POST-TRANSITION CORROSION OF ZIRCALOY-2, LOW-NICKEL ZIRCALOY-2 AM) ZIRCALOY-4 BY STEAM AT 300℃AND 340℃:DEUTERIUM ABSORPTION AND THE INFLUENCE OF HEAT TREATMENT

摘要

The rates of corrosion and deuterium absorption of the alloys have been compared at 300℃ and 340℃ in D20 steam at approximately 100 mg dm-2 weight gain. The post-transition region was reached by pre-oxidation in H2O steam at 450 ℃ followed by a prolonged exposure at the lower temperature until the rate of reaction became constant.nOn the basis of corrosion behaviour, the alloys can be divided into two groups. The alloys of group I, beta-quenched Zircaloy-2 and low-nickel Zircaloy-2, showed identical corrosion behaviour and had a lower deuterium absorption rate but a higher oxidation rate than alloys of group II (alpha-annealed Zircaloy-2, low-nickel Zircaloy-2 and Zircaloy-4 and beta-quenched Zircaloy-4). These alloys showed similar corrosion behaviour with a few exceptions. The presence of beta-quenched Zircaloy-4 with the alpha-annealed alloys is a reflection of the fact that the corrosion behaviour of Zircaloy-4 was insensitive to heat-treatment.