Estudio de la temperatura de revenido en la aleación cobre – 10% aluminio colado en molde de arena sobre la dureza, tiempo de ruptura en corrosión bajo tensión y microestructura
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Date
2024-03
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Universidad Nacional de Trujillo
Abstract
En el presente estudió se evaluó el efecto de la temperatura de revenido, en el rango de
200 a 500ºC, en la aleación cobre – 10% aluminio colado en molde de arena y templado desde 900ºC en un medio corrosivo de H2SO4 1N y una carga aplicada de 168 kg, sobre la dureza, tiempo de ruptura en corrosión bajo tensión (CBT) y la microestructura. Se experimentó con probetas según norma ASTM E-10 para el ensayo de dureza, con probetas según norma ASTM G-49 para el ensayo de corrosión bajo tensión y técnicas de metalografía para evaluar
microestructuras.
La microestructura del material de estudio está formada por fase alfa primaria ( ) y
eutectoide ( + 2) distribuido homogéneamente (aleación hipoeutectoide), luego de aplicar el temple desde los 900ºC en agua, se obtiene una microestructura de martensita (β')y solución sólida alfa (α) en forma de placas e inestable; y luego de aplicado el revenido hasta 400ºC la microestructura consta de una matriz de martensita (β') con placas alfa (α) delgadas y homogéneamente distribuidas lo que mejora la dureza y el tiempo de ruptura en corrosión bajo tensión, creando resistencia a la carga axial y evitando la formación de grieta para la fractura, siendo a esta temperatura de revenido donde se obtienen los mejores valores de las propiedades estudiadas. Con el incremento de la temperatura a 500ºC, las propiedades de dureza y el tiempo de ruptura en corrosión bajo tensión disminuyen, debido a que las placas alfa (α) se hacen bastas en la matriz de martensita (β') volviendo dúctil y plástica la aleación. Se concluye que, la temperatura de revenido afecta significativamente la dureza y tiempo de ruptura en CBT, ya que los datos obtenidos han sido contrastados mediante, análisis estadístico con un nivel de confianza de 95% demostrando la confiabilidad del
estudio realizado.
In the present study, the effect of tempering temperature in the range of 200 to 500°C was evaluated on a copper - 10% aluminum alloy cast in a sand mold and quenched from 900°C in a 1N H2SO4 corrosive environment with an applied load of 168 kg. The evaluation focused on hardness, time to failure in stress corrosion cracking (SCC), and microstructure. Test specimens were prepared according to ASTM E-10 standards for hardness testing, ASTM G-49 standards for stress corrosion testing, and metallographic techniques for microstructure evaluation. The microstructure of the studied material consists of primary alpha (α) and eutectoid (α+γ2) phases, evenly distributed (hypoeutectic alloy). After quenching from 900°C in water, a martensitic microstructure (β') and alpha (α) solid solution in the form of plates were obtained, which is unstable. Subsequent tempering at temperatures up to 400°C resulted in a microstructure comprising a matrix of martensite (β') with thin and evenly distributed alpha (α) plates. This improved hardness and the time to failure in stress corrosion cracking, providing resistance to axial load and preventing crack formation during fracture. The best values of the studied properties were achieved at this tempering temperature. However, as the temperature increased to 500°C, both hardness and time to failure in stress corrosion cracking decreased. This was attributed to the alpha (α) plates coarsening in the martensite (β') matrix, making the alloy more ductile and plastic. In conclusion, it can be observed that the tempering temperature significantly affects hardness and time to failure in SCC. The data obtained were statistically analyzed with a 95% confidence level, demonstrating the reliability of the study.
In the present study, the effect of tempering temperature in the range of 200 to 500°C was evaluated on a copper - 10% aluminum alloy cast in a sand mold and quenched from 900°C in a 1N H2SO4 corrosive environment with an applied load of 168 kg. The evaluation focused on hardness, time to failure in stress corrosion cracking (SCC), and microstructure. Test specimens were prepared according to ASTM E-10 standards for hardness testing, ASTM G-49 standards for stress corrosion testing, and metallographic techniques for microstructure evaluation. The microstructure of the studied material consists of primary alpha (α) and eutectoid (α+γ2) phases, evenly distributed (hypoeutectic alloy). After quenching from 900°C in water, a martensitic microstructure (β') and alpha (α) solid solution in the form of plates were obtained, which is unstable. Subsequent tempering at temperatures up to 400°C resulted in a microstructure comprising a matrix of martensite (β') with thin and evenly distributed alpha (α) plates. This improved hardness and the time to failure in stress corrosion cracking, providing resistance to axial load and preventing crack formation during fracture. The best values of the studied properties were achieved at this tempering temperature. However, as the temperature increased to 500°C, both hardness and time to failure in stress corrosion cracking decreased. This was attributed to the alpha (α) plates coarsening in the martensite (β') matrix, making the alloy more ductile and plastic. In conclusion, it can be observed that the tempering temperature significantly affects hardness and time to failure in SCC. The data obtained were statistically analyzed with a 95% confidence level, demonstrating the reliability of the study.
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TECHNOLOGY::Chemical engineering::Metallurgical process and manufacturing engineering::Metallurgical manufacturing engineering