Microstructural characterization of a plate of microalloyed pipeline steel that conforms to API 5L X65 in different regions of the plate as rolled and after austenitization and continous cooling under different cooling rates. / Caracterização microestrutural do aço para tubo API 5L-X65 em diferentes regiões da chapa como laminada e após austenitização e resfriamento sob diversas taxas de resfriamento.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This work aims to characterize and compare the microstructures of different regions of a plate of microalloyed pipeline steel that conforms to API 5L X65, employed in the transportation of natural gas and oil, as received and after being subjected to heat treatments of austenitization and continuous cooling under different cooling rates. The steel under study presents a central line of segregation that was originated during production. Specimens for dilatometry were machined from the central region and from different regions of the plate. The samples were austenitized at 1200°C and in quenched in water, with the purpose of solubilizing most of the precipitates in the steel. After the preliminary heat treatment, the specimens were austenitized at 950°C for 180s and cooled under the cooling rates: 0.5°C/s, 1°C/s, 5°C/s, 10°C/s, 20°C/s, 30°C/s, 40°C/s, 50ºC/s and 60ºC/s in a quench dilatometer. Values of temperature and time correspond of transformation for each rate of cooling were used for the determination of the Continuous Cooling Transformation (CCT) diagram.

ASSUNTO(S)

cct diagram microstructure ageing treatment high strength low alloy steel microscópio eletrônico solubilização ensaios da estrutura dos materiais materiais ferrosos revenido segregation microscópio ótico trabalho em metal ensaios não destrutivos

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