveness of nitriding process, the surface layers profile analysis examination, surface hardness and hardness profile examination, the analysis of surface layer structures and corrosion resistance tests were performed. It has been found that application...

  20. Corrosion behaviour of AISI 316L steel in artificial body fluids

    W. Kajzer

    2008-12-01

    Full Text Available Purpose: The paper presents the comparison of corrosion resistance of AISI 316L stainless steel in various corrosive media such as artificial urine, Tyrode’s physiological solution and artificial plasma.Design/methodology/approach: The tests were carried out on samples of the following surfaces: grinded – average roughness Ra = 0.31 μm and electropolished and chemically passivated average roughness Ra = 0.10 μm. The corrosion tests were realized by recording of anodic polarization curves with the use of the potentiodynamic method. The VoltaLab® PGP 201 system for electrochemical tests was applied. The tests were carried out in electrolyte simulating urine (pH = 6-6.4, Tyrode’s physiological solution (pH = 6.8-7.4 and plasma (pH = 7.2-7.6 at the temperature of 37±1°C.Findings: Surface condition of AISI 316L stainless steel determines its corrosion resistance. The highest values of breakdown potentials were recorded for all electropolished and chemically passivated samples in all simulated body fluids. The highest values of anodic current density were recorded for samples tested in artificial urine, the lowest values were recorded for samples tested in Tyrode’s physiological solution.Research limitations/implications: The obtained results are the basis for the optimization of physicochemical properties of the AISI 316L stainless steel.Practical implications: On the basis of the obtained results it can be stated that stainless steel meets the basic biocompatibility criteria and can be applied in reconstruction surgery, operative cardiology and urology.Originality/value: The paper presents the influence of various corrosive media simulating human body fluids on corrosion resistance of AISI 316L stainless steel.

  1. Investigation into the joining of MoSi{sub 2} to 316L stainless steel

    Vaidya, R.U.; Bartlett, A.H.; Conzone, S.D.; Butt, D.P.

    1996-10-01

    Partial transient liquid phase joining and low temperature brazing were applied in joining MoSi{sub 2} to 316L ss. Exploratory studies were carried out on various interlayer materials. Mechanical, physical, and chemical compatibilities between various interlayers, brazing material, and substrate materials were investigated. Effect of thermal expansion mismatch between various components of the joint on the overall joint integrity was also studied. Preliminary findings are outlined.

  2. Influence of the surface finishing on the corrosion behaviour of AISI 316L stainless steel

    Dundeková, S.; Zatkalíková, V.; Fintová, Stanislava; Hadzima, B.; Škorík, Viktor

    2015-01-01

    Roč. 22, č. 1 (2015), s. 48-53. ISSN 1335-0803 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * Corrosion * Immersion test * Corrosion rate Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/166/251

  3. Niobium coatings on 316L stainless steel for improving corrosion resistance

    Niobium coatings were deposited onto 316L stainless steel substrates by ion-beam-assisted deposition. The coatings, deposited under 250 eV ion bombardment with [Ar+]/[Nb] ratios ranging from 0.68 to 0.8, were dense and showed no sign of pitting corrosion in a 3% NaCl solution. Also, based on the result of scratch tests, niobium coatings may act as sacrificial anodes and protect substrates. (orig.)

  4. Comportamiento termomecánico de aceros AISI 304

    El Wahabi, M.

    2001-04-01

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

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

  5. Growth inhibition of cultured smooth muscle cells by corrosion products of 316 L stainless steel wire.

    Shih, C C; Shih, C M; Chen, Y L; Su, Y Y; Shih, J S; Kwok, C F; Lin, S J

    2001-11-01

    The potential cytotoxicity on vascular smooth muscle cells of corrosion products from 316 L stainless steel, one of most popular biomaterials of intravascular stents, has not been highlighted. In this investigation, 316 L stainless steel wires were corroded in Dulbecco's modified eagle's medium with applied constant electrochemical breakdown voltage, and the supernatant and precipitates of corrosion products were prepared as culture media. The effects of different concentrations of corrosion products on the growth of rat aortic smooth muscle cells were conducted with the [3H]-thymidine uptake test and cell cycle sorter. Both the supernatant and precipitates of corrosion products were toxic to the primary culture of smooth muscle cells. The growth inhibition was correlated well with the increased nickel ions in the corrosion products when nickel concentration was above 11.7 ppm. The corrosion products also changed cell morphology and induced cell necrosis. The cell growth inhibition occurred at the G0/G1 to S transition phase. Similar to our recent study of nitinol stent wire, the present investigation also demonstrated the cytotoxicity of corrosion products of 316 L stainless steel stent wire on smooth muscle cells, which might affect the poststenting vascular response. PMID:11484182

  6. Evaluation of hydroxyapatite coatings on borate passivated 316L SS in Ringer's solution

    Surgical grade stainless steel (316L SS) is one of the widely used implant material in orthopedic surgeries. But often the release of metal ions is evidenced from the implants and subsequently a second surgery is required to remove the implant material. One way to control this release of metal ions is to coat the implant material with a biocompatible material like hydroxyapatite. In this paper we have reported a successful coating of hydroxyapatite over borate passivated 316L SS by a dip coating method. The coatings were characterized by electrochemical techniques such as potentiodynamic polarization, electrochemical impedance and cyclic voltammetry (CV). Also X-ray diffraction (XRD) and scanning electron microscopic (SEM) studies were performed to confirm the quality of the coatings. Results of accelerated leach out characteristics by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and the evaluation of shear strength are also presented to support the corrosion resistant nature of the coatings. The enhanced bio-resistivity of the as-formed HAP coatings on passivated 316L SS is attributed to the protective passive layer formed by borate buffer solution at selected potentials.

  7. Laser cladding of nickel base alloy on SS316L for improved wear and corrosion behaviour

    Laser cladding by an Nd:YAG laser was employed to deposit Ni base alloy (Ni-Mo-Cr-Si) on stainless steel-316 L substrate. The resulting defect-free clad with minimum dilution of the substrate was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and Vickers microhardness test. Dry sliding wear of the cladding and the substrate was evaluated using a ball-on-plate reciprocating wear tester against different counter bodies (WC and 52100 Cr steel). The reciprocating sliding wear resistance of the coating was evaluated as a function of the normal load, keeping the sliding amplitude and sliding speed constant. Wear mechanisms were analyzed by observation of wear track morphology using SEM-EDS. The electrochemical corrosion behavior of clad layer was studied in reducing environment (HCl) to estimate the general corrosion resistance of the laser clad layer in comparison with the substrate SS-316L. The clad layer showed higher wear resistance under reducing condition than that of the substrate material stainless steel 316L. (author)

  8. ESTUDIO DE LA SINERGIA CORROSIÓN-EROSIÓN DE RECUBRIMIENTOS DUROS DE TiN Y CrN OBTENIDOS SOBRE ACERO AISI 1045

    HARVEY PAYÁN; WILLIAM APERADOR; ALEJANDRO VARGAS

    2008-01-01

    En este trabajo se presentan los resultados del estudio de los efectos sinergeticos de la corrosión-erosión en recubrimientos duros de TiN y CrN obtenidos sobre acero AISI 1045 por medio de la técnica de pulverización catódica con magnetrón y se hace una comparación con los resultados mostrados por un acero inoxidable comercial AISI 316 y el acero AISI 1045 sin recubrimiento. El proceso de deposición física de vapor (Physical Vapor Deposition), contribuye ampliamente a la aplicación de pelícu...

  9. Magnolias de acero (1989)

    Galache Montero, Aurora

    2009-01-01

    [ES] Magnolias de Acero (1989) acerca a los espectadores al lado humano de la enfermedad. Los pone en contacto con la capacidad de lucha de algunos enfermos por llevar una vida normal ante un proceso crónico ni las repercusiones negativas sobre su salud. La protagonista, que padece una diabetes, se esfuerza por vivir una vida sin limitaciones batallando constante con las barreras que su enfermedad le va poniendo constantemente, anteponiendo siempre su felicidad a las consecuencias fatales que...

  10. Microstructural changes of AISI 316L due to structural sensitization and its influence on the fatigue properties

    Dundeková, S.; Nový, F.; Fintová, Stanislava

    2014-01-01

    Roč. 21, č. 4 (2014), s. 172-177. ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L * Structural sensitization * Rotating bending fatigue test Subject RIV: JL - Materials Fatigue, Friction Mechanics

  11. Influence of binder system and temperature on rheological properties of water atomized 316L powder injection moulding feedstocks

    Uğur GÖKMEN; Türker, Mehmet; ÇİNİCİ, Hanifi

    2016-01-01

    In order to obtain a proper powder injection molding the rheological behavior of feedstocks should be known. To determine the binder effect on the rheological behavior of 316L stainless steel powders feedstock two different feedstock were prepared. In the current experiments water atomized 316L stainless steel powders (-20 µm) were used. Two types of binders, one of which is mainly paraffin wax can be dissolved in heptane and the other Polietilenglikol (PEG) based and can be dissolved in wate...

  12. Anisotropy changes in hardness and indentation modulus induced by plasma nitriding of 316L polycrystalline stainless steel

    The changes in anisotropic hardness and indentation modulus induced by plasma nitriding at 400 oC of a 316L polycrystalline austenitic stainless steel are analyzed. The dependence of hardness and elastic modulus modifications on the crystallographic orientation is investigated through instrumented indentation and electron backscattering diffraction. Both hardness and indentation modulus exhibit an inverted anisotropy compared to the untreated 316L, likely associated with the presence of the N atoms in interstitial sites.

  13. Investigation on 316L/W functionally graded materials fabricated by mechanical alloying and spark plasma sintering

    Tan, Chao; Wang, Guoyu; Ji, Lina; Tong, Yangang; Duan, Xuan-Ming

    2016-02-01

    316L-W (Tungsten) composite materials were fabricated by spark plasma sintering (SPS) of mechanically alloyed 316L-W powders for the development of functionally graded materials (FGMs). The effect of milling parameters on the morphology of the blended 316L/W powders and its subsequent effect on the transition between 316L and W particles during the SPS process were investigated. Samples were characterized by SEM, EDS and XRD analyses. The results so obtained show that with the increase of milling time, the mechanically activated W powder particles become thinner and smoother, with some broken fragments aggregated or inserted in the severely deformed 316L particles. A further SPS process under the conditions of 1050 °C × 45.5 MPa × 5 min leads to the densification of the powder compact and the formation of a distinguishable gray belt surrounding the retained W particles. Such a belt, which has a width of about 2-8 μm depending on different milling parameters and mainly contains Fe7W6, Fe3W3C and Fe2W phases, is bound to be a transitional region between the retained W particles and the 316L matrix. This favorable behavior with regards to the formation of a transitional belt, is accompanied by a substantial increase in the hardness values of the composite.

  14. Microstructure and mechanical properties of friction stir processed AISI 316L stainless steel

    Highlights: • FSP can be used to produce bulk ultrafine grained structures in AISI 316L SS. • The main mechanism for grain structure refinement of FSP 316L SS is DDRX. • However, some evidences of CDRX and SRX were also observed. • The material flow was found to be near simple shear deformation (A/A‾ and C). • FSP samples have an enhanced hardness and strength compared with the base metal. - Abstract: Friction stir processing was used to refine the grain structure in 2 mm thick AISI 316L stainless steel sheets, with a pinless tool, at a constant traverse speed of 63 mm/min and relatively low rotational speeds of 200 and 315 rpm. Depending on the processing conditions, the initial grain size of 14.8 μm in the base metal was subsequently decreased to 0.8–2.2 μm in the processed areas. The microstructural characterizations by orientation imaging and transmission electron microscopy revealed that the grain structure evolution in the stir zone is primarily dominated by discontinuous dynamic recrystallization. The material flow was found to be near simple shear deformation and the developed textures were composed of a mixture of A/A‾ and C components of ideal simple shear textures. The mechanical properties were also evaluated by the longitudinal tensile tests and microhardness measurements. The obtained results showed that, despite a 50% decrease in ductility, the highest yield and ultimate tensile strength of the friction stir processed samples are respectively about 1.6 and 1.2 times higher than those of the base metal. In good agreement with the tensile properties, the increased hardness of the stir zone was attributed to the grain structure refinement

  15. Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L

    Škorík, Viktor; Šulák, Ivo; Obrtlík, Karel; Polák, Jaroslav

    Ostrava: TANGER Ltd, 2015. ISBN 978-80-87294-58-1. [METAL 2015 - International Conference on Metallurgy and Materials /24./. Brno (CZ), 03.06.2015-05.06.2015] R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR(CZ) GA15-20991S; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : Thermo-mechanical fatigue (TMF) * In-phase cycling (IP) * Isothermal fatigue (IF) * AISI 316L * Fatigue life Subject RIV: JL - Materials Fatigue, Friction Mechanics

  16. AFM study of surface relief evolution in 316L steel fatigued at low and high temperatures

    Man, Jiří; Valtr, B.; Weidner, A.; Petrenec, Martin; Obrtlík, Karel; Polák, Jaroslav

    2010-01-01

    Roč. 2, č. 1 (2010), s. 1625-1633. ISSN 1877-7058. [Fatigue 2010. Praha, 06.06.2010-11.06.2010] R&D Projects: GA ČR GAP108/10/2371; GA AV ČR 1QS200410502; GA ČR GA106/06/1096 Institutional research plan: CEZ:AV0Z20410507 Keywords : Fatigue crack initiation * 316L steel * Persistent slip band (PSB) * Extrusion * Intrusion * Atomic force microscopy (AFM) Subject RIV: JL - Materials Fatigue, Friction Mechanics

  17. Cytotoxicity difference of 316L stainless steel and titanium reconstruction plate

    Ni Putu Mira Sumarta

    2011-03-01

    Full Text Available Background: Pure titanium is the most biocompatible material today and used as a gold standard for metallic implants. However, stainless steel is still being used as implants because of its strength, ductility, lower price, corrosion resistant and biocompatibility. Purpose: This study was done to revealed the cytotoxicity difference between reconstruction plate made of 316L stainless steel and of commercially pure (CP titanium in baby hamster kidney-21 (BHK-21 fibroblast culture through MTT assay. Methods: Eight samples were prepared from reconstruction plates made of stainless steel type 316L grade 2 (Coen’s reconstruction plate® that had been cut into cylindrical form of 2 mm in diameter and 3 mm long. The other one were made of CP titanium (STEMA Gmbh® of 2 mm in diameter and 2,2 mm long; and had been cleaned with silica paper and ultrasonic cleaner, and sterilized in autoclave at 121° C for 20 minutes.9 Both samples were bathed into microplate well containing 50 μl of fibroblast cells with 2 x 105 density in Rosewell Park Memorial Institute-1640 (RPMI-1640 media, spinned at 30 rpm for 5 minutes. Microplate well was incubated for 24 and 48 hours in 37° C. After 24 hours, each well that will be read at 24 hour were added with 50 μl solution containing 5mg/ml MTT reagent in phosphate buffer saline (PBS solutions, then reincubated for 4 hours in CO2 10% and 37° C. Colorometric assay with MTT was used to evaluate viability of the cells population after 24 hours. Then, each well were added with 50 μl dimethyl sulfoxide (DMSO and reincubated for 5 minutes in 37° C. the wells were read using Elisa reader in 620 nm wave length. Same steps were done for the wells that will be read in 48 hours. Each data were tabulated and analyzed using independent T-test with significance of 5%. Results: This study showed that the percentage of living fibroblast after exposure to 316L stainless steel reconstruction plate was 61.58% after 24 hours and 62

  18. Rheological Properties of Mixtures of 316L Stainless Stell Powders With Polyproplylen Based Binders

    KARATAŞ, Çetin

    1998-01-01

    The flowabilities of feedstocks for powder injection molding (PIM), of 316L stainless steel powders (mean diameters 5.84, 30.42, 40.35, 67.42 mm) with thermoplastic binders (60% paraffin, 35% polypropylene, 5% stearic acid) were investigated. For this purpose, a capillary rheometer was designed and constructed. The rheometer was heated in 30 minutes to 300 °C with an accuracy of \\pm 1 °C. Its load range was 63-55.000 grams. The best flow measurements were made at 175 °C for all feed...

  19. Processing and properties of sinters prepared from 316L steel nanopowders

    J. Paduch

    2007-04-01

    Full Text Available Purpose: The results of the research work on processing the sinters obtained from nanocrystalline powders of 316L steel are presented.Design/methodology/approach: The 316L steel powder has been mechanically alloyed from a set of elementary powders with use of Fritsch Vario-Planetary Mill Pulverisette 4. The time of 12 hours of milling has been needed for producing the powder. The X-ray diffraction has been used for controlling of the mechanical alloying process. The Rietveld method has been used to calculate the contents of the components of the powder. Cold and hot isostatic pressing have been applied to make the compacts. The pressure of 500 MPa and 900 MPa of cold pressing, and 150 MPa of hot pressing have been used. The green compacts have been pressed isostaticly using liquid aluminum in the temperature of 950°C (1223 K. The X-ray diffraction have been used to identify the phase components of the sinters. The structure of the sinters have been observed using scanning electron microscope. The hardness values have been obtained by Vicker’s test.Findings: The mechanically alloyed powder has consisted of about 94 wt.% of austenite, 5 wt.% of ferrite and not more than 1 wt.% of not alloyed molybdenum. Two kinds of sinters have been produced, one kind made of pure 316L powder, second one obtained with aluminum infiltration within the volume of the sinters. The observed porosity of the sinters has depended on the applied pressing conditions strongly, mainly on the value of cold isostatic pressure. The hardness of the first kind of sinters have achieved a value of 380 HV (98N, the hardness of the second kind - more than 400 HV (98N.Practical implications: The Al infiltrated sinter has been proposed as a material for a part of Diesel engine. As an example, a part of a fuel injection has been produced.Originality/value: The nanocrystalline 316L powder has been obtained using mechanical alloying process. The original method of hot isostatic

  20. Solute segregation on Σ3 and random grain boundaries in type 316L stainless steel

    Solute segregation and impurity segregation on random and Σ3 grain boundaries in a type 316L stainless steel were investigated by means of atom probe tomography (APT). Segregation of Mo, P, B, and C was observed on random grain boundaries, irrespective of grain boundary misorientation. Two-dimensional concentration maps along the grain boundary plane revealed that the concentrations of all segregated elements were not homogeneous and no co-segregation was observed. In contrast, no segregation was observed on Σ3 grain boundaries

  1. Lattice rotation induced by plasma nitriding in a 316L polycrystalline stainless steel

    Stinville, J.C. [Laboratoire de Mecanique et de Physique des Materiaux, ENSMA, 86961 Futuroscope-Chasseneuil (France)] [Laboratoire de Physique des Materiaux, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France); Villechaise, P., E-mail: patrick.villechaise@lmpm.ensma.fr [Laboratoire de Mecanique et de Physique des Materiaux, ENSMA, 86961 Futuroscope-Chasseneuil (France); Templier, C.; Riviere, J.P.; Drouet, M. [Laboratoire de Physique des Materiaux, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France)

    2010-05-15

    The introduction at moderate temperature of nitrogen in the 316L austenitic stainless steel by plasma nitriding modifies the crystallographic texture in the very near surface region. The evolution of texture components has been quantitatively characterized by electron backscattered diffraction. The analysis of these experiments shows that the amplitude of the lattice rotation as well as the direction of rotation are directly related to the initial orientation of each grain. The retexturing behaviour is consistent with the lattice rotation upon tensile elongation of polycrystalline materials predicted by the Taylor model.

  2. Modeling of the Tension and Compression Behavior of Sintered 316L Using Micro Computed Tomography

    Doroszko Michał

    2015-06-01

    Full Text Available This paper describes the method of numerical modeling of the tension and compression behavior of sintered 316L. In order to take into account the shape of the mesostructures of materials in the numerical modeling, X-ray microtomography was used. Based on the micro-CT images, three-dimensional geometrical models mapped shapes of the porosity were generated. To the numerical calculations was used finite element method. Based on the received stress and strain fields was described the mechanism of deformation of the materials until fracture. The influence of material discontinuities at the mesoscopic scale on macromechanical properties of the porous materials was investigated.

  3. Corrosion tests of 316L and Hastelloy C-22 in simulated tank waste solutions

    MJ Danielson; SG Pitman

    2000-02-23

    Both the 316L stainless steel and Hastelloy{reg_sign} C-22 gave satisfactory corrosion performance in the simulated test environments. They were subjected to 100 day weight loss corrosion tests and electrochemical potentiodynamic evaluation. This activity supports confirmation of the design basis for the materials of construction of process vessels and equipment used to handle the feed to the LAW-melter evaporator. BNFL process and mechanical engineering will use the information derived from this task to select material of construction for process vessels and equipment.

  4. Effects of hydrogen diffusion on the mechanical properties of austenite 316L steel at ambient temperature

    This study examined how the strain rate affects the room-temperature tensile behavior of hydrogen-charged 316L stainless steels. A high-temperature homogenization treatment was applied to the specimens after hydrogen charging and copper electroplating to remove the hydrogen concentration gradient. A softening phenomenon was observed in the hardening behavior of the H-charged and homogenized specimen at a strain rate of 2x10-3/s. The observation was further confirmed by an inspection of the fracture surface of the tensile test specimen. (author)

  5. Fine structure analysis of biocompatible ceramic materials based hydroxyapatite and metallic biomaterials 316L

    The aim of this paper was to obtain and characterize (surface morphology and fine structure) two types of materials: Ca10(PO4)6(OH)2 hydroxyapatite powder (HAp) as biocompatible ceramic materials and AISI 316L austenitic stainless steels as metallic biomaterials, which are the components of the metal–ceramic composites used for medical implants in reconstructive surgery and prosthetic treatment. The HAp was synthesized by coprecipitation method, heat treated at 200 °C, 800 °C and 1200 °C for 4 h, analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The stainless steel 316L type was made by casting, annealing and machined with a low speed (100 mm/s) in order to obtain a smooth surface and after that has been studied from residual stresses point of view in three polishing regimes conditions: at low speed polishing (150 rpm), at high speed polishing (1500 rpm) and high speed-vibration contact polishing (1500 rpm) using wide angle X-ray diffractions (WAXD). The chemical compositions of AISI 316 steel samples were measured using a Foundry Master Spectrometer equipped with CCD detector for spectral lines and the sparking spots of AISI 316L samples were analyzed using SEM. By XRD the phases of HAp powders have been identified and also the degree of crystallinity and average size of crystallites, and with SEM, we studied the morphology of the HAp. It has been found from XRD analysis that we obtained HAp with a high degree of crystallinity at 800 °C and 1200 °C, no presence of impurity and from SEM analysis we noticed the influence of heat treatment on the ceramic particles morphology. From the study of residual stress profiles of 316L samples were observed that it differs substantially for different machining regimes and from the SEM analysis of sparking spots we revealed the rough surfaces of stainless steel rods necessary for a better adhesion of HAp on it.

  6. Production of Ti-containing 316L stainless steel in a crucible induction furnace

    The production of type 316L stainless steel with titanium was studied. The stainless steel was produced in an induction furnace using 1010 steel as starting material. The carbon and impurities contents of the steel were lowered by means of the addition of iron oxide and lime respectively. Finally, the last slag was removed before adding nickel and ferroalloys. Experimental results showed the wear resistance of the crucibles with different contents of magnamix 363 and the corrosion resistance of the steel obtained caused by a solution of sulfuric acid. (author)

  7. Mechanical and physical behavior of newly developed functionally graded materials and composites of stainless steel 316L with calcium silicate and hydroxyapatite.

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Mehrali, Mehdi; Yau, Yat Huang; Tarlochan, Faris; Abu Osman, Noor Azuan

    2015-09-01

    This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application. PMID:26072197

  8. Effect of the aging treatment in the fractures mechanics of welded joints of steel 316L

    The austenitic stainless steel 316L is widely used in nuclear industry because of its excellent mechanical properties and corrosion resistance. These properties must be evaluated in order to prevent failure and extend the life of equipment. The microstructure in the weld fusion zone consists on an austenite matrix with 5-12% of delta ferrite met stable at room temperature. However the pressurized water reactors operate at temperatures in the range 290-325 deg C, thus welds may be susceptible to thermal aging embrittlement after long service life. According to the literature, this occurs due to the spinodal decomposition. Therefore, the purpose of this study was to evaluate the mechanical properties of 316L stainless steel welds by hardness and tensile tests before and after heat treatment. In this regard, two steel plates were welded and part of the material was heat treated at 335 deg C for 1000 hours. The tests after heat treatment showed an increase of only 4% in ultimate tensile strength and an increase of 28% in hardness. No changes were observed in the material microstructure, however according to literature changes can be identified by transmission electron microscopy. The curves of impact energy vs. temperature showed little change but, it was not able to observe a ductile-brittle transition and images of microstructure from scanning electronic microscopy (SEM) did not show fragile behavior. (author)

  9. Preparation and characterization of stainless steel 316L/HA biocomposite

    Gilbert Silva

    2012-01-01

    Full Text Available The austenitic stainless steel 316L is the most used metallic biomaterials in orthopedics applications, especially in the manufacture of articulated prostheses and as structural elements in fracture fixation, since it has high mechanical strength. However, because it is biologically inactive, it does not form chemical bond with bone tissue, it is fixed only by morphology. The development of biocomposites of stainless steel with a bioactive material, such as hydroxyapatite - HA, is presented as an alternative to improve the response in the tissue-implant interface. However significant reductions in mechanical properties of the biocomposite can occur. Different compositions of the biocomposite stainless steel 316L/HA (5, 20 and 50 wt. (% HA were prepared by mechanical alloying. After milling the powders for 10 hours, the different compositions of the biocomposite were compacted isostatically and sintered at 1200 ºC for 2 hours. The mechanical properties of the biocomposites were analyzed by compression tests. The powders and the sintered composites were analyzed by scanning electron microscopy (SEM and X-ray diffraction (XRD.

  10. Preparation and characterization of stainless steel 316L/HA biocomposite

    Gilbert Silva

    2013-04-01

    Full Text Available The austenitic stainless steel 316L is the most used metallic biomaterials in orthopedics applications, especially in the manufacture of articulated prostheses and as structural elements in fracture fixation, since it has high mechanical strength. However, because it is biologically inactive, it does not form chemical bond with bone tissue, it is fixed only by morphology. The development of biocomposites of stainless steel with a bioactive material, such as hydroxyapatite - HA, is presented as an alternative to improve the response in the tissue-implant interface. However significant reductions in mechanical properties of the biocomposite can occur. Different compositions of the biocomposite stainless steel 316L/HA (5, 20 and 50 wt. (% HA were prepared by mechanical alloying. After milling the powders for 10 hours, the different compositions of the biocomposite were compacted isostatically and sintered at 1200 ºC for 2 hours. The mechanical properties of the biocomposites were analyzed by compression tests. The powders and the sintered composites were analyzed by scanning electron microscopy (SEM and X-ray diffraction (XRD.

  11. Phase transformation of 316L stainless steel from wire to fiber

    In this work, quantitative crystalline phase analysis of 316L stainless steel from wire to fiber using a multi-pass cold drawing process was studied using the Rietveld whole XRD profile fitting technique. The different diameters of the fibers: 179, 112, 75, 50, 34, 20, and 8 μm, were produced from an as-received wire with a diameter of 190 μm. The crystalline phases were identified using MDI Jade 5.0 software. The volume fractions of crystalline phases were estimated using a Materials Analysis Using Diffraction software. XRD analysis revealed that the crystal structure of as-received wire is essentially a γ-austenite crystalline phase. The phase transformation occurred during the 316L stainless steel from wire to fiber. Three crystalline phases such as γ-austenite, α'-martensite, and sigma phase of the fine fiber were observed. A cold drawing accelerates the sigma phase precipitates, particularly during the heat treatment of the fiber.

  12. Parylene coatings on stainless steel 316L surface for medical applications — Mechanical and protective properties

    The mechanical and protective properties of parylene N and C coatings (2–20 μm) on stainless steel 316L implant materials were investigated. The coatings were characterized by scanning electron and confocal microscopes, microindentation and scratch tests, whereas their protective properties were evaluated in terms of quenching metal ion release from stainless steel to simulated body fluid (Hanks solution). The obtained results revealed that for parylene C coatings, the critical load for initial cracks is 3–5 times higher and the total metal ions release is reduced 3 times more efficiently compared to parylene N. It was thus concluded that parylene C exhibits superior mechanical and protective properties for application as a micrometer coating material for stainless steel implants. - Highlights: ► Parylene biocompatible coating was applied for steel implant surfaces by CVD method. ► Mechanical and protective properties of polymer layers were determined. ► Rival discrimination between parylene N and C on steel 316L was performed. ► Total metal ions release was reduced more efficiently by parylene C coating. ► Critical load for initial cracks was 3–5 times higher for parylene C coating.

  13. Fabrication of antibacterial and hydrophilic electroless Ni-B coating on 316L stainless steel

    Bülbül, Ferhat; Bülbül, Leman Elif

    2016-01-01

    Biomaterial-associated bacterial infection is one of the most common complications with medical vehicles and implants made of stainless steel. A surface coating treatment like electroless Ni-B deposition, a new candidate to be used in a broad range of engineering applications owing to many advantages such as low cost, thickness uniformity, good wear resistance, may improve the antibacterial activity and physical properties of biomedical devices made of stainless steel. In this study, the antibacterial property of the electroless Ni-B film coated on AISI 316L (UNS S31603) stainless steel is basically investigated. Inhibition halo diameter measurement after incubation at 37 °C and 24 h demonstrates the existence of antimicrobial activity of the electroless Ni-B coating deposited on 316L stainless steel over the Escherichia coli test bacteria. The results of X-ray diffraction, scanning electron microscopy, atomic force microscopy and microhardness measurement studies confirms that the coating deposited on the substrate has an uniform amorphous and a harder structure. Besides, the wettability property of the uncoated substrate and the coating was measured as the contact angle of water. The water contact angle reduced about from 97.7 to 69.25°.

  14. Mechanical properties and biocompatibility of plasma-nitrided laser-cut 316L cardiovascular stents.

    Arslan, Erdem; Iğdil, Mustafa C; Yazici, Hilal; Tamerler, Candan; Bermek, Hakan; Trabzon, Levent

    2008-05-01

    The effect of surface modification of laser-cut 316L cardiovascular stents by low-T plasma nitriding was evaluated in terms of mechanical properties and biocompatibility of the stents. The plasma nitriding was performed at 400, 450 or 500 degrees C using various ratios of nitrogen-hydrogen gas mixtures. The flexibility and radial strength were measured in crimped and expanded state of the stents, respectively. The mechanical properties could be adjusted and improved by plasma nitriding conducted at temperatures lower than 450 degrees C and/or nitrogen content less than 10% in the treatment gas. An osteoblast cell culture model system was utilized to investigate the effect of plasma nitriding of the stents on the biological response towards the stents, using biological criteria such as cell viability, alkaline phosphatase and nitric oxide production. In terms of cell viability and alkaline phosphatase production, the plasma nitriding procedure did not appear to negatively affect the biocompatibility of the 316L steel stents. However, in terms of nitric oxide production that was slightly increased in the presence of the plasma-nitrided stents, an indirect improvement in the biocompatibility could possibly be expected. PMID:17968502

  15. Stability of passivated 316L stainless steel oxide films for cardiovascular stents.

    Shih, Chun-Che; Shih, Chun-Ming; Chou, Kuang-Yi; Lin, Shing-Jong; Su, Yea-Yang

    2007-03-15

    Passivated 316L stainless steel is used extensively in cardiovascular stents. The degree of chloride ion attack might increase as the oxide film on the implant degrades from exposure to physiological fluid. Stability of 316L stainless steel stent is a function of the concentration of hydrated and hydrolyated oxide concentration inside the passivated film. A high concentration of hydrated and hydrolyated oxide inside the passivated oxide film is required to maintain the integrity of the passivated oxide film, reduce the chance of chloride ion attack, and prevent any possible leaching of positively charged ions into the surrounding tissue that accelerate the inflammatory process. Leaching of metallic ions from corroded implant surface into surrounding tissue was confirmed by the X-ray mapping technique. The degree of thrombi weight percentage [W(ao): (2.1 +/- 0.9)%; W(ep): (12.5 +/- 4.9)%, p electropolishing (EP) treatment groups was statistically significant in ex-vivo extracorporeal thrombosis experiment of mongrel dog. The thickness of neointima (T(ao): 100 +/- 20 microm; T(ep): 500 +/- 150 microm, p < 0.01) and the area ratio of intimal response at 4 weeks (AR(ao): 0.62 +/- 0.22; AR(ep): 1.15 +/- 0.42, p < 0.001) on the implanted iliac stents of New Zealand rabbit could be a function of the oxide properties. PMID:17072844

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

    Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3–6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

  17. Modelling of microstructural creep damage in welded joints of 316L stainless steel

    Welded joints of 316L stainless steel under service conditions at elevated temperature are known to be preferential sites of creep damage, as compared to the base material. This damage results in the formation of cavities and the development of creep cracks which can lead to a premature failure of welded components. The complex two-phase microstructure of 316L welds was simulated by manually filling a mould with longitudinal deposited weld beads. The moulded material was then aged during 2000 hours at 600 deg. C. High resolution Scanning Electron Microscopy was largely used to examine the microstructure of the simulated material before and after ageing. Smooth and notched creep specimens were cut from the mould and tested at 600 deg. C under various stress levels. A comparison of the lifetime versus nominal stress curves for the base and welded materials shows a greater dependence of the welded material to creep phenomena. Observation and EBSD analysis show that damage is preferentially located along the austenite grain boundaries. The stress and strain fields in the notched specimens were calculated by finite element method. A correlation of this field to the observed damage was made in order to propose a predictive law relating the creep damage to the mechanical conditions applied locally. Further mechanical tests and simulation on CT specimens and mode II tubular specimens allowed validating the model under various multiaxial loading conditions. (author)

  18. Cyclic mechanical behavior of 316L: Uniaxial LCF and strain-controlled ratcheting tests

    Facheris, G., E-mail: giacomo.facheris@psi.ch [Laboratory for Nuclear Materials, Nuclear Energy and Safety Research Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Janssens, K.G.F., E-mail: koen.janssens@psi.ch [Laboratory for Nuclear Materials, Nuclear Energy and Safety Research Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2013-04-15

    Highlights: ► Characterization of cyclic plastic deformation behavior of plate and tubular 316L. ► Strain-controlled ratcheting response between room temperature and 200 °C. ► Isotropic cyclic hardening is dependent on the yield criterion used. ► Ratcheting induced hardening mostly affects the kinematic hardening component. ► Ratcheting induced hardening is related to the mean strain and the ratcheting rate. -- Abstract: With the purpose of analyzing the fatigue behavior under loading conditions relevant for the primary cooling circuit of a light water nuclear reactor, a set of uniaxial low cycle fatigue and strain-controlled ratcheting tests (also named ‘cyclic tension tests’) has been performed at room temperature and at 200 °C on specimens manufactured from two different batches of stainless steel grade 316L. The experiments have been repeated varying strain amplitude, cyclic ratcheting rate and ratcheting direction in order to investigate the influence on the cyclic deformation behavior. In strain-controlled ratcheting tests, the stress response is found to be a superposition of two hardening mechanisms: the first one due to the zero mean strain cycling and the second one linked with the monotonic drifting of mean plastic strain. An approach is proposed to distinguish the effect of each mechanism and the influence of the test parameters on the hardening mechanisms is discussed.

  19. Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder

    Jeon Byoungjun

    2015-06-01

    Full Text Available 316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.

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

    Yang Cai

    2015-01-01

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

  1. Hydrogen uptake in 316L stainless steel: Consequences on the tensile properties

    Different charging conditions aimed at introducing significant hydrogen concentrations without microstructural damages in a 316L austenitic stainless steel were investigated. The equivalent hydrogen pressure developed at the surface of the samples during cathodic charging was estimated from hydrogen concentration measurements. A clear hydrogen absorption, controlled by diffusion, was evidenced during the immersion of 316L steel samples in 30% MgCl2 at the open circuit potential at 117 deg. C. Deuterium profiling by SIMS was performed to check the validity of the few literature data on hydrogen diffusivity in the near room temperature range in this material. On the other hand, the macroscopic effects of hydrogen on the tensile characteristics of the steel were investigated and compared at 20 deg. C and at -196 deg. C with samples cathodically pre-charged, charged during tensile straining or pre-charged at high temperature-high pressure in gas phase. Hydrogen is shown to affect both the short range and the long range forces exerted on the strain-induced mobile dislocations. The hydrogen-induced softening effect observed at 20 deg. C and the systematic decrease of the ductility support a mechanism involving the enhanced transport of hydrogen atoms by mobile dislocations. This mechanism is confirmed by the absence of softening and of ductility loss at -196 deg. C and by the strain-enhanced tritium desorption from samples cathodically pre-charged with tritium, measured by β counting during tensile deformation

  2. Dislocation evolution in 316L stainless steel subjected to uniaxial ratchetting deformation

    Dislocation patterns and their evolution in 316L stainless steel subjected to uniaxial stress-controlled cyclic loading with occurrence of ratchetting deformation were observed by transmission electron microscopy (TEM). The microscopic observations show that the dislocation patterns change from low density patterns such as dislocation lines and pile-ups to those with higher dislocation density such as dislocation tangles, veins, walls, and cells, when the macroscopic ratchetting strain progressively increases with the number of cycles. Although one or two kinds of dislocation patterns mentioned above are prevailing in most of the grains at certain stage of ratchetting deformation, other patterns can be also observed in some grains at the same time. The features of dislocation evolution presented during the uniaxial ratchetting deformation are summarized by comparing with the dislocation patterns observed during monotonic tension and symmetrical uniaxial strain-controlled cyclic loading. The uniaxial ratchetting of 316L stainless steel can be qualitatively explained by the observed dislocation patterns and their variation with the number of cycles.

  3. Controlling the electrodeposition, morphology and structure of hydroxyapatite coating on 316L stainless steel

    Hydroxyapatite (HAp) coatings were prepared on 316L stainless steel (316LSS) substrates by electrochemical deposition in the solutions containing Ca(NO3)2·4H2O and NH4H2PO4 at different electrolyte concentrations. Along with the effect of precursor concentration, the influence of temperature and H2O2 content on the morphology, structure and composition of the coating was thoroughly discussed with the help of X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra. The in vitro tests in simulated body fluids (SBF) were carried out and then the morphological and structural changes were estimated by SEM and electrochemical techniques (open circuit potential, polarization curves, Nyquist and Bode spectra measurements). Being simple and cost-effective, this method is advantageous for producing HAp implant materials with good properties/characteristics, aiming towards in vivo biomedical applications. - Highlights: ► Successful electrodeposition of HAp on 316L SS by a simple method ► The influence of some key parameters on the HAP morphology was discussed. ► Morphological and structural changes of HAP layer in SBF were thoroughly investigated

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

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

    2014-07-01

    Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3-6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

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

    Hajian, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Abdollah-zadeh, A., E-mail: zadeh@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Rezaei-Nejad, S.S.; Assadi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [Department of Materials Science and Engineering, MA University of Technology, Tehran (Iran, Islamic Republic of); Chung, K. [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Engineering Research Institute, Seoul National University, Seoul (Korea, Republic of); Shokouhimehr, M. [Department of Chemical Engineering, College of Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-07-01

    Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3–6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

  6. Characterization of 316L steel welded joints irradiated between 15 to 41 dpa

    Solution annealed austenitic stainless steel Type 316L has been selected for use in the Next European Torus First Wall. Specimens taken from the European Reference Type 316L steel and welds, including electron beam, manual metal arc and weld deposits, have been irradiated at temperatures between 4120C to 5450C to neutron doses ranging from 15 through 41 dpa. Post irradiation experiments conducted have included density and dimensional measurements, tensile, fracture mechanics, fatigue crack growth rate, low cycle fatigue, and creep-fatigue tests. Irradiated specimens undergo dimensional changes with a maximum swelling (about 5%) occurring in specimens irradiated to 41 dpa at about 4500C. Yield stress and ultimate tensile strength have been found to sharply increase, reaching levels as high as 250% in the temperature range of 400-4500C. A significant decrease has been observed in the tensile elongation with the uniform elongation of some welded specimens attaining values as low as 1%. Fracture toughness of welded materials have also been found to sharply decrease particularly in weld deposits. Fatigue crack growth rate and continuous fatigue resistance of weldments have been found to be particularly affected by irradiation. It is concluded that for NET conditions, where the irradiation doses are significantly lower than the doses used in the present study (<15 dpa) and consequently the mechanical property changes will be less severe, swelling data in the range of 5 to 15 dpa are mostly needed

  7. HIP of stainless steel 316L considered at the mesoscopic scale: Numerical modelling and experimental characterization

    A two and three-dimensional finite element simulation of HIP (Hot Isostatic Pressing) at mesoscopic scale is proposed, in view of an in-depth understanding of the different physical mechanisms involved in powder densification. The model is formulated in a Eulerian framework, using level set formulation and adaptive meshing and re-meshing strategy to identify particle interactions inside a representative elementary volume (REV). A statistical generator is in charge of the definition of the initial configuration under the constraint of accounting for the real particle size distribution. Mechanical boundary conditions are applied to the REV, resulting in the deformation of particles and densification of the REV. As a first approach, the power-law creep of particles is considered as the unique densification mechanism. Starting from data issued from macroscopic simulations of the HIPping of a part made of 316L powder, mesoscopic simulations in different locations of the part have been carried out (macro-to-meso approach). The results of these simulations are presented and discussed in the light of experimental studies (optical microscopy and SEM, EBSD, EPMA) of the structure and microstructure of the compact, which were obtained from interrupted compactions. Mechanical tests on fully densified 316L were also conducted. (author)

  8. Effects of heat treatments on microstructure changes in the interface of Cu/SS316L joint materials

    Precipitation and dispersion strengthened copper alloys joined with 316L austenitic stainless steel are expected to be heat sink materials in the first wall and divertor of International Thermonuclear Experimental Reactor (ITER) owing to the good thermal conductivity of Cu alloys. In the present study, the effects of heat treatment on microstructural stability in the interface of CuNiBe/SS316L and CuAl25/SS316L have been investigated. In the as-received CuNiBe/SS316L joints, voids were observed at the interface, and in the stainless steel side near the interface. But in the CuAl25/SS316L joints, voids were observed only in the Cu side near the interface. These voids would have a significant effect on the mechanical properties of joints. The results of annealing experiments showed that the microstructures in the interface of both types of joints were thermally stable during annealing at 573 and 673 K for 100 h

  9. Bone-like apatite formation on HA/316L stainless steel composite surface in simulated body fluid

    FAN Xin; CHEN Jian; ZOU Jian-peng; WAN Qian; ZHOU Zhong-cheng; RUAN Jian-ming

    2009-01-01

    HA/316L stainless steel(316L SS) biocomposites were prepared by hot-pressing technique. The formation of bone-like apatite on the biocomposite surfaces in simulated body fluid(SBF) was analyzed by digital pH meter, plasma emission spectrometer, scanning electron microscope(SEM) and energy dispersive X-ray energy spectrometer(EDX). The results indicate that the pH value in SBF varies slightly during the immersion. It is a dynamic process of dissolution-precipitation for the formation of apatite on the surface. With prolonging immersion time, Ca and P ion concentrations increase gradually, and then approach equilibrium. The bone-like apatite layer forms on the composites surface, which possesses benign bioactivity and favorable biocompatibility and achieves osseointegration, and can provide firm fixation between HA60/316L SS composite implants and human body bone.

  10. Effect of Cold-Rolling on Precipitation Phenomena in Sensitized Type 316L and 340L Austenitic Stainless Steels

    H.Tsubakino; A.Yamamoto; T. Yamada; L.Liu; M.Terasawa; S.Nakahigashi; H.Harada

    2004-01-01

    Precipitation phenomena in Type 316L and 304L stainless steels were studied mainly by transmission electron microscopic (TEM) observations after cold-rolling ranging from 0% (as solution annealed) to 80% reduction in thickness,and then by sensitization treatment. Precipitates were identified by electron diffraction analysis and EDS analysis.Precipitates observed in sensitized 316L stainless steel were sigma and chi phases, whereas carbide and sigma were observed in sensitized 304L stainless steel. Recrystallized grains were formed in 30% cold-rolled and sensitized 304L.However, the tendency toward recrystallization in sensitized 316L was much lower than in 304L. Precipitation of sigma and chi phases was accelerated by cold-rolling and they were observed at grain boundaries in lower cold-rolling; they were also seen, in grain interiors in higher cold-rolling. Higher deformation induced partially recrystallization combined with precipitation, resulting in the formation of heterogeneous microstructures.

  11. Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

    Nagarajan, S.; Rajendran, N.

    2009-01-01

    Porous titanium dioxide was coated on surgical grade 316L stainless steel (SS) and its role on the corrosion protection and enhanced biocompatibility of the materials was studied. X-ray diffraction analysis (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were carried out to characterise the surface morphology and also to understand the structure of the as synthesised coating on the substrates. The corrosion behaviour of titanium dioxide coated samples in simulated body fluid was evaluated using polarisation and impedance spectroscopy studies. The results reveal that the titanium dioxide coated 316L SS exhibit a higher corrosion resistance than the uncoated 316L SS. The titanium dioxide coated surface is porous, uniform and also it acts as a barrier layer to metallic substrate and the porous titanium dioxide coating induces the formation of hydroxyapatite layer on the metal surface.

  12. Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

    Porous titanium dioxide was coated on surgical grade 316L stainless steel (SS) and its role on the corrosion protection and enhanced biocompatibility of the materials was studied. X-ray diffraction analysis (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were carried out to characterise the surface morphology and also to understand the structure of the as synthesised coating on the substrates. The corrosion behaviour of titanium dioxide coated samples in simulated body fluid was evaluated using polarisation and impedance spectroscopy studies. The results reveal that the titanium dioxide coated 316L SS exhibit a higher corrosion resistance than the uncoated 316L SS. The titanium dioxide coated surface is porous, uniform and also it acts as a barrier layer to metallic substrate and the porous titanium dioxide coating induces the formation of hydroxyapatite layer on the metal surface.

  13. Corrosion, haemocompatibility and bacterial adhesion behaviour of TiZrN-coated 316L SS for bioimplants

    Gobi Saravanan Kaliaraj; Vinita Vishwakarma; Ananthakumar Ramadoss; D Ramachandran; Arul Maximus Rabel

    2015-08-01

    TiZrN coating was deposited on 316L stainless steel (SS) by the reactive magnetron co-sputtering technique. Cubic phase of TiZrN with uniform surface morphology was observed by X-ray diffraction and atomic force microscopy. Bacterial adhesion, haemocompatibility and corrosion behaviour of TiZrN coating were examined in order to evaluate the coating’s compatibility for ideal implant. Results revealed that TiZrN coatings exhibited less bacterial attachment against Staphylococcus aureus and Escherichia coli bacteria, negligible platelets activation and superior corrosion resistance than the uncoated 316L SS.

  14. Optimization of the contact mechanical strength of magnetron-sputtered nitrogen-doped AISI 316L physically vapour deposited coatings

    The reactive magnetron sputtering technique adopted produces perfectly adhering nitrogen-doped AISI 316L coatings on construction and stainless steel substrates (AISI 316L and 4135). Surface mechanical testing was done by indentation and sclerometric, frictional, low cycle fatigue. The major damage parameters adopted were the critical coating cracking loads, track depression and lateral pile-up volumes. It is shown that the detrimental effect of growth defects on coating brittleness can be controlled to some extent by optimizing substrate surface treatment prior to and bias voltage during deposition. (orig.)

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

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

  16. Rapid heating tensile tests of hydrogen-charged high-energy-rate-forged 316L stainless steel

    Mosley, W.C.

    1989-05-19

    316L stainless steel is a candidate material for construction of equipment that will be exposed to tritium. Proper design of the equipment will require an understanding of how tritium and its decay product helium affect mechanical properties. This memorandum describes results of rapid heating tensile testing of hydrogen-charged specimens of high-energy-rate-forged (HERF) 316L stainless steel. These results provide a data base for comparison with uncharged and tritium-charged-and-aged specimens to distinguish the effects of hydrogen and helium. Details of the experimental equipment and procedures and results for uncharged specimens were reported previously. 3 refs., 10 figs.

  17. Electrochemical and surface study of the oxide growth and conversion on 316L stainless steel

    Oxide formation and conversion mechanism as a function of potential on 316L stainless steel was investigated using electrochemical and surface analysis techniques. All of the results were consistent with the electrochemical thermodynamics. Four potential regions were identified for anodic oxidation. In Ox I, conversion of the defective chromium oxide layer to an iron/chromium spinel phase occurred. This was followed by conversion of the upper Fe3O4 oxide to a passivating γ-Fe2O3 layer in Ox II. At potentials > 0.0 VSCE, Ox III and IV involved the formation of γ-FeOOH and conversion of CrIII to soluble CrVI respectively contributing to film breakdown. (author)

  18. Cyclic deformation behavior of a 316L austenitic stainless steel processed by high pressure torsion

    The influence of severe plastic deformation (SPD) on the fatigue behavior of a modified 316L austenitic stainless steel is investigated. Different ultrafine-grained and nanocrystalline microstructures are obtained by changing the processing parameters and applying a post heat treatment procedure. Samples are fatigued using both, load and strain controlled experiments. High pressure torsion processing makes it possible to reach a saturation microstructure, which is cyclically stable up to a stress level three times higher than the stress level of the coarse-grained structure. Fracture surface investigations and surface damage clearly show that the failure behavior of the SPD states under cyclic loading is different to their coarse-grained counterparts. For these microstructures, localized deformation in shear bands seems to play a major role for crack initiation and propagation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

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

  20. Analysis of deformation induced martensite in AISI 316L stainless steel

    Jagarinec, Darko; Kirbis, Peter; Predan, Jozef; Vuherer, Tomaz; Gubeljak, Nenad [Maribor Univ. (Slovenia). Faculty of Mechanical Engineering

    2016-08-01

    Metastable austenite stainless steel AISI 316L is sensitive to cold deformation, where transformation from austenite to martensite occurred. The bending deformation as the formation process leads to tensile and compression throughout the thickness of the billet. Tensile testing of the specimen causes differences in the true stress-strain along the contraction neck prior to fracture as well. The aim of the paper is to find correlation between microhardness as brief inspection parameters and extension of martensitic transformation. The total equivalent plastic strain extend diagram obtained by numerical simulation of bending was compared with tensile true stress-strain diagram. Results show very good correlation between hardness, true strain and martesite content. Therefore, one can conclude that by hardness measurement, it is possible to measure the level of equivalent plastic strain until ultimate tensile stress as a linear correlation between hardness, true strain and martesite content.

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

    The total replacement of joints by the implantation of permanently indwelling prosthetic components has been one of the major successes of modern surgery in terms of relieving pain and correcting deformity. However, the aseptic loosening of a prosthetic-joint component is the most common reason for joint-revision surgery. Furthermore, it is thought that wear particles are one of the major contributors to the development and perpetuation of aseptic loosening. The aim of the present study was to identify the factors related to the aseptic loosening of an AISI 316L stainless steel total hip prosthesis. The stem was evaluated by x-ray photoelectron spectroscopy, with polished and rough regions being analyzed in order to establish the differences in the chemical compositions of both regions. Specific areas were examined using scanning electron microscopy with energy dispersive x-ray spectroscopy and light microscopy.

  2. The surface cleanliness of 316 L + N stainless steel studied by SIMS and AES

    Mathewson, A G

    1974-01-01

    Some cleaning methods for 316 L+N stainless steel including solvent cleaning, high temperature treatment in vacuo and gas discharge cleaning have been studied by SIMS and AES with a view to providing a clean vacuum chamber surface with low gas desorption under ion bombardment. After solvent cleaning the main surface contaminant was found to be C and its associated compounds. Laboratory investigations on small samples of stainless steel showed that clean surfaces could be obtained by heating in vacuo to 800 degrees C followed by exposure to air and by argon or argon/10% oxygen discharge cleaning. Due to a cross contamination within the vacuum system, the 800 degrees C treated chamber gave positive desorption coefficients under ion bombardment. The pure argon discharge cleaned chambers proved stable giving negative desorption coefficients up to 2200 eV ion energy even after several weeks storage discharge treatment and installation. (10 refs).

  3. Modeling of the lattice rotations induced by plasma nitriding of 316L polycrystalline stainless steel

    The anisotropic lattice rotation of individual grains induced by plasma nitriding of 316L austenitic stainless steel has been analyzed with the aim of identifying correlations between the initial grain’s orientation and the rotation behavior. Due to the quite large nitriding-induced strains (up to 20%), the Taylor–Bishop–Hill model has been chosen for the simulation of the lattice rotations. The model predicts the overall rotations, both amplitude and direction, reasonably well over the entire stereographic triangle. The magnitude of the rotations is in agreement with the level of deformation induced by insertion of nitrogen atoms into an austenitic lattice. With regard to plasticity, parallels between the nitriding process and tensile elongation along the normal surface can be drawn

  4. Influence of annealing on grain boundary segregation of neutron irradiated type 316L stainless steel

    Type 316L stainless steel was neutron irradiated (8x1025 n/m2, E>1MeV) and annealed at 673 K - 973 K for 1 hour. After the annealing, intergranular fracture ratio measurement by SSRT, grain boundary analysis by FE-TEM with EDS and simulation of grain boundary Cr depletion healing were performed in order to consider an effect of segregation healing on IASCC. The intergranular fracture ratio was healed to 0% by annealing above 723 K, but the healing of grain boundary Cr depletion of 723 K annealed specimen was not recognized by EDS analysis. Considering about the EDS analysis result and analysis probe diameter, concentration profiles were calculated. As a result, it was considered that grain boundary segregation which depleted to about 8 mass% by neutron irradiation, healed to about 12 mass% by annealing at 723 K, so that IASCC susceptibility was decreased. (author)

  5. Banded structure and its distribution in friction stir processing of 316L austenitic stainless steel

    Highlights: ► Friction stir processing (FSP) as a repair method. ► Sigma phase formed in the FSP zone. ► Low heat input contributes to restrain sigma phase precipitation. - Abstract: Banded structures, which vary with welding parameters, were observed in friction stir processing of 316L austenite stainless steel. Sigma phase precipitation was detected in banded structures by transmission electron microscopy. The amount of banded structure had direct ratio relations with heat input. The higher the heat input, the larger the area of banded structures. This is attributable to slower cooling rate at high heat input, which results in longer exposure to the temperature range for precipitation. The formation of sigma phase produced Cr depletion, which resulted in largely degraded corrosion resistance. The present study suggests that low heat input (i.e. low rotation speeds, low working loads and high welding speed) contributes to restrain sigma phase precipitation.

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

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

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

  7. Adhesion of composite carbon/hydroxyapatite coatings on AISI 316L medical steel

    J. Gawroński

    2009-07-01

    Full Text Available In this paper are contains the results of studies concerning the problems associated with increased of hydroxyapatite (HAp adhesion, manufactured by using Pulse Laser Deposition (PLD method, to the austenitic steel (AISI 316L through the coating of carbon interlayer on it. Carbon coating was deposited by Radio Frequency Plasma Assisted Chemical Vapour Deposition (RF PACVD method.Test results unequivocally showed that the intermediate carbon layer in a determined manner increase the adhesion of hydroxyapatite to the metallic substrate. Obtained results give rise to deal with issues of manufacturing composite bilayer – carbon film/HAp – on ready implants, casted from austenitic cast steel by lost-wax process method as well as in gypsum forms.

  8. Cytocompatibility and mechanical properties of novel porous 316 L stainless steel.

    Kato, Komei; Yamamoto, Akiko; Ochiai, Shojiro; Wada, Masahiro; Daigo, Yuzo; Kita, Koichi; Omori, Kenichi

    2013-07-01

    Novel 316 L stainless steel (SS) foam with 85% porosity and an open pore diameter of 70-440 μm was developed for hard tissue application. The foam sheet with a 200-μm diameter had superior cell proliferation and penetration as identified through in vitro experiments. Calcification of human osteosarcoma cells in the SS foam was observed. Multi-layered foam preparation is a potential alternative technique that satisfies multi-functional requirements such as cell penetration and binding strength to the solid metal. In tensile tests, Young's modulus and the strength of the SS foam were 4.0 GPa and 11.2 MPa respectively, which is comparable with human cancellous bone. PMID:23623090

  9. Anticoagulant surface of 316 L stainless steel modified by surface-initiated atom transfer radical polymerization.

    Guo, Weihua; Zhu, Jian; Cheng, Zhenping; Zhang, Zhengbiao; Zhu, Xiulin

    2011-05-01

    Polished 316 L stainless steel (SS) was first treated with air plasma to enhance surface hydrophilicity and was subsequently allowed to react with 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane to introduce an atom transfer radical polymerization (ATRP) initiator. Accordingly, the surface-initiated atom transfer radical polymerization of polyethylene glycol methacrylate (PEGMA) was carried out on the surface of the modified SS. The grafting progress was monitored by water contact angle measurements, X-ray photoelectron spectroscopy and atomic force microscopy. The polymer thickness as a function different polymerization times was characterized using a step profiler. The anticoagulative properties of the PEGMA modified SS surface were investigated. The results showed enhanced anticoagulative to acid-citrate-dextrose (ACD) blood after grafting PEGMA on the SS surface. PMID:21528878

  10. On the wear of TiBx/TiSiyCz coatings deposited on 316L steel

    Bilayer TiBx/TiSiyCz coatings were formed on AISI 316L steel substrates by dual beam ion beam assisted deposition from TiBx and TiSiyCz targets. Coated and uncoated substrates were subjected to nanoindentation, scratch and friction-wear tests. Scratch and ball-on-disc tests were conducted in non-lubricated sliding, using a diamond pin and 100Cr6 steel ball, respectively. Scanning electron microscopy and atomic force microscopy were used to examine the surfaces of coated samples, before and after tests. To investigate wear mechanisms in the coating-substrate systems, thin foils were prepared from worn areas for transmission electron microscopy observations. TiBx/TiSiyCz coatings proved to be well adherent to steel substrates. The main wear mechanism was of abrasive type. Intensive plastic deformation of steel substrate under critical loads was revealed.

  11. Hydrogen assisted failure of precracked specimens of 316L stainless steel

    The simultaneous action of cathodic hydrogen charging and slow mechanical loading on precracked samples of 316L stainless steel is examined in order to assess the flaw tolerance of this steel, which has been included in the group of possible structural materials for the first wall of the future fusion reactors. The steel is shown to retain a significant part of its flaw tolerance even in the most severe test conditions, but the loading rate is found to change the damage phenomenology of hydrogen from bifurcated crack extension to multi-cracking and enlargement of the blunted crack tip. This change is explained on the basis of a competition mechanism between hydrogen action and mechanical deformation. (orig.)

  12. The phase change in 316L S.S. irradiated at 500 degree C

    The home made 316L S.S. was irradiated by 1.5 MeV proton and 1.8 MeV alpha particle respectively. The phase stability in irradiated samples was investigated by X-ray diffraction. No new phase was found in the specimen which was irradiated by 1.8 MeV alpha particles. But some new phases such as Cr2O3, (CrM)N were found in the specimens irradiated by 1.5 MeV proton. The content of new phases is increased with the doses. The new phase are all the compound of element O, N, S, C and base element Fe, Cr, Ni, Mo

  13. On factors influencing fatigue process in steel 316L used in hydrogen energy technologies

    Full text: Investigations of fatigue in steels exposed to hydrogen media is extremely important problem, hi this work, an austenitic stainless steel ASTM 316L resistant to hydrogen destructive influence is examined. The experiments presented have used hydrogen charged and uncharged specimens and were carried out under rotating bending and tension-compression fatigue in three different laboratories: at The University of Chemical Technology and Metallurgy, Sofia, Bulgaria; at Sandia National Laboratory, California and The University of Tufts, Medford, Massachusetts, USA; The Institute Hydrogenous at Kyushu University, Japan. The results are presented in Wohler curves complemented by 'Short fatigue crack length - Number of cycles' curves and 'Frequency - Lifetimes' plots, and compared respectively. key words: fatigue, hydrogen fatigue, stainless steel, Wohler curve, short fatigue crack

  14. Effects of applied potential on SCC and HE for STS 316L in seawater

    Offshore structures that are made of austenitic stainless steels are exposed to a severe corrosion environment, with fracturing of the passive film occurring by chloride ion intrusion, stress from dynamic external forces and fatigue due to wave and tidal forces. In this paper, we report our evaluation of the durability of STS 316L with respect to stress corrosion cracking and hydrogen embrittlement in natural seawater, which was carried out via electrochemical methods and slow strain rate tests (SSRTs). The effect of hydrogen on the material was assessed using a SSRT with an applied potential of -0.95 V (versus Ag/AgCl). In addition, potentials below an applied potential of -1.2 V indicate samples that are affected by atomic and molecular hydrogen. Theoretically, the optimum corrosion protection range possible without stress corrosion cracking and hydrogen embrittlement occurring is thought to be between-0.56 and -0.9 V.

  15. Effects of applied potential on SCC and HE for STS 316L in seawater

    Han, Min-Su; Park, Jae-Cheul; Jang, Seok-Ki; Kim, Seong-Jong

    2010-05-01

    Offshore structures that are made of austenitic stainless steels are exposed to a severe corrosion environment, with fracturing of the passive film occurring by chloride ion intrusion, stress from dynamic external forces and fatigue due to wave and tidal forces. In this paper, we report our evaluation of the durability of STS 316L with respect to stress corrosion cracking and hydrogen embrittlement in natural seawater, which was carried out via electrochemical methods and slow strain rate tests (SSRTs). The effect of hydrogen on the material was assessed using a SSRT with an applied potential of -0.95 V (versus Ag/AgCl). In addition, potentials below an applied potential of -1.2 V indicate samples that are affected by atomic and molecular hydrogen. Theoretically, the optimum corrosion protection range possible without stress corrosion cracking and hydrogen embrittlement occurring is thought to be between-0.56 and -0.9 V.

  16. The Effect of Calcium Treatment on Pitting Corrosion of Type 316L Austenitic Stainless steel

    Pitting in chloride containing aqueous solution occurs mainly on manganese sulphide. Adding a slight amount of Ca as an alloying element prevents the MnS formation, since Ca is a stronger sulphide former than Mn. In this work, calcium treated Type 316L austenitic stainless steels have been investigated electrochemically to evaluate the effect of modified inclusions on pitting corrosion. Staircase polarization measurements were performed in 3.5% NaCl solution, where the occurrence of pits in materials caused current spikes. During staircase polarization test, steels with calcium treatment show low and discontinuous current spikes while those without calcium treatment show high and continuous current spikes. The results show that calcium treatment in Ca/S ratio of 1 ∼ 2 leads to an increase in the pitting potential of several hundred mV. A relationship between the calcium treatment and pit initiation sites was described

  17. Stress corrosion cracking of stainless steel AISI 316L HAZ in PWR nuclear reactor environment

    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 (303 deg C and 325 deg C). 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-activated mechanism and that brittle fracture caused by the corrosion process was observed at 325 deg C). (author)

  18. Creep-fatigue behaviour of type 304 and 316L(N) in flowing sodium

    Low cycle fatigue tests with hold periods up to 24 h have been performed on types 304 and 316L(N) stainless steel in air and in flowing sodium at 550deg C. It was shown that the number of cycles to failure decreases with increasing hold times and that the failure mode changes from trans- to intercrystalline fracture. A beneficial effect of sodium occurs under pure cyclic loading and with short hold times. With the longest hold times similar behaviour in both environments has been observed. Tests on long term pre-exposed (sodium, 550deg C, 10,000 h) specimens show that strong carbide precipitation increases the number of cycles to failure in flowing sodium. (orig.)

  19. Study of TiC+TiN Multiple Films On Type of 316L Stainless Steel

    XUE Qi; JIN Yong; HU Dong-ping; HUANG Ben-sheng; DENG Bai-quan

    2004-01-01

    In this paper, the synthesis process of TiC+TiN multiple films on super-low-carbon stainless steels is reported.The TiC layer is coated as the first layer in the multiple film, the change of growth rate of the film on the 316L Stainless steel is not same as the one on carbides substrates, while the mole ratio of CH4 to TiCl4 (mCH4/TiCl4) is changed from 1.2to 2.0. The Ti [C, N], as a kind of inter-layer between TiC and TiN layers, is helpful to improve the adhesion between the TiC and TiN layer. The cooling rate greatly influences the quality of the adhesion between the TiC+TiN film and substrates.

  20. Study of TiC+TiN Multiple Films On Type of 316L Stainless Steel

    XUEQi; JINYong; HUDong-ping; HUANGBen-sheng; DENGBai-quan

    2004-01-01

    In this paper, the synthesis process of TiC+TiN multiple films on super-low-carbon stainless steels is reported. The TiC layer is coated as the first layer in the multiple film, the change of growth rate of the film on the 316L Stainlesss teel is not same as the one on carbides substrates, while the mole ratio of CH4 to TiCl4 (mCH4/TiCl4) is changed from 1.2 to 2.0. The Ti [C,N], as a kind of inter-layer between TiC and TiN layers, is helpful to improve the adhesion hetween the TiC and TiN layer. The cooling rate greatly influences the quality of the adhesion between the TiC+TiN film and substrates.

  1. Neutron diffraction measurement and finite element analysis of stress distribution in welded 316L stainless pipe

    Stress distribution in welded AISI 316 L stainless steel pipes (diameter 4'' and 10'') was measured using residual stress instrument installed at 30MWt HANARO reactor of KAERI. The measurements were made along the axial direction transverse to the weld direction from the weld center to the pipe edge. Measurement tracks were repeated at the depth of 1.5mm from the surfaces of the pipes and at the mid-thickness of the pipes wall. As a whole the stress distribution in diameter 4'' and diameter 10'' pipes showed the similar tendency. The stress analysis of the welded pipe was carried out using the finite element method. Reasonable agreement in stress distribution with experimental data was observed. (orig.)

  2. Oblique Incidence Technique for Ultrasonic Nonlinear Characterization in SUS316L Alloy

    The oblique incidence technique for ultrasonic nonlinear characterization was studied in stainless steel 316L alloy subjected to high cycle fatigue. A dog-bone plate specimen was prepared to make different fatigue-driven deformation at each position where the stress concentration could occur in the middle of specimen. In addition to the normal transmission technique, the oblique incidence technique which is newly suggested in this study, was used to measure ultrasonic nonlinear parameter. The fatigued specimen shows higher ultrasonic nonlinear parameter than the virgin specimen for both techniques. Ultrasonic nonlinear parameter highly increases in the middle of test specimen where the stress concentration exists. Relative nonlinear parameter has strong correlation with fatigue damage. Consequently, the oblique incidence technique with longitudinal wave can be potential to characterize high cycle fatigue damage

  3. The effect of repeated repair welding on mechanical and corrosion properties of stainless steel 316L

    Highlights: • Microstructure and properties of the HAZ were analyzed. • Delta ferrite morphology changed, and ferrite content decreased. • Adverse effect on yield and ultimate tensile strength was negligible. • The absorbed energy and hardness decreases with increasing number of weld-repair. • The sensitivity to pitting corrosion was increased. - Abstract: The purpose of this study is to evaluate changes in the mechanical, micro structural and the corrosion properties of stainless steel 316L under repeated repair welding. The welding and the repair welding were conducted by shielded metal arc welding (SMAW). The SMAW welding process was performed using E316L filler metals. Specimen of the base metal and different conditions of shielded metal arc welding repairs were studied by looking in the micro structural changes, the chemical composition of the phases, the grain size (in the heat affected zone) and the effect on the mechanical and corrosion properties. The microstructure was investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The chemical composition of the phases was determined using energy dispersive spectrometry (EDS). The corrosion behavior in 1 M H2SO4 + 3.5% NaCl solution was evaluated using a potentiodynamic polarization method. Tensile tests, Charpy-V impact resistance and Brinell hardness tests were conducted. Hardness of the heat affected zone decreased as the number of repairs increased. Generally an increase in the yield strength (YS) and the ultimate tensile strength (UTS) occurred with welding. After the first repair, a gradual decrease in YS and UTS occurred but the values of YS and UTS were not less than values of the base metal. Significant reduction in Charpy-V impact resistance with the number of weld repairs were observed when the notch location was in the HAZ. The HAZ of welding repair specimen is more sensitive to pitting corrosion. The sensitivity of HAZ to pitting corrosion was increased by

  4. Investigating the correlation between some of the properties of plasma nitrided AISI 316L stainless steel

    M. Olzon-Dionysio

    2013-01-01

    Full Text Available When AISI 316L stainless steels are submitted to the nitriding process at temperatures lower than 450 °C, a high nitrogen content expanded austenite phase is formed, which shows higher hardness and higher pitting corrosion resistance compared to the untreated material. As a result, this material becomes adequate for biomedical application. The conditions of the nitriding technique, such as gas mixture, pressure, time and temperature, play an important role in some properties of the modified layer, including: thickness, hardness and N concentration along the layer. This paper explores a set of six samples of AISI 316L, nitrided at different times and temperatures, whose properties show important differences. The aim of this research is to investigate the correlation between the nitrided layer thickness (in the range of 0.77 to 11 µm with both X-ray patterns characteristics and hardness measurements, which used two distinct loads. The results of this study show that: whereas the 3.6 gf load was suitable to measure the real hardness for four of the nitrided layers showing thickness ≥ 2.9 µm, the 50 gf load measured a substrate contribution, probably even for the highest thickness, 11 µm. Moreover, analyzing different reflections of the X-ray patterns showed evidence of the clear consistency between the X-Ray depths and the nitrided layer thicknesses: if the layer thickness is lower than the penetration depth of X-rays, two phases (austenite and expanded substrate are present. If the layer thickness is higher, only the austenite is observed. Finally, concerning the citotoxicity property, all the samples, nitrided or not, were approved in the test for biocompatibility, indicating their potential use for biomedical applications.

  5. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings.

    Eric Jones, John; Chen, Meng; Yu, Qingsong

    2014-10-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20-25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH₃/O₂ plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O- and N-contents on the surfaces were substantially increased after NH₃/O₂ plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH₃/O₂ plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. PMID:24500866

  6. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    Mina, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Tecno-Academia ASTIN SENA Reginal Valle (Colombia); Castaño, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, J.C., E-mail: julio.cesar.caicedo@correo.univalle.edu.co [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, H.H. [Biologics Research, Biotechnology Center of Excellence, Janssen R& D, LLC, Pharmaceutical Companies of Johnson & Johnson, Spring House, PA 19477 (United States); National Biotechnology & Pharmaceutical Association, Chicago, IL 60606 (United States); Aguilar, Y. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia)

    2015-06-15

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices.

  7. Improving the empirical model for plasma nitrided AISI 316L corrosion resistance based on Moessbauer spectroscopy

    Campos, M.; Souza, S. D. de [Universidade Federal de Sao Carlos, Departamento de Fisica (Brazil); Souza, S. de [Instituto de Pesquisas Energeticas e Nucleares, Centro de Ciencia e Tecnologia de Materiais (Brazil); Olzon-Dionysio, M., E-mail: dmod@df.ufscar.br [Universidade Federal de Sao Carlos, Departamento de Fisica (Brazil)

    2011-11-15

    Traditional plasma nitriding treatments using temperatures ranging from approximately 650 to 730 K can improve wear, corrosion resistance and surface hardness on stainless steels. The nitrided layer consists of some iron nitrides: the cubic {gamma}{sup Prime} phase (Fe{sub 4}N), the hexagonal phase {epsilon} (Fe{sub 2 - 3}N) and a nitrogen supersatured solid phase {gamma}{sub N}. An empirical model is proposed to explain the corrosion resistance of AISI 316L and ASTM F138 nitrided samples based on Moessbauer Spectroscopy results: the larger the ratio between {epsilon} and {gamma}{sup Prime} phase fractions of the sample, the better its resistance corrosion is. In this work, this model is examined using some new results of AISI 316L samples, nitrided under the same previous conditions of gas composition and temperature, but at different pressure, for 3, 4 and 5 h. The sample nitrided for 4 h, whose value for {epsilon}/{gamma}{sup Prime} is maximum (= 0.73), shows a slightly better response than the other two samples, nitrided for 5 and 3 h ({epsilon}/{gamma}{sup Prime} = 0.72 and 0.59, respectively). Moreover, these samples show very similar behavior. Therefore, this set of samples was not suitable to test the empirical model. However, the comparison between the present results of potentiodynamic polarization curves and those obtained previously at 4 and 4.5 torr, could indicated that the corrosion resistance of the sample which only presents the {gamma}{sub N} phase was the worst of them. Moreover, the empirical model seems not to be ready to explain the response to corrosion and it should be improved including the {gamma}{sub N} phase.

  8. Wear of plasma nitrided and nitrocarburized AISI 316L austenitic stainless steel

    F.A.P. Fernandes

    2010-06-01

    Full Text Available Purpose: the purpose of the work is to compare the wear resistance, in dry and lubricated conditions, of AISI 316L austenitic stainless steel samples that were plasma nitrided or nitrocarburized at 450°C for 5 and 10 h, respectively.Design/methodology/approach: Hardness and wear resistance of austenitic stainless steel can be increased substantially, without losing corrosion resistance, by plasma nitriding or nitrocarburizing surface treatments. In this work, AISI 316L austenitic stainless steel was plasma nitrided and nitrocarburized at 450°C, for 5 and 10 h respectively.Findings: The obtained layers were characterized by optical microscopy, X-ray diffraction, microhardness and micro-wear tests in dry and lubricated conditions. Optical microscopy and X-ray diffraction analysis demonstrated that the nitrided layer is homogeneous and primarily composed of nitrogen rich expanded austenite with a thickness of about 15 µm. Nitrocarburized samples exhibited an external layer of chromium and iron compounds and a sub-layer of expanded austenite with a total thickness of 45 µm. Microhardness profiles showed that the hardness near to the surface was close to 1100 HV for nitriding and 1300 HV for nitrocarburizing. Plasma nitrided and nitrocarburized layers exhibited substantial wear reduction in dry and lubricated test conditions. The use of a lubricant oil reduces wear by a factor of approximately 200 compared to the dry test results.Research limitations/implications: The plasma nitrided layer yielded the best wear performance in both dry and lubricated conditions.Originality/value: Plasma nitriding resulted in the best wear performance when compared with nitrocarburizing in dry and lubricated sliding which is probably due to reduced layer fragility.

  9. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

    Jones, John Eric; Chen, Meng; Yu, Qingsong

    2015-01-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH3/O2 plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O-and N-contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH3/O2 plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electro-chemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. PMID:24500866

  10. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices

  11. Electron stimulated desorption of H3O+ from 316L stainless steel

    Surface ions generated by electron stimulated desorption from mass spectrometer ion source grids are frequently observed, but often misidentified. For example, in the case of mass 19, the source is often assumed to be surface fluorine, but since the metal oxide on grid surfaces has been shown to form water and hydroxides, a more compelling case can be made for the formation of hydronium. Further, fluorine is strongly electronegative, so it is rarely generated as a positive ion. A commonly used metal for ion source grids is 316L stainless steel. Thermal vacuum processing by bakeout or radiation heating from the filament typically alters the surface composition to predominantly Cr2O3. X-ray photoelectron spectral shoulders on the O 1s and Cr 2p3/2 peaks can be attributed to adsorbed water and hydroxides, the intensity of which can be substantially increased by hydrogen dosing. On the other hand, the sub-peak intensities are substantially reduced by heating and/or by electron bombardment. Electron bombardment diode measurements show an initial work function increase corresponding to predominant hydrogen desorption (H2) and a subsequent work function decrease corresponding to predominant oxygen desorption (CO). The fraction of hydroxide concentration on the surface was determined from X-ray photoelectron spectroscopy and from the deconvolution of temperature desorption spectra. Electron stimulated desorption yields from the surface show unambiguous H3O+ peaks that can be significantly increased by hydrogen dosing. Time of flight secondary ion mass spectrometry sputter yields show small signals of H3O+, as well as its constituents (H+, O+ and OH+) and a small amount of fluorine as F-, but no F+ or F+ complexes (HF+, etc.). An electron stimulated desorption cross-section of σ + ∼ 1.4 x 10-20 cm2 was determined for H3O+ from 316L stainless steel for hydrogen residing in surface chromium hydroxide

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

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

  13. Electron stimulated desorption of H 3O + from 316L stainless steel

    Cole, C. R.; Outlaw, R. A.; Champion, R. L.; Holloway, B. C.; Kelly, M. A.

    2007-02-01

    Surface ions generated by electron stimulated desorption from mass spectrometer ion source grids are frequently observed, but often misidentified. For example, in the case of mass 19, the source is often assumed to be surface fluorine, but since the metal oxide on grid surfaces has been shown to form water and hydroxides, a more compelling case can be made for the formation of hydronium. Further, fluorine is strongly electronegative, so it is rarely generated as a positive ion. A commonly used metal for ion source grids is 316L stainless steel. Thermal vacuum processing by bakeout or radiation heating from the filament typically alters the surface composition to predominantly Cr 2O 3. X-ray photoelectron spectral shoulders on the O 1s and Cr 2p 3/2 peaks can be attributed to adsorbed water and hydroxides, the intensity of which can be substantially increased by hydrogen dosing. On the other hand, the sub-peak intensities are substantially reduced by heating and/or by electron bombardment. Electron bombardment diode measurements show an initial work function increase corresponding to predominant hydrogen desorption (H 2) and a subsequent work function decrease corresponding to predominant oxygen desorption (CO). The fraction of hydroxide concentration on the surface was determined from X-ray photoelectron spectroscopy and from the deconvolution of temperature desorption spectra. Electron stimulated desorption yields from the surface show unambiguous H 3O + peaks that can be significantly increased by hydrogen dosing. Time of flight secondary ion mass spectrometry sputter yields show small signals of H 3O +, as well as its constituents (H +, O + and OH +) and a small amount of fluorine as F -, but no F + or F + complexes (HF +, etc.). An electron stimulated desorption cross-section of σ+ ˜ 1.4 × 10 -20 cm 2 was determined for H 3O + from 316L stainless steel for hydrogen residing in surface chromium hydroxide.

  14. Effect of oxygen on the corrosion behavior of SS316L in a buoyancy driven Pb-17Li loop

    Chakraborty, P., E-mail: myworld.pc@gmail.com [Fusion Reactor Materials Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fotedar, R.K.; Krishnamurthy, N. [Fusion Reactor Materials Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer We examined the role of oxygen in the mitigating corrosion of SS316L by Pb-17Li. Black-Right-Pointing-Pointer We compared the ferrite layer formed in the presence and absence of oxygen. Black-Right-Pointing-Pointer Introduction of oxygen developed a thinner ferrite layer on the SS316L surface. Black-Right-Pointing-Pointer The reduction in thickness was due to the formation of a Cr enriched passive layer. Black-Right-Pointing-Pointer The aforesaid protective layer on the surface of SS316L contained LiCrO{sub 2} and Cr{sub 2}O{sub 3}. - Abstract: Corrosion behavior of SS316L in lead-lithium eutectic in the presence of oxygen was investigated in a thermal convection loop for 1000 h of exposure. At a thermal gradient of 100 K, a 20 {mu}m deep ferrite layer was formed on the exposed surface. Introduction of oxygen resulted in a substantially high chromium depletion from the steel matrix. EPMA profiles revealed the presence of chromium enriched, lead free layer over the surface facing liquid lead-lithium. XRD data confirmed the presence of LiCrO{sub 2} and Cr{sub 2}O{sub 3} in this layer. It is expected that this layer at the interface can act as a passive boundary and thus prevent continued corrosion by liquid metal.

  15. Corrosion behaviour of 316L stainless steel and anti-corrosion materials in a high acidified chloride solution

    Jin, Z.H. [Shanghai University of Electric Power, Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai Key Laboratory of Colleges and Universities for Corrosion Control in Electric Power System and Applied Electrochemistry, 2103 Pingliang Road, Shanghai 200090 (China); Ge, H.H., E-mail: gehonghua@shiep.edu.cn [Shanghai University of Electric Power, Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai Key Laboratory of Colleges and Universities for Corrosion Control in Electric Power System and Applied Electrochemistry, 2103 Pingliang Road, Shanghai 200090 (China); Lin, W.W. [Shanghai University of Electric Power, Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai Key Laboratory of Colleges and Universities for Corrosion Control in Electric Power System and Applied Electrochemistry, 2103 Pingliang Road, Shanghai 200090 (China); Zong, Y.W.; Liu, S.J. [Power Plant of Baoshan Iron and Steel Co., Ltd, Tieli Road, Shanghai 200941 (China); Shi, J.M. [Technical University of Braunschweig (Germany)

    2014-12-15

    Highlights: • Severe general corrosion accompanied by localized pitting occurred on 316L SS surface in a high acidified chloride solution. • Surface roughness, surface potential difference and the electrochemical non-homogeneity of 316L SS in the test solution were investigated. • TA2, type 2507 SS and type 254SMo SS exhibit good corrosion resistance in the test solution. - Abstract: The corrosion behaviour of a type 316L (UNS S31603) stainless steel (SS) expansion joint in a simulated leaching solution of sediment on blast furnace gas pipeline in a power plant is investigated by using dynamic potential polarization curves, electrochemical impedance spectroscopy (EIS), optical microscope, atomic force microscope (AFM) and Scan Kelvin Probe (SKP). Severe general corrosion accompanied by pitting corrosion occurs on the type 316L SS surface in this solution. As the immersion period increases, the charge transfer resistance R{sub ct} decreases, the dissolution rate accelerates, the surface roughness increases and the surface potential difference enhances significantly. Then eight corrosion-resistant materials are tested, the corrosion rates of type 254SMo SS, type 2507 SS and TA2 are relatively minor in the solution. The corrosion resistance properties of TA2 is most excellent, indicating it would be the superior material choice for blast furnace gas pipeline.

  16. Corrosion behaviour of 316L stainless steel and anti-corrosion materials in a high acidified chloride solution

    Highlights: • Severe general corrosion accompanied by localized pitting occurred on 316L SS surface in a high acidified chloride solution. • Surface roughness, surface potential difference and the electrochemical non-homogeneity of 316L SS in the test solution were investigated. • TA2, type 2507 SS and type 254SMo SS exhibit good corrosion resistance in the test solution. - Abstract: The corrosion behaviour of a type 316L (UNS S31603) stainless steel (SS) expansion joint in a simulated leaching solution of sediment on blast furnace gas pipeline in a power plant is investigated by using dynamic potential polarization curves, electrochemical impedance spectroscopy (EIS), optical microscope, atomic force microscope (AFM) and Scan Kelvin Probe (SKP). Severe general corrosion accompanied by pitting corrosion occurs on the type 316L SS surface in this solution. As the immersion period increases, the charge transfer resistance Rct decreases, the dissolution rate accelerates, the surface roughness increases and the surface potential difference enhances significantly. Then eight corrosion-resistant materials are tested, the corrosion rates of type 254SMo SS, type 2507 SS and TA2 are relatively minor in the solution. The corrosion resistance properties of TA2 is most excellent, indicating it would be the superior material choice for blast furnace gas pipeline

  17. Morphological and Mechanical Properties of Hydroxyapatite Bilayer Coatings Deposited on 316L SS by Sol-Gel Method

    Sidane, Djahida; Khireddine, Hafit; Yala, Sabeha; Ziani, Salima; Bir, Fatima; Chicot, Didier

    2015-10-01

    The present paper reports on the influence of the addition of TiO2 and SiO2 oxides as sub-layer, on the morphological and mechanical properties of the hydroxyapatite (HAP) bioceramic coatings deposited on 316L stainless steel by sol-gel method in order to improve the properties of hydroxyapatite and expand its clinical application. The stability of the sols suspensions was evaluated by measuring the time dependence of the viscosity. Annealed properties of the coatings were analyzed by XPS, XRD, SEM, and EDS. The Vickers microhardness of the coatings is obtained under the same indentation load of 10 g. The hydroxyapatite coating deposited on the surface of the 316L SS substrate exhibits a porous carbonated apatitic structure. The results clearly demonstrate that HAP-TiO2 and HAP-SiO2 bilayer coatings where hydroxyapatite is deposited on the surface of TiO2- and SiO2-coated 316L SS substrate systems were highly homogeneous and uniform and show higher microhardness compared to HAP-coated 316L SS. A gap of nearly 10 pct is observed. The addition of TiO2 and SiO2 as sub-layer of a hydroxyapatite coating results in changes in surface morphology as well as an increase of the microhardness.

  18. Comparison of Strength and Serration at Cryogenic Temperatures among 304L, 316L and 310S Steels

    Shibata, K.; Ogata, T.; Nyilas, A.; Yuri, T.; Fujii, H.; Ohmiya, S.; Onishi, T.; Weiss, K. P.

    2008-03-01

    Tensile tests of 310S steel were performed at temperatures below 300 K and the yield strength and deformation behavior were compared with those of 304L and 316L steels. Computer simulations were also carried out to graph stress-elongation curves in order to discuss the effects of martensitic transformations induced during deformation on their strengths and deformation behavior at low temperatures. Tensile tests showed that yield strength of 310S steel is highest and that of 304L is lowest. The differences in yield strengths between 316L and 310S steels and between 304L and 316L steels are larger than those expected from the differences in solid solution strengthening. This can be explained by the effect of the strain through γ to ɛ martensitic transformation induced by elastic stress in 304L and 316L steels. The strength level and the shape of stress-elongation curves at cryogenic temperatures excluding serration can be qualitatively revealed by simulation when higher strength of ɛ phase comparing to α' phase and the window effect of α' were considered simultaneously. In liquid hydrogen, the three steels exhibit large serrations on the stress-elongation curves after the deformation near to the ultimate stress, while the curves are smooth before the onset of the serration. Such serrations in liquid hydrogen could not be revealed by simulation.

  19. Stainless steels low temperature nitriding; Nitruration a basse temperature de l`acier inoxydable AISI 316L. Resistance a la corrosion et proprietes tribologiques

    Roux, T.; Darbeida, A.; Von Stebut, J.; Michel, H. [Ecole Nationale Superieure des Mines, 54 - Nancy (France); Lebrun, J.P. [NITRUVID, 95 - Argenteuil (France); Hertz, D. [Framatome, 69 - Lyon (France)

    1995-12-31

    Nitrogen ions implantation of 316L stainless steel leads to monophasic diffusion layers, which are constituted of a solid solution ({gamma}{sub N}) fcc, metastable, nitrogen sur-saturated, and without order. This article shows that for 316L stainless steels,these layers improve the tribological properties without degradation of the corrosion resistance. (A.B.). 13 refs. 6 figs.

  20. un acero importado

    Wilson A. Hormaza R.

    2007-01-01

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

  1. Effect of laser beam position on mechanical properties of F82H/SUS316L butt-joint welded by fiber laser

    Highlights: • The micro hardness of weld metal in F82H/SUS316L joint partially decreases after PWHT by shifting beam position to SUS316L. • Charpy impact energy of F82H/SUS316L joint obviously increases after PWHT due to the release of residual stress. • The tensile strength of weld metal in F82H/SUS316L joint is higher than that of SUS316L. • The fiber laser welding seems to be one of the most candidate methods to join between F82H and SUS316L pipes practically. - Abstract: A dissimilar butt-joint between reduced activation ferritic/martensitic steel F82H and SUS316L austenitic stainless steel was made by 4 kW fiber laser and the influence of laser beam position on its mechanical properties before and after post-weld heat treatment (PWHT) was examined at room temperature. From the nano-indentation measurements and the microstructural observations, it is found that the micro hardness of weld metal partially decreases after PWHT by shifting beam position to SUS316L because its phase seems to move from only the martensitic phase to the mixture of austenitic and martensitic phases. In addition, Charpy impact test suggests that the impact energy slightly increases by shifting beam position before PWHT and obviously increases after PWHT due to the release of residual stress. Moreover, the tensile test indicates that the tensile strength of weld metal is higher than that of SUS316L and the fracture occurs at the base metal of SUS316L regardless of laser beam position

  2. Effect of laser beam position on mechanical properties of F82H/SUS316L butt-joint welded by fiber laser

    Serizawa, Hisashi, E-mail: serizawa@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Mori, Daiki; Ogiwara, Hiroyuki; Mori, Hiroaki [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-10-15

    Highlights: • The micro hardness of weld metal in F82H/SUS316L joint partially decreases after PWHT by shifting beam position to SUS316L. • Charpy impact energy of F82H/SUS316L joint obviously increases after PWHT due to the release of residual stress. • The tensile strength of weld metal in F82H/SUS316L joint is higher than that of SUS316L. • The fiber laser welding seems to be one of the most candidate methods to join between F82H and SUS316L pipes practically. - Abstract: A dissimilar butt-joint between reduced activation ferritic/martensitic steel F82H and SUS316L austenitic stainless steel was made by 4 kW fiber laser and the influence of laser beam position on its mechanical properties before and after post-weld heat treatment (PWHT) was examined at room temperature. From the nano-indentation measurements and the microstructural observations, it is found that the micro hardness of weld metal partially decreases after PWHT by shifting beam position to SUS316L because its phase seems to move from only the martensitic phase to the mixture of austenitic and martensitic phases. In addition, Charpy impact test suggests that the impact energy slightly increases by shifting beam position before PWHT and obviously increases after PWHT due to the release of residual stress. Moreover, the tensile test indicates that the tensile strength of weld metal is higher than that of SUS316L and the fracture occurs at the base metal of SUS316L regardless of laser beam position.

  3. Biocompatibility evaluation of surface-treated AISI 316L austenitic stainless steel in human cell cultures.

    Martinesi, M; Bruni, S; Stio, M; Treves, C; Bacci, T; Borgioli, F

    2007-01-01

    The effects of AISI 316L austenitic stainless steel, tested in untreated state or subjected to glow-discharge nitriding (at 10 or 20 hPa) and nitriding + post-oxidizing treatments, on human umbilical vein endothelial cells (HUVEC) and on peripheral blood mononuclear cells (PBMC) were evaluated. All the treated samples showed a better corrosion resistance in PBS and higher surface hardness in comparison with the untreated alloy. In HUVEC put in contact for 72 h with the sample types, proliferation and apoptosis decreased and increased, respectively, in the presence of the nitrided + post-oxidized samples, while only slight differences in cytokine (TNF-alpha, IL-6, and TGF-beta1) release were registered. Intercellular adhesion molecule-1 (ICAM-1) increased in HUVEC incubated with all the treated samples, while vascular cell adhesion molecule-1 (VCAM-1) and E-selectin increased in the presence of all the sample types. PBMC incubated for 48 h with the samples showed a decrease in proliferation and an increase in apoptosis in the presence of the untreated samples and the nitrided + post-oxidized ones. All the sample types induced a remarkable increase in TNF-alpha and IL-6 release in PBMC culture medium, while only the untreated sample and the nitrided at 10 hPa induced an increase in ICAM-1 expression. In HUVEC cocultured with PBMC, previously put in contact with the treated AISI 316L samples, increased levels of ICAM-1 were detected. In HUVEC coincubated with the culture medium of PBMC, previously put in contact with the samples under study, a noteworthy increase in ICAM-1, VCAM-1, and E-selectin levels was always registered, with the exception of VCAM-1, which was not affected by the untreated sample. In conclusion, even if the treated samples do not show a marked increase in biocompatibility in comparison with the untreated alloy, their higher corrosion resistance may suggest a better performance as the contact with physiological environment becomes longer. PMID

  4. Processing conditions and microstructural features of porous 316L stainless steel components by DMLS

    Direct metal laser sintering (DMLS), due to its flexibility in materials and shapes, would be especially interesting to produce complex shaped porous metallic components. In the present work, processing conditions and microstructural characteristics of direct laser sintered porous 316L stainless steel components were studied. It was found that a partial melting mechanism of powders gave a high feasibility in obtaining porous sintered structures possessing porosities of ∼21-∼55%. Linear energy density (LED), which was defined by the ratio of laser power to scan speed, was used to tailor the laser sintering mechanism. A moderate LED of ∼3400-∼6000 J/m and a lower scan speed less than 0.06 m/s proved to be feasible. With the favorable sintering mechanism prevailed, lowering laser power or increasing scan speed, scan line spacing, and powder layer thickness generally led to a higher porosity. Metallurgical mechanisms of pore formation during DMLS were addressed. It showed that the presence of pores was through: (i) the formation of liquid bridges between partially melted particles during laser irradiation; and (ii) the growth of sintering necks during solidification, leaving residual pores between solidified metallic agglomerates.

  5. Thermally driven stability of octadecylphosphonic acid thin films grown on SS316L.

    Lim, Min Soo; Smiley, Katelyn J; Gawalt, Ellen S

    2010-01-01

    Stainless steel 316L is widely used as a biomedical implant material; however, there is concern about the corrosion of metallic implants in the physiological environment. The corrosion process can cause mechanical failure due to resulting cracks and cavities in the implant. Alkyl phosphonic acid forms a thin film by self-assembly on the stainless steel surface and this report conclusively shows that thermal treatment of the octadecylphosphonic acid (ODPA) film greatly enhances the stability of the ODPA molecules on the substrate surface. AFM images taken from the modified substrates revealed that thermally treated films remain intact after methanol, THF, and water flushes, whereas untreated films suffer substantial loss. Water contact angles also show that the hydrophobicity of thermally treated films does not diminish after being incubated in a dynamic flow of water for a 3-hour period, whereas the untreated film becomes increasingly hydrophilic due to loss of ODPA. IR spectra taken of both treated and untreated films after water and THF flushes show that the remaining film retains its initial crystallinity. A model is suggested to explain the stability of ODPA film enhanced by thermal treatment. An ODPA molecule is physisorbed to the surface weakly by hydrogen bonding. Heating drives away water molecules leading to the formation of strong monodentate or mixed mono/bi-dentate bonds of ODPA molecule to the surface. PMID:20648546

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

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

  7. SCC crack growth rate of cold worked 316L stainless steel in PWR environment

    Du, Donghai; Chen, Kai; Yu, Lun; Lu, Hui [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Lefu, E-mail: lfzhang@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shi, Xiuqiang; Xu, Xuelian [Shanghai Nuclear Engineering Research and Design Institute, Shanghai 200233 (China)

    2015-01-15

    Many component failures in nuclear power plants were found to be caused by stress corrosion cracking (SCC) of cold worked austenitic steels. Some of the pressure boundary component materials are even cold worked up to 35% plastic deformation, leaving high residual stress and inducing high growth rate of corrosion crack. Controlling water chemistry is one of the best counter measure to mitigate this problem. In this work, the effects of temperature (200 up to 325 °C) and dissolved oxygen (0 up to 2000 μg/L) on SCC crack growth rates of cold worked austenitic stainless steel type 316L have been tested by using direct current potential drop (DCPD) method. The results showed that temperature affected SCC crack growth rates more significantly in oxygenated water than in deaerated water. In argon deaerated water, the crack growth rate exhibited a peak at about 250 °C, which needs further verification. At 325 °C, the SCC crack growth rate increased rapidly with the increase of dissolved oxygen concentration within the range from 0 up to 200 μg/L, while when dissolved oxygen was above 200 μg/L, the crack growth rate followed a shallower dependence on dissolved oxygen concentration.

  8. Laser Surface Alloying of 316L Stainless Steel with Ru and Ni Mixtures

    M. B. Lekala

    2012-01-01

    Full Text Available The surfaces of AISI 316L stainless steel were laser alloyed with ruthenium powder and a mixture of ruthenium and nickel powders using a cw Nd:YAG laser set at fixed operating parameters. The microstructure, elemental composition, and corrosion characteristics of the alloyed zone were analyzed using optical and scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX, and corrosion potential measurements. The depth of alloyed zone was measured using the AxioVision program and found to be approximately 1.8 mm for all the alloyed specimens. Hardness profile measurements through the surface-substrate interface showed a significant increase from 160 HV for the substrate to a maximum of 247 HV for the alloyed layer. The sample laser alloyed with 80 wt% Ni-20 wt% presented the most noble corrosion potential (Ecorr of −0.18 V and the lowest corrosion current density (icorr.

  9. Galvanic deposition and characterization of brushite/hydroxyapatite coatings on 316L stainless steel.

    Blanda, Giuseppe; Brucato, Valerio; Pavia, Francesco Carfì; Greco, Silvia; Piazza, Salvatore; Sunseri, Carmelo; Inguanta, Rosalinda

    2016-07-01

    In this work, brushite and brushite/hydroxyapatite (BS, CaHPO4·H2O; HA, Ca10(PO4)6(OH)2) coatings were deposited on 316L stainless steel (316LSS) from a solution containing Ca(NO3)2·4H2O and NH4H2PO4 by a displacement reaction based on a galvanic contact, where zinc acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of two different metallic materials (316LSS and Zn) immersed in an electrolyte, so forming a galvanic contact leading to the deposition of BS/HA on nobler metal. We found that temperature and deposition time affect coating features (morphology, structure, and composition). Deposits were characterized by means of several techniques. The morphology was investigated by scanning electron microscopy, the elemental composition was obtained by X-ray energy dispersive spectroscopy, whilst the structure was identified by Raman spectroscopy and X-ray diffraction. BS was deposited at all investigated temperatures covering the 316LSS surface. At low and moderate temperature, BS coatings were compact, uniform and with good crystalline degree. On BS layers, HA crystals were obtained at 50°C for all deposition times, while at 25°C, its presence was revealed only after long deposition time. Electrochemical studies show remarkable improvement in corrosion resistance. PMID:27127032

  10. Effects of the inner mould material on the aluminium–316L stainless steel explosive clad pipe

    Highlights: ► Different mould materials were adopted to evaluate the effect of the constraint on the clad quality. ► The interface characteristics of clad pipe were analyzed for the different clad pipe. ► The clad pipes possess excellent bonding quality. - Abstract: The clad pipe played an important part in the pipeline system of the nuclear power industry. To prepare the clad pipe with even macrosize and excellent bonding quality, in this work, different mould materials were adopted to evaluate the effect of the constraint on the clad quality of the bimetal pipe prepared by explosive cladding. The experiment results indicated that, the dimension uniformity and bonding interface of clad pipe were poor by using low melting point alloy as mould material; the local bulge or the cracking of the clad pipe existed when the SiC powder was utilized. When the steel mould was adopted, the outer diameter of the clad pipe was uniform from head to tail. In addition, the metallurgical bonding was formed. Furthermore, the results of shear test, bending test and flattening test showed that the bonding quality was excellent. Therefore, the Al–316L SS clad pipe could endure the second plastic forming

  11. Computational Modeling of the Stability of Crevice Corrosion of Wetted SS316L

    The stability of localized corrosion sites on SS 316L exposed to atmospheric conditions was studied computationally. The localized corrosion system was decoupled computationally by considering the wetted cathode and the crevice anode separately and linking them via a constant potential boundary condition at the mouth of the crevice. The potential of interest for stability was the repassivation potential. The limitations on the ability of the cathode that are inherent due to the restricted geometry were assessed in terms of the dependence on physical and electrochemical parameters. Physical parameters studied include temperature, electrolyte layer thickness, solution conductivity, and the size of the cathode, as well as the crevice gap for the anode. The current demand of the crevice was determined considering a constant crevice solution composition that simulates the critical crevice solution as described in the literature. An analysis of variance showed that the solution conductivity and the length of the cathode were the most important parameters in determining the total cathodic current capacity of the external surface. A semi-analytical equation was derived for the total current from a restricted geometry held at a constant potential at one end. The equation was able to reproduce all the model computation results both for the wetted external cathode and the crevice and give good explanation on the effects of physicochemical and kinetic parameters

  12. Low-temperature plasma nitriding of sintered PIM 316L austenitic stainless steel

    Mendes, Aecio Fernando; Scheuer, Cristiano Jose; Joanidis, Ioanis Labhardt; Cardoso, Rodrigo Perito; Mafra, Marcio; Klein, Aloisio Nelmo; Brunatto, Silvio Francisco, E-mail: brunatto@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Engenharia Mecanica. Grupo de Tecnologia de Fabricacao Assistida pro Plasma e Metalurgia do Po

    2014-08-15

    This work reports experimental results on sintered PIM 316L stainless steel low-temperature plasma nitriding. The effect of treatment temperature and time on process kinetics, microstructure and surface characteristics of the nitrided samples were investigated. Nitriding was carried out at temperatures of 350, 380, 410 and 440 °C , and times of 4, 8 and 16 h, using a gas mixture composed by 60% N2 + 20% H2 + 20% Ar, at a gas flow rate of 5.00 X 10{sup 6} Nm{sup 3-1}, and a pressure of 800 Pa. The treated samples were characterized by scanning electron microscopy, X-ray diffractometry and microhardness measurements. Results indicate that low-temperature plasma nitriding is a diffusion controlled process. The calculated activation energy for nitrided layer growth was 111.4 kJmol{sup -1}. Apparently precipitation-free layers were produced in this study. It was also observed that the higher the treatment temperature and time the higher is the obtained surface hardness. Hardness up to 1343 HV{sub 0.025} was verified for samples nitrided at 440 °C. Finally, the characterization of the treated surface indicates the formation of cracks, which were observed in regions adjacent to the original pores after the treatment. (author)

  13. The blistering of 316L stainless steel irradiated with energetic alpha particles at 500 degrees C

    The physical process of blistering is investigated in the 316L stainless steel in both the solid solution and 20% cold-worked states. The material was irradiated with 1.8 MeV alpha particles to various fluences at 500deg C. There is a threshold fluence for blistering in the range of (0.869-1.346)x 1018 α/cm2. The microstructure, determined by TEM observation in the cross-section of irradiated samples, shows that the bubbles are accumulated at the surface layer. There is a bubble size and density distribution along the direction of depth. The bubble size and swelling increase progressively from the edge of the specimen to the damage peak region (DPR), then decrease. After 3 μm there are no bubbles. Due to bubble formation the thermal conductivity of the surface layer becomes lower and the temperature increases due to the irradiation energy deposited. Beyond the threshold fluence, the temperature of the surface layer is high, bubble coalescence at DPR becomes more serious and the bubble pressure becomes high enough that blistering occurs. (orig.)

  14. SCC crack growth rate of cold worked 316L stainless steel in PWR environment

    Many component failures in nuclear power plants were found to be caused by stress corrosion cracking (SCC) of cold worked austenitic steels. Some of the pressure boundary component materials are even cold worked up to 35% plastic deformation, leaving high residual stress and inducing high growth rate of corrosion crack. Controlling water chemistry is one of the best counter measure to mitigate this problem. In this work, the effects of temperature (200 up to 325 °C) and dissolved oxygen (0 up to 2000 μg/L) on SCC crack growth rates of cold worked austenitic stainless steel type 316L have been tested by using direct current potential drop (DCPD) method. The results showed that temperature affected SCC crack growth rates more significantly in oxygenated water than in deaerated water. In argon deaerated water, the crack growth rate exhibited a peak at about 250 °C, which needs further verification. At 325 °C, the SCC crack growth rate increased rapidly with the increase of dissolved oxygen concentration within the range from 0 up to 200 μg/L, while when dissolved oxygen was above 200 μg/L, the crack growth rate followed a shallower dependence on dissolved oxygen concentration

  15. Mechanical properties of Austenitic Stainless Steel 304L and 316L at elevated temperatures

    Raghuram Karthik Desu

    2016-01-01

    Full Text Available Austenitic Stainless Steel grade 304L and 316L are very important alloys used in various high temperature applications, which make it important to study their mechanical properties at elevated temperatures. In this work, the mechanical properties such as ultimate tensile strength (UTS, yield strength (YS, % elongation, strain hardening exponent (n and strength coefficient (K are evaluated based on the experimental data obtained from the uniaxial isothermal tensile tests performed at an interval of 50 °C from 50 °C to 650 °C and at three different strain rates (0.0001, 0.001 and 0.01 s−1. Artificial Neural Networks (ANN are trained to predict these mechanical properties. The trained ANN model gives an excellent correlation coefficient and the error values are also significantly low, which represents a good accuracy of the model. The accuracy of the developed ANN model also conforms to the results of mean paired t-test, F-test and Levene's test.

  16. Microstructure characterisation and process optimization of laser assisted rapid fabrication of 316L stainless steel

    In the present study, laser assisted fabrication of 316L stainless steel has been attempted using a high power (1.5 kW) continuous wave diode laser. The main process variables for the present study were applied power density, scan speed and powder feed rate. A detailed microstructural study of the surface and cross-section of the fabricated layer were carried out using optical and scanning electron microscopy to understand the influence of laser parameters on microstructure of the surface and interface between the successive layers. The microstructure of the top layer was equiaxed, the near substrate region was fine dendritic, however, at the interface between two successive layers, it was coarsened. The morphology and degree of fineness of the microstructure was found to vary with laser parameters. The range of grain size (maximum grain size-minimum grain size) was taken as a measure of homogeneity. It was found that with increasing the scan speed, the range of grain size was minimized. Micro-porosities were present in the microstructure that reduced with increasing scan speed and found to be minimum at a medium powder feed rate. The optimum processing conditions have been established by correlating the characteristics of the fabricated layer with process parameters

  17. Fatigue crack propagation at high temperature (5500C) in stainless steel type 316 L

    The effect of different parameters such as temperature, stress ratio R, frequency f, have been investigated for fatigue crack propagation in stainless steel type 316 L. At high frequency (20 Hz), increasing temperature from room temperature to 5500C, produced an increase in crack propagation rate. Fractographic analysis of failed specimens indicated no change in failure mode which was transgranular with fatigue striations indicating a ductile failure process. Transmission electron microscopy analysis showed a change in the plastic deformation mode which was consisted, at room temperature, of twinning and martensitic transformation, characteristic of a low SFE material, and at high temperature, of a disoriented cellular structure characteristic of a high SFE material. At high temperature, raising stress ratio from 0.1 to 0.5, increased crack propagation rate with no change in the failure mode which was transgranular. At high temperature, decreased frequency from 1200 cpm to 4 cpm increased crack propagation rate. Combined effect of temperature and low frequency led to corrosion, and intergranular failure

  18. An in vitro investigation of the anodic polarization and capacitance behavior of 316-L stainless steel.

    Sutow, E J; Pollack, S R; Korostoff, E

    1976-09-01

    Determinations were made of how the corrosion-resistant properties of the passive film on 316-L stainless steel are influenced by the material's mechanical and surface states, and the variable pH and PO2 conditions of the interstitial fluid. Cold-rolled and annealed specimens were surface-prepared, commercially and in the laboratory, respectively, as if for orthopedic implantation. Passive film behavior was studied by the anodic polarization and pulse-potentiostatic capacitance methods. The pH and PO2 of the Ringer's test solution were varied to include interstitial fluid values occurring postoperatively and onto recovery. The anodic polarization behavior of all specimens was found to be pH- and PO2-independent. Breakdown potentials of annealed specimens were 800-950 mV (SCE), in contrast to previously reported values of approximately 350 mV. This substantial increase is related to the influence of surface preparation and, in particular, to the optimization of electropolishing time which acts to produce a microscopically smooth surface, free of debris and disarrayed material. Capacitance behavior of annealed material for potentials greater than 400 mV was consistent with a model involving the entry of chloride and metal ions (mostly Fe) into the passive film. This entry is related to the onset of pitting. PMID:10307

  19. The influence of electropolishing on the corrosion resistance of 316L stainless steel.

    Sutow, E J

    1980-09-01

    A study was conducted which examined the influence of electropolishing on the corrosion resistance of a cold rolled 316L stainless steel. Test specimens were surface prepared to a final mechanical finish of wetted 600 grit SiC paper, prior to electropolishing. An o-H3PO4/Glycerol/H2O electropolishing solution was employed for times of 15, 20, and 25 min. Control specimens were surface prepared only to the final mechanical finish. Anodic polarization tests were performed in a deaerated Ringer's solution (37 degrees C) which was acidified to pH 1, with HCl. The electropolished specimens demonstrated increased corrosion resistance, when compared to the control specimens. This was evidenced for the former by more anodic corrosion and breakdown potentials, and the absence of a dissolution peak which was observed for the control specimens at the initial polarization potentials. Surface hardness measurements indicated that this increase in corrosion resistance was produced, in part, by the removal of the cold worked surface layer produced by the mechanical finish. In terms of increasing corrosion resistance, no optimum electropolishing time was found within the 15-25 min treatment period. PMID:7349665

  20. Interlaboratory study of the AISI 316L steel tribo-corrosion

    Seven European laboratories have participated in an interlaboratory study of AISI 316L stainless steel tribo-corrosion. Different tests arrangements have been used (rotating pin-on-disc and disc-on-pin, rotating tube-on-flat, alternating pin-on-flat) depending on the test laboratory. The experimental conditions for the various tests have ranged from: 0.1 to 30 N for normal loads, 1 to 33 Hz for frequency and 5 to 150 mm/sec for linear speed, 0.79 to 25.50 cm2 for electrode surfaces, -244 to -71 mV for corrosion potentials, and -33 to 46 mV for passivation potentials. Data for electrochemical potentials during frictional wear, coefficients of friction, wear rates and wear channel size are tabulated in this article. A dispersion of data is observed between the laboratories for friction coefficients; but this dispersion of data is comparable and even inferior to that obtained in VAMAS interlaboratory tests. Electrochemical tests results also have a convergence that is typical of a previous interlaboratory test program conducted by EFC. A large deviation in coefficients of wear is observed and is also typical of previous VAMAS testing

  1. Surface analysis, by SNMS, of 316L steel exposed to simulated BWR conditions

    Samples of 316L steel have been exposed to Boiling Light Water Reactor chemistry for between forty and seven thousand hours. These samples, with three different surface finishes, 'as-delivered', mechanically polished and electro-polished, have been analysed by Sputtered Neutral Mass Spectrometry and profiles of the constituent alloying elements have been obtained. Differences in the oxide that has built-up are compared and discussed in terms of current ideas of corrosion mechanisms. The structure of the oxide changes with exposure time for the experimental conditions. The effect of surface finish and water velocity have a clear marked effect on the oxide structure and growth rate, respectively: samples in a low water velocity stream form the protective oxide, chromia, and some mixed spinels; electro-polished samples have no chromium layer but show possible secondary passivation through the build-up of nickel; and samples in high velocity water form a simple structured oxide that does not reach a saturation thickness after 291 days but steadily increases. (author) 9 figs., 3 tabs., 7 refs

  2. Low-temperature plasma nitriding of sintered PIM 316L austenitic stainless steel

    This work reports experimental results on sintered PIM 316L stainless steel low-temperature plasma nitriding. The effect of treatment temperature and time on process kinetics, microstructure and surface characteristics of the nitrided samples were investigated. Nitriding was carried out at temperatures of 350, 380, 410 and 440 °C , and times of 4, 8 and 16 h, using a gas mixture composed by 60% N2 + 20% H2 + 20% Ar, at a gas flow rate of 5.00 X 106 Nm3-1, and a pressure of 800 Pa. The treated samples were characterized by scanning electron microscopy, X-ray diffractometry and microhardness measurements. Results indicate that low-temperature plasma nitriding is a diffusion controlled process. The calculated activation energy for nitrided layer growth was 111.4 kJmol-1. Apparently precipitation-free layers were produced in this study. It was also observed that the higher the treatment temperature and time the higher is the obtained surface hardness. Hardness up to 1343 HV0.025 was verified for samples nitrided at 440 °C. Finally, the characterization of the treated surface indicates the formation of cracks, which were observed in regions adjacent to the original pores after the treatment. (author)

  3. Boron content in type 316 L stainless steel by neutron induced autoradiography

    Boron is effective to the improvement of various properties of alloys, but it is difficult to characterize its behavior during the alloy processing. Neutron induced autoradiography (or called as F.T.E: Fission Track Etching) technique was attempted to quantitatively analyze boron content in type 316 L austenitic stainless steel. Reference samples with nine different boron contents were prepared and analyzed by conventional analysis method as well as by autoradiography technique using 'HANARO', a 30 MW research reactor in K.A.E.R.I. (Korea Atomic Energy Research Institute). Cd ratio of the neutron flux was about 200 and thermal neutron flux was around 2x1013/cm2/sec. A Kodak CN-85TM detector with an alloy sample was irradiated with two different thermal neutron fluences of 1013 and 1014/cm2. Track densities on the autoradiographs were measured using image analyzer. Within the range of 10 to 50 ppm of boron, track densities from autoradiography showed the linear relationship with results from conventional analyses. When complementarily applied with other analysis technique like E.B.S.D. (Electron Backscattered Diffraction) or E.D.S. (Energy Dispersive Spectroscopy) neutron induced autoradiography technique was found very useful in distinguishing and identifying phases with the different distribution coefficient of boron. (author)

  4. Changes of surface layer of nitrogen-implanted AISI316L stainless steel

    The effects of nitrogen ion implantation into AISI316L stainless steel on friction, wear, and microhardness have been investigated at an energy level of 125 keV at a fluence of 1·1017 - 1·1018 N/cm2. The composition of the surface layer was investigated by RBS, XRD (GXRD), SEM and EDX. The friction coefficient and abrasive wear rate of the stainless steel were measured in the atmospheres of air, oxygen, argon, and in vacuum. As follows from the investigations, there is an increase in resistance to frictional wear in the studied samples after implantation; however, these changes are of different characters in various atmospheres. The largest decrease in wear was observed during tests in the air, and the largest reduction in the value of the friction coefficient for all implanted samples was obtained during tests in the argon atmosphere. Tribological tests revealed larger contents of nitrogen, carbon, and oxygen in the products of surface layer wear than in the surface layer itself of the sample directly after implantation

  5. On the fate of tritium in thermally treated stainless steel type 316L

    Several type 316L stainless steel specimens of 6 mm thickness were charged with tritium at 473 K at Joint European Torus (JET) using five sets of conditions. Isothermal tritium release rates were investigated at Hydrogen Isotope Research Centre (HRC) over extended periods of time at 473, 573, or 673 K constant temperature. The HTO/HT ratio of the liberated tritium was generally high, but decreased with decreasing release temperature. Nearly complete release of tritium required additional prolonged heating at 1073 K. Chemical etching and beta-ray-induced X-ray spectrometry measurements carried out at HRC provided complementary information on the tritium distribution in surface and bulk of thermally treated specimens. Whereas the thickness of the material and initial distribution of tritium in its bulk were found to play an important role for expedient thermal decontamination, the influence of the type of purge gas was only minor. Experimental evidence for tritium grain boundary diffusion is provided. Implications of the results for waste conditioning are discussed.

  6. Multiaxial isothermal and thermal cycling tests of AISI 316 L(N) austenitic steel tubes

    Multiaxial isothermal and thermal cycling tests of tubes made of AISI 316 L(N) austenitic steel are described. The thermal cycling load is generated by periodic induction heating of the outer tube wall and simultaneous continuous cooling by means of water of the inner tube wall. Temperature gradients in excess of 100 K/mm are produced which give rise to fatigue-induced cracks mainly in the inner tube wall. In the tube specimens subjected to isothermal loads, the equibiaxial stress condition typical of thermal cycling tests is to be simulated. This stress load is produced in tubes by superimposing a longitudinal load (tension/compression) upon a circumferential load (internal/external pressures). A new test rig has been built especially for this purpose. The design and mode of operation of the rig as well as the measurement systems, especially for the measurement of circumferential strain, are described. The reference base for the multiaxial tests are uniaxial alternating strain tests of small round solid specimens. The tests are conducted in the LCF range and consequently are strain controlled. The test results obtained to date are presented. In all tests, special attention is paid to the generation and propagation of fatigue-induced cracks. In this connection, the measurement of crack lengths is described. (author)

  7. On the fate of tritium in thermally treated stainless steel type 316L

    Penzhorn, R.-D.; Torikai, Y.; Watanabe, K.; Matsuyama, M.; Perevezentsev, A.

    2012-10-01

    Several type 316L stainless steel specimens of 6 mm thickness were charged with tritium at 473 K at Joint European Torus (JET) using five sets of conditions. Isothermal tritium release rates were investigated at Hydrogen Isotope Research Centre (HRC) over extended periods of time at 473, 573, or 673 K constant temperature. The HTO/HT ratio of the liberated tritium was generally high, but decreased with decreasing release temperature. Nearly complete release of tritium required additional prolonged heating at 1073 K. Chemical etching and beta-ray-induced X-ray spectrometry measurements carried out at HRC provided complementary information on the tritium distribution in surface and bulk of thermally treated specimens. Whereas the thickness of the material and initial distribution of tritium in its bulk were found to play an important role for expedient thermal decontamination, the influence of the type of purge gas was only minor. Experimental evidence for tritium grain boundary diffusion is provided. Implications of the results for waste conditioning are discussed.

  8. Study of a design criterion for 316L irradiated represented by a strain hardened material

    The aim of this study is to analyse the consequence of radiation on different structure submitted to imposed displacement loading and for damages due to plastic instability or rupture. The main consequence of radiation is a material hardening with a ductility decrease. This effect is similar to initial mechanical hardening: the mechanical properties (determined on smooth tensile specimen) evolve in the same way while irradiation or mechanical hardening increase. So in this study, radiation hardening is simulated by mechanical hardening (swaging). Tests were carried out for which two damages were considered: plastic instability and rupture. These two damages were studied with initial mechanical hardening (5 tested hammering rate 0, 15, 25, 35 and 45% on 316L stainless steel). Likewise two types of loading were studied: tensile or bending loading on specimens with or without geometrical singularities (notches). From tensile tests, two deformation criteria are proposed for prevention against the two quoted damages. Numerical study is carried out allowing to confirm hypothesis made at the time of the tensile test result interpretation and to validate the rupture criterion by applying on bending test. (author)

  9. Study on microstructure of pulse laser welding on dissimilar materials hastelloy C-276 and 316L

    To estimate the reliability of laser welding components of AP1000 and study the distribution of elements and microstructure of dissimilar weld of Hastelloy C-276 and 316L welded by Nd: YAG pulse laser, the microstructure, element distribution and phase of the weld were systematically analyzed by optical microscope, electron probe x ray micro-analyser and other analysis, measuring and test instruments. The results show that the gain of microstructure of weld is refined, and tiny equiaxed grains are in the center and columnar grains are near the weld edge. Heat-affected zones are very narrow on two sides of the weld joint. According to macro distribution of elements, there are three zones in the weld. Element compositions vary drastically on two sides of the weld and become uniform in the center. Micro-segregation of elements exists and Mo enriched at the grain boundary of the weld is observed. Austenite is the main microstructure of the weld and little delta ferrite is found. (authors)

  10. Local approach on mixed-mode ductile fracture of an aged stainless steel 316L

    In the frame of the structural integrity of the fast breeder reactor vessel, the local approach of fracture is applied to the ductile crack initiation under mixed-mode I+II loading for a 316L type stainless steel thermally aged for 1000 hours at 700 deg C. Experimental and numerical tests are performed on axisymmetric notched specimens, compact tension specimens and disymmetric four-point bend specimens. From elastoplastic finite element analyses, the damage variables are evaluated with various models: the Beremin model, the McClintock model, the Guennouni-Francois model and the Lemaitre model. The critical values of damage variable obtained on simple tensile specimens and axisymmetric notched specimens are used for the prediction of crack initiation under mixed-mode loading. The damage variable at crack initiation seems to be rather dependent on the fracture mode related to the stress triaxiality and the brittle fracture of banded ferrite of the aged material. The results are compared with those of the J values at crack initiation. (author). 9 ref., 2 figs

  11. Study of the Mechanical Properties of a Nanostructured Surface Layer on 316L Stainless Steel

    F. C. Lang

    2016-01-01

    Full Text Available A nanostructured surface layer (NSSL was generated on a 316L stainless steel plate through surface nanocrystallization (SNC. The grains of the surface layer were refined to nanoscale after SNC treatment. Moreover, the microstructure and mechanical properties of NSSL were analyzed with a transmission electron microscope (TEM and scanning electron microscope (SEM, through nanoindentation, and through reverse analysis of finite element method (FEM. TEM results showed that the grains in the NSSL measured 8 nm. In addition, these nanocrystalline grains took the form of random crystallographic orientation and were roughly equiaxed in shape. In situ SEM observations of the tensile process confirmed that the motions of the dislocations were determined from within the material and that the motions were blocked by the NSSL, thus improving overall yielding stress. Meanwhile, the nanohardness and the elastic modulus of the NSSL, as well as those of the matrix, were obtained with nanoindentation technology. The reverse analysis of FEM was conducted with MARC software, and the process of nanoindentation on the NSSL and the matrix was simulated. The plastic mechanical properties of NSSL can be derived from the simulation by comparing the results of the simulation and of actual nanoindentation.

  12. Estudio experimental del desgaste del flanco y de la rugosidad superficial en el torneado en seco de alta velocidad del acero AISI 316L

    Morales Tamayo, Yoandrys

    2014-01-01

    La mejora continua de los procesos de fabricación es fundamental para alcanzar niveles óptimos de productividad, calidad y coste en la producción de componentes y productos. Para ello es necesario disponer de modelos que relacionen de forma precisa las variables que intervienen en el proceso de corte. Esta investigación tiene como objetivo determinar la influencia de la velocidad de corte y el avance en el desgaste del flanco de los insertos de carburos recubiertos GC1115 y GC2015 y en la rug...

  13. Compatibility of SS316L with Pb-17at%Li with reference to Indian-TBM

    The present work deals with the study of corrosion behaviour of Pb-17Li flowing in thermal buoyancy driven loop made of SS316L with a thermal gradient of 100 deg C. The corrosion of SS316L tube was studied after 1000 hrs of exposure using scanning electron microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX). Preferential dissolution of major constituent elements namely, Fe, Ni, Cr from the tube walls with the formation of a ferrite layer was observed in the hot leg at 500 deg C. Both Ni and Cr rich deposits were found in the cold leg at 400 deg C but no penetration of Pb-17Li was observed. Chemical analysis of Pb-17Li showed highest concentrations of Ni due to higher solubility. (author)

  14. Result of International Round Robin Test on Young's Modulus Measurement of 304L and 316L Steels at Cryogenic Temperatures

    Ogata et al. reported in 1996 results of international Round Robin tests on mechanical property measurement of several metals at cryogenic temperatures. Following the report, the standard deviation of Young's modulus of 316L steel is much larger than those of yield and tensile strengths, that is, 4.6 % of the mean value for Young's modulus, while 1.4 % and 1.6 % of the mean values for yield and for tensile strengths, respectively. Therefore, an international Round Robin test on Young's modulus of two austenitic stainless steels at cryogenic temperatures under the participation often institutes from four nations has been initiated within these two years. As a result, the ratios of standard deviation to the mean values are 4.2 % for 304L and 3.6 % for 316L. Such a drop in the standard deviation is attributable to the decrease in the number of institute owing to the application of single extensometer or direct strain gage technique

  15. Effects of grain size and specimen size on small punch test of type 316L austenitic stainless steel

    Miniature specimen test technique has been extensively studied for quantifying the properties of bulk materials. In this paper small punch test (SPT) is used to clarify the effects of specimen thickness (t), grain size (d) and ratio of thickness to grain size (t/d) on mechanical properties of 316L austenitic stainless steel (SS). Five sheet of 316L SS with the same texture but different thicknesses and grain sizes were prepared using rolling and heating treatment technique. Effective SPT yield strength was measured, and then used to correlate with conventional tensile test by empirical equation. The results show that the SPT is sensitive not only to differences in the thickness, but also to changes in the grain size and value of t/d. The present work provides information that enhance the understanding of reliability of SPT in analysis of the mechanical properties of small specimens and bulk materials. (author)

  16. Microstructural, Micro-hardness and Sensitization Evaluation in HAZ of Type 316L Stainless Steel Joint with Narrow Gap Welds

    Islam, Faisal Shafiqul; Jang, Changheui [KAIST, Daejeon (Korea, Republic of); Kang, Shi Chull [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2015-10-15

    From Micro-hardness measurement HAZ zone was found approximately 1-1.5 mm in NGW and DL-EPR test confirmed that 316L NGW HAZ was not susceptible to sensitization as DOS <1% according to sensitization criteria based on reference. In nuclear power plants 316L stainless steels are commonly used material for their metallurgical stability, high corrosion resistance, and good creep and ductility properties at elevated temperatures. Welding zone considered as the weakest and failure initiation source of the components. For safety and economy of nuclear power plants accurate and dependable structural integrity assessment of main components like pressure vessels and piping are need as it joined by different welding process. In similar and dissimilar metal weld it has been observed that weld microstructure cause the variation of mechanical properties through the thickness direction. In the Heat Affected Zone (HAZ) relative to the fusion line face a unique thermal experience during welding.

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

    Triwiyanto A.

    2014-07-01

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

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

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

    1997-07-01

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

  19. Stress corrosion cracking and oxidation of austenitic stainless steel 316 L and model alloy in supercritical water reactor

    In this work, an austenitic stainless steel type 316 L was tested in deaerated supercritical water at 400 deg. C and 500 deg. C and 25 MPa to determine how variations in water conditions influence its stress corrosion cracking behaviour and to make progress in the understanding of mechanisms involved in SCC processes in this environment. Moreover, the influence of plastic deformation in the resistance of the material to SCC was also studied at both temperatures. In addition to this, previous oxidation experiments at 400 deg. C and 500 deg. C and at 25 MPa were taken into account to gain some insight in this kind of processes. Furthermore, a cold worked model alloy based on the stainless steel 316 L with some variations in the chemical composition in order to simulate the composition of the grain boundary after irradiation was tested at 400 deg. C and 25 MPa in deaerated supercritical water. (authors)

  20. Effect of ITER blanket manufacturing process on the properties of the 316L(N)-IG steel

    Austenitic stainless steel 316L(N)-IG is proposed as one of the base structural materials for the international thermonuclear experimental reactors (ITER) in-vessel components. Various fabrication techniques (hot isostatic pressing (HIP), powder metallurgy, fusion welding and casting etc.) were assessed for the high heat flux components. HIP is the most perspective option because it allows to manufacture components with complicated shape and to provide joining of heat sink and plasma facing materials, simultaneously, during the same HIP cycle. The paper deals with the results of investigations of the repeated thermal cycle effect on the 316L(N)-IG steel properties. It is shown that most significant changes of strength were observed after first heat treatment (HIP) cycle. Results of microstructure investigation and stress corrosion cracking (SCC) are also presented in the paper

  1. Preparation and properties of enamel barrier on 316L stainless steel for resistance of hydrogen and its isotopes penetration

    In order to solve the problems of the resistance of hydrogen and its isotopes penetration for 316L stainless steel, the enamel coating with a thickness of 90-110 μm was prepared on the stainless steel substrate with the aid of coating and enameling for twice. The microstructure and the interfacial morphology of the samples were characterized respectively by X-ray diffractometer, optical and scanning electron microscopy. Moreover, the profiles of main elements at the interface between the coating and the substrate were analyzed by EDS line-scanning. The experimental results indicated that the dense enamel coatings were chemically bonded with 316L stainless steel substrate, and possessed perfect thermal shock and ball-dropping impact properties. Finally, a conclusion was drawn from the results of hydrogen charging in a Sieverts apparatus and the Vickers microhardness test that the as-prepared dense enamel coating exhibited a good barrier effect to hydrogen nad its isotopes penetration. (authors)

  2. Corrosion behaviour of 316L stainless steel and anti-corrosion materials in a high acidified chloride solution

    Jin, Z. H.; Ge, H. H.; Lin, W. W.; Zong, Y. W.; Liu, S. J.; Shi, J. M.

    2014-12-01

    The corrosion behaviour of a type 316L (UNS S31603) stainless steel (SS) expansion joint in a simulated leaching solution of sediment on blast furnace gas pipeline in a power plant is investigated by using dynamic potential polarization curves, electrochemical impedance spectroscopy (EIS), optical microscope, atomic force microscope (AFM) and Scan Kelvin Probe (SKP). Severe general corrosion accompanied by pitting corrosion occurs on the type 316L SS surface in this solution. As the immersion period increases, the charge transfer resistance Rct decreases, the dissolution rate accelerates, the surface roughness increases and the surface potential difference enhances significantly. Then eight corrosion-resistant materials are tested, the corrosion rates of type 254SMo SS, type 2507 SS and TA2 are relatively minor in the solution. The corrosion resistance properties of TA2 is most excellent, indicating it would be the superior material choice for blast furnace gas pipeline.

  3. The silica-titania layer deposited by sol-gel method on the AISI 316L for contact with blood

    W. Walke

    2013-02-01

    Full Text Available Purpose: The study analyses influence of surface modification of Si:Ti on physical and chemical properties of samples made from AISI 316L steel in solution simulating blood-vascular system.Design/methodology/approach: Sol-gel layer was selected on the ground of data from literature. TEOS and TET made the ground for initial solution. Application of the layer on the surface of samples made of AISI 316L steel was preceded by mechanical working - grinding (Ra = 0.40 µm and mechanical polishing (Ra = 0.12 µm. Corrosion resistance tests were performed on the ground of registered anodic polarisation curves and Stern method. In order to evaluate phenomena that take place on the surface of the tested alloys EIS was also applied. The tests were performed in artificial blood plasma at the temperature of T = 37.0±1°C and pH = 7.0±0.2.Findings: Obtained results on the ground of voltammetric and impedance tests showed differentiated electrochemical properties of AISI 316L steel depending on the type of surface treatment. Practical implications: Suggested subject matter of the article supports development of entrepreneurship sector due to high social demand for this type of technologies and relatively easy way of putting obtained laboratory tests data into inductrial and clinical practice.Originality/value: Suggestion of proper variants of surface treatment with application of sol-gel method is meaningful in future perspective and it shall promote determination of technological conditions with precise parameters of creation of oxide layers on metallic implants made of AISI 316L steel that come into contact with blood.

  4. Numerical models and experimental simulation of irradiation hardening and damage effects on the fracture toughness of 316L stainless steel

    Cornacchia, Giuseppe

    2013-01-01

    In nuclear environments, irradiation hardening and damage have a detrimental effect on materials performance. Among others, fracture toughness of austenitic stainless steels decreases under neutron irradiation. Helium arising from transmutation reactions is one source of embrittlement leading to that decrement and it is here assumed as a case study, austenitic steel 316L being the material under investigation. The experimental reproduction of irradiation hardening effect on yield stress is at...

  5. Hydrophilic property of 316L stainless steel after treatment by atmospheric pressure corona streamer plasma using surface-sensitive analyses

    Al-Hamarneh, Ibrahim, E-mail: hamarnehibrahim@yahoo.com [Department of Physics, Faculty of Science, Al-Balqa Applied University, Salt 19117 (Jordan); Pedrow, Patrick [School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164 (United States); Eskhan, Asma; Abu-Lail, Nehal [Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164 (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Surface hydrophilic property of surgical-grade 316L stainless steel was enhanced by Ar-O{sub 2} corona streamer plasma treatment. Black-Right-Pointing-Pointer Hydrophilicity, surface morphology, roughness, and chemical composition before and after plasma treatment were evaluated. Black-Right-Pointing-Pointer Contact angle measurements and surface-sensitive analyses techniques, including XPS and AFM, were carried out. Black-Right-Pointing-Pointer Optimum plasma treatment conditions of the SS 316L surface were determined. - Abstract: Surgical-grade 316L stainless steel (SS 316L) had its surface hydrophilic property enhanced by processing in a corona streamer plasma reactor using O{sub 2} gas mixed with Ar at atmospheric pressure. Reactor excitation was 60 Hz ac high-voltage (0-10 kV{sub RMS}) applied to a multi-needle-to-grounded screen electrode configuration. The treated surface was characterized with a contact angle tester. Surface free energy (SFE) for the treated stainless steel increased measurably compared to the untreated surface. The Ar-O{sub 2} plasma was more effective in enhancing the SFE than Ar-only plasma. Optimum conditions for the plasma treatment system used in this study were obtained. X-ray photoelectron spectroscopy (XPS) characterization of the chemical composition of the treated surfaces confirms the existence of new oxygen-containing functional groups contributing to the change in the hydrophilic nature of the surface. These new functional groups were generated by surface reactions caused by reactive oxidation of substrate species. Atomic force microscopy (AFM) images were generated to investigate morphological and roughness changes on the plasma treated surfaces. The aging effect in air after treatment was also studied.

  6. Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants

    The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings. - Highlights: • Effect of Nb2O5 nanoparticles on the bio activity of PPy coatings was evaluated. • Hydrophilic, more compact and smooth morphology of nanocomposite was achieved. • Nb2O5 nanoparticles enhanced the corrosion protection performance of PPy coating. • Mechanical and surface wettability of nanocomposite exhibited higher than PPy. • Nano Nb2O5 in PPy coating improved the biocompatibility on osteoblast MG63 cells

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

    Triwiyanto A.; Zainuddin A.; Abidin K.A.Z; Billah M.A; Hussain P.

    2014-01-01

    This paper present mathematical model which developed to predict the nitrided layer thickness (case depth) of gas nitrided and plasma nitrided austenitic stainless steel according to Fick’s first law for pure iron by adapting and manipulating the Hosseini’s model to fit the diffusion mechanism where nitrided structure formed by nitrided AISI 316L austenitic stainless steel. The mathematical model later tested against various actual gas nitriding and plasma nitriding experimental results with ...

  8. Effect of forming technique BixSiyOz coatings obtained by sol- gel and supported on 316L stainless steel

    Bautista Ruiz, J.; Olaya Flórez, J.; Aperador, W.

    2016-02-01

    BixSiyOz type coatings via sol-gel synthesized from bismuth nitrate pentahydrate, and tetraethyl orthosilicate as precursors; glacial acetic acid and 2-ethoxyethanol as solvents, and ethanolamine as complexing. The coatings were supported on AISI 316L stainless steel substrate through dip-coating and spin-coating techniques. The study showed that the spin-coating technique is efficient than dip-coating because it allows more dense and homogeneous films.

  9. Embrittlement of types 316l and 347 weld overlay by post-weld heat treatment and hydrogen

    Tyson, W.

    1984-07-01

    The effects of post-weld heat treatment and hydrogen on the tensile properties of weld overlay of types 316L and 347 have been studied. Formation of sigma phase (σ) from the delta ferrite (σ) in the as-welded microstructure leads to significant loss of ductility and increased sensitivity to hydrogen. Although hydrogen charging caused ductility losses in all conditions, no change in fracture mode was found by scanning electron and optical microscopy.

  10. Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants

    Madhan Kumar, A. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Nagarajan, S. [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, Tokyo (Japan); Ramakrishna, Suresh [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Sudhagar, P.; Kang, Yong Soo [Energy Materials Laboratory, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Hyongbum [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Gasem, Zuhair M. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Rajendran, N., E-mail: nrajendran@annauniv.edu [Department of Chemistry, Anna University, Chennai (India)

    2014-10-01

    The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb{sub 2}O{sub 5} nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb{sub 2}O{sub 5} nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb{sub 2}O{sub 5} nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb{sub 2}O{sub 5} nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb{sub 2}O{sub 5} nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings. - Highlights: • Effect of Nb{sub 2}O{sub 5} nanoparticles on the bio activity of PPy coatings was evaluated. • Hydrophilic, more compact and smooth morphology of nanocomposite was achieved. • Nb{sub 2}O{sub 5} nanoparticles enhanced the corrosion protection performance of PPy coating. • Mechanical and surface wettability of nanocomposite exhibited higher than PPy. • Nano Nb{sub 2}O{sub 5} in PPy coating improved the biocompatibility on osteoblast MG63 cells.

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

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

    2005-01-01

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

  12. Creep deformation and fracture behavior of types 316 and 316L(N) stainless steels and their weld metals

    Sasikala, G.; Mannan, S. L.; Mathew, M. D.; Rao, K. Bhanu

    2000-04-01

    The creep properties of a nuclear-grade type 316(L) stainless steel (SS) alloyed with nitrogen (316L(N) SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on a nuclear-grade type 316 SS, which is lean in nitrogen. The creep rupture lives of the weld metals were found to be lower than those of the respective base metals by a factor of 5 to 10. Both the base and weld metals of 316L(N) SS exhibited better resistance to creep deformation compared to their 316 SS counterparts at identical test conditions. A power-law relationship between the minimum creep rate and applied stress was found to be obeyed for both the base and weld metals. Both the weld metals generally exhibited lower rupture elongation than the respective base metals; however, at 873 K, the 316 SS base and weld metals had similar rupture elongation at identical applied stresses. Comparison of the rupture lives of the two steels to the ASME curves for the expected minimum stress to rupture for 316 SS base and weld metals showed that, for 316L(N) SS, the specifications for maximum allowable stresses based on data for 316 SS could prove overconservative. The influence of nitrogen on the creep deformation and fracture behavior, especially in terms of its modifying the precipitation kinetics, is discussed in light of the microstructural observations. In welds containing δ ferrite, the kinetics of its transformation and the nature of the transformation products control the deformation and fracture behavior. The influence of nitrogen on the δ ferrite transformation behavior and coarsening kinetics is also discussed, on the basis of extensive characterization by metallographic techniques.

  13. The role of the microstructure and defects on crack initiation in 316L stainless steel under multiaxial high cycle fatigue

    GUERCHAIS, Raphaël; Morel, Franck; Saintier, Nicolas

    2014-01-01

    The aim of this study is to analyse the influence of both the microstructure and defects on the high cycle fatigue behaviour of the 316L austenitic stainless steel, using finite element simulations of polycrystalline aggregates. High cycle fatigue tests have been conducted on this steel under uniaxial (push-pull) and multiaxial (combined in-phase tension and torsion) loading conditions, with both smooth specimens and specimens containing artificial semi-spherical surface defects. 2D numerical...

  14. Repassivation behavior of 316L stainless steel in borate buffer solution: Kinetics analysis of anodic dissolution and film formation

    Xu, Haisong; Sun, Dongbai; Yu, Hongying

    2015-12-01

    The repassivation behavior of metals or alloys after oxide film damage determines the development of local corrosion and corrosion resistance. In this work, the repassivation kinetics of 316L stainless steel (316L SS) are investigated in borate buffer solution (pH 9.1) by using the abrading electrode technique. The current densities flowing from bare 316L SS surface are measured by potentiostatic method and analyzed to characterize repassivation kinetics. The initial stages of current decay (t Avrami kinetics. Then the two independent components are analyzed individually. The film formation rate and the thickness of film are compared in different applied potential. It is shown that anodic dissolution dominates the repassivation for a short time during the early times, and a higher applied potential will promote the anodic dissolution of metal. The film growth rate increases slightly with increasing in potential. Correspondingly, increase in applied potential from 0 VSCE to 0.8 VSCE results in thicker monolayer, which covers the whole bare surface at the time of θ = 1. The electric field strengths through the thin passive film could reach 3.97 × 106 V cm-1.

  15. Study on corrosion resistance of palladium films on 316L stainless steel by electroplating and electroless plating

    Palladium films with good adhesive strength were deposited on 316L stainless steel by electroless plating and electroplating. Scanning electronic microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, weight loss tests and electrochemical methods were used to study the properties of the films. The electroless plated palladium film mainly consisted of palladium, phosphorus and nitrogen, and the electroplated palladium film was almost pure palladium. XPS analysis indicated that palladium was present in the films as metal state. The palladium plated stainless steel samples prepared by both methods showed excellent corrosion resistance in strong reductive corrosion mediums. In boiling 20% dilute sulfuric acid solution, the corrosion rates of the palladium plated 316L stainless steel samples were four orders of magnitude lower than that of the original 316L stainless steel samples. In the solution with 0.01 M NaCl, the palladium plated samples also showed better corrosion resistance. In comparison, the electroplated samples showed slightly better corrosion resistance than electroless plated samples, which may be attributed to less impurities and thereby higher corrosion potential for the former

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

    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

  17. The high temperature three point bend testing of proton irradiated 316L stainless steel and Mod 9Cr 1Mo

    Maloy, Stuart A.; Zubelewicz, A.; Romero, T.; James, M. R.; Sommer, W. F.; Dai, Y.

    2005-08-01

    The predicted operating conditions for a lead-bismuth eutectic target to be used in an accelerator driven system for the Advanced Fuel Cycle Initiative span a temperature range of 300-600 °C while being irradiated by a high energy (˜600 MeV) proton beam. Such spallation conditions lead to high displacement rates coupled with high accumulation rates of helium and hydrogen up to 150 appm/dpa. Some candidate materials for these applications include Mod9Cr-1Mo and 316L stainless steel. To investigate the effect of irradiation on these materials, the mechanical properties are being measured through three point bend testing on Mod 9Cr-1Mo and 316L at 25, 250, 350 and 500 °C after irradiation in a high energy proton beam (500-800 MeV) to a dose of 9.8 dpa at temperatures from 200 to 320 °C. By comparing measurements made in bending to tensile measurements measured on identically irradiated materials, a measurement of 0.2% offset yield stress was obtained from 0.05% offset yield stress measured in three point bend testing. Yield stress increased by more than a factor of two after irradiation to 9.8 dpa. Observation of the outer fiber surface of 316L showed very localized deformation when tested after irradiation at 70 °C and deformation on multiple slip systems when tested after irradiation at 250-320 °C.

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

    Shibata, K.; Fujii, H.

    2004-06-01

    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.

  19. COMPUTATIONAL MODELING OF CATHODIC LIMITATIONS ON LOCALIZED CORROSION OF WETTED SS 316L, AT ROOM TEMPERATURE

    F. Cui; F.J. Presuel-Moreno; R.G. Kelly

    2005-10-13

    The ability of a SS316L surface wetted with a thin electrolyte layer to serve as an effective cathode for an active localized corrosion site was studied computationally. The dependence of the total net cathodic current, I{sub net}, supplied at the repassivation potential E{sub rp} (of the anodic crevice) on relevant physical parameters including water layer thickness (WL), chloride concentration ([Cl{sup -}]) and length of cathode (Lc) were investigated using a three-level, full factorial design. The effects of kinetic parameters including the exchange current density (i{sub o,c}) and Tafel slope ({beta}{sub c}) of oxygen reduction, the anodic passive current density (i{sub p}) (on the cathodic surface), and E{sub rp} were studied as well using three-level full factorial designs of [Cl{sup -}] and Lc with a fixed WL of 25 {micro}m. The study found that all the three parameters WL, [Cl{sup -}] and Lc as well as the interactions of Lc x WL and Lc x [Cl{sup -}] had significant impact on I{sub net}. A five-factor regression equation was obtained which fits the computation results reasonably well, but demonstrated that interactions are more complicated than can be explained with a simple linear model. Significant effects on I{sub net} were found upon varying either i{sub o,c}, {beta}{sub c}, or E{sub rp}, whereas i{sub p} in the studied range was found to have little impact. It was observed that I{sub net} asymptotically approached maximum values (I{sub max}) when Lc increased to critical minimum values. I{sub max} can be used to determine the stability of coupled localized corrosion and the critical Lc provides important information for experimental design and corrosion protection.

  20. Characteristics of sintered HA coating deposited by chemical method on AISI 316L substrate

    Graphical abstract: Potentiodynamic polarization curves of various conditions tested in Ringer’s solution at 37 ± 1 °C. - Highlights: • Sintering resulted in a well-dispersed HA-coating. • Sintering of HA resulted in a slightly higher surface roughness. • Sintering improved the coating/substrate adhesion. • Sintering of HA-coated samples possessed higher corrosion resistance. - Abstract: Hydroxyapatite (HA) coating is widely applied for biomaterials because of its chemical similarity to the mineral component of bones. The bioactive nature of HA coating enhances the formation of strong chemical bonds with surrounding bones. The present work is aimed at investigating the effects of sintering at 500, 600 and 700 °C on the crystallization and adhesive properties of HA coating, deposited by chemical method on AISI 316L stainless steel substrate. The properties of HA coating were studied by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and standard tensile adhesion test. In addition, the corrosion behavior after heat treatments was evaluated in Ringer’s solution at 37 °C as a simulated body fluid. The results refer to a good enhancement of the crystallization of the HA coating sintered at 700 °C. The adhesive strength of as-coated (AC) material increased from 8.3 MPa to 12.2, 16.8 and 19.8 MPa after sintering at 500, 600 and 700 °C, respectively. The corrosion rate of the as-coated material reduced sharply from 0.405 to 0.094 μA cm−2 after sintering at 700 °C

  1. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    Wilbraham, Richard J.; Boxall, Colin; Goddard, David T.; Taylor, Robin J.; Woodbury, Simon E.

    2015-09-01

    For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H2O2-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H2O2] ⩽ 100 μmol dm-3 the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H2O2 concentrations between 1 mmol dm-3 and 0.1 mol dm-3, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H2O2] > 0.1 mol dm-3 the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve. This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO2 films has not hitherto been observed or explored, either in terms of corrosion processes or otherwise. Through consideration of thermodynamic solubility product and complex formation constant data, we attribute the transition to the formation of soluble uranyl-peroxide complexes under mildly alkaline, high [H2O2] conditions - a conclusion that has implications for the design of both acid minimal, metal ion oxidant-free decontamination strategies with low secondary waste arisings, and single step processes for spent nuclear fuel dissolution such as the Carbonate-based Oxidative Leaching (COL) process.

  2. Prediction of microcracking in laser overly welds of alloy 690 to type 316L stainless steel

    The occurrence of ductility-dip crack in the laser overlay welds of alloy 690 to type 316L stainless steel was predicted by the mechanical and metallurgical approaches. Ductility-dip temperature ranges (DTRs) of alloy 690 laser overlay welds were estimated by Varestraint test during GTA welding. The grain boundary segregation of impurity elements such as P and S was numerically analyzed based on the non-equilibrium cosegregation theory when the welding speed and the amounts of P and S in the weld metal were varied. In accordance with the repression approximation between the DTR and the calculated grain boundary concentrations of P and S, the DTRs of alloy 690 were computed in laser overlay welding. The estimated DTR in laser overlay welds was reduced with an increase in welding speed and with a decrease in the amounts of P and S in the weld metal. Ductility-dip cracking in laser overlay welds was predicted by the plastic strain-temperature curve intersected the DTR. The plastic strain in laser overlay welding was numerically analyzed using the thermo elasto-plastic finite element method. The plastic strain-temperature curve in laser overlay welds intersected the DTR at decreased welding speed and increased (P+S) content in the weld metal. The predicted results of ductility-dip cracking in laser overlay welds were approximately consistent with experiment results. It follows that ductility-dip cracking in laser overlay welds could be successfully predicted based on the estimated DTR from grain boundary segregation analysis combined with the computed plastic strain by FEM analysis. (author)

  3. Fracture under mixed-mode I+II of the austenitic stainless steel 316L

    The stability of cracks under mixed-mode l+ll in an aged stainless steel type 316L is investigated using four-points bent specimens. The formulas of the bending moment, the shearing force, the mode mixity, the limit load and the J estimations are established and compared with the numerical results from elastoplastic finite element calculations. From the experimental and numerical tests results, the application and the validation of the R6 method and various local criteria (Beremin, McClintock, Guennouni-Francois and Lemaitre models) are carried out. For the R6 method, it is noted that the FAD (Failure Assessment Diagram) is nearly independent of the loading mode and the specimen geometry. The FAD of the option 1 is conservative for all the test results, but the option 3 seems to be non-conservative, especially in the cases near to the mode I. This apparent non-conservatism is probably due to the different definition of the crack initiation of the CT specimens and the 4-point bend specimens. According to the applied local criteria, the values of the damage variables at crack initiation are sufficiently stable, particularly for the Beremin model and the Guennouni-Francois model but not in the cases nearer to the mode I. The use of these local criteria is questionable in the case of axisymmetric notched specimens because of the influence of the fracture of transformed ferrite. A fractographic investigation is also discussed for different fracture modes. (author). 85 refs., 99 figs., 14 tabs

  4. Investigation of oxide film formation on 316L stainless steel in high-temperature aqueous environments

    Highlights: → Oxide films formed in high temperature and high pressure aqueous environment (250 deg. C and 7 MPa) is much thicker than air-formed films (25 deg. C). → Oxide films formed at 250 deg. C have higher charge transfer resistance and smaller passive current density than air-formed films. → Fe exists in the form of FeO, Fe2O3 and FeOOH, Cr of Cr2O3, Cr(OH)3 and CrO3 and Ni of Ni(OH)2 in oxide films formed at 250 deg. C. - Abstract: Oxide films were grown on the surface of 316L stainless steel subjected to high temperatures and a high-pressure aqueous environment (250 deg. C and 7 MPa). The morphology, chemical compositions and corrosion properties of oxide films were investigated by scanning electron microscopy (SEM), auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results indicated that oxide films formed at 250 deg. C were more corrosion resistant and thicker than were oxide films formed in air at room temperature (25 deg. C). These distinctions are correlated with the structure and chemical compositions of oxide films. It was found that both films contained a double-layer structure comprised of mixed iron-nickel oxides and chromium oxides. Iron was present as FeO, Fe2O3 and FeOOH; Cr was present as Cr2O3, Cr(OH)3 and CrO3; and Ni existed as Ni(OH)2 within the oxide films formed at 250 deg. C.

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

    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)

  6. Aceros inoxidables de nuevo diseño resistentes a la corrosión localizada

    Otero, E.; Botella, J.; Botana, J.; Matres, V.; Merello, R.

    2005-01-01

    A new material, usually, is a classic material with small modifications. The modifications provide new and/or superior properties to the material, making it competitive. The development of a new austenitic stainless steel based on the modified AISI 304 is described in the present work. This new steel shows a pitting corrosion resistance similar, or even better, than AISI 316. The behaviour of a stainless duplex steel with a low content in Ni is also described here. Its pitting corrosion resis...

  7. Effect of grain refinement and electrochemical nitridation on corrosion resistance of the 316L stainless steel for bipolar plates in PEMFCs environment

    Jinlong, Lv; Tongxiang, Liang; Hongyun, Luo

    2015-10-01

    The stain-induced nanocrystalline α'-martensite was obtained by cryogenic cold rolling at liquid-nitrogen temperature for 316L stainless steel. The electrochemical results showed nanocrystalline 316L stainless steel deteriorated its corrosion resistance in a typical proton exchange membrane fuel cell environment compared with coarse grained one. However, comparing with electrochemically nitrided coarse grained stainless steel, electrochemically nitrided nanocrystalline stainless steel improved significantly corrosion resistance in the same environment, which was supported further by Mott-Shottky analysis. X-ray photoelectron spectroscopy analysis revealed that the nanocrystalline promoted the enrichment of nitrogen and chromium and inhibited form of NH3 on the surface, which could significantly improve the corrosion resistance of the 316L stainless steel. The present study showed that the electrochemically nitrided 316L stainless steel was more suitable for the bipolar plates in proton exchange membrane fuel cell environment than the untreated one, especially for nanocrystalline stainless steel.

  8. Nanohardness, corrosion and protein adsorption properties of CuAlO2 films deposited on 316L stainless steel for biomedical applications

    Chang, Shih-Hang; Chen, Jian-Zhang; Hsiao, Sou-Hui; Lin, Guan-Wei

    2014-01-01

    This study preliminarily assesses the biomedical applications of CuAlO2 coatings according to nanoindentation, electrochemical, and protein adsorption tests. Nanoindentation results revealed that the surface hardness of 316L stainless steel increased markedly after coating with CuAlO2 films. Electrochemical tests of corrosion potential, breakdown potential, and corrosion current density showed that the corrosion resistance properties of 316L stainless steel are considerably improved by CuAlO2 coatings. Bicinchoninic acid (BCA) protein assay results revealed that the protein adsorption behavior of 316L stainless steel did not exhibit notable differences with or without CuAlO2 coatings. A CuAlO2 coating of 100 nm thickness improved the surface nanohardness and corrosion resistance ability of 316L stainless steel. CuAlO2 is a potential candidate for biomaterial coating applications, particularly for surface modification of fine, delicate implants.

  9. Possible mechanism for formation of a ferromagnetic phase in stainless steel Fe/Cr/Ni/Mo, 17/11/8/2 (Type 316L) irradiated in reactor

    Results of experiments are summarized indicating that the occurrence of ferromagnetism in 316L steels is at least in part explained by the conversion of austenite to ferrite, induced by hydrogen resulting from nuclear reactions in the Rapsodie reactor

  10. Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

    Mahmoud Hassan R. S.; Yusoff Syafiq A.; Zainuddin Azman; Hussain Patthi; Ismail Mokhtar; Abidin Kamal

    2014-01-01

    High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The incr...

  11. Tearing-fatigue interactions in 316L(N) austenitic stainless steel

    Sherry, A.H. [University of Manchester, Sackville Street, Manchester M60 1QD (United States)]. E-mail: andrew.sherry@manchester.ac.uk; Wardle, G. [Warhelle Consulting Ltd, 79 Garton Drive, Lowton, Cheshire WA3 2TR (United States); Jacques, S. [Serco Assurance, Birchwood Park, Risley, Warrington WA3 6AT (United States); Hayes, J.P. [Serco Assurance, Birchwood Park, Risley, Warrington WA3 6AT (United States)

    2005-11-01

    This paper presents the results from a programme of tearing, fatigue and tearing-fatigue tests performed on specimens from a 316L(N) stainless steel plate. All tests were carried out at ambient temperature. The experimental results have been compared with assessments performed using current guidance within the R6 defect assessment method. The work has shown that there is some evidence that fatigue cycling modifies the JR-curve behaviour of this material. In most cases, the data lie approximately 20-30% above the base-line JR-curve. However, whilst there may be a modest influence of fatigue crack growth on the ductile tearing characteristics, it is difficult to separate this from experimental scatter. In tearing-fatigue tests performed at a stress ratio, R=0.2, ductile tearing reduces the fatigue crack growth rates by up to 50%. This is likely to result from the presence of a residual compressive zone at the crack-tip, and increased crack closure due to the irregular and non-matching fracture surfaces generated by the ductile crack growth mechanisms. For R=0.1 tearing-fatigue tests, fatigue crack growth rates are apparently enhanced by a factor up to of 10, particularly during the latter stages of the tests when {delta}K>60 MPam. This is likely to result from: (i) loading being in the elastic-plastic regime where the J-integral (rather than K) characterises the crack-tip fields (ii) increments of ductile tearing which may occur during each fatigue cycle, and (iii) crack blunting which reduces crack closure effects. For the R=0.2 tearing-fatigue tests, the linear summation approach described in R6 provides a consistently conservative prediction of ductile, fatigue and total crack growth during the tests. However, for the R=0.1 tearing-fatigue tests, the Paris law under-predicts fatigue crack growth rates. This may be corrected by using the Kaiser equation, which acknowledges loading in the elastic-plastic regime and incorporates incremental growth due to tearing as

  12. Tearing-fatigue interactions in 316L(N) austenitic stainless steel

    This paper presents the results from a programme of tearing, fatigue and tearing-fatigue tests performed on specimens from a 316L(N) stainless steel plate. All tests were carried out at ambient temperature. The experimental results have been compared with assessments performed using current guidance within the R6 defect assessment method. The work has shown that there is some evidence that fatigue cycling modifies the JR-curve behaviour of this material. In most cases, the data lie approximately 20-30% above the base-line JR-curve. However, whilst there may be a modest influence of fatigue crack growth on the ductile tearing characteristics, it is difficult to separate this from experimental scatter. In tearing-fatigue tests performed at a stress ratio, R=0.2, ductile tearing reduces the fatigue crack growth rates by up to 50%. This is likely to result from the presence of a residual compressive zone at the crack-tip, and increased crack closure due to the irregular and non-matching fracture surfaces generated by the ductile crack growth mechanisms. For R=0.1 tearing-fatigue tests, fatigue crack growth rates are apparently enhanced by a factor up to of 10, particularly during the latter stages of the tests when ΔK>60 MPam. This is likely to result from: (i) loading being in the elastic-plastic regime where the J-integral (rather than K) characterises the crack-tip fields (ii) increments of ductile tearing which may occur during each fatigue cycle, and (iii) crack blunting which reduces crack closure effects. For the R=0.2 tearing-fatigue tests, the linear summation approach described in R6 provides a consistently conservative prediction of ductile, fatigue and total crack growth during the tests. However, for the R=0.1 tearing-fatigue tests, the Paris law under-predicts fatigue crack growth rates. This may be corrected by using the Kaiser equation, which acknowledges loading in the elastic-plastic regime and incorporates incremental growth due to tearing as well

  13. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    Highlights: • The first report of the presence of both UO2 and polymeric UO22+ in the same electrodeposited U oxide sample. • The action of H2O2 on electrodeposited U oxides is described using corrosion based concepts. • Electrodeposited U oxide freely dissolves at hydrogen peroxide concentrations <100 μmol dm−3. • At [H2O2] > 0.1 mmol dm−3 dissolution is inhibited by formation of a studtite passivation layer. • At [H2O2] ⩾ 1 mol dm−3 studtite formation competes with uranyl–peroxide complex formation. - Abstract: For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H2O2-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H2O2] ⩽ 100 μmol dm−3 the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H2O2 concentrations between 1 mmol dm−3 and 0.1 mol dm−3, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H2O2] > 0.1 mol dm−3 the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve. This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO2 films has not hitherto been observed or explored, either in terms of corrosion processes or otherwise. Through consideration of thermodynamic solubility product and complex formation constant data, we attribute the

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

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

  15. Surface analysis of localized corrosion of austenitic 316L and duplex 2205 stainless steels in simulated body solutions

    Conradi, Marjetka, E-mail: marjetka.conradi@imt.si [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Schoen, Peter M. [Materials Science and Technology of Polymers and MESA Institute for Nanotechnology, University of Twente, Enschede 7500 AE (Netherlands); Kocijan, Aleksandra; Jenko, M. [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Vancso, G. Julius [Materials Science and Technology of Polymers and MESA Institute for Nanotechnology, University of Twente, Enschede 7500 AE (Netherlands)

    2011-10-17

    Highlights: {yields} In situ steel surface morphology observations in simulated body solutions. {yields} Pitting, square-like and elliptic-like corrosion products. {yields} Corrosion products' shapes related to the growth of Cr and Fe oxides. {yields} Direct relation of the size of the deposition products to surface roughness. - Abstract: We report on cyclic voltammetry and in situ electrochemical atomic force microscopy (EC-AFM) studies of localized corrosion of duplex 2205 stainless steel (DSS 2205) and austenitic stainless steel of the type AISI 316L in two model solutions, including artificial saliva (AS) and a simulated physiological solution known as - Hank's solution (PS). The AFM topography analysis illustrated the higher corrosion resistance of DSS 2205 steel for the chosen range of electrochemical potentials that were applied to the steel surface in both solutions. In contrast, pitting corrosion was observed at the surface of AISI 316L steel, with the pits becoming more evident, larger and deeper, when the sample was electrochemically treated in the PS. On both surfaces the growth of corrosion products formed during the oxidation process was observed. As a result, depending on the sample's metallurgical structure, different types of oxides covered the surface close to the breakdown potential. We distinguished between the square-like type of oxides on the surface of the DSS 2205, and the AISI 316L with its ellipse-like oxide deposits. The X-ray photoelectron spectroscopy (XPS) revealed the chemical composition of the deposition products, which consisted of two main elements, Fe and Cr. However, the oxides of the alloying elements Ni and Mo were negligible compared to the bulk.

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

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

    2012-09-15

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

  17. Comparative electrochemical study of 08H18N10T, AISI 304 and AISI 316L stainless steels

    The aim of this work was to determine the main characteristics of the passivation and surface oxidation of 08H18N10T, AISI304 and AISI316L stainless steels, which serve as structural materials of VVER and PWR nuclear reactors. With the help of electrochemical experiments these materials were ranked according to their resistance against uniform corrosion. The measurements were done as a function of temperature in the range between room temperature and 80 deg. C. A sample of 08H18N10T steel was irradiated in the Budapest research reactor. With cyclic voltammetry we found that AISI 304 exhibits a very large passivation peak as a classical example for passivation. The peak is much smaller for AISI 316L and it is very small for 08H18N10T. This implies that the native oxide layer on AISI 316L and 08H18N10T is more protective than on AISI 304. The 08H18N10T steel has the best protective passive oxide layer which forms already in air and it is very difficult to remove it even at negative potentials. By comparing impedance spectra of the various stainless steels results lead to the same conclusions we obtained from cyclic voltammetry. Our experimental results of the irradiated steel are in accord with the fact that neutron irradiation increases the number of defect sites within the oxide layer. We found that irradiation has no considerable effect on the active-to-passive transition process. The small variations in the alloy composition do not alter the transition process significantly, as well

  18. Comparative electrochemical study of 08H18N10T, AISI 304 and AISI 316L stainless steels

    Kerner, Zsolt; Horvath, Akos [KFKI Atomic Energy Research Institute, H-1525 Budapest 114, P.O. Box 49 (Hungary); Nagy, Gabor [KFKI Atomic Energy Research Institute, H-1525 Budapest 114, P.O. Box 49 (Hungary)], E-mail: nagyg@sunserv.kfki.hu

    2007-10-10

    The aim of this work was to determine the main characteristics of the passivation and surface oxidation of 08H18N10T, AISI304 and AISI316L stainless steels, which serve as structural materials of VVER and PWR nuclear reactors. With the help of electrochemical experiments these materials were ranked according to their resistance against uniform corrosion. The measurements were done as a function of temperature in the range between room temperature and 80 deg. C. A sample of 08H18N10T steel was irradiated in the Budapest research reactor. With cyclic voltammetry we found that AISI 304 exhibits a very large passivation peak as a classical example for passivation. The peak is much smaller for AISI 316L and it is very small for 08H18N10T. This implies that the native oxide layer on AISI 316L and 08H18N10T is more protective than on AISI 304. The 08H18N10T steel has the best protective passive oxide layer which forms already in air and it is very difficult to remove it even at negative potentials. By comparing impedance spectra of the various stainless steels results lead to the same conclusions we obtained from cyclic voltammetry. Our experimental results of the irradiated steel are in accord with the fact that neutron irradiation increases the number of defect sites within the oxide layer. We found that irradiation has no considerable effect on the active-to-passive transition process. The small variations in the alloy composition do not alter the transition process significantly, as well.

  19. Comparative study of mechanical properties of 316L stainless steel between traditional production methods and selective laser melting

    Lackey, Alton Dale

    Additive manufacturing, also known as 3D printing, is a technology which has recently seen expanding use, as well as expansion of the materials and methods able to be used. This thesis looks at the comparison of mechanical properties of 316L stainless steel manufactured by both traditional methods and selective laser melting found by tensile testing. The traditional method used here involved cold rolled 316L steel being machined to the desired part geometry. Selective laser melting used additive manufacturing to produce the parts from powdered 316L stainless steel, doing so in two different build orientations, flat and on edge with regards to the build plate. Solid test specimens, as well as specimens containing a circular stress concentration in the center of the parts, were manufactured and tensile tested. The tensile tests of the specimens were used to find the mechanical properties of the material; including yield strength, ultimate tensile strength (UTS), and Young's modulus of elasticity; where statistical analyses were performed to determine if the different manufacturing processes caused significant differences in the mechanical properties of the material. These analysis consisting of f-tests, to test for variance, and t-test, testing for significant difference of means. Through this study it was found that there were statistically significant differences existing between the mechanical properties of selective laser melting, and its orientations, and cold roll forming of production of parts. Even with a statistical difference, it was found that the results were reasonably close between flat oriented SLM parts and purchased parts. So it can be concluded that, with regards to strength, SLM methods produce parts similar to traditional production methods.

  20. One-dimensional migration of interstitial clusters in SUS316L and its model alloys at elevated temperatures

    Satoh, Y.; Abe, H.; Matsukawa, Y.; Matsunaga, T.; Kano, S.; Arai, S.; Yamamoto, Y.; Tanaka, N.

    2015-05-01

    For self-interstitial atom (SIA) clusters in various concentrated alloys, one-dimensional (1D) migration is induced by electron irradiation around 300 K. But at elevated temperatures, the 1D migration frequency decreases to less than one-tenth of that around 300 K in iron-based bcc alloys. In this study, we examined mechanisms of 1D migration at elevated temperatures using in situ observation of SUS316L and its model alloys with high-voltage electron microscopy. First, for elevated temperatures, we examined the effects of annealing and short-term electron irradiation of SIA clusters on their subsequent 1D migration. In annealed SUS316L, 1D migration was suppressed and then recovered by prolonged irradiation at 300 K. In high-purity model alloy Fe-18Cr-13Ni, annealing or irradiation had no effect. Addition of carbon or oxygen to the model alloy suppressed 1D migration after annealing. Manganese and silicon did not suppress 1D migration after annealing but after short-term electron irradiation. The suppression was attributable to the pinning of SIA clusters by segregated solute elements, and the recovery was to the dissolution of the segregation by interatomic mixing under electron irradiation. Next, we examined 1D migration of SIA clusters in SUS316L under continuous electron irradiation at elevated temperatures. The 1D migration frequency at 673 K was proportional to the irradiation intensity. It was as high as half of that at 300 K. We proposed that 1D migration is controlled by the competition of two effects: induction of 1D migration by interatomic mixing and suppression by solute segregation.

  1. Cavitation erosion resistance of AISI 316L stainless steel laser surface-modified with NiTi

    Chiu, K.Y. [Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Cheng, F.T. [Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)]. E-mail: apaftche@polyu.edu.hk; Man, H.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2005-02-15

    The present study is part of a project on the surface modification of AISI 316 stainless steel using various forms of NiTi for enhancing cavitation erosion resistance. In this study, NiTi powder was preplaced on the AISI 316L substrate and melted with a high-power CW Nd:YAG laser. With appropriate laser processing parameters, an alloyed layer of a few hundred micrometers thick was formed and fusion bonded to the substrate without the formation of a brittle interface. EDS analysis showed that the layer contained Fe as the major constituent element while the XRD patterns of the surface showed an austenitic structure, similar to that of 316 stainless steel. The cavitation erosion resistance of the modified layer (316-NiTi-Laser) could reach about 29 times that of AISI 316L stainless steel. The improvement could be attributed to a much higher surface hardness and elasticity as revealed by instrumented nanoindentation tests. Among various types of samples, the cavitation erosion resistance was ranked in descending order as: NiTi plate > 316-NiTi-Laser > 316-NiTi-TIG > AISI 316L, where 316-NiTi-TIG stands for samples surfaced with the tungsten inert gas (TIG) process using NiTi wire. Though the laser-surfaced samples and the TIG-surfaced samples had similar indentation properties, the former exhibited a higher erosion resistance mainly because of a more homogeneous alloyed layer with much less defects. In both the laser-surfaced and TIG-surfaced samples, the superelastic behavior typical of austenitic NiTi was only partially retained and the superior cavitation erosion resistance was thus still not fully attained.

  2. Cavitation erosion resistance of AISI 316L stainless steel laser surface-modified with NiTi

    The present study is part of a project on the surface modification of AISI 316 stainless steel using various forms of NiTi for enhancing cavitation erosion resistance. In this study, NiTi powder was preplaced on the AISI 316L substrate and melted with a high-power CW Nd:YAG laser. With appropriate laser processing parameters, an alloyed layer of a few hundred micrometers thick was formed and fusion bonded to the substrate without the formation of a brittle interface. EDS analysis showed that the layer contained Fe as the major constituent element while the XRD patterns of the surface showed an austenitic structure, similar to that of 316 stainless steel. The cavitation erosion resistance of the modified layer (316-NiTi-Laser) could reach about 29 times that of AISI 316L stainless steel. The improvement could be attributed to a much higher surface hardness and elasticity as revealed by instrumented nanoindentation tests. Among various types of samples, the cavitation erosion resistance was ranked in descending order as: NiTi plate > 316-NiTi-Laser > 316-NiTi-TIG > AISI 316L, where 316-NiTi-TIG stands for samples surfaced with the tungsten inert gas (TIG) process using NiTi wire. Though the laser-surfaced samples and the TIG-surfaced samples had similar indentation properties, the former exhibited a higher erosion resistance mainly because of a more homogeneous alloyed layer with much less defects. In both the laser-surfaced and TIG-surfaced samples, the superelastic behavior typical of austenitic NiTi was only partially retained and the superior cavitation erosion resistance was thus still not fully attained

  3. Surface analysis of localized corrosion of austenitic 316L and duplex 2205 stainless steels in simulated body solutions

    Highlights: → In situ steel surface morphology observations in simulated body solutions. → Pitting, square-like and elliptic-like corrosion products. → Corrosion products' shapes related to the growth of Cr and Fe oxides. → Direct relation of the size of the deposition products to surface roughness. - Abstract: We report on cyclic voltammetry and in situ electrochemical atomic force microscopy (EC-AFM) studies of localized corrosion of duplex 2205 stainless steel (DSS 2205) and austenitic stainless steel of the type AISI 316L in two model solutions, including artificial saliva (AS) and a simulated physiological solution known as - Hank's solution (PS). The AFM topography analysis illustrated the higher corrosion resistance of DSS 2205 steel for the chosen range of electrochemical potentials that were applied to the steel surface in both solutions. In contrast, pitting corrosion was observed at the surface of AISI 316L steel, with the pits becoming more evident, larger and deeper, when the sample was electrochemically treated in the PS. On both surfaces the growth of corrosion products formed during the oxidation process was observed. As a result, depending on the sample's metallurgical structure, different types of oxides covered the surface close to the breakdown potential. We distinguished between the square-like type of oxides on the surface of the DSS 2205, and the AISI 316L with its ellipse-like oxide deposits. The X-ray photoelectron spectroscopy (XPS) revealed the chemical composition of the deposition products, which consisted of two main elements, Fe and Cr. However, the oxides of the alloying elements Ni and Mo were negligible compared to the bulk.

  4. 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

    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.

  5. The Effect of pH and Temperature on Corrosion Rate Stainless Steel 316L Used as Biomaterial

    Zainab R. Muslim

    2015-10-01

    Full Text Available The weight loss of stainless steel 316L on corrosion rate was studied using two different temperatures (25 and 37oC and different pH (1,3, 6.3 and 7.4. It was shown that the weight loss was decreased with the increasing in pH ,this effect on the corrosion rate which decrease with increasing in pH . Temperature effect on weight loss, an increasing in weight loss was observed with the increasing in temperature.

  6. STATISTICAL MODELING OF ELECTROCHEMICAL REACTIVATION CONDITIONS FOR DETECTING SENSITIZATION TO IGC OF AUSTENITIC STAINLESS STEEL TYPE 316L

    Kriaa, A.; Hamdi, N.; K. Jbali; H. Sidhom

    2007-01-01

    The aim of this study was to determine optimum conditions of the DL EPR test in order to evaluate the highest values of the degree of sensitization (DOS) of a forged austenitic stainless steel type 316L, evaluated by the ratio Ir/Ia or Qr/Qa in %. The criteria of sensitization to the IGC corresponds to Ir/Ia >1% and Qr/Qa >1%. A model using a full factorial design has been established and the selected factors were the sweep rate (dE/dt), sulphuric acid concentration (H2SO4), ammonium th...

  7. Application of dynamical ion mixing techniques to the improvement of the fatigue resistance of a 316L stainless steel

    In the last years new techniques involving ion implantation combined with a simultaneous deposition method in a sputtering evaporator have been developed at the University of Poitiers. These techniques have been employed to elaborate NiTi amorphous coatings in order to improve the fatigue resistance of a 316 L austenitic stainless steel at room temperature and 573 K. It has been shown that a significant improvement of the fatigue life is obtained by this way at 293 K and at 573 K due to a considerable modification of surface damage leading to an important delay for crack initiation. (orig.)

  8. Corrosion of stainless steel 316L in simulated formation water environment with CO2-H2S-Cl-

    A synergistic effect of high concentration of chloride and H2S on oxide formation and metal dissolution has been studied on 316L stainless steel by electrochemical measurements, inductive coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). Chloride concentration had a significant effect on semiconductor properties of the oxide film, while the gases had little effect. A relatively high concentration of sulphur was found inside the oxide formed in a high chloride concentration electrolyte with high H2S compared to the oxide formed in low concentrations, which indicates that sulphur entered the oxide film through local weakening of the oxide by the chloride.

  9. Improving the oxidation resistance of 316L stainless steel in simulated pressurized water reactor primary water by electropolishing treatment

    Han, Guangdong; Lu, Zhanpeng; Ru, Xiangkun; Chen, Junjie; Xiao, Qian; Tian, Yongwu

    2015-12-01

    The oxidation behavior of 316L stainless steel specimens after emery paper grounding, mechanical polishing, and electropolishing were investigated in simulated pressurized water reactor primary water at 310 °C for 120 and 500 h. Electropolishing afforded improved oxidation resistance especially during the early immersion stages. Duplex oxide films comprising a coarse Fe-rich outer layer and a fine Cr-rich inner layer formed on all specimens after 500 h of immersion. Only a compact layer was observed on the electropolished specimen after 120 h of immersion. The enrichment of chromium in the electropolished layer contributed to the passivity and protectiveness of the specimen.

  10. Slip activity of persistent slip bands in early stages of fatigue life of austenitic 316L steel

    Man, Jiří; Weidner, A.; Klapetek, P.; Polák, Jaroslav

    Zurich : Trans Tech Publications, 2014 - (Šandera, P.), s. 785-788 ISBN 978-3-03785-934-6. ISSN 1013-9826. - (Key Engineering Materials. 592-593). [MSMF 7 - International Conference on Materials Structure & Micromechanics of Fracture /7./. Brno (CZ), 01.07.2013-03.07.2013] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA ČR(CZ) GAP108/10/2371; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : 316L steel * persistent slip band * slip activity * slip irreversibility * half-cycle deformation Subject RIV: JL - Materials Fatigue, Friction Mechanics

  11. Probing the deterioration of 316L stainless steel welds due to ageing and creep by indentation creep tests

    Authors have probed into the creep behaviour of AISI 316L stainless steel welds through the indentation creep test methodology and assessed the deterioration effects of these welds under different ageing conditions subjecting them to different test conditions. Comparison is made between the parent metal and the weld metal for integrity at different levels of ageing and test loads. It is concluded that although the aged weld's deteriorated status is not revealed at low temperature and low load test conditions, it is explicitly revealed when tested at higher temperature and higher loads. Microstructural evidences have been given by the authors and they have suggested mechanisms of creep at different test conditions.

  12. Effect of CO2 laser cutting process parameters on edge quality and operating cost of AISI316L

    Eltawahni, Hayat; Hagino, M.; Benyounis, Khaled; Inoue, T; Olabi, Abdul-Ghani

    2012-01-01

    Laser cutting is a popular manufacturing process utilized to cut various types of materials economically. The width of laser cut or kerf, quality of the cut edges and the operating cost are affected by laser power, cutting speed, assist gas pressure, nozzle diameter and focus point position as well as the work-piece material. In this paper CO2 laser cutting of stainless steel of medical grade AISI316L has been investigated. Design of experiment (DOE) was implemented by applying Box-Behnken de...

  13. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    Wilbraham, Richard J., E-mail: r.wilbraham@lancaster.ac.uk [The Lloyd’s Register Foundation Centre for Nuclear Engineering, Engineering Department, Lancaster University, Bailrigg, Lancashire LA1 4YR (United Kingdom); Boxall, Colin, E-mail: c.boxall@lancaster.ac.uk [The Lloyd’s Register Foundation Centre for Nuclear Engineering, Engineering Department, Lancaster University, Bailrigg, Lancashire LA1 4YR (United Kingdom); Goddard, David T., E-mail: dave.t.goddard@nnl.co.uk [National Nuclear Laboratory, Preston Laboratory, Springfields, Preston, Lancashire PR4 0XJ (United Kingdom); Taylor, Robin J., E-mail: robin.j.taylor@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Seascale, Cumbria CA20 1PG (United Kingdom); Woodbury, Simon E., E-mail: simon.woodbury@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Seascale, Cumbria CA20 1PG (United Kingdom)

    2015-09-15

    Highlights: • The first report of the presence of both UO{sub 2} and polymeric UO{sub 2}{sup 2+} in the same electrodeposited U oxide sample. • The action of H{sub 2}O{sub 2} on electrodeposited U oxides is described using corrosion based concepts. • Electrodeposited U oxide freely dissolves at hydrogen peroxide concentrations <100 μmol dm{sup −3}. • At [H{sub 2}O{sub 2}] > 0.1 mmol dm{sup −3} dissolution is inhibited by formation of a studtite passivation layer. • At [H{sub 2}O{sub 2}] ⩾ 1 mol dm{sup −3} studtite formation competes with uranyl–peroxide complex formation. - Abstract: For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H{sub 2}O{sub 2}-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H{sub 2}O{sub 2}] ⩽ 100 μmol dm{sup −3} the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H{sub 2}O{sub 2} concentrations between 1 mmol dm{sup −3} and 0.1 mol dm{sup −3}, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H{sub 2}O{sub 2}] > 0.1 mol dm{sup −3} the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve. This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO{sub 2} films has not hitherto been observed or explored, either in terms

  14. A New Vacuum Brazing Route for Niobium-316L Stainless Steel Transition Joints for Superconducting RF Cavities

    Kumar, Abhay; Ganesh, P.; Kaul, R.; Bhatnagar, V. K.; Yedle, K.; Ram Sankar, P.; Sindal, B. K.; Kumar, K. V. A. N. P. S.; Singh, M. K.; Rai, S. K.; Bose, A.; Veerbhadraiah, T.; Ramteke, S.; Sridhar, R.; Mundra, G.; Joshi, S. C.; Kukreja, L. M.

    2015-02-01

    The paper describes a new approach for vacuum brazing of niobium-316L stainless steel transition joints for application in superconducting radiofrequency cavities. The study exploited good wettability of titanium-activated silver-base brazing alloy (CuSil-ABA®), along with nickel as a diffusion barrier, to suppress brittle Fe-Nb intermetallic formation, which is well reported during the established vacuum brazing practice using pure copper filler. The brazed specimens displayed no brittle intermetallic layers on any of its interfaces, but instead carried well-distributed intermetallic particles in the ductile matrix. The transition joints displayed room temperature tensile and shear strengths of 122-143 MPa and 80-113 MPa, respectively. The joints not only exhibited required hermeticity (helium leak rate ultra-high vacuum but also withstood twelve hour degassing heat treatment at 873 K (suppresses Q-disease in niobium cavities), without any noticeable degradation in the microstructure and the hermeticity. The joints retained their leak tightness even after undergoing ten thermal cycles between the room temperature and the liquid nitrogen temperature, thereby establishing their ability to withstand service-induced low cycle fatigue conditions. The study proposes a new lower temperature brazing route to form niobium-316L stainless steel transition joints, with improved microstructural characteristics and acceptable hermeticity and mechanical properties.

  15. Influence of binder system and temperature on rheological properties of water atomized 316L powder injection moulding feedstocks

    Uğur GÖKMEN

    2016-02-01

    Full Text Available In order to obtain a proper powder injection molding the rheological behavior of feedstocks should be known. To determine the binder effect on the rheological behavior of 316L stainless steel powders feedstock two different feedstock were prepared. In the current experiments water atomized 316L stainless steel powders (-20 µm were used. Two types of binders, one of which is mainly paraffin wax can be dissolved in heptane and the other Polietilenglikol (PEG based and can be dissolved in water, were used. Polypropylene was used as binder and steric acid was used as lubricant for both binder systems as skeleton binder. Dry binder system were mixed for 30 min in a three dimensional Turbola. Capillary rheometer was used to characterize the rheological properties of feed stocks at 150-200 °C and a pressures of 0.165-2.069 MPa. Powder loading capacity of PEG and PW based feed stocks were found to be %55 and %61 respectively. The lowest viscosity of PEG and PW based feed stocks were found to be 304.707 Pa.s and 48.857 Pa.s respectively.Keywords: PIM, Binder, Rheological properties

  16. Optimizing wear behavior of TiN coated SS 316L against Ti alloy using Response Surface Methodology

    Highlights: • The hardness was increased nine times greater than uncoated steel surface. • Higher sliding speed influenced the friction and wear rate. • The test parameters for minimum wear rate were effectively optimized. - Abstract: Titanium nitride (TiN) is a hard ceramic biocompatible material, which is deposited over stainless steel (SS) 316L to improve the mechanical and wear properties when sliding against Ti–6Al–4V alloy for artificial hip joints. Arc deposited TiN coating thickness was measured, using an optical microscope. The surface hardness of the TiN coated surface has been improved 9 times more than that of the uncoated steel surface. The crystallography of the coated surface was examined by the X-ray diffraction analysis, and the topography of the coated surface was inspected, using the Atomic Force Microscope. The wear test was conducted, using the ball-on-disc, with the varying parameters of the applied load (2–6 N), sliding velocity (0.25–0.75 m/s) and sliding distance (500–1500 m). The Worn surface of the coated and uncoated sample was studied, using the Field Emission Scanning Electron Microscope. It was concluded that the presence of TiN coating on the SS 316L surface exhibits superior wear resistance and coefficient of friction. The optimum parameters of wear and friction were identified, using Response Surface Methodology, and some useful conclusions were made

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

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

    2016-07-01

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

  18. A study of precipitation in as-welded 316LN plate using 316L/317L weld metal

    A study was undertaken of the precipitation in multi-pass 316L and 317L weldments in as-welded conditions. A feature of the work was that the microstructure of the welds was compared by trepanning 3 mm discs from specific positions. Specimens for transmission electron microscopy (TEM) were prepared from the discs. The volume percentages of delta(δ)-ferrite and intermetallics were determined by taking the mean of values obtained from 30-40 fields of view. Selected area electron diffraction (SAED) and energy dispersive X-ray analysis (EDAX) were used to identify the phases present in the various positions within each weld. In regions where overlapping of two welding passes occurred and hence where there was some remelting of the initial pass, the chi(χ) phase was identified. This precipitated usually at the delta/austenite phase boundary in the size range 0.05-0.1 μm probably due to the higher Mo and Cr, and lower N in these regions. The higher Mo content resulted in a higher volume % of χ phase in the overlapped pass region of the 317L welds compared to the 316L welds. One case was observed of sigma(σ) phase which was probably transformed from the χ phase. (orig.)

  19. Corrosion-erosion test of SS316L grain boundary engineering material (GBEM) in lead bismuth flowing loop

    Saito, Shigeru; Kikuchi, Kenji; Hamaguchi, Dai; Tezuka, Masao; Miyagi, Masanori; Kokawa, Hiroyuki; Watanabe, Seiichi

    2012-12-01

    To evaluate the lifetime of structural materials utilized in a spallation neutron source, corrosion tests in lead-bismuth eutectic (LBE) have been done at JAEA. Austenitic steels are preferable as the structural material for ADS. However, previous studies have revealed that austenitic steel SS316 shows severe corrosion-erosion in LBE because of LBE penetration through grain boundaries and separation of grains. So it was considered that GBE (grain-boundary engineered) materials may be effective to improve the corrosion resistance of austenitic steels in LBE. In this study, the results of corrosion tests on austenitic steel SS316L-BM (base metal) and SS316L-GBEM (grain-boundary-engineered material) under flowing LBE conditions will be reported. The corrosion test was performed using the JAEA lead-bismuth material corrosion loop (JLBL-1). The experimental conditions were as follows: The high and low temperature parts of the loop were 450 °C and 350 °C, respectively. The flow velocity at the test specimens was about 0.7 m/s. The oxygen concentration in LBE was not controlled and was estimated to have been very low. After the 3600 h of operation, macroscopic, SEM, and SIM observations and EDX analysis were carried out. The results showed that the corrosion depth and LBE penetration through the grain boundaries of the 316SS-GBEM were smaller than those of the 316SS-BM.

  20. Corrosion-erosion test of SS316L grain boundary engineering material (GBEM) in lead bismuth flowing loop

    Saito, Shigeru, E-mail: saito.shigeru@jaea.go.jp [JAEA, Tokai-mura, Ibaraki-ken 319-1195 (Japan); Kikuchi, Kenji [Ibaraki Univ., Frontier Research Center, Tokai-mura, Ibaraki-ken 319-1106 (Japan); Hamaguchi, Dai [JAEA, Tokai-mura, Ibaraki-ken 319-1195 (Japan); Tezuka, Masao [Sukegawa Electic Co., Takahagi-shi, Ibaraki-ken 318-0004 (Japan); Miyagi, Masanori; Kokawa, Hiroyuki [Tohoku Univ., Sendai-shi, Miyagi-ken 980-8579 (Japan); Watanabe, Seiichi [Hokkaido Univ., Sapporo-shi, Hokkai-do 060-8628 (Japan)

    2012-12-15

    To evaluate the lifetime of structural materials utilized in a spallation neutron source, corrosion tests in lead-bismuth eutectic (LBE) have been done at JAEA. Austenitic steels are preferable as the structural material for ADS. However, previous studies have revealed that austenitic steel SS316 shows severe corrosion-erosion in LBE because of LBE penetration through grain boundaries and separation of grains. So it was considered that GBE (grain-boundary engineered) materials may be effective to improve the corrosion resistance of austenitic steels in LBE. In this study, the results of corrosion tests on austenitic steel SS316L-BM (base metal) and SS316L-GBEM (grain-boundary-engineered material) under flowing LBE conditions will be reported. The corrosion test was performed using the JAEA lead-bismuth material corrosion loop (JLBL-1). The experimental conditions were as follows: The high and low temperature parts of the loop were 450 Degree-Sign C and 350 Degree-Sign C, respectively. The flow velocity at the test specimens was about 0.7 m/s. The oxygen concentration in LBE was not controlled and was estimated to have been very low. After the 3600 h of operation, macroscopic, SEM, and SIM observations and EDX analysis were carried out. The results showed that the corrosion depth and LBE penetration through the grain boundaries of the 316SS-GBEM were smaller than those of the 316SS-BM.

  1. Hardness and elastic modulus gradients in plasma-nitrided 316L polycrystalline stainless steel investigated by nanoindentation tomography

    Graphical abstract: - Abstract: Correlations between the grain orientations and elastic properties of plasma-nitrided polycrystalline 316L austenitic stainless steel are investigated. The grain orientations (h k l) in a delimited area were obtained from electron backscatter diffraction and related to hardness (Hhkl) and elastic modulus (Ehkl) maps obtained from large nanoindentation matrices. The influence of nitrogen concentration on the local mechanical properties has been studied by repeating these indentation matrices in the same area after successive partial removals of the nitrided layer. This nanoindentation tomography allowed the orientation, the shape and the surroundings of individual grains to be taken into account. The results show that plasma nitriding leads to a complete reversal of the elastic behaviour anisotropy: while the non-nitrided 316L austenitic stainless steel shows the typical elastic anisotropy of face-centred-cubic-type metals with a maximum of Ehkl for the 〈111〉 oriented grains, the maximum of Ehkl is observed for the 〈001〉 oriented grains in the nitrided layer. A similar anisotropy reversal is observed for the hardness Hhkl. These observations are discussed on the basis of the microstructural changes induced by the nitrogen incorporation.

  2. Effect of the hydrogen absorption on the positioning of the plastic deformation of a stainless steel-316L

    The aim of this work is to quantify the absorbed hydrogen effects on the plastic deformation (at the grain scale) of stainless steel-316L polycrystals. Tensile tests in air have been carried out on specimens previously cathodically loaded in hydrogen (135 wt.ppm) and unloaded polycrystals. After the tensile tests, a number statistically representative of gliding bands emergent in surface has been observed. In parallel to this experimental study, the plastic gliding level in each grain has been obtained by a finite element method from the polycrystalline microstructure modeled with the EBSD cartography. The Zebulon code developed by the Ecole des Mines de Paris allows to account for the plastic behaviour of the studied polycrystals using the crystalline plasticity model. The coupled analysis of the numerical and experimental results allows to know the gliding plan having produced the gliding steps observed in each grain by AFM. This allows then to quantify the number of emergent dislocations to create the average gliding band. It is then possible to compare the modifications of the positioning of the plastic deformation of the stainless steel-316L induced by hydrogen absorption. (O.M.)

  3. Effects of strain rate and notch geometry on hydrogen embrittlement of AISI type 316L austenitic stainless steel

    This paper presents the first results of the work which the author has been performing for the European Fusion Technology Programme. The contribution deals with the effects of strain rate and notch geometry on hydrogen embrittlement of 316L austenitic stainless steel, which will be used for the first wall of the next European fusion reactor. Slow strain rate fracture tests on round notched specimens of 316L steel were carried out under cathodic polarization during the mechanical loading. A wide range of strain rates was covered in the tests, in order to obtain very different degrees of damage produced by the hydrogen. Two notch geometries with very different radii were used, to analyze the influence of the stress state in the vicinity of the notch tip on hydrogen embrittlement. Samples were machined in two directions (the rolling direction and the perpendicular one), thus permitting a study of anisotropy effects. Results are compared with those for a high-strength pearlitic steel tested with the same technique under the same electrochemical potential. (orig.)

  4. In vitro corrosion investigations of plasma-sprayed hydroxyapatite and hydroxyapatite–calcium phosphate coatings on 316L SS

    Gurpreet Singh; Hazoor Singh; Buta Singh Sidhu

    2014-10-01

    The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer’s solution). Three types of coatings, i.e. HA + 20 wt% CaP (type 1), HA + 10 wt% CaP (type 2), HA (type 3), were laid on 316L SS using plasma-spraying technique. Structural characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to investigate the crystallinity, microstructure and morphology of the coatings. Electrochemical potentiodynamic tests were performed to determine the corrosion resistance of uncoated and all the three coatings. After the electrochemical corrosion testing, the samples were examined by XRD, SEM and EDX. The electrochemical study showed a significant improvement in the corrosion resistance after HA coating and corrosion resistance of type 3 coating was found maximum.

  5. Long-term corrosion investigation of AISI 316L, Co-28Cr-6Mo, and Ti-6Al-4V alloys in simulated body solutions

    The long-term weight loss, ion release and surface composition of AISI 316L, the Co-28Cr-6Mo and Ti-6Al-4V alloys were investigated in phosphate buffered solutions (PBS) with various bovine serum albumin (BSA) concentrations. All the samples lost weight up to 14 weeks and then started to gain weight. This can be explained by precipitation of dissolved ions on the surface after 14 weeks of immersion. The quantities of the dissolved ions were measured in immersed solution for 8, 14 and 22 weeks by induced coupled plasma-optical emission spectrometer (ICP-OES). The amounts of Fe released from 316L, and Co and Mo released from the Co-28Cr-6Mo alloy decreased after 14 weeks of immersion in PBS and BSA solutions. This observation coincides with the weight change of the samples. The oxide layer composition and concentration of the specimens exposed to solutions for 22 weeks were identified by X-ray photoelectron spectroscopy (XPS) analysis. The XPS results revealed that chromium is the main component of the 316L and Co-28Cr-6Mo alloy. The high Cr concentration of the 316L and Co-Cr-Mo oxide layer corresponds with the slow dissolution rate of Cr compared to other alloying elements of the 316L and Co-28Cr-6Mo alloy.

  6. Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties.

    Gulsoy, H Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, Ozal

    2015-11-01

    The research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350°C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment. PMID:26275484

  7. The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

    Neissi, R.; Shamanian, M.; Hajihashemi, M.

    2016-05-01

    In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

  8. The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

    Neissi, R.; Shamanian, M.; Hajihashemi, M.

    2016-04-01

    In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

  9. The hardiness of numerical simulation of TIG welding. Application to stainless steel 316L structures; La robustesse de la simulation numerique du soudage TIG. Application sur des structures en acier 316L

    El-Ahmar, Walid; Jullien, Jean-Francois [INSA-Lyon, LaMCoS, CNRS UMR 551, 20 Avenue Albert Einstein, 69621 Villeurbanne, (France); Gilles, Philippe [AREVA NP, 92084 Paris La Defense, (France); Taheri, Said [EDF, 92141 Clamart, (France); Boitout, Frederic [ESI-GROUP, 69458 Lyon, (France)

    2006-07-01

    The welding numerical simulation is considered as one of the mechanics problems the most un-linear on account of the great number of the parameters required. The analysis of the hardiness of the welding numerical simulation is a current questioning whose expectation is to specify welding numerical simulation procedures allowing to guarantee the reliability of the numerical result. In this work has been quantified the aspect 'uncertainties-sensitivity' imputable to different parameters which occur in the simulation of stainless steel 316L structures welded by the TIG process: that is to say the mechanical and thermophysical parameters, the types of modeling, the adopted behaviour laws, the modeling of the heat contribution.. (O.M.)

  10. Effect of tool geometry on tool wear characterization and weld formation in friction stir welding of 316L stainless steel

    316L stainless steel plate was friction stir welded using PCBN tools. The effect of tool shoulder profile and tool probe profile on tool wear characterization and weld formation was investigated. Two different shoulder profiles (screw with different pitches) with four different tool probe profiles (two different probe end shapes and two different probe lengths) have been used to fabricate FSW zone. Experimental results show that the tools with narrow pitch screw shoulder profile produce deeper FSW zone compared to the tools with wide pitch. The tools with spiral probe profile produce deeper FSW zone compared to the tools with chamber probe profile. The tools with wide pitch screw shoulder profile is apt to produce lower working loads. The wear resistant of tools with chamber probe profile is significantly higher than that of tools with spiral probe profile. The relation between tool geometries and tool wear and weld formation is discussed. (author)

  11. Full 3D spatially resolved mapping of residual strain in a 316L austenitic stainless steel weld specimen

    A three-pass slot weld specimen in austenitic stainless steel 316L, manufactured for the purpose of benchmarking Finite Element weld residual stress simulation codes, is currently undergoing extensive characterization within a research network. A comprehensive data set from non-destructive full three-dimensional spatially resolved macro-strain mapping in this specimen is presented here. Focussed high-energy synchrotron radiation together with the spiral slit technique was used to obtain depth-resolved information about the variation of lattice parameters. A novel full-pattern analysis approach, based on the evaluation of distinct diffraction spots from individual grains, was developed. The results show high tensile transverse stresses within the bead deposited first. The maximum longitudinal stresses were found beneath the slot. Furthermore significant weld start- and stop-effects were observed. The validity of the results is discussed with respect to the possible impact of intergranular strains due to plastic deformation.

  12. Evaluation of the electromagnetic characteristics of type 316L stainless steel welds from the viewpoint of eddy current inspections

    This study evaluated the electromagnetic characteristics of austenitic stainless steel welds from the viewpoint of eddy current testing. Seven welded plate specimens, which were welded using JIS Z3221:2010 YS316L welding metals, were prepared. Two welding metals and several welding conditions were adopted to discuss the generality. The results of eddy current examination of the specimens using three different types of eddy current probes, that is, an absolute pancake probe, a differential plus-point probe, and a uniform eddy current probe, confirmed that the welds cause a large noise especially when the absolute pancake probe was used. The analysis of the signals through finite element simulations revealed that the magnetic property of the welds is not negligible from the viewpoint of eddy current testing. Complementary experiments were conducted using a vibrating sample magnetometer to validate the results. (author)

  13. Microstructural aspects of creep-rupture life of type 316L(N) stainless steel in liquid sodium environment

    The influence of flowing sodium on creep-rupture properties of AISI Type 316L(N) stainless steel base material has been investigated at 550 and 660 C. In sodium test results were compared with reference creep-rupture data generated in air. The creep-rupture lives were longer in air than in sodium environment at 550 C, however, at 600 C, creep-rupture lives were longer in the latter than in the former environment. Microstructural studies showed the presence of sensitization and χ phase on longer duration test specimens at both temperatures. Surface cracks in sodium tested specimens were sharp and relatively more in numbers than in air where cracks were blunted. Cracks seem to follow the intergranular mode. Cavities were formed in long duration tests and propagated ahead of the χ phase. (orig.)

  14. Microstructural aspects of creep-rupture life of Type 316L(N) stainless steel in liquid sodium environment

    Mishra, M. P.; Borgstedt, H. U.; Frees, G.; Seith, B.; Mannan, S. L.; Rodriguez, P.

    1993-04-01

    The influence of flowing sodium on creep-rupture properties of AISI Type 316L(N) stainless steel base material has been investigated at 550 and 600°C. In sodium test results were compared with reference creep-rupture data generated in air. The creep-rupture lives were longer in air than in sodium environment at 550°C, however, at 600°C, creep-rupture lives were longer in the latter than in the former environment. Microstructural studies showed the presence of sensitization and χ phase on longer duration test specimens at both temperatures. Surface cracks in sodium tested specimens were sharp and relatively more in numbers than in air where cracks were blunted. Cracks seem to follow the intergranular mode. Cavities were formed in long duration tests and propagated ahead of the χ phase.

  15. Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels

    Sgobba, Stefano

    2003-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). This 27 km long accelerator requires 1248 superconducting dipole magnets operating at 1.9 K. The cold mass of the dipole magnets is closed by a shrinking cylinder with two longitudinal welds and two end covers at both extremities of the cylinder. The end covers, for which fabrication by welding, casting or Powder Metallurgy (PM) was considered, are dished-heads equipped with a number of protruding nozzles for the passage of the different cryogenic lines. Structural materials and welds must retain high strength and toughness at cryogenic temperature. AISI 316L-type austenitic stainless steel grades have been selected because of their mechanical properties, ductility, weldability and stability of the austenitic phase against low-temperature spontaneous martensitic transformation. 316LN is chosen for the fabrication of the end covers, while the interconnection components to be welded on the protrud...

  16. Microstructural characteristics and creep rupture behavior of electron beam and laser welded AISI 316L stainless steel

    AISI 316L stainless steel was welded by the electron beam (EB) and laser techniques. Microstructural characteristics, hardness profile, creep rupture properties and creep damage of the welds were investigated. Fully austenitic microstructure was obtained in the two welds. The solidification structure of the welds consisted of the cellular and equiaxed dendrites. The creep rupture lives of the two welds were almost the same, and they were reduced by a factor of about two compared to the base metal. Moreover, the rupture elongation of the welds was lower than that of the base metal. Creep damage was observed in the ''parting'' region of the welds and in the heat-affected zone (HAZ), respectively. Final creep fracture occurred in the ''parting'' region of the welds. (orig.)

  17. Analysis of notch strengthening of 316L stainless steel with and without irradiation-induced hardening using EBSD and FEM

    Wu, Xianglin; Pan, Xiao; Stubbins, James F.

    2007-04-01

    Notch strengthening analysis of 316L stainless steel was carried out using electron backscatter diffraction (EBSD) and the finite element modeling (FEM) techniques. The influence of exposure to irradiation was examined by employing irradiated tensile properties in the FEM analyses. The major issue of interest is the possibility that low ductility, often found following irradiation exposure, will translate into low notch toughness. It was found that notch depth plays an important role in notch strengthening and mechanical properties degradation. Differences in notch depth and shape result in various sizes of deformation and twinning zones. Experimental results and FEM modeling results correlate well over the range of notch conditions examined here. It is found that notch ductility and plastic deformation can be highly localized for irradiated materials, exacerbating the flow localization problem. Thus irradiation exposure can also lead to flow localization problems with components with notches or stress concentrators, but notch constraints can limit the extent of localized flow.

  18. Characteristics of sulfide corrosion products on 316L stainless steel surfaces in the presence of sulfate-reducing bacteria

    It has been found that microbial communities play a significant role in the corrosion process of steels exposed in aquatic and soil environments. Biomineralization influenced by microorganisms is believed to be responsible for the formation of corrosion products via complicated pathways of electron transfer between microbial cells and the metal. In this study, sulfide corrosion products were investigated for 316L stainless steel exposed to media with sulfate-reducing bacteria media for 7 weeks. The species of inorganic and organic sulfides in the passive film on the stainless steel were observed by epifluorescence microscope, environmental scanning electron microscope combined with energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The transformation from metal oxides to metal sulfides influenced by sulfate-reducing bacteria is emphasized in this paper

  19. Eddy Current and Ultrasonic IRIS Signal Characteristics of Reboiler Tube by Using STS 316L Calibration Specimen

    In this study, a field applicability of reboiler tube was evaluated by comparing ECT signal with IRIS signal about wall loss rate and remaining wall thickness using worked austenite STS 316L ASME standard calibration tube. In the case of wall-loss rate, as a result, tolerance about flat bottom hole and 10% O D groove(ECT), 80% defect and 10% O D groove(IRIS) occurred up to ±15%. In the case of remaining wall thickness, ECT was satisfied with the both tolerance, but tolerance about 80% defect occurred up to ±15% in IRIS. Therefore, if the IRIS is performed for interpretation of non-relevant indication and measurement of wall-loss rate after ECT, reliability is supposed to be improved

  20. Methodology for optimizing the electropolishing of stainless steel AISI 316L combining criteria of surface finish and dimensional precision

    Núñez, P. J.; García-Plaza, E.; Martín, A. R.; Trujillo, R.; De la Cruz, C.

    2009-11-01

    This work examines a methodology for optimizing electrochemical polishing conditions bearing in mind the criteria that enhance minimum surface roughness and dimensional precision (minimum loss of thickness). The study consisted in electrochemically polishing stainless steel AISI 316L (ISO 4954 X2CrNiMo17133E) under a combination of different temperatures (T) baths and current densities (J), and application times (t). The surface finish (ΔRa) and dimensional variations (Δh) of the electrochemically polished workpieces were assessed, and the experimental data of the variables was correlated as can be seen by the response surfaces. This methodology enables optimum working areas to be specified using the sole criteria of surface finish, or by using a combination of both criteria (minimum roughness and maximum precision). The methodology has proven to be an optimum method for selecting electrochemical polishing conditions using the combined criteria of surface finish and dimensional precision in accordance with design requirements.

  1. Characterization of deposits build-up on austenitic stainless steel AISI 316L exposed in high purity water system

    For the characterization of deposit layers on AISI 316L surfaces in high purity water systems, operating up to 80 deg C Moessbauer spectroscopy (ME), scanning electron microscopy (SEM), X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) are used. Austenitic steel particles were identified on the surfaces of systems not properly cleaned before start-up. Long exposition of austenitic surfaces to high purity water promotes the build-up, composed by trivalent iron and chromium oxidehydroxides and oxide. The oxidehydroxide phase is located mainly at the solid-water interface, whereas oxide phase is in direct contact with metal. Spheroid-like morphology of particles in these layers and the lack of metal attack suggest that coagulation and crystallization processes are the way for oxide production from existing dissolved species. (author)

  2. Helium effects on the post-implantation creep properties and the microstructure of AISI 316L welds and parent material

    The influence of implanted helium on the creep properties in electron-beam welds of the Next European Torus (NET) reference material, AISI 316L, and its parent material in the as-received condition has been investigated at 873 K. Helium degredation effects (i.e. reduced creep rupture time and creep rupture strain) are more serious in the parent material than in the welds. The fracture mode for implanted weld specimens is usually transgranular, while for the parent material specimens it is mixed trans- and intergranular. TEM investigations show that in the welds there is a lot of δ-ferrite at grain boundaries (occupying about 50% of grain boundary area) and in the interior of grains as well. Helium bubble sizes increase with increasing helium concentration, while helium bubble densities remain constant. Helium bubbles in the matrix are larger in size but much lower in density than those at boundaries or interfaces. (orig.)

  3. Dependence of the tensile properties of 316 L parent material and welds on implanted hydrogen and/or helium

    Schroeder, Herbert; Liu, Wanpei

    1992-09-01

    The interest in the low temperature tensile properties of candidate alloys for first wall and blanket structures of future fusion devices is due to the possible low pressure water cooling and the associated low operation temperature in recent design studies. Therefore, the tensile properties of hydrogen and/or helium implanted 316 L stainless steel and its weldments as a function of gas concentrations and temperature were investigated. The main effects of the implantation are hardening, resulting in large increases of the yield strength proportional to the implanted gas concentration, and a gradual decrease of the corresponding rupture strain. The ultimate tensile stresses are less affected. The effect of helium implantation seems to be more pronounced than that of hydrogen implantation. At 673 K most of the implantation induced changes are recovered. Generally parent material and welds still show large ductility (≥20%) under all conditions investigated.

  4. Helium effects on the post-implantation creep properties and the microstructure of AISI 316L welds and parent material

    Dai, Yong; Schroeder, Herbert

    1992-09-01

    The influence of implanted helium on the creep properties in electron-beam welds of the Next European Torus (NET) reference material, AISI 316L, and its parent material in the as-received condition has been investigated at 873 K. Helium degredation effects (i.e. reduced creep rupture time and creep rupture strain) are more serious in the parent material than in the welds. The fracture mode for implanted weld specimens is usually transgranular, while for the parent material specimens it is mixed trans- and intergranular. TEM investigations show that in the welds there is a lot of σ-ferrite at grain boundaries (occupying about 50% of grain boundary area) and in the interior of grains as well. Helium bubble sizes increase with increasing helium concentration, while helium bubble densities remain constant. Helium bubbles in the matrix are larger in size but much lower in density than those at boundaries or interfaces.

  5. Effect of Different Degrees of Sensitization on the EIS Response of 316L and 316 SS in Transpassive Region

    Morshed Behbahani, K.; Pakshir, M.

    2014-06-01

    Different heat treatments were conducted on 316L and 316 stainless steels, and the sensitized specimens were characterized using anodic polarization and EIS tests in 0.5 M H2SO4 containing 0.01 molar KSCN. The potential ranges related to the transpassive region related to each specimen were determined. The EIS experiments were conducted at different potentials in that region, and the results showed the presence of three different regions, namely the anodic dissolution of the passive layer, dissolution of the grain boundaries, and the occurrence of pitting corrosion owing to the variations in the anodic potential. The higher the applied sensitization temperature, the lower the obtained charge-transfer resistance ( R ct) values, but healing effect was observed at the temperatures above 600 °C for these alloys.

  6. Experimental evaluation of micromechanical damage produced by hydrogen in 316L steel for the first wall of fusion reactors

    This paper analyzes the process of progressive damage produced by mechanical origins (plasticity) and environmental causes (hydrogen embrittlement) in 316L austenitic stainless steel for the first wall of fusion reactors. Results of the analysis show that the micromechanical damage created by hydrogen is concentrated in an external circumferential ring with the same center as the cross sectional area of the notched samples. The microscopical appearance of this embrittled zone or damaged area is very rough and irregular at the microscale, with evidence of microcracking or secondary cracking, in contrast with the smooth surface (at the microscale) created by microvoid coalescence (dimpled fracture) in the inner core which is not embrittled by hydrogen and thus fails by mechanical reasons. The depth of the hydrogen damaged zone is quantified by fractographic methods and related to the test variables. (orig.)

  7. Helium dilution effect on hydrogen permeation in 316L stainless steel and nickel-base heat-resistant alloys

    Effects of inert-gas dilution on hydrogen permeation have been investigated in 316L stainless steel, Inconel 600, Inconel 750, Nimonic 80A and Hastelloy X at 1173 K and 1073 K, by employing a gas-flow system. We used gas mixtures of hydrogen and helium, whose hydrogen concentration ranged from 10-5 to 10-1. For the steady-state permeation, the dilution of hydrogen caused no anomalous effects and the permeation rate conformed to Sieverts' law. However, for the transient state, the hydrogen permeation was retarded by the dilution with helium. The retardation effect is discussed in terms of an adsorption model and explained by a decrease in sticking probability at the alloy surface with the dissociative adsorption of hydrogen. (orig.)

  8. Dependence of the tensile properties of 316L parent material and welds on implanted hydrogen and/or helium

    The interest in the low temperature tensile properties of candidate alloys for first wall and blanket structures of future fusion devices is due to the possible low pressure water cooling and the associated low operation temperature in recent design studies. Therefore, the tensile properties of hydrogen and/or helium implanted 316L stainless steel and its weldments as a function of gas concentrations and temperature were investigated. The main effects of the implantation are hardening, resulting in large increases of the yield strength proportional to the implanted gas concentration, and a gradual decrease of the corresponding rupture strain. The ultimate tensile stresses are less affected. The effect of helium implantation seems to be more pronounced than that of hydrogen implantation. At 673 K most of the implantation induced changes are recovered. Generally parent material and welds still show large ductility (≥ 20%) under all conditions investigated. (orig.)

  9. Microstructure and nano-hardness analyses of stress corrosion cracking, utilizing 316L core shroud of BWR power reactors

    The water cooled shield blanket made of Type 316L SS for the international thermonuclear experimental reactor (ITER) has potential issues related to stress corrosion cracking (SCC). Shroud mock-ups and boat samples taken from the core shroud of the boiling water reactor (BWR) with SCC were investigated from the viewpoint of microstructures and nano-hardness. Fine grains and deformation bands were observed in the hardened surface thin layers of the shroud mock-up, where hardness profiles in the ground portion was different from those in the milled portion. In the fine grain region, crevices were found only in the ground surface. In the core shroud, hardened surface regions were also found. Results showed that the crevices found on the ground surface could be one possible factor for SCC initiation

  10. Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

    Saeidi, K.; Gao, X. [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden); Lofaj, F. [Institute of Materials Research of the Slovak Academy of Sciences, Watsonova 47, Košice (Slovakia); Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 916 24 Trnava (Slovakia); Kvetková, L. [Institute of Materials Research of the Slovak Academy of Sciences, Watsonova 47, Košice (Slovakia); Shen, Z.J. [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

    2015-06-05

    Highlights: • Mechanical properties, phase and microstructure stability of laser melted steel was studied. • Duplex austenite-ferrite assembly with improved mechanical properties was formed. • Dissolution of Mo in the steel matrix resulted in ferrite stabilization and stress relief. • Enhanced mechanical properties were achieved compared to conventionally casted and annealed steel. - Abstract: Laser melting (LM), with a focused Nd:YAG laser beam, was used to form solid bodies from 316L austenite stainless steel powder and the laser melted samples were heat treated at various temperatures. The phase changes in heat treated samples were characterized using X-ray diffraction (XRD). Samples heat treated at 800 °C and 900 °C remained single austenite while in samples heat treated at 1100 °C and 1400 °C a dual austenite-ferrite phase assembly was formed. The ferrite formation was further verified by electron back scattering diffraction (EBSD) and selective area diffraction (SAD). Microstructural changes were studied by scanning and transmission electron microscopy (SEM, TEM). In samples heat treated up to 900 °C, coalescence of the cellular-sub grains was noticed, whereas in sample heat treated at and above 1100 °C the formation of ferrite phase was observed. The correlation between the microstructure/phase assembly and the measured strength/microhardness were investigated, which indicated that the tensile strength of the laser melted material was significantly higher than that of the conventional 316L steel even after heat treatment whereas caution has to be taken when laser melted material will be exposed to an application temperature above 900 °C.

  11. Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

    Highlights: • Mechanical properties, phase and microstructure stability of laser melted steel was studied. • Duplex austenite-ferrite assembly with improved mechanical properties was formed. • Dissolution of Mo in the steel matrix resulted in ferrite stabilization and stress relief. • Enhanced mechanical properties were achieved compared to conventionally casted and annealed steel. - Abstract: Laser melting (LM), with a focused Nd:YAG laser beam, was used to form solid bodies from 316L austenite stainless steel powder and the laser melted samples were heat treated at various temperatures. The phase changes in heat treated samples were characterized using X-ray diffraction (XRD). Samples heat treated at 800 °C and 900 °C remained single austenite while in samples heat treated at 1100 °C and 1400 °C a dual austenite-ferrite phase assembly was formed. The ferrite formation was further verified by electron back scattering diffraction (EBSD) and selective area diffraction (SAD). Microstructural changes were studied by scanning and transmission electron microscopy (SEM, TEM). In samples heat treated up to 900 °C, coalescence of the cellular-sub grains was noticed, whereas in sample heat treated at and above 1100 °C the formation of ferrite phase was observed. The correlation between the microstructure/phase assembly and the measured strength/microhardness were investigated, which indicated that the tensile strength of the laser melted material was significantly higher than that of the conventional 316L steel even after heat treatment whereas caution has to be taken when laser melted material will be exposed to an application temperature above 900 °C

  12. Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

    Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

    2016-06-01

    Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

  13. Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

    Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

    2016-08-01

    Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

  14. Improving the empirical model for plasma nitrided AISI 316L corrosion resistance based on Mössbauer spectroscopy

    Traditional plasma nitriding treatments using temperatures ranging from approximately 650 to 730 K can improve wear, corrosion resistance and surface hardness on stainless steels. The nitrided layer consists of some iron nitrides: the cubic γ′ phase (Fe4N), the hexagonal phase ε (Fe2 − 3N) and a nitrogen supersatured solid phase γN. An empirical model is proposed to explain the corrosion resistance of AISI 316L and ASTM F138 nitrided samples based on Mössbauer Spectroscopy results: the larger the ratio between ε and γ′ phase fractions of the sample, the better its resistance corrosion is. In this work, this model is examined using some new results of AISI 316L samples, nitrided under the same previous conditions of gas composition and temperature, but at different pressure, for 3, 4 and 5 h. The sample nitrided for 4 h, whose value for ε/γ′ is maximum (= 0.73), shows a slightly better response than the other two samples, nitrided for 5 and 3 h (ε/γ′ = 0.72 and 0.59, respectively). Moreover, these samples show very similar behavior. Therefore, this set of samples was not suitable to test the empirical model. However, the comparison between the present results of potentiodynamic polarization curves and those obtained previously at 4 and 4.5 torr, could indicated that the corrosion resistance of the sample which only presents the γN phase was the worst of them. Moreover, the empirical model seems not to be ready to explain the response to corrosion and it should be improved including the γN phase.

  15. Development of Silica Glass Coatings on 316L SS and Evaluation of its Corrosion Resistance Behavior in Ringer's Solution

    Vijayalakshmi, U.; Rajeswari, S.

    2012-12-01

    Sol-gel derived silica glasses have many promising features, including low-temperature preparation as well as chemical and physical stability. Two silica glasses with Si100 and Si80 composition were prepared to understand the factors contributing to the rate of bioactivity. The effects of pH, solution aging temperature, and molar ratio of H2O/tetraethyl orthosilicate (TEOS) were studied, and the obtained powder sample was characterized by Fourier transform infrared spectroscopy, X-ray diffraction studies, and scanning electron microscopy. The synthesized silica glasses were deposited on 316L SS by the spin coating method at the optimized speed of 2000 revolutions per minute. The corrosion resistance behavior of the coatings was determined by (1) open-circuit potential vs time of exposure, (2) electrochemical impedance spectroscopy, and (3) cyclic polarization in Ringer's solution. A higher breakdown potential ( E b) and repassivation potential ( E p) value with lower current density was obtained from cyclic polarization. Similar results were observed from impedance analysis with higher charge transfer resistance ( R ct) and lower double layer capacitance ( C dl) indicating the corrosion resistance behavior of the coatings compared with the uncoated 316L stainless steel. From the results, it was observed that both Si100 and Si80 glass coatings had a positive effect on the corrosion resistance behavior. An adhesive strength of 46 MPa and 45 MPa was obtained for the Si100 and Si80 coatings, respectively. An accelerated leach out study was carried out by impressing the potential at their breakdown potential to determine the effect of glass coating for long-term contact between the implant and a normal biological medium.

  16. Cálculo de variables termodinámicas de la difusión de especies iónicas dentro de los poros de un recubrimiento bioactivo mediante espectroscopia de impedancia electroquímica

    Vesga Prada, Yuly Katherine

    2010-01-01

    La investigación en el área de los biomateriales, apunta hacia el desarrollo de nuevos materiales aplicables en implantes médicos. Uno de los biomateriales más usados en la actualidad es el acero inoxidable 316L, ya que es un material que a pesar de su bajo costo presenta unas condiciones satisfactorias de uso en cuanto a su baja velocidad de corrosión; sin embargo, a pesar de considerarse inoxidable cuando se expone a atmósferas tan corrosivas como los fluidos corporales presenta un proceso ...

  17. Effects of dissolved oxygen and hydrogen peroxide on the corrosion potential of 316L stainless steel in hot lithium hydroxide solution

    In the present work, the effects of dissolved oxygen and hydrogen peroxide on corrosion potential have been studied on type 316L stainless steel in a hot lithium hydroxide solution. The results indicate that the corrosion potential will remain at around -850 mV vs SCE if the dissolved oxygen in the solution is controlled at a level of less than 10 ppb. However, 316L stainless steel will become completely passivated when about 650 ppb of oxygen exists in the solution. As a result, the corrosion potential of 316L steel will rise to around -400 mV vs SCE, and eventually, with longer immersion times, to even higher values, e.g. -300 mV vs SCE. However, the presence of less than 500 ppb H2O2 has no significant effect on the corrosion potential. A potential jump (from -850 to -500 mV vs SCE) is observed only when a large amount of H2O2, for instance 1 ppm, is present in the solution. Related to radiolysis of water and with potential-dependent stress corrosion cracking, the effects of dissolved oxygen and hydrogen peroxide on the corrosion potential of 316L stainless steel in the hot lithium hydroxide solution have been discussed. ((orig.))

  18. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Zhang, Litao; Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn

    2014-03-15

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  19. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Zhang, Litao; Wang, Jianqiu

    2014-03-01

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  20. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics

  1. Analysis of bi-layer oxide on austenitic stainless steel, 316L, exposed to Lead–Bismuth Eutectic (LBE) by X-ray Photoelectron Spectroscopy (XPS)

    Koury, D., E-mail: dan@physics.unlv.edu [Dept. of Physics and Astronomy, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Johnson, A.L. [Harry Reid Center, MS 4009, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Ho, T. [Dept. of Chemistry, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States); Farley, J.W. [Dept. of Physics and Astronomy, MS 4002, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 (United States)

    2013-09-15

    Corrosion of the austenitic stainless steel alloy 316L by Lead–Bismuth Eutectic (LBE) was studied using X-ray Photoelectron Spectroscopy (XPS) with Sputter-Depth Profiling (SDP), and compared to data taken by Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays (EDXs). Exposed and unexposed samples were compared. Annealed 316L samples, exposed to LBE for durations of 1000, 2000 and 3000 h, developed bi-layer oxides up to 30 μm thick. Analysis of the charge-states of the 2p{sub 3/2} peaks of iron, chromium, and nickel in the oxide layers reveal an inner layer consisting of iron and chromium oxides (likely spinel-structured) and an outer layer consisting of iron oxides (Fe{sub 3}O{sub 4}). Cold-rolled 316L samples, exposed for the same durations, form a chromium-rich, thin (⩽1 μm) oxide with some oxidized iron in the outermost ∼200 nm of the oxide layer. This is the first experiment to investigate what components of the 316L are oxidized by LBE exposure. It is shown here that nickel is metallic in the inner layer.

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

    Patiño Infante, Maritza

    2015-01-01

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

  3. Recubrimientos de 560 as producidos con el sistema de proyección térmica por arco

    Vélez Sánchez, Hernando

    2013-01-01

    Atendiendo la importancia en el desarrollo de nuevos recubrimientos para mejorar las propiedades de los materiales, en particular en las aplicaciones expuestas a desgaste abrasivo y corrosión, se ha estudiado el comportamiento del recubrimiento en acero inoxidable AS 560, similar a los aceros de la familia ASTM 420, aplicado sobre sustratos AISI/SAE 1045 y ASTM 316L, utilizando la técnica de rociado térmico por arco, orientado a la potencial recuperación dimensional de piezas u...

  4. Low-temperature aging of delta-ferrite in 316L SS welds. Changes in mechanical properties and etching properties

    Thermal aging embrittlement of LWR components made of stainless cast (e.g. CF-8 and CF-8M) is a potential degradation issue, and careful attention has been paid on it. Although welds of austenitic stainless steels (SSs) have γ-δ duplex microstructure, which is similar to that of the stainless cast, examination on thermal aging characteristics of the SS welds is very limited. In order to evaluate thermal aging behavior of weld metal of austenitic stainless steel, the 316L SS weld metal has been prepared and changes in mechanical properties and in etching properties at isothermal aging at 335degC have been investigated. The hardness of the ferrite phase has increased with aging, while the hardness of austenite phase has stayed same. It has been suggested that spinodal decomposition has occurred in δ-ferrite by the 335degC aging. The etching rates of δ-ferrite at immersion test in 5wt% hydrochloric acid solution have been also investigated using an AFM technique. The etching rate of ferrite phase has decreased consistently with the increase in hardness of ferrite phase. It has been thought that this characteristic is also caused by spinodal decomposition of ferrite into chromium-rich (α') and iron-rich (α). (author)

  5. Shielding gas effects on flux cored arc welding of AISI 316L (N) austenitic stainless steel joints

    Highlights: ► The effects of shielding gasses are analyzed. ► The impact strength increases with increasing of percentage of CO2 in shielding gas mixtures. ► The ferrite percentage decreases with increasing of percentage of CO2 in shielding gas mixtures. ► Microhardness values increases with increasing of ferrite percentage in the weld metal. -- Abstract: This paper deals with the flux cored arc welding (FCAW) of AISI 316L (N) austenitic stainless steel with 1.2 mm diameter of flux cored 316LT filler wire. The welding was carried out with different shielding gas mixtures like 100% Ar, 95% Ar + 05% CO2, 90% Ar + 10% CO2, 80% Ar + 20% CO2, 75% Ar + 23% CO2 + 2% O2 and 70% Ar + 25% CO2 + 5% O2 and 100% CO2. The main aim of the work is to study the effect of various shielding gas mixtures on mechanical properties and metallurgical characters. The microstructures and ferrite content of the welds were analyzed. The mechanical characteristics such as impact test, microhardness and ductility of welds were carried out. The fracture surface impact samples were analyzed through scanning electron microscope (SEM). The fracture surface revealed a ductile rupture at room temperature and ductile rupture with a few cleavages at lower temperatures occurred. The toughness and ferrite percentages of the welds were decreased for increase of the CO2 in shielding gas mixtures.

  6. Outboard first wall (AISI 316L) activation evaluations with different activation codes, neutron data libraries, and data processing

    This paper presents the main results of a benchmark exercise that has been set up in order to compare nuclear cross section data libraries and data processing techniques (123-group AMPX, VITAMI-C, and VITAMIN-J) and activation codes. (ANITA, ORIGEN and FISPACT-2) for activation evaluations in fusion field. The Torus outboard region of a fusion machine like NET-II/TTER has been considered, and the attention was focused on the first wall stainless steel AISI 316L. The update of the ORIGEN neutron Data library was obtained by collapsing the 100-group GREAC-ECN-5 Activation library with the flux-weighted spectrum provided by XSDRNPM-S code; this method allows the radioactivity inventory and the decay heat power evaluations to be done by the ORIGEN-S code. The test case has been used to verify the effect of the neutron power load and of the fluence on the isotope specific activity of the irradiated steel, too

  7. Radiation defects formed in ion-irradiated 316L stainless steel model alloys with different Si additions

    The 304/316 series of austenite stainless steels are used in light water reactors as structural materials. As a result of the high temperatures and neutron irradiation in reactor, dislocation defects will form in stainless steel, causing an increase in the hardness and a decrease in the ductility of the material. In this work, high purity 316L stainless steel model alloys with three different Si contents were ion irradiated at 290°C or 400°C to investigate the black dot and Frank loop formation mechanism influenced by Si addition. Black dot defect formation mainly occurs at 290°C. It is Frank loop in nature with its formation not affected by Si addition. Frank loop is the main defect at 400°C, and both loop density and the average size are substantially suppressed by Si addition. This may be caused by silicon’s role in enhancing effective vacancy diffusivity and thus promoting recombination. The trend of irradiation hardening measured verses temperature matches the microstructure observed. (author)

  8. Effect of thermal treatment on the corrosion resistance of Type 316L stainless steel exposed in supercritical water

    Jiao, Y.; Zheng, W.; Guzonas, D. A.; Cook, W. G.; Kish, J. R.

    2015-09-01

    There are still unknown aspects about the growth mechanism of oxide scales formed on candidate stainless steel fuel cladding materials during exposure in supercritical water (SCW) under the conditions relevant to the Canadian supercritical water-cooled reactor (SCWR). The tendency for intermetallic precipitates to form within the grains and on grain boundaries during prolonged exposure at high temperatures represents an unknown factor to corrosion resistance, since they tend to bind alloyed Cr. The objective of this study was to better understand the extent to which intermetallic precipitates affects the mode and extent of corrosion in SCW. Type 316L stainless steel, used as a model Fe-Cr-Ni-Mo alloy, was exposed to 25 MPa SCW at 550 °C for 500 h in a static autoclave for this purpose. Mechanically-abraded samples were tested in the mill-annealed (MA) and a thermally-treated (TT) condition. The thermal treatment was conducted at 815 °C for 1000 h to precipitate the carbide (M23C6), chi (χ), laves (η) and sigma (σ) phases. It was found that although relatively large intermetallic precipitates formed at the scale/alloy interface locally affected the oxide scale formation, their discontinuous formation did not affect the short-term overall apparent corrosion resistance.

  9. Effect of thermal treatment on the corrosion resistance of Type 316L stainless steel exposed in supercritical water

    There are still unknown aspects about the growth mechanism of oxide scales formed on candidate stainless steel fuel cladding materials during exposure in supercritical water (SCW) under the conditions relevant to the Canadian supercritical water-cooled reactor (SCWR). The tendency for intermetallic precipitates to form within the grains and on grain boundaries during prolonged exposure at high temperatures represents an unknown factor to corrosion resistance, since they tend to bind alloyed Cr. The objective of this study was to better understand the extent to which intermetallic precipitates affects the mode and extent of corrosion in SCW. Type 316L stainless steel, used as a model Fe–Cr–Ni–Mo alloy, was exposed to 25 MPa SCW at 550 °C for 500 h in a static autoclave for this purpose. Mechanically-abraded samples were tested in the mill-annealed (MA) and a thermally-treated (TT) condition. The thermal treatment was conducted at 815 °C for 1000 h to precipitate the carbide (M23C6), chi (χ), laves (η) and sigma (σ) phases. It was found that although relatively large intermetallic precipitates formed at the scale/alloy interface locally affected the oxide scale formation, their discontinuous formation did not affect the short-term overall apparent corrosion resistance

  10. Optimization of Process Parameters of Hybrid Laser-Arc Welding onto 316L Using Ensemble of Metamodels

    Zhou, Qi; Jiang, Ping; Shao, Xinyu; Gao, Zhongmei; Cao, Longchao; Yue, Chen; Li, Xiongbin

    2016-08-01

    Hybrid laser-arc welding (LAW) provides an effective way to overcome problems commonly encountered during either laser or arc welding such as brittle phase formation, cracking, and porosity. The process parameters of LAW have significant effects on the bead profile and hence the quality of joint. This paper proposes an optimization methodology by combining non-dominated sorting genetic algorithm (NSGA-II) and ensemble of metamodels (EMs) to address multi-objective process parameter optimization in LAW onto 316L. Firstly, Taguchi experimental design is adopted to generate the experimental samples. Secondly, the relationships between process parameters ( i.e., laser power ( P), welding current ( A), distance between laser and arc ( D), and welding speed ( V)) and the bead geometries are fitted using EMs. The comparative results show that the EMs can take advantage of the prediction ability of each stand-alone metamodel and thus decrease the risk of adopting inappropriate metamodels. Then, the NSGA-II is used to facilitate design space exploration. Besides, the main effects and contribution rates of process parameters on bead profile are analyzed. Eventually, the verification experiments of the obtained optima are carried out and compared with the un-optimized weld seam for bead geometries, weld appearances, and welding defects. Results illustrate that the proposed hybrid approach exhibits great capability of improving welding quality in LAW.

  11. Optimization of Process Parameters of Hybrid Laser-Arc Welding onto 316L Using Ensemble of Metamodels

    Zhou, Qi; Jiang, Ping; Shao, Xinyu; Gao, Zhongmei; Cao, Longchao; Yue, Chen; Li, Xiongbin

    2016-04-01

    Hybrid laser-arc welding (LAW) provides an effective way to overcome problems commonly encountered during either laser or arc welding such as brittle phase formation, cracking, and porosity. The process parameters of LAW have significant effects on the bead profile and hence the quality of joint. This paper proposes an optimization methodology by combining non-dominated sorting genetic algorithm (NSGA-II) and ensemble of metamodels (EMs) to address multi-objective process parameter optimization in LAW onto 316L. Firstly, Taguchi experimental design is adopted to generate the experimental samples. Secondly, the relationships between process parameters (i.e., laser power (P), welding current (A), distance between laser and arc (D), and welding speed (V)) and the bead geometries are fitted using EMs. The comparative results show that the EMs can take advantage of the prediction ability of each stand-alone metamodel and thus decrease the risk of adopting inappropriate metamodels. Then, the NSGA-II is used to facilitate design space exploration. Besides, the main effects and contribution rates of process parameters on bead profile are analyzed. Eventually, the verification experiments of the obtained optima are carried out and compared with the un-optimized weld seam for bead geometries, weld appearances, and welding defects. Results illustrate that the proposed hybrid approach exhibits great capability of improving welding quality in LAW.

  12. Effect of thermal treatment on the corrosion resistance of Type 316L stainless steel exposed in supercritical water

    Jiao, Y. [Department of Materials Science & Engineering, McMaster University, Hamilton, ON (Canada); Zheng, W. [CanmetMATERIALS, Natural Resources Canada, Hamilton, ON (Canada); Guzonas, D.A. [Canadian Nuclear Laboratories Chalk River Laboratories, ON (Canada); Cook, W.G. [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB (Canada); Kish, J.R., E-mail: kishjr@mcmaster.ca [Department of Materials Science & Engineering, McMaster University, Hamilton, ON (Canada)

    2015-09-15

    There are still unknown aspects about the growth mechanism of oxide scales formed on candidate stainless steel fuel cladding materials during exposure in supercritical water (SCW) under the conditions relevant to the Canadian supercritical water-cooled reactor (SCWR). The tendency for intermetallic precipitates to form within the grains and on grain boundaries during prolonged exposure at high temperatures represents an unknown factor to corrosion resistance, since they tend to bind alloyed Cr. The objective of this study was to better understand the extent to which intermetallic precipitates affects the mode and extent of corrosion in SCW. Type 316L stainless steel, used as a model Fe–Cr–Ni–Mo alloy, was exposed to 25 MPa SCW at 550 °C for 500 h in a static autoclave for this purpose. Mechanically-abraded samples were tested in the mill-annealed (MA) and a thermally-treated (TT) condition. The thermal treatment was conducted at 815 °C for 1000 h to precipitate the carbide (M{sub 23}C{sub 6}), chi (χ), laves (η) and sigma (σ) phases. It was found that although relatively large intermetallic precipitates formed at the scale/alloy interface locally affected the oxide scale formation, their discontinuous formation did not affect the short-term overall apparent corrosion resistance.

  13. The Effect of Post-Heat Treatment on Microstructure of 316L Cold-Sprayed Coatings and Their Corrosion Performance

    Dikici, B.; Yilmazer, H.; Ozdemir, I.; Isik, M.

    2016-04-01

    The combined effects of process gases and post-heat treatment temperature on the microstructure of 316L cold-sprayed coatings on Al5052 substrates have been investigated in this study. The stainless steel coatings were subjected to heat treatment at four different temperatures (250, 500, 750, and 1000 °C) to study the effect of heat treatment. In addition, the corrosion performances of the coatings at different process temperatures have been compared using the potentiodynamic scanning technique. Microstructural characterization of the coatings was carried out using scanning and transmission electron microscopy and x-ray diffraction. The results of present study showed that cold-sprayed stainless steel coatings processed with helium exhibited higher corrosion resistance than those of coatings sprayed with nitrogen process gas. This could partially be attributed to the reduction in porosity level (4.9%) and improvement of particle-particle bonding. In addition, evaluation of the mechanical and microstructural properties of the coatings demonstrated that subsequent heat treatment has major influence on the deposited layers sprayed with He process gas.

  14. Explosive welding method for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member

    Highlights: • Develop a new explosive welding method to fabricate the cooling channel of FW. • Utilize effective energy model to accurately calculate optimal welding parameters. • Provide an efficient way for manufacturing high-ductility hollow structural member. - Abstract: In this study, a new explosive welding method provided an effective way for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member. The welding parameters (stand-off distance and explosion rate) were calculated respectively using equivalent frontal collision wave model and effective energy model. The welded samples were subject to two step heat treatment cycles (solution annealing and aging). Optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to analyze the microstructure of bonding interface. The mechanical properties of the welded samples were evaluated through microhardness test and tensile test. Moreover, the sealing property of the welded specimens was measured through helium leak test. Microstructural analysis showed that the welded sample using effective energy model had an ideal wavy interface. The results of microhardness test revealed an increase in hardness for both sides near to the bonding interface. And the hardening phenomenon of interface region disappeared after the solution annealing. SEM observation indicated that the samples with the post heat treatments exhibited a ductile fracture with dimple features after tensile test. After the specimens undergo aging strengthening, there was an obvious increase in the strength for all specimens. The helium leak test results have proven that the welded specimens are soundness

  15. Creep properties and microstructures of helium implanted AISI 316L electron-beam weld and parent material

    Creep properties and microstructures of the ''as-received'' electron-beam welds and its parent material of the former Next European Torus (NET) reference material AISI 316L (now a candidate material for the International Thermonuclear Experimental Reactor (ITER) program) have been investigated at 873K as a function of applied stress and pre-implanted helium concentration. The results show that helium embrittlement effects are more serious in the parent material than in the welds. The creep properties of the welds are almost unaffected by helium concentrations below 300appm. Weld specimens with low helium concentrations (CHe23C6 etc.) and austenite during high temperature treatments. Preferential helium bubble sites are grain boundaries, δ-ferrite-matrix interfaces, incoherent parts of twin boundaries and disloactions. Quantitative helium bubble size and number distribution results indicate that in the matrix helium bubble sizes are lager but the bubble densities are lower than at boundaries or interfaces. With increasing helium concentration helium bubble densities at the different sites do not change much, while the sizes increase with slopes of about 0.3 in a power law fit. (orig.)

  16. Determination of the morphological textures of fibres in a composite material made from a textile of AISI 316L fibres

    The orientation distribution (morphological texture) of fibres in a composite is very important in determining the properties of the material. Therefore, methods which can provide quantitative descriptions of the morphological texture are essential. One approach to determining the morphological texture function (MTF) is to measure the orientation distribution of the crystals in the fibres. Since many types of fibres used for reinforcements are crystalline and textured (i.e. carbon fibres, steel fibres, etc.) this approach may be interesting for commercial/industrial applications. For this technique to be applied, the crystallographic texture intrinsic to the fibres must be determined and subsequently, measurements of the 'global' crystallographic texture should be made in the composite. The morphological texture can then be calculated by a deconvolution of the composite texture with the fibre's crystallographic texture. The deconvolution is most easily performed using the series expansion representation of texture functions. In this paper, the morphological texture was determined in a woven fabric made from bundle drawn AISI 316L stainless steel fibres embedded in an Al-13wt% Si alloy matrix. Straight fibres removed from the fabric serve as the reference material for the deconvolution. Neutron diffraction pole figures were used to determine the MTF's. (orig.)

  17. The Effect of Surface Finish on Low-Temperature Acetylene-Based Carburization of 316L Austenitic Stainless Steel

    Ge, Yindong; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

    2014-12-01

    We observed a strong influence of surface finish on the efficacy of low-temperature acetylene-based carburization of AISI 316L austenitic stainless steel. Steel coupons were prepared with different surface finishes prior to carburization, from P400 SiC grit paper to 1- µm-diameter-diamond-paste. The samples with the finer surface finish developed a thicker "case" (a carbon-rich hardened surface layer) and a larger surface carbon concentration. Transmission electron microscopy revealed that the differences arose mainly from the nature of the deformation-induced disturbed layer on the steel surface. A thick (>400 nm) disturbed layer consisting of nano-crystalline grains (≈10 nm diameter) inhibits acetylene-based carburization. The experimental observations can be explained by assuming that during machining or coarse polishing, the surface oxide layer is broken up and becomes incorporated into the deformation-induced disturbed layer. The incorporated oxide-rich films retard or completely prevent the ingress of carbon into the stainless steel.

  18. Microstructural Development and Technical Challenges in Laser Additive Manufacturing: Case Study with a 316L Industrial Part

    Marya, Manuel; Singh, Virendra; Marya, Surendar; Hascoet, Jean Yves

    2015-08-01

    Additive manufacturing (AM) brings disruptive changes to the ways parts, and products are designed, fabricated, tested, qualified, inspected, marketed, and sold. These changes introduce novel technical challenges and concerns arising from the maturity and diversity of today's AM processes, feedstock materials, and process parameter interactions. AM bears a resemblance with laser and electron beam welding in the so-called conduction mode, which involves a multitude of dynamic physical events between the projected feedstock and a moving heat source that eventually influence AM part properties. For this paper, an air vent was selected for its thin-walled, hollow, and variable cross section, and limited size. The studied air vents, randomly selected from a qualification batch, were fabricated out of 316L stainless steel using a 4 kW fiber laser powder-fed AM system, referred to as construction laser additive direct (CLAD). These were systematically characterized by microhardness indentation, visual examination, optical and scanning electron microscopy, and electron-back-scattering diffraction in order to determine AM part suitability for service and also broadly discuss metallurgical phenomena. The paper then briefly expands the discussion to include additional engineering alloys and further analyze relationships between AM process parameters and AM part properties, consistently utilizing past experience with the same powder-fed CLAD 3D printer, the well-established science and technology of welding and joining, and recent publications on additive manufacturing.

  19. Evaluation of Mid-IR Laser radiation effect on 316l stainless steel corrosion resistance in physiological saline

    The effects of a short pulsed (∼ 400 ns ) multi line hydrogen fluoride laser radiation operating on average at 2.8 μm has been studied on 316l stainless steel in terms of optical and physical parameters. At low fluences ≤ 8 Jcm-2 (phase l) no morphological changes occurred at the surface and melting began at ∼ 8.8 Jcm-2 (phase l l) which continued up to about 30 Jcm-2 . In this range the melting zone was effectively produced by high temperature surface centres growth which subsequently joined these centres together. Thermal ablation via surface vaporization began at ∼ 33 Jcm-2 (phase lll). The results of scanning electron microscopy evaluation and corrosion resistance experiment which was carried out using Eg and G device with cyclic potentiodynamic polarization method in a physiological (Hank's) solution indicated that pitting corrosion sensitivity was decreased i.e.. enhancement of corrosion resistance. Also, the x-ray diffraction results showed a double increase of γ (lll) at microstructure, thus in effect a super austenite stainless steel was obtained at an optimized melting fluence

  20. Preliminary studies of the welding zone of AISI 316L austenitic stainless steel capsules, for Cs137 sealed sources

    Currently, the treatment for cervix, endometrium and vaginal cancer, uses radioactive seeds, shaped like spheres, seeds or threads, with the brachytherapy technique. The brachytherapy sources are encased in surgical grade stainless steel cylinders. This geometry aims to contain the radioactive material, by providing safe barriers, thereby reducing other undesirable radiations from the radioisotopes during their disintegration and by providing rigidity to the source. The properties of the stainless steels are greatly influenced by their chemical composition, which also determines the microstructural characteristics of these alloys. AISI 316L steel is one of the raw materials used most frequently for surgical use, due to its stability and inert character when in contact with the human organism. Small stainless steel cylindrical capsules (about 10 mm long, 2mm diameter) were prepared for this work, with caps welded at both ends using the TIG process, producing an airtight closure. The welds are described by cut, surface, grain-revealing chemical attack, and chemical analysis using dispersive energy spectroscopy and metallographic analysis. Vickers hardness measurements are also presented in the zones affected by the welding. The dendritic-granular interface of the welded stainless matrix under the TIG process, shows resistance to corrosion from human plasma at 36.5oC

  1. Modelling hydrogen embrittlement in 316L austenitic stainless steel for the first wall of the Next European Torus

    This paper presents the final results of the work which the authors have been performing for the European Fusion Technology Programme (the NET Team). The contribution deals with the modelling of hydrogen embrittlement in AISI type 316L solution-annealed austenitic stainless steel, to be used for the first wall of NET (Next European Torus). Numerical modelling of hydrogen diffusion in the samples was performed on the basis of a set of non-conventional diffusion equations, in which hydrogen diffuses not only to the points of minimum concentration, but also towards those places of maximum hydrostatic stress. The diffusion computer program was coupled with an elastic-plastic finite element program to allow the calculation of both the stress state and the distribution of hydrogen concentration at the sample points step by step. Hydrogen penetration rates due to diffusion were extremely low in the unaltered material, even under mechanical loading. However, a clear loss of load bearing capacity of the notched specimens in hydrogen environment was observed even for extremely short tests. A possible explanation is that hydrogen embrittlement might not be associated with bulk diffusion through the specimen (there was not enough time for this) but rather with a localized degrading action, due to hydrogen, on the area surrounding the notch. In particular, hydrogen enhanced multi-cracking is a possibility which must be taken into account. (orig.)

  2. Creep fatigue interaction. Hold time effects on low cycle fatigue resistance of 316 L steel at 6000C

    This is a study of hold time effects on the low cycle fatigue properties of 316 L austenitic stainless steel at 6000C in air. Results obtained for different plastic strain levels indicate that a tension hold time at peak strain lead to a reduction in fatigue life. The importance of this effect depend on the length of hold period, and also on the strain amplitude. No saturation had been observed. Metallographic and microstructural analysis of failed specimens indicates mechanisms by which failure is produced. For continuous cycling the fracture occurs by the initiation and the propagation of a transgranular crack. Creep damage in the bulk of material is formed during periods of tensile stress relaxation; it causes a change in the failure mode which became intergranular. It is the interaction between this creep-damage and fatigue cracks which is partly responsable for the reduction in the fatigue life. Several approaches are used for evaluating creep-fatigue interaction damage and estimating the fatigue life. Among those proposed approaches, the linear damage rule and the strain range partitioning method are discussed

  3. Investigations of a type 316L steam dryer plate material suffering from IGSCC after few years in BWRs

    A steam dryer plate material suffered from intergranular stress corrosion cracking after only one and two years of operation in two BWR plants. Numerous indications were observed on the inner roof plates of the steam dryers adjacent to the support beam welds. The material was Type 316L austenitic stainless steel with carbon content below 0.02%. The material was subjected to detailed investigations using optical microscopy, EBSD/SEM, TEM, hardness and nano-indentation. The material showed macro-segregation through the plate thickness. These bands coincided with the location of delta-ferrite islands indicating non-optimal solution heat treatment. α'-martensite was observed deep in the plate indicating cold deformation after solution annealing. A nonhomogeneous distribution of grain orientation was also observed through the plate thickness. Further, surface deformation, although not extending very deep, was observed using EBSD and surface hardness values above 300 HV when measured using small loads. Although the material fulfills the set requirements, the material characteristics have obviously increased the susceptibility of the material to IGSCC. The paper will discuss the possible role of changes in manufacturing over the years and the challenges in quality definitions in material specifications. (authors)

  4. Effect of strain-induced martensite on the formation of nanocrystalline 316L stainless steel after cold rolling and annealing

    Eskandari, M.; Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kermanpur, A., E-mail: ahmad_k@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-08-30

    This work aimed to study the effects of cold rolling temperature and pre-strain on the volume fraction of strain-induced martensite in order to obtain nanocrystalline structures of 316L stainless steel. Hot rolling and cold rolling followed by annealing treatments were conducted under different conditions. The microstructures and the volume fraction of phases were characterized by scanning electron microscopy and feritscope tests, respectively. The hardness and tensile properties of the specimens were also measured. The results showed that decreasing the rolling temperature while increasing pre-strain leads to increased the volume fraction of martensite accompanied by decreased saturating strain and, further, that this behavior affects the degree of grain refinement. The smallest grain size of about 30-40 nm was obtained via 30% pre-strain at 523 K and subsequent conventional cold rolling at 258 K with a strain and a strain rate of 95% and 0.5 s{sup -1}, respectively, followed by annealing at 1023 K for 300 s. Uniaxial tensile tests at room temperature showed that this specimen exhibits very high tensile strength of about 1385 MPa.

  5. Biocompatibility studies of low temperature nitrided and collagen-I coated AISI 316L austenitic stainless steel.

    Martinesi, M; Stio, M; Treves, C; Borgioli, F

    2013-06-01

    The biocompatibility of austenitic stainless steels can be improved by means of surface engineering techniques. In the present research it was investigated if low temperature nitrided AISI 316L austenitic stainless steel may be a suitable substrate for bioactive protein coating consisting of collagen-I. The biocompatibility of surface modified alloy was studied using as experimental model endothelial cells (human umbilical vein endothelial cells) in culture. Low temperature nitriding produces modified surface layers consisting mainly of S phase, the supersaturated interstitial solid solution of nitrogen in the austenite lattice, which allows to enhance surface microhardness and corrosion resistance in PBS solution. The nitriding treatment seems to promote the coating with collagen-I, without chemical coupling agents, in respect of the untreated alloy. For biocompatibility studies, proliferation, lactate dehydrogenase levels and secretion of two metalloproteinases (MMP-2 and MMP-9) were determined. Experimental results suggest that the collagen protection may be favourable for endothelial cell proliferation and for the control of MMP-2 release. PMID:23471501

  6. TEM study of the nucleation of bubbles induced by He implantation in 316L industrial austenitic stainless steel

    Jublot-Leclerc, S.; Lescoat, M.-L.; Fortuna, F.; Legras, L.; Li, X.; Gentils, A.

    2015-11-01

    10 keV He ions were implanted in-situ in a TEM into thin foils of 316L industrial austenitic stainless steel at temperatures ranging from 200 to 550 °C. As a result, overpressurized nanometric bubbles are created with density and size depending strongly on both the temperature and fluence of implantation. An investigation on their nucleation and growth is reported through a rigorous statistical analysis whose procedure, including the consideration of free surface effects, is detailed. In the parameter range considered, the results show that an increase of fluence promotes both the nucleation and growth of the bubbles whilst an increase of temperature enhances the growth of the bubbles at the expense of their nucleation. The confrontation of resulting activation energies with existing models for bubble nucleation enables the identification of the underlying mechanisms. In spite of slight differences resulting from different conditions of implantation among which the He concentration, He production rate and He/dpa ratio, it appears that the dominating mechanisms are the same as those obtained in metals in previous studies, which, in addition to corroborating literature results, shows the suitability of in-situ TEM experiments to simulate the production of helium in nuclear materials.

  7. Electrochemical and In Vitro Behavior of Nanostructure Sol-Gel Coated 316L Stainless Steel Incorporated with Rosemary Extract

    Motalebi, Abolfazl; Nasr-Esfahani, Mojtaba

    2013-06-01

    The corrosion resistance of AISI 316L stainless steel for biomedical applications, was significantly enhanced by means of hybrid organic-inorganic sol-gel thin films deposited by spin-coating. Thin films of less than 100 nm with different hybrid characters were obtained by incorporating rosemary extract as green corrosion inhibitor. The morphology, composition, and adhesion of hybrid sol-gel coatings have been examined by SEM, EDX, and pull-off test, respectively. Addition of high additive concentrations (0.1%) did not disorganize the sol-gel network. Direct pull-off test recorded a mean coating-substrate bonding strength larger than 21.2 MPa for the hybrid sol-gel coating. The effect of rosemary extract, with various added concentrations from 0.012 to 0.1%, on the anticorrosion properties of sol-gel films have been characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in simulated body fluid (SBF) solution and has been compared to the bare metal. Rosemary extract additions (0.05%) have significantly increased the corrosion protection of the sol-gel thin film to higher than 90%. The in vitro bioactivity of prepared films indicates that hydroxyapatite nuclei can form and grow on the surface of the doped sol-gel thin films. The present study shows that due to their excellent anticorrosion properties, bioactivity and bonding strength to substrate, doped sol-gel thin films are practical hybrid films in biomedical applications.

  8. Femtosecond laser treatment of 316L improves its surface nanoroughness and carbon content and promotes osseointegration: An in vitro evaluation.

    Kenar, Halime; Akman, Erhan; Kacar, Elif; Demir, Arif; Park, Haiwoong; Abdul-Khaliq, Hashim; Aktas, Cenk; Karaoz, Erdal

    2013-08-01

    Cell-material surface interaction plays a critical role in osseointegration of prosthetic implants used in orthopedic surgeries and dentistry. Different technical approaches exist to improve surface properties of such implants either by coating or by modification of their topography. Femtosecond laser treatment was used in this study to generate microspotted lines separated by 75, 125, or 175μm wide nanostructured interlines on stainless steel (316L) plates. The hydrophobicity and carbon content of the metallic surface were improved simultaneously through this method. In vitro testing of the laser treated plates revealed a significant improvement in adhesion of human endothelial cells and human bone marrow mesenchymal stem cells (hBM MSCs), the cells involved in microvessel and bone formation, respectively, and a significant decrease in fibroblast adhesion, which is implicated in osteolysis and aseptic loosening of prostheses. The hBM MSCs showed an increased bone formation rate on the laser treated plates under osteogenic conditions; the highest mineral deposition was obtained on the surface with 125μm interline distance (292±18mg/cm(2) vs. 228±43mg/cm(2) on untreated surface). Further in vivo testing of these laser treated surfaces in the native prosthetic implant niche would give a real insight into their effectiveness in improving osseointegration and their potential use in clinical applications. PMID:23563298

  9. Effect of strain-induced martensite on the formation of nanocrystalline 316L stainless steel after cold rolling and annealing

    This work aimed to study the effects of cold rolling temperature and pre-strain on the volume fraction of strain-induced martensite in order to obtain nanocrystalline structures of 316L stainless steel. Hot rolling and cold rolling followed by annealing treatments were conducted under different conditions. The microstructures and the volume fraction of phases were characterized by scanning electron microscopy and feritscope tests, respectively. The hardness and tensile properties of the specimens were also measured. The results showed that decreasing the rolling temperature while increasing pre-strain leads to increased the volume fraction of martensite accompanied by decreased saturating strain and, further, that this behavior affects the degree of grain refinement. The smallest grain size of about 30-40 nm was obtained via 30% pre-strain at 523 K and subsequent conventional cold rolling at 258 K with a strain and a strain rate of 95% and 0.5 s-1, respectively, followed by annealing at 1023 K for 300 s. Uniaxial tensile tests at room temperature showed that this specimen exhibits very high tensile strength of about 1385 MPa.

  10. Fundamental distribution of stress corrosion crack depth on Type 316L stainless steels induced by creviced bent beam test

    The creviced bent beam (CBB) test has been applied for many materials such as nickel base alloys and low carbon austenitic stainless steels. For sensitized austenitic stainless steels, fundamental distribution of crack depth induced by CBB tests was evaluated to establish SCC initiation model and lifetime prediction method. On the other hand, there are a few studies about distribution of crack depth on low carbon austenitic stainless steels. In this study, statistical analysis of crack depth was conducted in Type 316L stainless steels after CBB tests. The results are summarized as follows, (1) Distribution of grain boundary depth designated as distance from surface to triple point of grain boundary fit lognormal probability distribution and exponential probability distribution. (2) Distribution of crack depth approaches lognormal or exponential probability distribution with passage of test duration. Distribution of plastic strain on the specimen surface is not affect to type of crack depth distribution. (3) Inflection or bent point appears on the probability plot at depth of the median of grain boundary depth distribution. (4) Less than median of grain boundary depth, distribution of crack depth is identical to grain boundary depth distribution. More than median + standard deviation of grain boundary depth, crack depth distribution is described by the exponential distribution. (author)

  11. Numerical modeling of residual stresses generation due to 316L turning. A new experimental and numerical approach

    The main goal of this thesis proposed by AREVA NP is to predict the residual stresses induced by finishing turning of AISI 316L. The numerical model is simulating the residual stresses generation with a new approach by applying directly equivalent thermo-mechanical loadings onto the finished work piece surface without modeling the chip removal process. Thus, this study is divided in two complementary main subsections. On one hand, an experimental campaign is carried out to record data and to compute thermomechanical loadings. This task is made using the AREVA NP parameters. On the other hand numerical models are set up using previous measured values. They are made to reproduce the residual stresses generation by applying and moving the thermo mechanical loadings. The study leads to interesting results because the shapes of the residual stresses curves agree with previous works concerning this topic and with XRD measured residual stresses. The new approach seems to be pertinent because it is possible to simulate several tool passages like no other numerical model. (author)

  12. Sensitization behaviour of modified 316N and 316L stainless steel weld metals after complex annealing and stress relieving cycles

    Parvathavarthini, N. [Indira Gandhi Centre for Atomic Research, Corrosion Science and Technology Division, Materials Characterisation Group, Kalpakkam, Tamil Nadu 603 102 (India); Dayal, R.K. [Indira Gandhi Centre for Atomic Research, Corrosion Science and Technology Division, Materials Characterisation Group, Kalpakkam, Tamil Nadu 603 102 (India)]. E-mail: rkd@igcar.gov.in; Khatak, H.S. [Indira Gandhi Centre for Atomic Research, Corrosion Science and Technology Division, Materials Characterisation Group, Kalpakkam, Tamil Nadu 603 102 (India); Shankar, V. [Materials Technology Division, Materials Development Group, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102 Tamil Nadu (India); Shanmugam, V. [Materials Technology Division, Materials Development Group, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102 Tamil Nadu (India)

    2006-09-01

    Sensitization behaviour of austenitic stainless steel weld metals prepared using indigenously developed modified 316N (C = 0.05%; N = 0.12%) and 316L (C = 0.02%; N = 0.07%) electrodes was studied. Detailed optical and scanning electron microscopic examination was carried out to understand the microstructural changes occurring in the weld metal during isothermal exposure at various temperatures ranging from 500 deg. C to 850 deg. C (773-1123 K). Based on these studies the mechanism of sensitization in the austenite-ferrite weld metal has been explained. Time-temperature-sensitization (TTS) diagrams were established using ASTM A262 Practice E test. From the TTS diagrams, critical cooling rate (CCR) above which there is no risk of sensitization was calculated for both materials. The heating/cooling rates to be followed for avoiding sensitization during heat treatment cycles consisting of solution-annealing and stress-relieving in fabrication of welded components of AISI 316LN stainless steel (SS) were estimated taking into account the soaking time and the number of times the component undergoes thermal excursions in the sensitization regime. The results were validated by performing controlled heating and cooling heat treatment trials on welded specimens.

  13. Sensitization behaviour of modified 316N and 316L stainless steel weld metals after complex annealing and stress relieving cycles

    Sensitization behaviour of austenitic stainless steel weld metals prepared using indigenously developed modified 316N (C = 0.05%; N = 0.12%) and 316L (C = 0.02%; N = 0.07%) electrodes was studied. Detailed optical and scanning electron microscopic examination was carried out to understand the microstructural changes occurring in the weld metal during isothermal exposure at various temperatures ranging from 500 deg. C to 850 deg. C (773-1123 K). Based on these studies the mechanism of sensitization in the austenite-ferrite weld metal has been explained. Time-temperature-sensitization (TTS) diagrams were established using ASTM A262 Practice E test. From the TTS diagrams, critical cooling rate (CCR) above which there is no risk of sensitization was calculated for both materials. The heating/cooling rates to be followed for avoiding sensitization during heat treatment cycles consisting of solution-annealing and stress-relieving in fabrication of welded components of AISI 316LN stainless steel (SS) were estimated taking into account the soaking time and the number of times the component undergoes thermal excursions in the sensitization regime. The results were validated by performing controlled heating and cooling heat treatment trials on welded specimens

  14. In situ monitoring the pulse CO2 laser interaction with 316-L stainless steel using acoustical signals and plasma analysis

    In most laser material processing, material removal by different mechanisms is involved. Here, application of acoustic signals with thermoelastic (below threshold) and breakdown origin (above threshold) together with plasma plume analysis as a simple monitoring system of interaction process is suggested. In this research the interaction of pulse CO2 laser with 200 ns duration and maximum energy of 1.3 J operating at 1 Hz with austenitic stainless steel (316-L) is reported. The results showed that the non-linear point of the curve can serve as a useful indicator of melting fluence threshold (in this case ∼830 J cm-2) with corresponding temperature calculated using plasma plume analysis. Higher acoustic amplitudes and larger plasma plume volume indicates more intense interaction. Also, analysis showed that a phase explosion process with material removal (ejecta) in the form of non-adiabatic (i.e., dt >> α-1) is at play after laser pulse is ended. Also, SEM photographs show different surface quality medication at different laser intensities, which indicates the importance of recoil momentum pressure and possibly electrons and ions densities in heat transfer. Finally, electrochemical test indicate an improved corrosion resistance for laser treated samples compared to untreated ones.

  15. Microstructural Variations Across a Dissimilar 316L Austenitic: 9Cr Reduced Activation Ferritic Martensitic Steel Weld Joint

    Thomas Paul, V.; Karthikeyan, T.; Dasgupta, Arup; Sudha, C.; Hajra, R. N.; Albert, S. K.; Saroja, S.; Jayakumar, T.

    2016-03-01

    This paper discuss the microstructural variations across a dissimilar weld joint between SS316 and 9Cr-RAFM steel and its modifications on post weld heat treatments (PWHT). Detailed characterization showed a mixed microstructure of austenite and martensite in the weld which is in agreement with the phases predicted using Schaeffler diagram based on composition measurements. The presence of very low volume fraction of δ-ferrite in SS316L has been identified employing state of the art electron back-scattered diffraction technique. PWHT of the ferritic steel did not reduce the hardness in the weld metal. Thermal exposure at 973 K (700 °C) showed a progressive reduction in hardness of weld joint with duration of treatment except in austenitic base metal. However, diffusion annealing at 1073 K (800 °C) for 100 hours resulted in an unexpected increase in hardness of weld metal, which is a manifestation of the dilution effects and enrichment of Ni on the transformation characteristics of the weld zone. Migration of carbon from ferritic steel aided the precipitation of fine carbides in the austenitic base metal on annealing at 973 K (700 °C); but enhanced diffusion at 1073 K (880 °C) resulted in coarsening of carbides and thereby reduction of hardness.

  16. Dynamic strain aging in stress controlled creep-fatigue tests of 316L stainless steel under different loading conditions

    Stress controlled fatigue-creep tests were carried out for 316L stainless steel under different loading conditions, i.e. different loading levels at the fixed temperature (loading condition 1, LC1) and different temperatures at the fixed loading level (loading condition 2, LC2). Cyclic deformation behaviors were investigated with respect to the evolutions of strain amplitude and mean strain. Abrupt mean strain jumps were found during cyclic deformation, which was in response to the dynamic strain aging effect. Moreover, as to LC1, when the minimum stress is negative at 550 deg. C, abrupt mean strain jumps occur at the early stage of cyclic deformation and there are many jumps during the whole process. While the minimum stress is positive, mean strain only jumps once at the end of deformation. Similar results were also found in LC2, when the loading level is fixed at -100 to 385 MPa, at higher temperatures (560, 575 deg. C), abrupt mean strain jumps occur at the early stage of cyclic deformation and there are many jumps during the whole process. While at lower temperature (540 deg. C), mean strain only jumps once at the end of deformation.

  17. Characterization of aluminide coatings formed on 1.4914 and 316L steels by hot-dipping in molten aluminium

    Protective coatings are commonly used to extend the life of alloys in oxidation, corrosion or erosion environments encountered in various industrial fields. For example, in the fusion nuclear technology area, coatings applied to the surface of structural materials have to be developed because of the use of the liquid alloy Pb-17Li as a tritium breeder material and a coolant in future reactors. In this specific case, it is necessary to protect the steel containment from liquid metal corrosion and to prevent the loss of tritium from the coolant by diffusion/permeation through steel or elevated temperatures. Greater success has been reported for intermetallic coatings as aluminides which form protective aluminium oxide scales on steel surface. Therefore, the purpose of this work is to study aluminide coatings produced on steel substrate by hot-dipping in molten aluminium. In the present paper, 1.4914 martensitic steel and 316L austenitic stainless steel (materials suggested as structural steels for the future blanket of fusion reactors) have been studied. Some tests have also been carried out with pure metals as iron, nickel and chromium. The chemical composition, structure and growth properties of intermetallic layers formed during the interaction of materials with liquid aluminium are presented and compared

  18. Influence of the cutting parameters on flank wear of coated inserts during turning of AISI 316L

    Yusimit Zamora Hernández

    2015-03-01

    Full Text Available (Received: 2015/01/20 - Accepted: 2015/03/25The continuous improvement of manufacturing processes is critical to achieve optimum levels of productivity, quality and cut production of components and products. This research aims to determine the cutting tool flank wearing progression, during a high speed dry turning, for AISI 316L steel parts. Experimental data were acquired using two cutting feed levels, two material levels, three cutting speeds, and four principal cutting times. A scanning electron microscope (SEM was used to measure and analyze the wear of the cutting tools. Results were compared using analysis of variance and multiple regression for describing the relation between the variables used in the study. The analysis showed that the three layers coating insert did not exceed the end of life wearing criterion, while the one layer insert suffered a catastrophic wearing at the highest cutting speed. It was found that a relation exists between the experimental data and the predicted values for flank wear with a general average error of 4.1182%.

  19. Hydrogen effects on the passive film formation and pitting susceptibility of nitrogen containing type 316L stainless steels

    The effects of hydrogen on the passivity and pitting susceptibility of type 316L stainless steels have been investigated with alloys containing different nitrogen contents (0.015, 0.198 and 0.556 wt.% N). The study revealed that electrochemically pre-charged hydrogen significantly reduced the pitting resistance of alloys conatining 0.015 and 0.198 wt.% nitrogen contents. In alloy with highest nitrogen content (0.556 wt.% N), an increase in the passive film current density with hydrogen was observed without affecting breakdown potential. Auger electron spectroscopy (AES) analysis of the passive film indicated the presence of nitrogen in the passive film. On other hand, for hydrogen charged samples, nitrogen was found to be significantly less in the passive film. In Electrochemical impedance spectroscopy (EIS) measurement, the decrease in semi-circle radius of Nyquist plot, and the polarization resistance, R P associated with the resistance of the passive film was observed with hydrogen, indicating that hydrogen decreased the stability of the passive film. The present investigation indicated that precharged hydrogen deteriorated the passive film stability and pitting corrosion resistance in these alloys, and the increase in nitrogen content of the alloy offsets the deleterious effect of precharged hydrogen

  20. Stress corrosion cracking and corrosion fatigue on 316L stainless steel in boric acid concentrated media at 320 C

    Stress Corrosion Cracking (SCC) and Corrosion-Fatigue (CF) tests were performed in autoclave at 320 C in concentrated boric acid chlorinated media in presence of oxygen or hydrogen on type 316L austenitic stainless steel. Crack Growth Rates (CGR) are higher in non deaerated solutions for both SCC and CF than in hydrogenated solutions. CGR are relatively similar in CF and in SCC, excepted for high load ratio in CF where CGR are higher than in SCC. Detailed analysis of the fracture surface shows some distinct features between SCC and CF. Intergranular and transgranular mode of fracture are observed on SCC and CF. Fracture modes depend on the chemistry of solution in SCC and on frequency in CF. Traces of slip bands and crack front marking associated with oxide scale present on fracture surfaces exist in SCC and CF. Fatigue striations appear for low load ratio and high frequency. Secondary intergranular and transgranular cracking is observed only on SCC fracture surfaces and ligament morphology can be different in SCC relative to FC

  1. Effect of the hydrogen peroxide formed in tritiated water on the behavior of 316L stainless steel

    The tritiated water used (at a concentration of 20 mg cm-3) contains radiolytic hydrogen peroxide and dissolved oxygen. In the plants for the reprocessing of this water, the pH necessarily has various values, and consequently we used two different pH, 4 and 11, in our studies. The free corrosion potential of the stainless steel, as well as the redox potential of the tritiated water taken immediately from stock are in the transpassive region. This results from the concentrations of the dissolved radiolytic species. If these are decomposed in the voltametric scans, these potentials shift to the prepassive region. This will show the importance of the concentration of radiolytic H2O2 on the corrosion of 316L stainless steel. Scanning electron microscope examinations show, that at the free corrosion potential of the steel located in transpassive region, small cracks are formed over all of the oxidized surface. Pits and cavities are also found, the latter tend to be located on the grain boundaries. ((orig.))

  2. Generation of hydroxyl radicals by sonochemistry: Effects on the electrochemical behaviour of a 316L stainless steel

    Research highlights: → Presence of water sonolysis products (OH·, H2O2 and H2) in diffusion layer affect electrochemical behaviour of SS. → OCP jump is more abrupt with thinner diffusion layer. → Current densities increase under ultrasonic irradiation. → Cavitation activity grows with gas solubility and leads to an increase of sonolysis products. → Growth of concentration of sonolysis products yields to an increase of current densities values. - Abstract: In this study, water radiolysis occurring in nuclear power plants was simulated by sonochemistry. Generated hydroxyl radicals can recombine in others species such as H2O2 and H2. It is shown that solution conductivity is an important parameter on the evolution of open circuit potential due to the thickness variation of the diffusion layer which may contain sonolysed species (OH·, H2, H2O2) in different concentrations. Dissolved gases have also an impact on the 316L electrochemical behaviour. Increase of gas solubility leads to cavitation activity enhancement and further hydroxyl radical production. The latter leads to increased current density values under irradiation.

  3. Hydrogen diffusion and solution at high temperatures in 316L stainless steel and nickel-base heat-resistant alloys

    Hydrogen-permeation behaviors of 316L stainless steel, Inconel 600, Inconel 750, Nimonic 80A and Hastelloy X at 873 K-1173 K have been investigated under a pressure range of 0.1 MPa-0.7 MPa by using a gas-flow system. Measurements have been carried out by use of a helium-carrier-gas method. It has been proved that this method is good for examining transient-permeation behaviors as well as steady-state permeation if the instrumental time-lag is taken into account. Diffusivity and solubility of hydrogen for the alloys are derived from the transient and steady-state permeation. The γ'-precipitation strengthened alloys - Inconel 750 and Nimonic 80A - show a larger activation energy of diffusion and a smaller solution heat than the other nickel-base alloys. This result is ascribed to the trapping effect due to titanium in the former alloys, i.e. solute titanium atoms and/or γ'-precipitations. (orig.)

  4. Enzymatic mechanism in low chloride media: influence of glucose oxidase on the electrochemical behaviour of AISI 316L stainless steel

    The open circuit potential (OCP) of stainless steels immersed in natural waters generally increases with time. This phenomenon is strongly linked to the formation of a bio-film on the surface. Several studies have proved that the bio-film modifies the reaction of reduction of dissolved oxygen and that it acts mainly on the cathodic processes. One of the hypotheses explaining the action of the bio-film involves certain bacteria which use dissolved oxygen and extracellular enzymes to produce reactive oxygen species. Among this kind of metabolites is hydrogen peroxide H2O2. This compound interacts with the passive layer of stainless steels and affects their electrochemical behaviour, even when the chloride concentration is low. The aim of this work is to study the influence of an enzymatic reaction (of the oxidoreductase type) on anodic and cathodic processes on AISI 316L stainless steel. Experiments are carried out in two artificial electrolytes simulating natural fresh waters, with two different chloride concentrations. The role of enzymatically-produced hydrogen peroxide is shown by OCP measurements and volt-amperometric methods. (authors)

  5. Hydrogen absorption associated with the corrosion mechanism of 316L stainless steels in primary medium of Pressurized Water Reactor (PWR)

    Highlights: • Samples of stainless steel were oxidized in isotopically labelled primary water. • Hydrogen and oxygen diffusion in the oxide layer were studied. • A mechanism for the inner oxide growth in primary water is proposed. • The proposed mechanism links the hydrogen absorption and oxidation processes. - Abstract: Samples of 316L were exposed at 325 °C to PWR primary water labelled with deuterium and oxygen 18. The SIMS and GD-OES analysis has revealed the presence of deuterium in the internal oxide layer and in the underlying alloy. Two-stage corrosion experiments have shown that the oxygen and hydrogen transport in the oxide layer is not coupled and that the short-circuit diffusion coefficient of 18O in the oxide scale: Dsc = (9 ± 1)·10−17 cm2 s−1. These results are used to propose a mechanism describing the anionic growth of the protective oxide layer and the concomitant adsorption of hydrogen in the alloy

  6. Characterization of hydroxyapatite coating by pulse laser deposition technique on stainless steel 316 L by varying laser energy

    Highlights: ► Hydroxyapatite coating was successfully deposited on stainless steel substrate by pulse laser deposition at different energy levels (i.e. 300 mJ and 500 mJ, respectively). ► Variation in laser energy affects the surface characteristic of hydroxyapatite coating (particle size, surface roughness, uniformity, Ca/P ratio). ► Laser energy between 300 mJ and 500 mJ is the optimal choice for obtaining ideal Ca/P ratio. - Abstract: Hydroxyapatite is an attractive biomaterial mainly used in bone and tooth implants because it closely resembles human tooth and bone mineral and has proven to be biologically compatible with these tissues. In spite of this advantage of hydroxyapatite it has also certain limitation like inferior mechanical properties which do not make it suitable for long term load bearing applications; hence a lot of research is going on in the development of hydroxyapatite coating over various metallic implants. These metallic implants have good biocompatibility and mechanical properties. The aim of the present work is to deposit hydroxyapatite coating over stainless steel grade 316 L by pulse laser deposition technique by varying laser energy. To know the effect of this variation, the coatings were than characterized in detail by X-ray diffraction, finite emission-scanning electron microscope, atomic force microscope and energy dispersive X-ray spectroscopy.

  7. Effects of Hydrogen Gas Environment on Fatigue Strength at 107 cycles in Plain Specimen of Type 316L Stainless Steel

    Kawamoto, Kyohei; Ochi, Kazuhiko; Oda, Yasuji; Noguchi, Hiroshi

    In order to clarify the hydrogen effect on the fatigue strength at 107 cycles in a plain specimen of type 316L austenitic stainless steel, rotating bending fatigue tests in laboratory air and plane bending fatigue tests in 1.0 MPa dry hydrogen gas and in air at 313 K were carried out. The main results obtained are as follows. The observed fatigue behavior showed that the fatigue strength at 107 cycles in both environments is determined by the non-propagation of a fatigue crack of the order of the grain size. Also, the strength at 107 cycles in hydrogen gas is slightly higher than that in air. In the region of high-cycle fatigue, the fatigue life in hydrogen gas is longer than that in air, which is mainly caused by the longer crack initiation life in hydrogen gas. The crack propagation life in hydrogen gas is shorter than that in air but has only a small ratio to the fatigue life in this region.

  8. Residual stress and microstructure evolution by manufacturing processes for welded pipe joint in austenitic stainless steel type 316L

    Stress corrosion cracking (SCC) has been observed near the heat affected zone (HAZ) of welded pipe joint made of austenitic stainless steel type 316L, even though sensitization is not observed. Therefore, It can be considered that the effect of residual stress on SCC is more important. In the joining process of pipes, butt-welding is conducted after machining. Residual stress is generated by both processes. In case of welding after machining, it can be considered that residual stress due to machining is changed by welding thermal cycle. In this study, residual stress and microstructure evolution due to manufacturing processes is investigated. Change of residual stress distribution caused by processing history is examined by X-ray diffraction method. Residual stress distribution has a local maximum stress in the middle temperature range of the HAZ caused by processing history. Hardness measurement result also has a local maximum hardness in the same range of the HAZ. By using FE-SEM/EBSD, it is clarified that microstructure shows recovery in the high temperature range of HAZ. Therefore, residual stress distribution is determined by microstructure evolution and superposition effect of processing history. In summary, not only any part of manufacturing processes such as welding or machining but also treating all processes as processing history of pipes are important to evaluate SCC. (author)

  9. In situ monitoring the pulse CO 2 laser interaction with 316-L stainless steel using acoustical signals and plasma analysis

    Khosroshahi, M. E.; pour, F. Anoosheh; Hadavi, M.; Mahmoodi, M.

    2010-10-01

    In most laser material processing, material removal by different mechanisms is involved. Here, application of acoustic signals with thermoelastic (below threshold) and breakdown origin (above threshold) together with plasma plume analysis as a simple monitoring system of interaction process is suggested. In this research the interaction of pulse CO 2 laser with 200 ns duration and maximum energy of 1.3 J operating at 1 Hz with austenitic stainless steel (316-L) is reported. The results showed that the non-linear point of the curve can serve as a useful indicator of melting fluence threshold (in this case ≈830 J cm -2) with corresponding temperature calculated using plasma plume analysis. Higher acoustic amplitudes and larger plasma plume volume indicates more intense interaction. Also, analysis showed that a phase explosion process with material removal (ejecta) in the form of non-adiabatic (i.e., dt ≫ α-1) is at play after laser pulse is ended. Also, SEM photographs show different surface quality medication at different laser intensities, which indicates the importance of recoil momentum pressure and possibly electrons and ions densities in heat transfer. Finally, electrochemical test indicate an improved corrosion resistance for laser treated samples compared to untreated ones.

  10. Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel

    Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

    2012-04-01

    Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

  11. Summary of recommended correlations for ITER-grade type 316L(N) for the ITER materials properties handbook

    Billone, M.C.; Pawel, J.E.

    1996-04-01

    The focus of this effort is the effects of irradiation on the ultimate tensile strengths (UTS), the yield strength (YS), the uniform elongation (UE), the total elongation (TE) and the reduction in area (RA) in the ITER-relevant temperature range of 100-400{degrees}C. For the purpose of this summary, data for European heats of 316 with 0.020.08 wt.% are referred to as E316L(N) data and grouped together. Other heats of 316 and Ti-modified 316 are also included in the data base. For irradiation and postirradiation-test temperatures in the range of 200-400{degrees}C, the common behavior of these heats of stainless steel is a yield strength approaching the ultimate tensile strength approaching 800 MPa, a uniform elongation approaching 0.3%, a total elongation approaching 3-9%, and a high (about 60%) reduction in area as the neutron damage approaches 10 dpa.

  12. Corrosion Behavior of V2AlC and Cr2AlC Compared with SS 316L in NaOH at Four Temperatures

    Rana A. Anaee

    2015-06-01

    Full Text Available This work involves the manufacturing of MAX phase materials include V2AlC and Cr2AlC using powder metallurgy as a new class of materials which characterized by regular crystals in lattice. Corrosion behavior of these materials was investigated by Potentiostat to estimate corrosion resistance and compared with the most resistant material represented by SS 316L. The experiments were carried out in 0.01N of NaOH solution at four temperatures in the range of 30–60oC. Polarization resistance values which calculated by Stern-Geary equation indicated that the MAX phase materials more resistant than SS 316L. Also cyclic polarization tests confirmed the resistivity of MAX phase materials through disappears of hysteresis loop.

  13. Super austenitic stainless steels - a promising replacement for the currently used type 316L stainless steel as the construction material for flue-gas desulphurization plant

    Rajendran, N.; Rajeswari, S. [University of Madras, Madras (India). Dept. of Analytical Chemistry

    1996-12-15

    Potentiodynamic anodic cyclic polarization experiments on type 316L stainless steel and 6Mo super austenitic stainless steels were carried out in simulated flue-gas desulphurization (FGD) environment in order to assess the localized corrosion resistance. The pitting corrosion resistance was higher in the case of the super austenitic stainless steel containing 6Mo and a higher amount of nitrogen. The accelerated leaching study conducted for the alloys showed that the super austenitic stainless steels have a little tendency for leaching of metal ions such as iron, chromium and nickel at different impressed potentials. This may be due to surface segregation of nitrogen as CrN, which would, in turn, enrich a chromium and molybdenum mixed oxide film and thus impede the release of metal ions. The present study indicates that the 6Mo super austenitics can be adopted as a promising replacement for the currently used type 316L stainless steel as the construction material for FGD plants.

  14. Plasma nitriding of AISI 304L and AISI 316L stainless steels: effect of time in the formation of S phase and the chromium nitrides

    Plasma nitriding can improve hardness and wear resistance of austenitic stainless steels without losses in corrosion resistance. This fact relies on a nitrided layer constituted only by S phase, without chromium nitrides precipitation. In this work, the effect of nitriding time on phases formed on nitrided layer was investigated in two austenitic stainless steels: AISI 304L e AISI 316L. The samples were nitrided at 420 deg C, using a mixture of 60 % N2 and 40% H2, during 5, 7 and 9 hours. It was noted that chromium nitrides were formed on samples of AISI 304L, nitrided for 7 e 9 hours, while all nitrided samples of AISI 316L showed only formation of S phase. The nitrided layers were characterized using optical microscope and x-ray diffraction. (author)

  15. The study of the laser parameters and environment variables effect on mechanical properties of high compact parts elaborated by selective laser melting 316L powder

    In this work, a systematic analysis of the main parameters for the selective laser melting (SLM) of a commercial stainless steel 316L powder was conducted to improve the mechanical properties and dimensional accuracy of the fabricated parts. First, the effects of the processing parameters, such as the laser beam scanning velocity, laser power, substrate condition and thickness of the powder layer, on the formation of single tracks for achieving a continuous melting and densification of the material were analysed. Then, the influence of the environmental conditions (gas nature) and of the preheating temperature on the density and dimensional accuracy of the parts was considered. The microstructural features of the SLM SS 316L parts were carefully observed to elucidate the melting-solidification mechanism and the thermal history, which are the basis of the manufacturing process. Finally, the mechanical properties of the corresponding material were also determined

  16. Study on stress corrosion of the zone affected by the AISI 316L steel heat under PWR reactor environment at 325 deg Celsius

    This paper evaluates the stress corrosion susceptibility of the HAZ (heat affected zone) of the AISI 316L stainless steel of a dissimilar welding done between the ASTM A-508 steel and the AISI 316L steel, using a nickel alloy, under a chemical environment similar to the PWR (Pressurized Water Reactor) nuclear reactor primary circuit. The nickel 82 and 182 alloys were used in the GTAW (Gas Tungsten Arc Welding) and SMAW (Shielded Metal Arc Welding) processes respectively. The test at slow deformation - SSRT (Slow Strain Rate Test) was applied, using a deformation rate of 3x10-7 s-1, at a temperature of 325 degree Celsius and pressure of 12.5 MPa. The susceptibility under tress corrosion evaluation was performed comparing the resistance limit, the total deformation and the fracture time obtained at the inert medium (nitrogen) and at the PWR medium. Also, the fracture surfaces were observed under a scanning electron microscope, verifying the fragile fracture regions

  17. The study of the laser parameters and environment variables effect on mechanical properties of high compact parts elaborated by selective laser melting 316L powder

    Zhang, Baicheng, E-mail: baicheng.zhang@utbm.fr; Dembinski, Lucas; Coddet, Christian

    2013-11-01

    In this work, a systematic analysis of the main parameters for the selective laser melting (SLM) of a commercial stainless steel 316L powder was conducted to improve the mechanical properties and dimensional accuracy of the fabricated parts. First, the effects of the processing parameters, such as the laser beam scanning velocity, laser power, substrate condition and thickness of the powder layer, on the formation of single tracks for achieving a continuous melting and densification of the material were analysed. Then, the influence of the environmental conditions (gas nature) and of the preheating temperature on the density and dimensional accuracy of the parts was considered. The microstructural features of the SLM SS 316L parts were carefully observed to elucidate the melting-solidification mechanism and the thermal history, which are the basis of the manufacturing process. Finally, the mechanical properties of the corresponding material were also determined.

  18. LOTION 3. Dynamic fracture toughness tests of AISI 316L, TIG and electron beam weld specimens irradiated at 315K. Final report PSM 2-2

    In he framework of the CEC-DGXII-Fusion NET Technology Programme, AISI 316L base material and TIG metal deposit and electron beam specimens have been irradiated at a temperature of about 350K, up to 5 dpa. Instrumented Charpy tests have been performed on irradiated and unirradiated specimens at room temperature.The fracture toughness has been calculated and irradiation hardening is observed. The TIG metal deposit and the electron beam weld show lower fracture toughness values

  19. The structural and bio-corrosion barrier performance of Mg-substituted fluorapatite coating on 316L stainless steel human body implant

    Sharifnabi, A., E-mail: sharifnabi@yahoo.com [Biomaterials Group, Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, 16844 (Iran, Islamic Republic of); Fathi, M.H. [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 8415683111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Eftekhari Yekta, B.; Hossainalipour, M. [Biomaterials Group, Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, 16844 (Iran, Islamic Republic of)

    2014-01-01

    In this study, Mg-substituted fluorapatite coatings were deposited on medical grade AISI 316L stainless steel via sol–gel dip coating method. Phase composition, crystallite size and degree of crystallinity of the obtained coatings were evaluated by X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy was also used to evaluate functional groups of the obtained coatings. The surface morphology and cross-section of the final coatings were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy was used to determine elemental chemical composition of the obtained coatings. In order to determine and compare the corrosion behavior of uncoated and Mg-substituted fluorapatite coated 316L stainless steel, electrochemical potentiodynamic polarization tests were performed in physiological solutions at 37 ± 1 °C. Moreover, the released metallic ions from uncoated and coated substrates were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) within 2 months of immersing in Ringer's solution at 36.5 ± 1 °C as an indication of biocompatibility. The results showed that fluoride and magnesium were successfully incorporated into apatite lattice structure and the prepared coatings were nanostructured with crystallinity of about 70%. Obtained coatings were totally crack-free and uniform and led to decrease in corrosion current densities of 316L stainless steel in physiological solutions. In addition, coated sample released much less ions such as Fe, Cr and Ni in physiological media. Therefore, it was concluded that Mg-substituted fluorapatite coatings could improve the corrosion resistance and biocompatibility of 316L stainless steel human body implants.

  20. Extrusions and intrusions in fatigued metals. Part 2. AFM and EBSD study of the early growth of extrusions and intrusions in 316L steel fatigued at room temperature

    Man, Jiří; Klapetek, P.; Man, O.; Weidner, A.; Obrtlík, Karel; Polák, Jaroslav

    2009-01-01

    Roč. 89, č. 16 (2009), s. 1337-1372. ISSN 1478-6435 R&D Projects: GA ČR GA106/06/1096; GA ČR GA101/07/1500; GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : 316L steel * fatigue * AFM Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.273, year: 2009

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

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

    2016-01-01

    This article investigates the effect of low-level ionizing radiation, namely X-rays, on the micro structural characteristics, resistance, and corrosion resistance of TIG-welded joints of AISI 304 austenitic stainless steel made using AISI 316L filler rods. The welds were made in two different environments: natural atmospheric conditions and a closed chamber filled with inert argon gas. The influence of different doses of radiation on the resistance and corrosion characteristics of the welds i...

  2. Multilayered Zr-C/a-C film on stainless steel 316L as bipolar plates for proton exchange membrane fuel cells

    Bi, Feifei; Peng, Linfa; Yi, Peiyun; Lai, Xinmin

    2016-05-01

    A multilayered zirconium-carbon/amorphous carbon (Zr-C/a-C) coating is synthesized by magnetron sputtering in order to improve the corrosion resistance and interfacial conductivity of stainless steel 316L (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). Zr-C/a-C film contains an outmost pure amorphous carbon layer and a sub zirconium containing carbon layer. Interfacial contact resistance (ICR) between carbon paper and coated SS316L decreases to 3.63 mΩ cm2 at 1.4 MPa. Potentiodynamic polarization results reveal that the corrosion potential of Zr-C/a-C coated sample is more positive than pure a-C coated sample and the current density is only 0.49 μA cm-2 at the cathode applied potential 0.6 V. Electrochemical impendence spectroscopy also indicates that multilayered Zr-C/a-C film coated SS316L has much higher charge transfer resistance than the bare sample. After potentiostatic polarization, ICR values are 3.92 mΩ cm2 and 3.82 mΩ cm2 in the simulated PEMFCs cathode and anode environment, respectively. Moreover, XPS analysis of the coated samples before and after potential holding tests shows little difference, which disclose the chemical stability of multilayered Zr-C/a-C film. Therefore, the multilayered Zr-C/a-C coating exhibits excellent performance in various aspects and is preferred for the application of stainless steel bipolar plates.

  3. Influences of Restaurant Waste Fats and Oils (RWFO) from Grease Trap as Binder on Rheological and Solvent Extraction Behavior in SS316L Metal Injection Molding

    Mohd Halim Irwan Ibrahim; Azriszul Mohd Amin; Rosli Asmawi; Najwa Mustafa

    2016-01-01

    This article deals with rheological and solvent extraction behavior of stainless steel 316L feedstocks using Restaurant Waste Fats and Oils (RWFO) from grease traps as binder components along with Polypropylene (PP) copolymer as a backbone binder. Optimal binder formulation and effect of solvent extraction variables on green compacts are being analyzed. Four binder formulations based on volumetric ratio/weight fraction between PP and RWFO being mixed with 60% volumetric powder loading of SS31...

  4. The structural and bio-corrosion barrier performance of Mg-substituted fluorapatite coating on 316L stainless steel human body implant

    In this study, Mg-substituted fluorapatite coatings were deposited on medical grade AISI 316L stainless steel via sol–gel dip coating method. Phase composition, crystallite size and degree of crystallinity of the obtained coatings were evaluated by X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy was also used to evaluate functional groups of the obtained coatings. The surface morphology and cross-section of the final coatings were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy was used to determine elemental chemical composition of the obtained coatings. In order to determine and compare the corrosion behavior of uncoated and Mg-substituted fluorapatite coated 316L stainless steel, electrochemical potentiodynamic polarization tests were performed in physiological solutions at 37 ± 1 °C. Moreover, the released metallic ions from uncoated and coated substrates were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) within 2 months of immersing in Ringer's solution at 36.5 ± 1 °C as an indication of biocompatibility. The results showed that fluoride and magnesium were successfully incorporated into apatite lattice structure and the prepared coatings were nanostructured with crystallinity of about 70%. Obtained coatings were totally crack-free and uniform and led to decrease in corrosion current densities of 316L stainless steel in physiological solutions. In addition, coated sample released much less ions such as Fe, Cr and Ni in physiological media. Therefore, it was concluded that Mg-substituted fluorapatite coatings could improve the corrosion resistance and biocompatibility of 316L stainless steel human body implants.

  5. Effect of temperature, chloride ions and sulfide ions on the electrochemical properties of 316L stainless steel in simulated cooling water

    2008-01-01

    The influence of temperature, chloride ions and sulfide ions on the anticorrosion behavior of 316L stainless steel in simulated cooling water was studied by electrochemical impedance spectroscopy and anodic polarization curves. The results show that the film resistance increases with the solution temperature but decreases after 8 days' immersion, which indicates that the film formed at higher temperature has inferior anticorrosion behavior; Chloride ions and sulfide ions have remarkable effects on the elect...

  6. A study of TaxC1-x coatings deposited on biomedical 316L stainless steel by radio-frequency magnetron sputtering

    In this paper, TaxC1-x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures (Ts) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that Ts could significantly change the microstructure of TaxC1-x coatings. When Ts was xC1-x coatings were in amorphous condition, whereas when Ts was ≥150 deg. C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15-25 nm (Ts = 300 deg. C). Atomic force microscope (AFM) results showed that with the increase of Ts, the root-mean-square (RMS) values of the TaxC1-x coatings decreased. The nano-indentation experiments indicated that the TaxC1-x coating deposited at 300 deg. C had a higher hardness and modulus. The scratch test results demonstrated that TaxC1-x coatings deposited above 150 deg. C exhibited good adhesion performance. Tribology tests results demonstrated that TaxC1-x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited TaxC1-x coatings. The platelet adhesion test results indicated that the TaxC1-x coatings deposited at Ts of 150 deg. C and 300 deg. C possessed better hemocompatibility than the coating deposited at Ts of 25 deg. C. Additionally, the hemocompatibility of the TaxC1-x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.

  7. ESTUDIO DE LA UNIÓN SOLDADA DISÍMIL DE UN ACERO INOXIDABLE SUPERDÚPLEX SAF 2507 CON UN ACERO HSLA API X-52.

    Mendoza Bravo, Ivan

    2012-01-01

    Las uniones soldadas disímiles (USD) han sido utilizadas en la industria química, petroquímica y en la conducción de hidrocarburos como una alternativa para solucionar problemas de corrosión o pérdida de propiedades mecánicas que experimenta un componente o sección de un equipo. Actualmente, la Industria Petrolera Nacional presenta problemas con una sección del ducto ascendente que se encuentra en la zona de marea y oleajes, por lo que está expuesta a medios salinos. Este ducto...

  8. Effect of Surface Condition and Heat Treatment on Corrosion of Type 316L Stainless Steel in a Mercury Thermal Convection Loop; FINAL

    Two thermal convection loops (TCLs) fabricated from 316L stainless steel and containing mercury and a variety of 316L coupons representing variable surface conditions and heat treatments have been operated continuously for 2000 h. Surface conditions included surface ground, polished, gold-coated, chemically etched, bombarded with Fe to simulate radiation damage, and oxidized. Heat treatments included solution treated, welded, and sensitized. In addition, a nitrogen doped 316L material, termed 316LN, was also examined in the solution treated condition. Duplicate TCLs were operated in this experiment-both were operated with a 305 C peak temperature, a 65 C temperature gradient, and mercury velocity of 1.2 m/min-but only one included a 36 h soak in Hg at 310 C just prior to operation to encourage wetting. Results indicate that the soak in Hg at 310 C had no lasting effect on wetting or compatibility with Hg. Further, based on examination of post-test wetting and coupon weight loss, only the gold-coated surfaces revealed significant interaction with Hg. In areas wetted significantly by Hg, the extreme surface of the stainless steel (ca 10(micro)m) was depleted in Ni and Cr compared to the bulk composition

  9. In vitro response of human peripheral blood mononuclear cells to AISI 316L austenitic stainless steel subjected to nitriding and collagen coating treatments.

    Stio, Maria; Martinesi, Maria; Treves, Cristina; Borgioli, Francesca

    2015-02-01

    Surface modification treatments can be used to improve the biocompatibility of austenitic stainless steels. In the present research two different modifications of AISI 316L stainless steel were considered, low temperature nitriding and collagen-I coating, applied as single treatment or in conjunction. Low temperature nitriding produced modified surface layers consisting mainly of S phase, which enhanced corrosion resistance in PBS solution. Biocompatibility was assessed using human peripheral blood mononuclear cells (PBMC) in culture. Proliferation, lactate dehydrogenase (LDH) levels, release of cytokines (TNF-α, IL-1β, IL-12, IL-10), secretion of metalloproteinase (MMP)-9 and its inhibitor TIMP-1, and the gelatinolytic activity of MMP-9 were determined. While the 48-h incubation of PBMC with all the sample types did not negatively influence cell proliferation, LDH and MMP-9 levels, suggesting therefore a good biocompatibility, the release of the pro-inflammatory cytokines was always remarkable when compared to that of control cells. However, in the presence of the nitrided and collagen coated samples, the release of the pro-inflammatory cytokine IL-1β decreased, while that of the anti-inflammatory cytokine IL-10 increased, in comparison with the untreated AISI 316L samples. Our results suggest that some biological parameters were ameliorated by these surface treatments of AISI 316L. PMID:25655502

  10. Corrosion and electrical properties of CrN- and TiN-coated 316L stainless steel used as bipolar plates for polymer electrolyte membrane fuel cells

    Cathode arc ion plating was applied to deposit CrN and TiN coating layers on stainless steel 316L (SS316L) to produce metallic bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs). The interfacial contact resistance between samples and carbon paper was measured and found to be 10 and 23 mΩ ∗ cm2 for TiN and CrN coating layer respectively under 150 N cm−2 compaction forces. The corrosion properties were investigated in the operating environments of PEMFC. While TiN coating layer was dissolved in the operating environments of PEMFC, the corrosion current density of 0.1 μA cm−2 was obtained for CrN coating layer at anodic condition and its protective efficiency was revealed as 99%. This analysis indicates that the improvement may be attributed to the extremely dense coating and the synergistic function of the CrN layered structure. - Highlights: ► CrN and TiN are deposited on the surface of SS316L by cathode arc ion plating. ► Coating layers of CrN and TiN lead to high electrical conductivity. ► CrN coating layer provides higher corrosion resistance than TiN coating layer

  11. Fabrication,property characterization and toughening mechanism of HA-ZrO2(CaO)/316L fibre composite biomaterials

    2008-01-01

    HA-ZrO2(CaO)/316L fibre composites were successfully fabricated with vacuum sintering method and their properties and toughening mechanism were studied. The results showed that HA-ZrO2(CaO)/316L fibre biocomposite having 20 vol% fibres had optimal comprehensive properties with bending strength, Young’s modulus, fracture toughness and relative density equal to 140.1 MPa, 117.8 GPa, 5.81 MPa·m1/2 and 87.1%, respectively. The research also addressed that different volume ratios of the composites led to different metallographic microstructures, and that metallographic morphologies change regularly with volume ratios of the composites. 316L fibres were distributed randomly and evenly in the composites and the integration circumstance of the two phases was very well since there were no obvious flaws or pores in the composites. Two toughening mechanisms including ZrO2 phase transformation toughening mechanism and fibre pulling-out toughening mechanism existed in the compsites with the latter being the main toughening mechanism.

  12. Vacuum brazing of OFE Copper-316L stainless steel transition joints without electroplating stainless steel part for application in particle accelerators

    Brazed transition Joints between OFE copper and type 316L austenitic stainless steel (SS) find extensive applications in particle accelerators all over the world. In contrast to excellent wettability of OFE copper, austenitic SS is well known for its poor wettability for BVAg-8 (72Ag/28Cu; melting point: 1052 K) braze filler metal (BFM). High surface wettability is believed to be necessary to drag molten BFM into the capillary gap between mating metallic surfaces. Therefore, the widely accepted practice for vacuum brazing of such transition joints involves electroplating of SS parts with nickel or copper to enhance its wettability. A recently concluded in-house study, involving Nb to Ni-plated 316L SS brazing, has demonstrated that satisfactory ingress of BFM into a capillary joint between two dissimilar metals is possible if the poor wettability of one of the mating surfaces is compensated by good wettability of its counterpart. In the light of these observations, the present study was undertaken to explicitly evaluate the requirement of electroplating the SS part for establishment of sound OFE copper-316L SS brazed joints suitable for service in ultra-high vacuum (UHV) of particle accelerators

  13. MC3T3-E1 cell response to stainless steel 316L with different surface treatments

    In the present study, stainless steel 316L samples with polishing, aluminum oxide blasting, and hydroxyapatite (HA) coating were prepared and characterized through a scanning electron microscope (SEM), optical interferometer (surface roughness, Sq), contact angle, surface composition and phase composition analyses. Osteoblast-like MC3T3-E1 cell adhesion on the samples was investigated by cell morphology using a SEM (4 h, 1 d, 3 d, 7 d), and cell proliferation was assessed by MTT method at 1 d, 3 d, and 7 d. In addition, adsorption of bovine serum albumin on the samples was evaluated at 1 h. The polished sample was smooth (Sq: 1.8 nm), and the blasted and HA coated samples were much rougher (Sq: 3.2 μm and 7.8 μm). Within 1 d of incubation, the HA coated samples showed the best cell morphology (e.g., flattened shape and complete spread), but there was no significant difference after 3 d and 7 d of incubation for all the samples. The absorbance value for the HA coated samples was the highest after 1 d and 3 d of incubation, indicating better cell viability. However, it reduced to the lowest value at 7 d. Protein adsorption on the HA coated samples was the highest at 1 h. The results indicate that rough stainless steel surface improves cell adhesion and morphology, and HA coating contributes to superior cell adhesion, but inhibits cell proliferation. - Highlights: • Rough stainless steel surface improves cell adhesion and proliferation. • HA coating results in superior cell morphology and cell attachment. • HA coating inhibits osteoblast cell proliferation after 7 d of incubation

  14. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S

  15. MC3T3-E1 cell response to stainless steel 316L with different surface treatments

    Zhang, Hongyu [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Han, Jianmin, E-mail: siyanghan@163.com [Dental Materials Laboratory, National Engineering Laboratory for Digital and Material Technology of Stomatology, Peking University School and Hospital of Stomatology, Beijing 100081 (China); Sun, Yulong [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Huang, Yongling [Jinghang Biomedicine Engineering Division, Beijing Institute of Aeronautical Material, Beijing 100095 (China); Zhou, Ming [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2015-11-01

    In the present study, stainless steel 316L samples with polishing, aluminum oxide blasting, and hydroxyapatite (HA) coating were prepared and characterized through a scanning electron microscope (SEM), optical interferometer (surface roughness, Sq), contact angle, surface composition and phase composition analyses. Osteoblast-like MC3T3-E1 cell adhesion on the samples was investigated by cell morphology using a SEM (4 h, 1 d, 3 d, 7 d), and cell proliferation was assessed by MTT method at 1 d, 3 d, and 7 d. In addition, adsorption of bovine serum albumin on the samples was evaluated at 1 h. The polished sample was smooth (Sq: 1.8 nm), and the blasted and HA coated samples were much rougher (Sq: 3.2 μm and 7.8 μm). Within 1 d of incubation, the HA coated samples showed the best cell morphology (e.g., flattened shape and complete spread), but there was no significant difference after 3 d and 7 d of incubation for all the samples. The absorbance value for the HA coated samples was the highest after 1 d and 3 d of incubation, indicating better cell viability. However, it reduced to the lowest value at 7 d. Protein adsorption on the HA coated samples was the highest at 1 h. The results indicate that rough stainless steel surface improves cell adhesion and morphology, and HA coating contributes to superior cell adhesion, but inhibits cell proliferation. - Highlights: • Rough stainless steel surface improves cell adhesion and proliferation. • HA coating results in superior cell morphology and cell attachment. • HA coating inhibits osteoblast cell proliferation after 7 d of incubation.

  16. Hydrogen effects on pitting corrosion and semiconducting properties of nitrogen-containing type 316L stainless steel

    The effects of hydrogen pre-charging on pitting corrosion resistance and semiconducting nature of passive film formed on two different nitrogen-containing type 316L stainless steel (0.076 and 0.086 wt% N) have been studied. Auger electron spectroscopy (AES) analysis of the alloys after passivation indicated weak nitrogen peak, but the presence of nitrogen and NH3/NH4+ was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The results of pitting corrosion in 0.5 M NaCl (pH ∼ 5.7) solution revealed that hydrogen increased the passive current density and significantly reduced the pitting resistance. In 0.3 M H3BO3 + 0.075 M Na2B4O7.10H2O (pH ∼ 8.45) solution, increase in passive current density without affecting the breakdown or transpassive potential was observed for both the alloys. Electrochemical impedance spectroscopy (EIS) measurement after hydrogen pre-charging showed decrease in semi-circle radius of Nyquist plot, and the polarization resistance, RP associated with the resistance of the passive film. The decrease was significant with increasing hydrogen-charging current density (-50 to -100 mA/cm2). The results of the capacitance measurement and Mott-Schottky plots revealed that passive films exhibit n-type and p-type semiconductivity films for both the uncharged and hydrogen charged specimens of the investigated alloys. Doping densities obtained from Mott-Schottky plots increased with hydrogen pre-charging. The overall results indicated that hydrogen pre-charging deteriorated the passive film stability and lowered pitting corrosion resistance. The effects of hydrogen pre-charging on pitting corrosion, passive film and semiconducting properties are discussed in light of the above results.

  17. Corrosion resistance improvement in Gas Tungsten Arc Welded 316L stainless steel joints through controlled preheat treatment

    Highlights: → Though the preheat treatment reduced the cooling rate, no sensitization occurred. → The delta ferrite content of welds reduced due to cooling retardment in welds. → Reduction in δ/γ boundaries was accompanied by decrement of passivation current. → Preheat treatment improved pitting resistance characteristics. → Increment of preheat temperature increased breakdown and repassivation potential. -- Abstract: In the present study, an attempt has been made to improve the corrosion characteristics of 316L stainless steel weldments through preheating at 450 oC and 650 oC. The infrared and Tungsten-Rhenium thermocouples were utilized to probe the cooling trend of heat affected zone (HAZ) and weld pool, respectively. X-ray diffraction (XRD) patterns, optical microscopy, electron microscopy, Energy Dispersion Spectroscopy (EDS) and ferritscope were also used to investigate the effect of preheating on microstructural characteristics within the weld and HAZ. Moreover, cyclic potentiodynamic test was carried out to evaluate the corrosion features of welds such as corrosion current, passivation current (IPP), breakdown potential (EB) and repassivation potential (Ere). Results revealed that preheating reduces the cooling rate of weld pool, accompanied by reduction of delta ferrite content of weldments. Moreover, it was observed that increment of preheat temperature improves corrosion behavior of weldments, including a lower passivation current and a more pitting resistance. These outcomes were mainly ascribed to decrease of austenite/delta ferrite interfaces as vulnerable sites to corrosion attacks, through preheat treatment. Observations showed no evidence of sensitization in preheated samples, which guaranteed the feasibility of suggested heat treatment.

  18. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    Wang, Jin, E-mail: wangjinustb@gmail.com [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Matsuda, Nozomu [Bar and Wire Product Unit, Nippon steel and Sumitomo Metal Corporation, Fukuoka, 802-8686 (Japan); Shinozaki, Nobuya [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Miyoshi, Noriko [The Center for Instrumental Analysis, Kyushu Institute of Technology, Fukuoka, 804-8550 (Japan); Shiraishi, Takanobu [Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588 (Japan)

    2015-02-01

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S.

  19. Evaluation of the soft tissue biocompatibility of MgCa0.8 and surgical steel 316L in vivo: a comparative study in rabbits

    Lucas Arne

    2010-10-01

    Full Text Available Abstract Background Recent studies have shown the potential suitability of magnesium alloys as biodegradable implants. The aim of the present study was to compare the soft tissue biocompatibility of MgCa0.8 and commonly used surgical steel in vivo. Methods A biodegradable magnesium calcium alloy (MgCa0.8 and surgical steel (S316L, as a control, were investigated. Screws of identical geometrical conformation were implanted into the tibiae of 40 rabbits for a postoperative follow up of two, four, six and eight weeks. The tibialis cranialis muscle was in direct vicinity of the screw head and thus embedded in paraffin and histologically and immunohistochemically assessed. Haematoxylin and eosin staining was performed to identify macrophages, giant cells and heterophil granulocytes as well as the extent of tissue fibrosis and necrosis. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection. Evaluation of all sections was performed by applying a semi-quantitative score. Results Clinically, both implant materials were tolerated well. Histology revealed that a layer of fibrous tissue had formed between implant and overlying muscle in MgCa0.8 and S316L, which was demarcated by a layer of synoviocyte-like cells at its interface to the implant. In MgCa0.8 implants cavities were detected within the fibrous tissue, which were surrounded by the same kind of cell type. The thickness of the fibrous layer and the amount of tissue necrosis and cellular infiltrations gradually decreased in S316L. In contrast, a decrease could only be noted in the first weeks of implantation in MgCa0.8, whereas parameters were increasing again at the end of the observation period. B-lymphocytes were found more often in MgCa0.8 indicating humoral immunity and the presence of soluble antigens. Conversely, S316L displayed a higher quantity of T-lymphocytes. Conclusions Moderate inflammation was detected in both implant materials

  20. Micro mechanical study of the stress corrosion cracking of the 316L austenitic stainless steel in chloride medium

    Because of the synergetic actions of a corrosive medium and mechanical loading which occur in stress corrosion cracking, modelling this kind of damage on actual industrial structures can be very challenging. However, when studying one single couple material/medium, it is possible to only consider the mechanical aspect of damaging. Establishing this sort of purely mechanical simulation implies to have extensive information on the behavior of the propagating cracks. Several types of tests are commonly used to gather experimental data on crack propagation, among which are tests conducted on fracture mechanics sample (CT, WOL, etc.) and slow strain rate tests (SSRT) on smooth tensile specimens. The first category of tests is mainly used to obtain the propagation rate of long cracks and the so-called KISCC, the mode I stress intensity factor below which no propagation can be detected for constant displacement tests. The SSRT are preferred to study initiation, mechanisms and short cracks propagation (below KISCC). However, as the analyses of the cracking of these tensile tests are essentially statistical, it is somewhat difficult to separate the behavior of a single short crack from mechanisms resulting from cracks interaction. For instance, for alloy 600 in primary water, the transition of crack growth rate from a slow to a fast regime for cracks attaining the KISCC can be interpreted as a mechanism existing for the single crack or as a result of a natural selection within the cracks population. In order to obtain experimental data on the propagation of one single short crack, we have developed SSRT on micro-notched tensile specimens. This new kind sample allows the initiation and the propagation of one single crack at notch's tip. The experiments were conducted for an austenitic stainless steel (316L) in a model chloride medium (30% MgCl2 at 117 deg C). The use of interrupted tests permits us to obtain crack propagation rate in function of the global loading. Modelling

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

    Amigo, V.

    2004-12-01

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

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

  2. The passive oxide films growth on 316L stainless steel in borate buffer solution measured by real-time spectroscopic ellipsometry

    Highlights: • The optical properties of passive oxide films on 316L stainless steel were studied. • The thickness of the oxide films (1.5–2.6 nm) increased linearly with the potentials. • The growth of passive film followed high electric field ion conduction model. • Selective solubility of oxide induced compositional change of passive film. - Abstract: Passive film growth on 316L stainless steel was investigated in borate buffer electrolyte (pH = 9.1) by real-time spectroscopic ellipsometry (SE) and the composition was estimated by X-ray photoelectron spectroscopy (XPS). Anodic passivation of 316L SS was carried out in the potential range from 0 VSCE to 0.9 VSCE, after potentiostatic polarization for 1800s, the current density decayed from 10−2 A cm−2 to 10−6 A cm−2. The passive film thickness was simulated from Frenel and Drude reflection equations, the average complex refractive index was assumed to be N = 2.3 − j0.445. The estimated thickness increased linearly with potential from 1.5 nm at 0 V to 2.6 nm at 0.8 V. The growth of passive film followed high electric field ion conduction model. The passive film mainly contained the oxide/hydroxide of iron and chromium. The selective solubility of oxide in passive film explained the change of iron and chromium content at different potentials. Few nickel and molybdenum also contributed to the passive film with a constant content

  3. In-vitro bioactivity, biocorrosion and antibacterial activity of silicon integrated hydroxyapatite/chitosan composite coating on 316 L stainless steel implants.

    Sutha, S; Kavitha, K; Karunakaran, G; Rajendran, V

    2013-10-01

    A simple and effective ultrasonication method was applied for the preparation of 0, 0.4, 0.8, 1.0 and 1.6 wt% silicon substituted hydroxyapatite (HAp) (SH). The Ca/P ratio of the synthesised SH nanoparticles were in the range of 1.58-1.70. Morphological changes were noticed in HAp with respect to the amount of Si from 0 to 1.6 wt%. The morphology of the particles changed from spherical shape to rod-like morphology with respect to the amount of Si which was confirmed using transmission electron microscopy. X-ray diffraction studies confirm the formation of phase pure SH nanoparticles without any secondary phase. Chitosan (CTS) blended SH nanocomposites coating on surgical grade 316 L stainless steel (316 L SS) implant was made by spin coating technique. The surface of the coated implant was characterised using scanning electron microscopy which confirms the uniform coating without cracks and pores. The increased corrosion resistance of the 1.6 wt% of SH/CTS-coated SS implant in the simulated body fluid (SBF) indicates the long-term biostability of SH composite-coated ceramics in vitro than the 0 wt% SH/CTS. The testing of SH/CTS nanocomposites with gram-positive and gram-negative bacterial strains confirms that the antibacterial ability improves with the higher substitution of Si. In addition, formation of bone-like apatite layer on the SH/CTS-coated implant in SBF was studied through SEM analysis and it confirms the ability to increase the HAp formation on the surface of 1.0 wt% SH/CTS-coated 316 L SS implant. PMID:23910313

  4. High-Temperature Oxidation Resistance of a Nanoceria Spray-Coated 316L Stainless Steel Under Short-Term Air Exposure

    Lopez, Hugo F.; Mendoza, Humberto; Church, Ben

    2013-10-01

    Nanoceria coatings using a spray method were implemented on a 316L stainless steel (SS). Coated and uncoated coupons were exposed to dry air at 1073 K to 1273 K (800 °C to 1000 °C) for short time periods (up to 24 hours) and in situ measurements of oxidation were carried out using a highly sensitive thermogravimetric balance. From the experimental outcome, activation energies were determined in both, coated and uncoated 316 SS coupons. The estimated exhibited activation energies for oxidation in the coated and uncoated conditions were 174 and 356 kJ/mol, respectively. In addition, the developed scales were significantly different. In the coated steel, the dominant oxide was an oxide spinel (Fe, Mn)3O4 and the presence of Fe2O3 was sharply reduced, particularly at 1273 K (1000 °C). In contrast, no spinel was found in the uncoated 316L SS, and Fe2O3 was always present in the scale at all the investigated oxidation temperatures. The coated steels developed a highly adherent fine-grained scale structure. Apparently, the nanoceria particles enhanced nucleation of the newly formed scale while restricting coarsening. Coarse grain structures were found in the uncoated steels with scale growth occurring at grain ledges. Moreover, the oxidation rates for the coated 316L SS were at least an order of magnitude lower than those exhibited by the steel in the uncoated condition. The reduction in oxidation rates is attributed to a shift in the oxidation mechanism from outward cation diffusion to inward oxygen diffusion.

  5. The passive oxide films growth on 316L stainless steel in borate buffer solution measured by real-time spectroscopic ellipsometry

    Xu, Haisong; Wang, Lu; Sun, Dongbai [National Center for Materials Service Safety (NCMS), University of Science and Technology Beijing, Beijing 100083 (China); Yu, Hongying, E-mail: hyyu@ustb.edu.cn [Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-10-01

    Highlights: • The optical properties of passive oxide films on 316L stainless steel were studied. • The thickness of the oxide films (1.5–2.6 nm) increased linearly with the potentials. • The growth of passive film followed high electric field ion conduction model. • Selective solubility of oxide induced compositional change of passive film. - Abstract: Passive film growth on 316L stainless steel was investigated in borate buffer electrolyte (pH = 9.1) by real-time spectroscopic ellipsometry (SE) and the composition was estimated by X-ray photoelectron spectroscopy (XPS). Anodic passivation of 316L SS was carried out in the potential range from 0 V{sub SCE} to 0.9 V{sub SCE}, after potentiostatic polarization for 1800s, the current density decayed from 10{sup −2} A cm{sup −2} to 10{sup −6} A cm{sup −2}. The passive film thickness was simulated from Frenel and Drude reflection equations, the average complex refractive index was assumed to be N = 2.3 − j0.445. The estimated thickness increased linearly with potential from 1.5 nm at 0 V to 2.6 nm at 0.8 V. The growth of passive film followed high electric field ion conduction model. The passive film mainly contained the oxide/hydroxide of iron and chromium. The selective solubility of oxide in passive film explained the change of iron and chromium content at different potentials. Few nickel and molybdenum also contributed to the passive film with a constant content.

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

    H. A. COLORADO

    2009-01-01

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

  7. THE EMPHASIS OF PHASE TRANSFORMATIONS AND ALLOYING CONSTITUENTS ON HOT CRACKING SUSCEPTIBILITY OF TYPE 304L AND 316L STAINLESS STEEL WELDS

    RATI SALUJA; K. M. MOEED

    2012-01-01

    Hot cracking is a significant problem due to transformation of retained ferrite into sigma phase, which results preferential corrosion of ferrite. The Hot Cracking Susceptibility is high for fully austenitic compositions but specimens with 5 to 30% ferrite were quite resistant to cracking. Hot cracking in 304L and 316L is amplified by low-melting eutectics containing impurities such as S, P, Si, N. It could be diminished by small increase in C, N, Cr, Ni, Si or by substantial increase in Mn c...

  8. Laser surface texturing of 316L stainless steel in air and water: A method for increasing hydrophilicity via direct creation of microstructures

    Razi, Sepehr; Madanipour, Khosro; Mollabashi, Mahmoud

    2016-06-01

    Laser processing of materials in water contact is sometimes employed for improving the machining, cutting or welding quality. Here, we demonstrate surface patterning of stainless steel grade 316L by nano-second laser processing in air and water. Suitable adjustments of laser parameters offer a variety of surface patterns on the treated targets. Furthermore alterations of different surface features such as surface chemistry and wettability are investigated in various processing circumstances. More than surface morphology, remarkable differences are observed in the surface oxygen content and wettability of the samples treated in air and water at the same laser processing conditions. Mechanisms of the changes are discussed extensively.

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

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

    2016-01-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure. PMID:27158647

  10. Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes

    Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs

  11. Chemical reactivity of Li17Pb83 with nitrogen and oxygen, and its compatibility with AISI 316L under known partial pressure of these gases

    The chemical reactivity of the lithium-lead eutectic with nitrogen and oxygen has been studied. While nitrogen is inert towards Li17Pb83 up to 1073 K, oxygen reacts, already at 750 K, with the lithium contained in the alloy. Compatibility tests at 873 K between AISI 316L stainless steel and Li17Pb83 under known partial pressures of nitrogen and oxygen have shown that the former gas does not influence the corrosion phenomenon while the latter greatly enhances it. (author)

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

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

    2016-06-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure. PMID:27158647

  13. Development and Characterization of 316 L Stainless Steel Coated by Melt-derived and Sol-gel derived 45S5 Bioglass for orthopedic applications

    Seyed Morteza Naghib

    2012-03-01

    Full Text Available The 316L austenitic stainless steel (SS was coated by 45S5 bioactive glass produced by melting and sol-gel techniques to increase the bioactivity and to provide a high mechanical strength for orthopedic and dental applications. The morphologies of coated specimens were investigated by scanning electron microscopy (SEM. Then, the coated specimens were immersed in simulated body fluid (SBF at 37°C for 14 days, and their microstructures after withdrawal were also investigated by SEM. All the specimens were analyzed by FTIR and XRD in order to survey the formation of hydroxyapatite layer.

  14. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-01

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process. In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  15. The Influence of Post Weld Heat Treatment in Alloy 82/182 Dissimilar Metal Weld between Low Alloy Steel and 316L Stainless Steel

    Dissimilar metal welds (DMWs) using an Alloy 82/182 are widely used to join low alloy steel components and stainless steel pipes in pressurized water reactors (PWRs). It has been reported that tensile residual stress would be generated within DMWs during the welding processes. It is thought as main reason for primary water stress corrosion cracking (PWSCC) resulting in deterioration of long-term integrity. The application of post weld heat treatment (PWHT) has been considered to reduce the tensile residual stress after welding process. Meanwhile, the PWHT could affect the changes in microstructure, mechanical properties, and corrosion resistance. Therefore, in this study, the effects of PWHT on the microstructure, mechanical properties and corrosion behaviors of base metals of low alloy steel and stainless steel and welding materials of Alloy 82/182 are evaluated. The influence of PWHT in DMW has been investigated. SA 508 and 316L SS exhibited tempered bainite and austenitic grains with a few residual stringer type ferrite. Grain boundary carbides are not precipitated owing to low carbon and insufficient exposure time in 316L SS. The change of mechanicals properties in base metals is not observed. In case of Alloy 182, after PWHT, grain boundaries are covered with film-like continuous Cr-rich carbides

  16. Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

    Mahmoud Hassan R. S.

    2014-07-01

    Full Text Available High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The increase in surface hardness is due to the high nitrogen concentration at or near the surface. At 245HV, the graph of the effective duration of nitriding process was plotted to achieve the maximum depth of nitrogen diffuse under the surface. Using Sigma Plot software best fit lines of the experimental result found and plotted to find out effective duration of nitriding equation as Y=1.9491(1-0.7947x, where Y is the thickness of nitrided layer below the surface and X is duration of nitriding process. Based on this equation, the duration of gas nitriding process can be estimated to produce desired thickness of nitrided layer.

  17. Effects of passive films on corrosion resistance of uncoated SS316L bipolar plates for proton exchange membrane fuel cell application

    Yang, Ying; Ning, Xiaohui; Tang, Hongsheng; Guo, Liejin; Liu, Hongtan

    2014-11-01

    The effects of passive films on the corrosion behaviors of uncoated SS316L in anode and cathode environments of proton exchange membrane fuel cells (PEMFCs) are studied. Potentiodynamic and potentiostatic polarizations are employed to study the corrosion behavior; Mott-Schottky measurements are used to characterize the semiconductor properties of passive films; X-ray photoelectron spectroscopy (XPS) analyses are used to identify the compositions and the depth profiles of passive films. The passive films formed in the PEMFC anode and cathode environments under corresponding conditions both behave as n-type semiconductor. The passive film formed in the anode environment has a single-layer structure, Cr is the major element (Cr/Fe atomic ratio > 1), and the Cr/Fe atomic ratio decreases from the surface to the bulk; while the passive film formed in the PEMFC cathode environment has a bi-layer structure, Fe is the major element (Cr/Fe atomic ratio < 0.5), and in the external layer of the bi-layer structure Fe content increases rapidly and gradually in the internal layer. SS316L shows better corrosion resistance owing to both the high content of Cr oxide in the passive film and low band bending in normal PEMFC anode environments.

  18. Structural and chemical analysis of silica-doped β-TCP ceramic coatings on surgical grade 316L SS for possible biomedical application

    Karuppasamy Prem Ananth

    2015-09-01

    Full Text Available We have developed a novel approach to introduce silica-doped β-tricalcium phosphate (Si-β-TCP on 316L SS substrates for enhanced biological properties. Doping of β-TCP with silica loadings ranging from 0 to 8 mol% was carried out using chemical precipitation method. Si-β-TCP powder was sintered at 800 °C followed by coating it on 316L SS substrate using electrophoretic deposition. The coated and uncoated samples were investigated by various characterization techniques such as X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, field emission scanning electron microscopy (FESEM and X-ray fluorescence spectroscopy (XRF. Biomineralization ability of the coatings was evaluated by immersing in simulated body fluid (SBF solution for different number of days such as 7, 14, 21 and 28 days. The results obtained in our study have shown that the apatite formation ability was high for the 8 mol% of Si-β-TCP. This will promote better biomineralization ability compared to the other coatings.

  19. Effect of tensile stress on the formation of S-phase during low-temperature plasma carburizing of 316L foil

    Low-temperature plasma carburizing of austenitic stainless steel can produce a carbon-supersaturated austenite layer, the 'S-phase', on the surface, which has high hardness, excellent wear and fatigue properties, and good corrosion resistance. Although the S-phase was discovered some years ago, the basic understanding of S-phase formation remains incomplete. In this paper, the effect of tensile stresses (0-80 MPa) on the formation and stability of S-phase during carburizing of 316L stainless steel foils at 400, 425 and 450 deg. C for 10 h has been investigated for the first time. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and the mechanical properties were evaluated by microhardness and tensile tests. The results showed that the in situ applied tensile stress effectively thickened S-phase layers. The calculated activation energy for carbon diffusion in 316L was reduced from 142.76 to 133.91 kJ mol-1 when a tensile stress of 40 MPa was applied. However, chromium carbides were formed in the outmost surface when the tensile stress exceeded 40 MPa. The results are discussed and explained through appropriate thermodynamic calculations.

  20. Electrochemical Evaluation of Si-Incorporated Diamond-Like Carbon (DLC) Coatings Deposited on STS 316L and Ti Alloy for Biomedical Applications

    DLC coatings have been deposited onto substrate of STS 316L and Ti alloy using r.f. PACVD (plasma-assisted chemical vapor deposition) with a mixture of C6H6 and SiH4 as the process gases. Corrosion performance of DLC coatings was investigated by electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analysis (scanning electron microscopy). the electrolyte used in this test was a 0.89% NaCl solution of pH 7.4 at temperature 37 .deg. C. The porosity and protective efficiency of DLC coatings were obtained using potentiodynamic polarization test. Moreover, the delamination area and volume fraction of water uptake of DLC coatings ass a function of immersion time were calculated using electrochemical impedance spectroscopy. This study provides the reliable and quantitative data for assessment of the effect of substrate on corrosion performance of Si-DLC coatings. the results showed that Si-DLC coating on Ti alloy could improve corrosion resistance more than that on STS 316L in the simulated body fluid environment. This could be attributed to the formation of a dense and low-porosity coating, which impedes the penetration of water and ions