Influence of pro-stress and in-situ stress on the corrosion behavior of zircaloy-4

Influence of pre-stress and in-situ stress on the corrosion behavior of zircaloy-4 was evaluated in steam at 400 .deg. C. In order to observe the pre-stress on the corrosion behavior, the alloys were tensile tested up to three conditions (before YS, between YS and UTS, and after UTS) at room temperature. The microstructures of pre-deformed specimens revealed a high dislocation density as the deformation increased. The results of corrosion tests revealed that the corrosion resistance was not affected by the pre-stress. It is thus concluded that the dislocation formed by the pre-stress does not affect the corrosion behavior of Zr-alloys. However, the corrosion resistance under high applied tensile stress was accelerated. It would be attributed to accelerate the phase transformation near the matrix-oxide interface from tetra-ZrO2 to mono-ZrO2 due to the relaxation of compressive stress in the oxide scales