Crack initiation of alloy 600 in PWR water

Abstract

Crack initiation has often been measured using simple, unmonitored tests such as bolt-loaded U bends, where the time to initiation is only estimated by occasional interruption, and the stress drops by ~12% from the change in modulus along with stress relaxation, which can be substantial in some materials and heats. The objective of this study was to develop and demonstrate improved techniques using actively loaded tensile specimens and continuous on-line monitoring of crack development using reversing DC potential drop. To complement the crack initiation data, the crack growth response of the heats and conditions was also evaluated.