XRD-FEM Coupled Hydrogen Diffusion Analysis Within Duplex Steel Microstructure
Please login to view abstract download link
Understanding of hydrogen within duplex steels at the microscopic level is of great importance for getting insight into possible failure mechanisms and the kinetics of hydrogen diffusion. Hydrogen introduced during production or from external sources tends to accumulate at microstructural inhomogeneities such as grain boundaries, inclusions and pre-existing cracks leading to premature failure. In this work we investigate hydrogen diffusion by coupling in-situ hydrogen charging experiments performed at the synchrotron with finite element simulations of a duplex steel exhibiting a multi-phase microstructure, consisting of ferrite and austenite. The synchrotron experiments enable indirect determination of the hydrogen content within austenite grains via lattice expansion. These measurements are reproduced using a finite element model of the actual microstructure in combination with a diffusion model that captures trapping and also explicitly accounts for grain boundary diffusion. The results of the proposed model are validated by XRD data showing hydrogen redistribution within the microstructure. The model also allows to evaluate hydrogen diffusion within the microstructure during hydrogen charging in analogy to the experimental conditions.
