Coupled Chemo-Thermo-Mechanical Phase Field Modeling of Hydrogen Assisted Cracking

Hydrogen-assisted cracking (HAC), including sulfide stress cracking (SSC), poses a critical threat to the integrity of materials in sour environments. However, existing models neglects the complex interplay of temperature and hydrogen transport. This paper introduces a thermodynamically consistent chemo-thermo-mechanical phase-field framework to simulate HAC under realistic, varying thermal and chemical conditions. The model uniquely integrates temperature-dependent hydrogen diffusion, hydrogen-induced critical energy release rate degradation, and thermally induced mechanical stresses, enabling accurate prediction of crack initiation and propagation in corrosive sour environments. Validation against Double Cantilever Beam (DCB) tests for low-alloy oil country tubular goods (OCTG) steels demonstrates excellent agreement with experimental results, capturing the temperature-driven reduction in fracture toughness. Numerical simulations of pipes with defects and residual stresses further showcase the model's ability to replicate real-world failure scenarios. By addressing the crucial interplay of thermal, chemical, and mechanical fields, this work significantly advances predictive capabilities for HAC and provides a robust foundation for designing resilient infrastructure in the oil and gas industry, ultimately enhancing safety and reliability.