Interacción creep fatiga de aceros 1Cr-0.5Mo
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2018-10
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Abstract
En el presente trabajo se estudia el comportamiento al creep y al creep – fatiga de aceros de baja aleación 1Cr 0,5Mo, que son utilizados en la industria para servicios a altas temperaturas, principalmente en tubos de calderas y en intercambiadores de calor. Se pretende relacionar las propiedades mecánicas y la vida útil a partir de los resultados obtenidos de ensayos de creep y de creep fatiga (sin y con tiempo de permanencia). Los ensayos se realizan a 70 MPa de tensión axial y a 540 °C de temperatura, ya que se considera superior a la temperatura equicohesiva, donde la
resistencia del grano es aproximadamente igual a la del borde de grano. Se realizaron ensayos de corta duración, en los que a partir de la velocidad de la etapa secundaria se puede extrapolar la vida útil en casos de larga duración (menor a 5 % para 10000 hs). Los ensayos de creep – fatiga se realizaron con ciclos de tensiones positivas entre 20 y 70 MPa y en el caso particular de simular una permanencia, quedaron en el pico de máxima tensión durante 30 minutos. En forma simultánea se estudió la microestructura del material en cada caso y se observó, en los casos de interacción creep – fatiga con permanencia, la presencia de gran número de microfisuras y el crecimiento de las mismas que derivan en el deterioro de las propiedades mecánicas del material.
This work examines the behavior of creep and creep - fatigue of low alloy steels 1Cr 0, 5Mo, which are used in industry for services at high temperatures, mainly in pipes of boilers and heat exchangers. It is intended to relate the mechanical properties and the life from the results of trials of creep and creep fatigue (without and with hold time). The tests are performed to 70 MPa of axial tension and 540 ° C temperature, since it is higher than the temperature equicohesive, where the strength of grain is approximately equal to the edge of grain. Trials of short duration, in which by the rate of the secondary stage life in cases of long duration (less than 5% to 10000 hours) can be extrapolated were. Trials of creep - fatigue were conducted with cycles of positive tensions between 20 and 70 MPa and in the particular case of simulating a hold time, were at the peak of maximum tension for 30 minutes. At the same time we studied the microstructure of the material in each case and was observed, in cases of interaction creep - fatigue with hold time, the presence of large number of microcracks and the growth of them resulting in the deterioration of the properties mechanical material.
This work examines the behavior of creep and creep - fatigue of low alloy steels 1Cr 0, 5Mo, which are used in industry for services at high temperatures, mainly in pipes of boilers and heat exchangers. It is intended to relate the mechanical properties and the life from the results of trials of creep and creep fatigue (without and with hold time). The tests are performed to 70 MPa of axial tension and 540 ° C temperature, since it is higher than the temperature equicohesive, where the strength of grain is approximately equal to the edge of grain. Trials of short duration, in which by the rate of the secondary stage life in cases of long duration (less than 5% to 10000 hours) can be extrapolated were. Trials of creep - fatigue were conducted with cycles of positive tensions between 20 and 70 MPa and in the particular case of simulating a hold time, were at the peak of maximum tension for 30 minutes. At the same time we studied the microstructure of the material in each case and was observed, in cases of interaction creep - fatigue with hold time, the presence of large number of microcracks and the growth of them resulting in the deterioration of the properties mechanical material.
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Creep, Creep-fatiga, Interacción, Acero 1Cr 0.5Mo, Aceros ferriticos, Altas temperaturas, Temperatura equicohesiva
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