Stress-induced reorientation of hydrides and mechanical properties of zircaloy-4 cladding tubes

Stress-induced reorientation of hydrides and its effect on the stress-strain response of Zircaloy-4 cladding tubes were investigated. The reorientation of hydrides along the radial direction was most pronounced if the tube was cooled from 300 to 200 degrees C under circumferential loading. Reorientation occurred much less frequently at either higher (cooled from 400 to 300 degrees C) or lower (cooled from 200 to 100 degrees C) temperature range. The population of radial hydrides in R43H7 (which was cooled from 400 to 300 degrees C and maintained at 300 degrees C for 7 h) increased drastically during annealing at 300 degrees C, suggesting time dependent stress-aided dissolution of circumferential hydrides and reprecipitation of radial hydrides. The drastic decrease of the strength and the complete loss of the ductility were observed in R32AC and R43H7. (c) 2005 Elsevier B.V. All rights reserved.