Efecto del tratamiento térmico pos soldadura de reparación en acero 1,25Cr0,5Mo con 20 años de servicio
Fecha
2018
Autores
Marín Báez, Eliecer
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Editor
Universidad Central ‘‘Marta Abreu’’ de Las Villas. Facultad de Ingeniería Mecánica e Industrial. Departamento de Ingeniería Mecánica
Resumen
En el trabajo se tiene como objetivo establecer el efecto (y posibles causas) del tratamiento térmico pos soldadura de reparación sobre la resistencia a la fluencia lenta y la microestructura en acero 1,25Cr0,5Mo previamente expuesto a servicio por más de 20 años. Se emplearon secciones de una tubería de vapor de acero 1,25Cr0,5Mo que ha trabajado alrededor de 20 años a 480 oC; de las mismas, una parte se sometió en condiciones de laboratorio a régimen de tratamiento térmico pos soldadura de reparación con parámetros similares a los recomendados por los códigos de fabricación. Probetas de estas secciones se sometieron al ensayo de fluencia lenta. Se obtiene la microestructura mediante microscopía electrónica de barrido y aplicando el procesamiento digital de imagen se determinaron los parámetros estereográficos de los precipitados en el interior de la ferrita. Se concluye que el tratamiento térmico pos soldadura propicia el desarrollo del fenómeno de crecimiento competitivo de los precipitados en el interior de la ferrita con una implicación en la disminución de la resistencia a la fluencia lenta del acero estudiado.
The objective of the work is to establish the effect (and possible causes) of the heat treatment after repair welding on the slow creep resistance and the microstructure in steel 1.25Cr0.5Mo previously exposed to service for more than 20 years. Sections of a 1.25Cr0.5Mo steel steam pipe that has worked around 20 years at 480 oC were used; of them, a part was subjected to laboratory conditions under heat treatment regime after repair welding with parameters similar to those recommended by the manufacturing codes. Test tubes from these sections were subjected to the slow creep test. The microstructure was obtained by means of scanning electron microscopy and by applying the digital image processing, the stereographic parameters of the precipitates inside the ferrite were determined. It is concluded that the heat treatment after welding promotes the development of the competitive growth phenomenon of the precipitates inside the ferrite with an implication in the decrease of the resistance to slow creep of the steel studied.
The objective of the work is to establish the effect (and possible causes) of the heat treatment after repair welding on the slow creep resistance and the microstructure in steel 1.25Cr0.5Mo previously exposed to service for more than 20 years. Sections of a 1.25Cr0.5Mo steel steam pipe that has worked around 20 years at 480 oC were used; of them, a part was subjected to laboratory conditions under heat treatment regime after repair welding with parameters similar to those recommended by the manufacturing codes. Test tubes from these sections were subjected to the slow creep test. The microstructure was obtained by means of scanning electron microscopy and by applying the digital image processing, the stereographic parameters of the precipitates inside the ferrite were determined. It is concluded that the heat treatment after welding promotes the development of the competitive growth phenomenon of the precipitates inside the ferrite with an implication in the decrease of the resistance to slow creep of the steel studied.
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Palabras clave
Tratamiento Térmico, Fluencia Lenta, Soldadura, Acero 1.25Cr0.5Mo