Microstructure Anisotropy Effect on Stress and Hydrogen Distribution in Micro Area for Martensitic Stainless Steel

Abstract

Elastic stiffness distribution of martensite microstructure was analyzed by using Electron Back Scatter Diffraction(EBSD) experiment, based on which the coupled finite element model of stress-hydrogen interaction was established to study the influence of martensitic microstructure anisotropy on the micro local stress and hydrogen distribution. The results show that misorientation between adjacent Block Laths is 60°, and different Block Laths have different elastic stiffness in the same loading direction, which resulted in the heterogeneous distribution of micro stress and hydrogen, and micro stress can be characterized by microstructure element of Block Lath.Elastic stiffness gradient and Block size play a significant role in stress concentration among microstructures, and while stress concentration can affect hydrogen distribution. High elastic stiffness gradient and large size of Block Lath cause high stress concentration, accumulate high concentration of hydrogen, which initiate crack of hydrogen embrittlement in the end. The above results are consistent with micro fracture morphology and EBSD experiment on crack region.

Keywords

• anisotropy
• hydrogen diffusion
• elastic stiffness
• hydrogen embrittlement
• FEM
• EBSD