Influencia del granallado en los aceros inoxidables austeníticos metaestables

En el presente trabajo se muestra el efecto del granallado sobre la microestructura y las propiedades mecánicas de un acero inoxidable austenítico metaestable EN 1.4318 (AISI 301LN). Se han considerado dos condiciones de partida distintas: recocido (microestructura totalmente austenítica) y laminado en frío (con un porcentaje inicial de martensita del 38%). La granalla utilizada es de acero inoxidable S300, proyectada a una velocidad de 65 m/s con factores de cobertura del 200 y 400%. El análisis microestructural se ha llevado a cabo por difracción de rayos-X, microscopía láser confocal (CLSM) y microscopía electrónica de barrido (MEB). Para cada condición se han realizado ensayos de fatiga a alto número de ciclos. Los resultados ponen de manifiesto que el proceso de granallado permite aumentar en un 25% el límite a fatiga del acero laminado, mientras que no se observa ningún efecto sobre el acero recocido. Para esta condición, la creación de microgrietas en la superficie enmascara el efecto beneficioso del endurecimiento debido a la formación de martensita por deformación durante el proceso de granallado.The aim of this work is to study the microstructural changes and its effect on mechanical properties of a metastable austenitic stainless steel grade EN 1.4318 (AISI 301LN) subjected to shot peening process. Two different material conditions were considered: annealed (totally austenitic microstructure) and cold rolled (with an initial martensite content of 38%). Stainless steel shots type S300 impacted the surface at 65 m/s with two different coverage factors: 200 and 400%. Microstructural analysis was performed by x-ray diffraction, Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM). For each condition fatigue tests at high number of cycles were carried out. Results point out that only cold rolled samples displayed an improvement of 25% on the fatigue limit while no effect was detected for annealed steel. For this condition, the presence of surface microcracks was expected to offset the advantages introduced by the presence of deformation induced martensite formed during shot peening process.Peer Reviewe

Influencia del granallado en los aceros inoxidables austeníticos metaestables

En el presente trabajo se muestra el efecto del granallado sobre la microestructura y las propiedades mecánicas de un acero inoxidable austenítico metaestable EN 1.4318 (AISI 301LN). Se han considerado dos condiciones de partida distintas: recocido (microestructura totalmente austenítica) y laminado en frío (con un porcentaje inicial de martensita del 38%). La granalla utilizada es de acero inoxidable S300, proyectada a una velocidad de 65 m/s con factores de cobertura del 200 y 400%. El análisis microestructural se ha llevado a cabo por difracción de rayos-X, microscopía láser confocal (CLSM) y microscopía electrónica de barrido (MEB). Para cada condición se han realizado ensayos de fatiga a alto número de ciclos. Los resultados ponen de manifiesto que el proceso de granallado permite aumentar en un 25% el límite a fatiga del acero laminado, mientras que no se observa ningún efecto sobre el acero recocido. Para esta condición, la creación de microgrietas en la superficie enmascara el efecto beneficioso del endurecimiento debido a la formación de martensita por deformación durante el proceso de granallado.The aim of this work is to study the microstructural changes and its effect on mechanical properties of a metastable austenitic stainless steel grade EN 1.4318 (AISI 301LN) subjected to shot peening process. Two different material conditions were considered: annealed (totally austenitic microstructure) and cold rolled (with an initial martensite content of 38%). Stainless steel shots type S300 impacted the surface at 65 m/s with two different coverage factors: 200 and 400%. Microstructural analysis was performed by x-ray diffraction, Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM). For each condition fatigue tests at high number of cycles were carried out. Results point out that only cold rolled samples displayed an improvement of 25% on the fatigue limit while no effect was detected for annealed steel. For this condition, the presence of surface microcracks was expected to offset the advantages introduced by the presence of deformation induced martensite formed during shot peening process.Peer Reviewe

Contested voices? Methodological tensions in creative visual research with children

This paper contributes to the body of work within the social studies of childhood on creative visual methods and the emerging critique on the participatory assumptions of child-centred creative visual methodology. Drawing on ethnographically informed research with a group of children aged 8-12 which utilised a range of creative methods including child-led video and photography, the paper provides a methodological focus on the children’s interactions with the adult research team, each other and with the children whom they filmed, interviewed and photographed. The paper suggests that attention to the dynamics between children as researchers and participants is essential for understanding how children’s voices are made (and diminished) in child-led creative visual methods. Methodological attention to the ways in which children’s voices are differently (and unequally) heard in the research encounter is essential for evaluating what such methods bring to research with children and challenges theorizations of a singular children’s voice suggested in the literature

Intergenerational Transmission of Conflict-Related Trauma in Northern Ireland: A Behavior Analytic Approach

Intergenerational transmission of trauma describes the impact that traumatic events experienced by one generation have for the subsequent generation. In Northern Ireland, violent conflict raged between 1969 and 1998, when a peace process begun. This study explored to what extent (if any) parents’ experiences of the conflict influenced how children perceived life in this society. Parents completed a questionnaire, and their children drew 2 pictures, depicting Northern Ireland now and before they were born. Children’s behaviors and awareness of the conflict were influenced by their parents’ experiences and narratives, their age, gender, and school. Parental narrative about the violence was influenced by individual learning history, the child’s age and gender, and present circumstances. A behavior analytic approach is offered.<br/