Permeácia vodíku v oceliach TRIP

Abstract

The presented thesis is devoted to description of hydrogen permeation and evaluation of the hydrogen diffusion coefficient in the TRIP 800 steel based on C-Mn-Si-P composition by means of the electrochemical permeation technique. Because of the close relationship between the hydrogen diffusion characteristics and micro-structure of the TRIP steel, some of the specimens were plastically deformed to reduce the retained austenite content as a result of its strain – induced transformation to martensite. In order to ensure reliable results, the output side of specimens was palladium coated and two hydrogen chargings were performed with an increasing current density. The hydrogen diffusion coefficients were obtained from the permeation curves using the time-lag method. The lowest values of the hydrogen diffusion coefficients were observed at the first hydrogen charging. On the contrary the highest measured hydrogen diffusion coefficients were recorded during the second hydrogen charging. The hydrogen diffusion coefficients for the specimens without plastic deformation reached lower values compared to the values for the plastically deformed specimens.