SIMULATION OF THE DELAYED HYDRIDE CRACKING VELOCITY FOR ZIRCONIUM ALLOY MATERIALS CONSIDERING IRRADIATION EFFECTS

Delayed hydride cracking (DHC) is one of the major factors that affect the safety of zircaloy tubes. In order to effectively simulate DHC, the coupling process including hydrogen diffusion, hydride precipitation, energy flow and mechanical fields should be correctly simulated. In this study, a cohesive model considering irradiation embrittlement and damage accumulation is used to simulate the cracking behavior of zircaloy, and in the finite element model its traction-separation relation is converted to the boundary condition between the traction and normal displacement component in the surfaces to be cracked. The coupling calculation procedures to simulate the DHC behavior using the automatic finite element program generator (FEPG) are obtained and validated, in which the three-dimensional constitutive relation involves plastic strain hardening, irradiation hardening and hydride-induced anisotropic expansion. We find it effective to study the DHC behavior. And we draw the conclusion that irradiation embrittlement and irradiation hardening could visibly accelerate the cracking process. This study improves the numerical simulation method for DHC, provides a reference basis for theoretical study and lays a foundation for further researches on DHC of zircaloy tubes.