Simulations of crack extensions in arc-shaped tension specimens of uncharged and hydrogen-charged 21-6-9 austenitic stainless steels using cohesive zone modeling with varying cohesive parameters

•Simulate crack extensions in A(T) specimens using cohesive zone modeling approach.•Calibrate fixed cohesive parameters to fit experimental load–displacement curves.•Calibrate varying cohesive parameters to fit experimental load-crack extension curves.•Computational results with varying cohesive parameters fit experimental data well.•Compare cohesive parameters for uncharged and hydrogen-charged A(T) specimens. Crack extensions in uncharged and hydrogen-charged side-grooved A(T) specimens of conventionally forged 21-6-9 austenitic stainless steels are simulated using the cohesive zone modeling approach. Two-dimensional plane strain finite element analyses with fixed cohesive parameters are first conducted to fit the experimental load-displacement curves. Similar analyses using varying cohesive parameters as functions of the crack extension are then conducted to fit the experimental load-crack extension and crack extension-displacement curves. The computational results with varying cohesive parameters can fit very well the experimental data. The computational results also indicate that the average cohesive energy for the hydrogen-charged A(T) specimen is lower than that for the uncharged A(T) specimen.