Publication: Distribución y evolución de tensiones residuales en materiales compuestos de matriz metálica
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2018-08-31
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Universidad Complutense de Madrid
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Abstract
El objetivo de este trabajo es alcanzar, desde un punto de vista experimental, un conocimiento más profundo del modo en que las tensiones residuales, generadas por temple, se distribuyen a lo largo de un material y evolucionan con tratamientos termo-mecánicos. Así mismo, del modo en que la matriz metálica de un material compuesto con refuerzo cerámico acomoda el desajuste térmico y mecánico inducido por la presencia de una segunda fase de refuerzo. Además, se tendrá en cuenta cómo factores, tales como el tipo de aleación, la microestructura, el tipo de refuerzo o incluso el proceso de fabricación pueden afectar a la distribución de tensiones residuales. La presencia de tensiones residuales juega un papel primordial en el diseño y fabricación actual de componentes de ingeniería . Su generación, por la mayoría de técnicas de procesado, tales como conformado, mecanizado, soldadura, etc. se conoce desde hace tiempo. Los modelos de análisis por elementos finitos son capaces de predecir mapas útiles de tensión residual macroscópica. Sin embargo, los resultados obtenidos mediante técnicas de medida tradicionales no corroboran estas predicciones de forma suficientemente precisa. El planteamiento se complica cuando entra en juego la tensión residual microscópica, la que se genera como consecuencia de la presencia de segundas fases. Este es el caso de los Materiales compuestos de Matriz Metálica. Para ello, se ha realizado una caracterización completa y comparativa de tres Materiales Compuestos de Matriz Aluminio con Refuerzo Discontinuo, y las tres aleaciones sin reforzar. Por un lado, se han investigado la microestructura, los Coeficientes de Expansión Térmica y las Propiedades Mecánicas (dureza, tracción compresión y endurecimiento), con diferentes tratamientos de envejecimiento y recocido...
The aim of this work is to achieve, from an experimental standpoint, a deeper understanding of the way in which residual stress, generated by quenching, is distributed along the material and evolves with thermo-mechanical treatments. Also, the way in which the metallic matrix of a ceramic reinforced composite material accommodates thermal and mechanical mismatches induced by the presence of a reinforcing second phase. It will be taken into account as well, how factors such as alloy type, microstructure, type of reinforcement, or even manufacturing processes, may influence the distribution of residual stress. The presence of Residual Stress plays a paramount role in current design and fabrication of engineering components. Its generation by most of processing techniques, such as shaping, machining, welding, etc., has long been known. Finite element analysis models are usually capable of predicting useful macroscopic stress maps, but stress determination by traditional experimental techniques does not support these predictions accurately enough. The picture becomes more complex when microscopic residual stress, such as those arisen from the presence of second phases are involved. This is the case of Metal Matrix Composites. The aim of this work is to achieve, from an experimental standpoint, a deeper understanding of the way in which metallic matrix accommodates thermal and mechanical mismatches induced by the presence of a second phase, and how factors such as alloy type, microstructure, type of reinforcement, or even manufacturing processes, may influence the distribution of residual stress...
The aim of this work is to achieve, from an experimental standpoint, a deeper understanding of the way in which residual stress, generated by quenching, is distributed along the material and evolves with thermo-mechanical treatments. Also, the way in which the metallic matrix of a ceramic reinforced composite material accommodates thermal and mechanical mismatches induced by the presence of a reinforcing second phase. It will be taken into account as well, how factors such as alloy type, microstructure, type of reinforcement, or even manufacturing processes, may influence the distribution of residual stress. The presence of Residual Stress plays a paramount role in current design and fabrication of engineering components. Its generation by most of processing techniques, such as shaping, machining, welding, etc., has long been known. Finite element analysis models are usually capable of predicting useful macroscopic stress maps, but stress determination by traditional experimental techniques does not support these predictions accurately enough. The picture becomes more complex when microscopic residual stress, such as those arisen from the presence of second phases are involved. This is the case of Metal Matrix Composites. The aim of this work is to achieve, from an experimental standpoint, a deeper understanding of the way in which metallic matrix accommodates thermal and mechanical mismatches induced by the presence of a second phase, and how factors such as alloy type, microstructure, type of reinforcement, or even manufacturing processes, may influence the distribution of residual stress...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 15-06-2017