Determinação de parâmetros cinéticos e de aprisionamento do hidrogênio em aços API 5L X60, X65 e X70 pela técnica de permeação eletroquímica.

Abstract

The objective of the present work was to study the hydrogen trapping in steel class API 5L X60, X65 and X70, classified as High-strength low-alloy (HSLA). The respective implication of the diffusion of hydrogen, i.e., adsorbed and dissolved in the metallic matrix of the steels, the trapping in microstructural defects, were approached through the study of the trapping kinetics, with the determination of the release (k) and capture (p ), The trapping energy (EA) and the density of trap sites (N). Through the trapping energy, determined by electrochemistry, it was possible to characterize the types of trap sites, present in the studied materials, in which the presence of reversible sites was configured and whose microstructural characteristic it shows the existence of grain boundaries, with phases of ferrite and perlite, identified after chemical attack with 2% nital and by optical microscopy. The results obtained for the kinetic entrapment parameters are consistent with the results found in the literature and by thermal desorption analysis for these types of steels.