Elastic-plastic crack-tip field in hydride forming metals under hydrogen chemical equilibrium

Abstract

Hydride precipitation ahead of a crack is examined under conditions of hydrogen chemical equilibrium, constant temperature and elastic-plastic power-law hardening metal behavior. The limiting conditions are approached via the interaction of the operating physical mechanisms of material deformation, hydrogen diffusion and hydride precipitation. Hydrides are characterized by hydride volume fraction and isotropic transformation strain. Analytical relations are presented for hydride volume fraction and stress, as well as for hydride precipitation zone boundary. It is shown that there is an annulus, within the hydride precipitation zone, where stresses, although vary according to \({\left(1/r\right)}^{1/n+1}\) -singularity, deviate significantly from the well-known HRR-field, being smaller, according to the difference of hydrostatic stress before and after hydride precipitation. Hydride precipitation zone increases with crack-tip constraint, given by triaxiality parameter \(Q\).