Chemo-Thermo-Mechanical Phase Field Modeling of Sulfide Stress Cracking in DCB Testing and Effect of Plasticity

Hydrogen-assisted cracking (HAC), particularly sulfide stress cracking (SSC) in sour environments, threatens the structural integrity of critical components. While a prior model developed by the authors have addressed temperature-dependent hydrogen diffusion and fracture energy degradation within an elastic phase-field framework, the influence of plastic deformation remains underexplored. This work enhances the developed chemo-thermo-mechanical phase-field model by incorporating standard elasto-plasticity and a coupling mechanism where plastic work partially drives fracture. The formulation accounts for temperature-induced stress, hydrogen-induced toughness degradation, and diffusion kinetics. Validation is performed using DCB simulations of P110 steel under sour conditions across various temperatures, benchmarked against experimental data. Both the elastic and elasto-plastic models capture the observed rise in the SSC threshold K ISSC with temperature, while the elasto-plastic variant predicts slightly more accurate thresholds. For the SSC conditions examined, plasticity had a limited impact on macroscopic behavior, with temperature-dependent transport and degradation being the dominant factors. The proposed model offers a more complete tool for HAC analysis and can support future studies where plasticity plays a larger role.