Electrochemical hydrogen permeation measurement through TRIP steel under loading condition of phase transition

Abstract

In-situ observation of the change in hydrogen permeation current under loading condition of the phase transition in the TRIP steel was successfully evaluated by utilizing the new electrochemical permeation technique. This study clearly shows that after the initial drop of the permeation current upon application of plastic stress, the current increases slowly, but it continues going up much higher than the steady-state current value. It is attributed to the combined effect of the dislocation generation and deformation-induced martensitic decomposition of austenite during the loading in the transient range from elastic to plastic stress. This result indicates clearly that hydrogen atoms trapped initially in austenite matrix become mobile hydrogen atoms which can easily diffuse in transformed-martensite by the additional loading to plastic range. It results in the faster diffusion of hydrogen atoms and increase in the permeation flux. (C) 2012 Elsevier B.V. All rights reserved.