Effect of hydride orientation on the stress–strain state of zirconium cladding under circumferential tension

A reproducible three-dimensional finite element methodology has been developed to quantify the effect of δ-ZrH1.66 hydride orientation on stress and plastic strain localization in a tubular zirconium alloy segment under circumferential tension. The orientation state of the hydride ensemble was characterized by the orientation factor Fn (the fraction of radially oriented hydrides) in the range from 0 to 1 with a step of 0.1; for each Fn value, 150 statistically independent realizations were generated at fixed hydride morphology and concentration. The matrix was modeled as an anisotropic elastic–plastic material with texture taken into account, whereas hydrides were treated as linear-elastic inclusions. To analyze the distributions of the von Mises equivalent stress σeq, the normal stress components σRR, σTT, σLL and the equivalent plastic strain εp in the vicinity of hydrides, a volume-weighted kernel density estimation (KDE) was applied to matrix elements within 10 μm of inclusion surfaces. It is shown that increasing Fn results in a transition from sharply localized stress and strain extrema for tangentially oriented hydrides to a more spatially extended stress redistribution for radially oriented hydrides, accompanied by an increased contribution of the compressive σRR and σLL components and suppression of local plastic relaxation. The results indicate that radially oriented hydride configurations impose stronger local constraint on the surrounding matrix and reduce its plastic relaxation capacity, which is consistent with previously reported quantitative fractographic trends.

1. Russian Science Foundation - Project No. 24-79-10289, https://rscf.ru/en/project/24-79-10289/