Evaluation of the thermal creep behaviors and microstructure of Zircaloy-4 strip Original Research Article

The thermal creep behaviors and the microstructure characteristics for the crept specimens of Zircaloy-4 strip were investigated under a constant load stress in the temperature range of 350–450 °C and a stress range from 110 to 230 MPa. A microstructure evaluation was carried out for the specimens before and after the creep test by using a TEM to understand the correlation between the creep mechanism and the microstructure. A variation of the crystal orientation with the creep deformation was investigated by using the electron back-scattered diffraction (EBSD) analysis. The stress exponent was in the range of 8–10 and the value of the stress exponent was varied by the applied stress. From the analysis of the stress exponent and a TEM microstructural observation of the crept specimens, the creep of Zircaloy-4 strip at a tested condition was mainly controlled by dislocations. From the EBSD results, it was observed that the crystal orientation in the crept sample strained about 10% was not changed as compared to the as-received sample.