Maestría en Diseño Mecánico
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Item Análisis de aceros y recubrimientos utilizados en tambores de mezclado de los mixers de la empresa Holcim Ambato y su influencia en el desgaste abrasivo bajo la norma ASTM G105(Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica. Maestría en Diseño Mecánico, 2017) Villacrés Padilla, David Andrés; Núñez Núñez, Diego FernandoThis research project was developed under the objective of analyzing the types of steels and coatings used in the mixing drums of the mixers of the HOLCIM company Ambato and its influence on the abrasive wear under the ASTM G105 standard, which tests were carried out from abrasive wear and an analysis of the rate of such coatings. For the development of the research, a bibliographic, field and experimental methodology was used, also exploratory and descriptive to address the study phenomenon that included 8 trials with the application of different configurations for the evaluation of the variable, besides a 40 sample scheme was developed with ASTM AISI 1020 steels and ASTM A514 grade F high strength steel corresponding to the Holcim Mixer drum, which were applied to three types of coatings such as nitrided, metallized and cemented. Due to this it was possible to conclude that the application of coatings and thermal treatments on the steels improve the characteristics and properties with respect to the abrasive wear, these processes contribute to a greater hardness and abrasive resistance. In addition, it is determined that, in the case of the amorphous tungsten alloy coating, it presents the greatest increase of hardness of the surfaces, which defines as the best treatment applicable in the steels, reason why a procedure for the recovery of the mixers according to the location of the parts of the mixer drum of the HOLCIM company.Item Análisis del blindaje del acero AISI 1045 por proyección térmica de aleación micropulverizada Eutalloy 11496 y su influencia en la resistencia al desgaste superficial(Universidad Técnica de Ambato, Facultad de Ingeniería Civil y Mecánica. Maestría en Diseño Mecánico, 2017) Paredes Zumbana, Jorge Alexandro; Espín Lagos, Segundo ManuelIn the present research, shielding tests were carried out on three surfaces of different roughness, which have as substrate the AISI 1045 steel, extracted from a cane miller. The three types of roughness were obtained by means of the processes of mechanical polishing with abrasive disc, sandblasting with mineral abrasive of volcanic nature and metallic blasting. The shielding material was the Eutalloy micropulverized alloy 11496, applied by means of the flame thermal projection technique. Shielded samples were subjected to abrasion wear tests and accelerated corrosion wear in a salt spray chamber; The results indicate that the best resistance to abrasive wear occurs in samples prepared superficially by sandblasting, which have a surface preheating between 320 and 420 ° C, to achieve a suitable anchorage of the metal alloy. The results of accelerated corrosion showed the highest corrosion rates in the unshielded substrate and it was also evidenced that the corrosion resistance in the shielding is good as long as there are no surface defects. Finally, a procedure proposal is proposed for the shielding of a cane mill tipping machine, in order to ensure that its useful life is favorable to milling with a duration of 8 months.Item 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 HenryASTM 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.