Modeling of hydrogen diffusion in duplex stainless steel based on microstructure using finite element method

Duplex stainless steels (DSS) are subjected to a deleterious effect known as hydrogen assisted cracking (HAC). Revealing the hydrogen diffusion behavior in DSS is the key to understanding the mechanism of HAC, since hydrogen diffusivity and solubility are different in ferrite and austenite. In this study, finite element (FE) analyses on hydrogen diffusion behavior in DSS were performed by considering the combined effect of heterogeneous microstructure and hydrostatic stress with the help of finite element program-ABAQUS. Two-dimensional dual-phase models with representative volume element were applied based on the obtained microstructure using optical microscopy. The constant loading catholic charging experiments were also carried out to provide comparative results for characterization on the susceptibility of DSS to HAC. Results indicate that hydrogen diffusion in DSS is strongly dependent on the morphological diversity of microstructure. Compared to the coupled analysis with stress effect, hydrogen diffusivity and concentration are observed with an increase, and experimental results show that most of the HAC cracks initiate in the ferrite phase and arrested by austenite.