Avaliação de sítios aprisionadores de hidrogênio em aços API 5L X65 e API 5L X70 utilizados no setor petroquímico.

Abstract

Steels used in the petrochemical sector generally have good mechanical strength. However, due to exposure to aggressive chemical substances present in the oil, such as H2S, these materials suffer corrosive processes, among which to hydrogen embrittlement. The process of embrittlement occurs mainly when hydrogen is present in the external medium because it is an element very small diffusion coefficient of high and low activation energy is adsorbed on the metal surface and diffuses into the crystal lattice. As the materials, especially metals, have defective sites in the crystal lattice (cores, dislocations, voids, gaps and interfaces), these sites can serve as traps for hydrogen. This study aims to evaluate the trapping of hydrogen in two types of steels used in the petrochemical industry, API 5L X65 and API 5L X70, by applying the Technique Electrochemical Permeation of Hydrogen. The determination the density of hydrogen trapping sites was for permeation curve analysis, demonstrating the presence of high concentration of hydrogen in the crystal lattice of materials. The technique of scanning electron microscopy (SEM) was used for analysis of samples microstructure steels, allowing visualization of the damage caused by the hydrogen microstructure of materials. The data provided in this study aim to contribute to the understanding of the corrosion mechanism and trapping of hydrogen in metals, in order to find solutions to the problems of hydrogen embrittlement and avoid accidents such as leaks and ruptures of studies which mainly entail economic losses and environmental.