A mechanistic framework for hydrogen embrittlement

A new mechanism-based approach for hydrogen assisted cracking is proposed. The modeling framework incorporates: (i) the role of statistically stored and geometrically necessary dislocations on crack tip stresses and hydrogen diffusion, (ii) a novel dislocation-based approach to deal with the reversibly trapped hydrogen concentration and (iii) a cohesive zone formulation to account for hydrogen-lowering of the fracture resistance. Finite element computations are conducted, with a control algorithm being employed to ensure convergence in crack propagation studies. Results reveal a very good agreement with the experiments and the important implications of the results in the understanding of hydrogen embrittlement mechanisms are thoroughly discussed