The Impact of Stress-Strain States on Hydrogen Flux in Martensitic Steels

Abstract

The role of stress-strain states in hydrogen distribution, concentration and mobility on martensitic steel is outlined by performing tensile tests until fracture on flat, smooth, tensile specimens under simultaneous electrochemical permeation test. A specific device was designed in order to combined mechanical and electrochemical permeation (EP) experiments. Hydrogen charging was performed in sulfuric acid solution and the hydrogen detection was performed in NaOH solution. It is demonstrated that hydrogen state can be influenced by elastic distortion at different microstructural scales related to mechanical defects (vacancies, dislocations), metallurgical components (grain boundaries, precipitates), internal and applied constraints. In additional, the mobile dislocations increase the hydrogen flux in relation with a drag process and the storage dislocations decrease the hydrogen flux in accordance with a trapping mechanism.