Cohesive zone modeling of hydrogen-induced stress cracking in 25% Cr duplex stainless steel

Hydrogen-influenced cohesive zone elements are implemented in finite element models of rectangular notched tensile specimens of 25% Cr stainless steel. A three-step procedure consisting of stress analysis, diffusion analysis and cohesive zone fracture initiation analysis was performed. A linear traction separation law gives a good fit with experimental results for stress levels just below the material yield stress. Hydrogen concentrations of 40 ppm at the surface and 1 ppm in bulk always produces crack initiation at the surface.