Multiphase materials are widely used in commercial applications where hydrogen degrades the materials’ performance. Additionally, during its lifetime, the metal will experience different stress states. Therefore, more knowledge about the hydrogen-metal interaction when the steel is subjected to a particular stress level is of great importance. Since the hydrogen diffusivity is closely related to the hydrogen embrittlement phenomenon, this work investigates hydrogen diffusion through dual phase (DP) steel and transformation induced plasticity (TRIP) steel using electrochemical hydrogen permeation. The permeation test cell is based on the classic concept of Devanathan and Stachurski which is modified in order to study hydrogen permeation under a constant uniaxial tensile load. Variable tensile loads were applied to investigate the influence of elastic microstructural changes on the hydrogen diffusion coefficient.
Additionally, permeation experiments were also performed when applying loads near the yield strength. As such, different hydrogen traps are introduced in the materials, which have a considerable effect on the hydrogen diffusion. In case of TRIP steel, the applied plastic load will imply the austenite-martensite transformation and hydrogen which was initially trapped in the austenite phase will become mobile.