First Principles Study on Cross Scale Hydrogen Induced Fracture of Stainless Steel Matrix

Hydrogen induced delayed fracture is a common form of failure in steel materials. Hydrogen embrittlement is caused by the combined effect of hydrogen and stress, resulting in a decrease in the toughness and plasticity of steel materials. The influence of hydrogen atoms on the mechanical properties of stainless steel matrix was studied using first principles method based on density functional theory, and a hydrogen embrittlement fracture mechanism of stainless steel based on cohesive force was proposed. This work found that by calculating the cohesive force at different hydrogen concentrations, it was discovered that hydrogen doping causes severe lattice distortion in the stainless steel matrix. The reason for this is that hydrogen invades the matrix and undergoes plastic deformation along the [001] crystal direction, reducing the cohesive force inside the matrix and leading to material fracture. Furthermore, it was found that cohesion mainly depends on the charge density distribution between hydrogen and surrounding metal atoms, which can enhance the strength of the matrix under certain hydrogen doping concentration conditions. This discovery provides a theoretical basis for subsequent research on hydrogen induced fracture warning technology.