Ingeniería Civil y Mecánica

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Subject: search.filters.subject.MARTENSITA

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    Análisis de revestimientos duros aplicados por proceso SMAW sobre acero al carbono A36 y su incidencia en el desgaste abrasivo evaluado bajo la norma ASTM G-65
    (Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica. Carrera de Ingeniería Mecánica, 2018) Bautista Romero, Milton Andrés; Vaca Ortega, Wilson Henry
    This experimental work has as main objective: Analyze the hard coatings applied by the SMAW process on carbon steel A36 and its incidence in the abrasive wear evaluated under the ASTM G-6 standard, for which 72 x 60 x 12 mm specimens were manufactured , were coated with three types of Indura brand electrodes, 10 specimens were coated with chromium carbide based electrode (Overlay - 62), 5 with one pass and 5 with two passes, the same procedure was performed with the electrodes based on Martensitic alloys (Antifrix-450) and with the electrodes based on Austenitic alloys high in manganese. The machine in which the abrasive wear tests were carried out established the parameters of the ASTM G-65 standard. The metallography tests helped to verify their microstructure in each type of electrode, hardness and spectrometry tests were also carried out to obtain their percentage in chemical composition, in order to analyze the parameters that provide better resistance to wear. Finally the samples were weighed to obtain the difference of mass loss (g) and calculate the volumetric losses in each one of the cases, with which it was possible to determine that the smaller volumetric loss was obtained with the electro-Overlay-62 with a volumetric loss of 49.909mm3 and 41.697 mm3 with one and two passes respectively the second best result was with the Weldmang-14 electrode with a volumetric loss of 74.58 mm3 and 65.189 mm3with one and two passes respectively, The electrode that did not provide good characteristics for wear resistance was the Antifrix-450 electrode with a loss of 305.548mm3 and 274.876 with one and two passes respectively
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    Estudio del tratamiento térmico post soldadura del acero inoxidable martensítico ASTM A743 grado CA6-NM y su incidencia en las propiedades mecánicas del material aplicado a la recuperación de rodetes hidráulicos
    (Universidad Técnica de Ambato, Facultad de Ingeniería Civil y Mecánica. Maestría en Diseño Mecánico, 2017) Auz Mogrovejo, Juan José; Vaca Ortega, Wilson Henry
    ASTM A743 grade CA6-NM Martensitic Stainless Steel is used in the manufacture of runners and other components of hydraulic turbines to provide a good combination between mechanical properties and resistance to cavitation and corrosion. Due to its low carbon content it has good weldability; however, it is necessary to perform post-weld heat treatment to alleviate stress and to fine tune the microstructure and mechanical properties in order to recover characteristics similar to those of the original material. Through the present work the effect of the heat treatment of ASTM A743 grade CA6-NM steel was studied after applying deposits of multi-step welding of accumulation type or restoration the thickness of the base metal using a GMAW robotized process with ER410NiMo electrodes on slotted coupons which reproduce part of the worn surface of a hydraulic runner. The welded coupons were subjected to different heat treatments in order to compare the mechanical properties of the weld material without heat treatment and with post-weld tempering at a temperature of 600 °C during two different holding times, one and two hours; in addition, this process was performed for one, two and three cycles of recovery by welding plus heat treatment. Eight cases of study were considered, including the original base material, the weld without heat treatment and six cases of post-welding tempering, which were subjected to tests of tension, impact, hardness and metallography to characterize and establish the variation of the mechanical properties. From this analysis it was determined that the post-weld heat treatment applied allows to improve the properties that are affected by the welding process. The best combination of mechanical properties was obtained for tempering at 600 °C during two hours in the first recovery. It was verified that even in the third recovery the properties of the material are within the parameters required by the standard ASTM A743. Finally, a procedure is proposed for the recovery of Francis hydraulic runners as an alternative for the maintenance of turbines at a lower cost.
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    Estudio del temple en el acero utilizando grasas vegetales y su incidencia en las propiedades mecánicas
    (Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica. Carrera de Ingeniería Mecánica, 2011) Criollo Camacho, Marcia Ximena; Vaca Ortega, Wilson Henry
    En el siguiente trabajo estructurado de manera independiente se desarrolla el estudio de la utilización de Grasas Vegetales como medio de enfriamiento para templar aceros, en éste caso se toma como patrón el Acero AISI 1045, en nuestro medio se realiza el Temple del acero de una manera artesanal motivo por el cual se ha propuesto realizar el presente trabajo, el cual es de gran utilidad técnica al momento de optar por medios de enfriamiento alternativos que presenten características similares o mejores a los medios comúnmente utilizados. Para la ejecución del trabajo planteado se ha realizados una investigación netamente experimental la cual se basa en una serie de pruebas y ensayos realizados en los Laboratorios de la Facultad de Ingeniería Civil y Mecánica, sin dejar de lado la bibliografía utilizada para obtener información referente al tema. Con la investigación se ha determinado que el mejor resultado en cuanto a propiedades mecánicas se lo obtiene en el Aceite de Oliva, el cual es de fácil adquisición en el medio comercial, las propiedades obtenidas cumplen con las necesidades que el tratamiento térmico requiere, dando un valor de dureza elevado y sin la presencia de fragilidad lo cual es lo óptimo para el acero según la aplicaciones que se vaya a dar, de tal modo que se puede implementarlo a nivel de industrias.