Modelling Hydrogen Induced Stress Corrosion Cracking in Austenitic Stainless Steel

A model has been developed which simulates the deformation of single crystal austenitic stainless steels and captures the effects of hydrogen on stress corrosion cracking. The model is based on the crystal plasticity theory which relates critical resolved shear stress to plastic strain and the strength of the crystal. We propose an analytical representation of hydrogen interactions with the material microstructure during deformation and simulate the effects hydrogen will have on void growth prior to fracture. Changes in the mechanical properties of the crystal prior to fracture are governed by the interaction of hydrogen atoms and ensembles of dislocations as the crystal plastically deforms and is based on the hydrogen enhanced localised plasticity (HELP) mechanism. The effects of hydrogen on void growth are considered by analysing the effect of hydrogen on the mechanical property of material bounding an embedded void. The model presented has been implemented numerically using the User Material (UMAT) subroutine in the finite element software (ABAQUS) and has been validated by comparing simulated results with experimental data. Influencing parameters have been varied to understand their effect and test sensitivities.