EFFECT OF DISSOLVED HYDROGEN ON THE DUCTILE PROPERTIES OF METALS AS A RESULT OF NUCLEATION ON DISLOCATIONS

It is shown that stress concentration on dislocations in hydrogenized metals gives rise to stable alpha' phase nuclei on a background of bulk alpha phase (or stable alpha phase nuclei on a background of bulk alpha' phase). The nuclei both decrease the linear tension of dislocations, which leads to instability of the dislocation structure, and generate an additional friction force, which acts on the dislocations. Estimations show that this mechanism results in metal embrittlement. The decrease in dislocation linear tension intensifies the plasticity in the vicinity of stress concentrators, the plastic zone being highly localized.