Abstract
To study the subcritical crack growth (SCG) behavior for hydrided Zircaloy-4 plate, sustained load tests were performed on fatigue precracked specimens in Ar atmosphere at 200, 250, and 300 °C with hydrogen contents up to 290 ppm. Log crack velocity versus stress intensity curves showed typical three-stage crack growth behavior. The values of threshold stress intensity (K th ) were not sensitive to both temperature and hydrogen content and were about a constant value, 21 MPa√m. The crack growth velocity at stage II, (da/dt) II , increased with increasing temperature. In general, the SCG behavior is not consistent with the classical Dutton-Puls delayed hydride cracking model, except for the specimen containing 110 ppm H tested at 200 °C. On the basis of metallographic and fractographic results, the crack propagation process is proposed. The critical stress intensity, K c , decreased with increasing hydrogen content, which indicates that the effect of increasing hydrogen concentration is to shorten the K range in stage II.