Hydrogen-enhanced localized plasticity (HELP) is a major cause of material ductility reduction. In this study, the effect of hydrogen on ductile fracture is demonstrated by its influence on the process of void growth and coalescence. Assuming an initially uniform hydrogen distribution and a periodic array of spherical voids present in the material, a series of finite element analyses of a representative material volume subjected to various stress states was carried out. The evolution of local stress and deformation states results in hydrogen redistribution in the material, which in turn changes the material’s flow property because of the HELP effect. The results show that hydrogen reduces the ductility of the material by accelerating void growth and coalescence, and the effect of hydrogen on ductile fracture is strongly influenced by the stress state experienced by the material, as characterized by the stress triaxiality and the Lode parameter.
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