EFFECT OF CREVICE ON LOW-CYCLE FATIGUE BEHAVIOR OF PRESSURE-VESSEL STEEL IN HIGH-TEMPERATURE PRESSURIZED-WATER

The effect of crevice on low cycle fatigue behavior oi a low alloy steel JIS SQV2A (equivalent to ASTM A533B cl. 1) for reactor pressure vessel was investigated in high temperature pressurized water at 561K and 7.8Mpa. Crevice were made on the specimen surface by attaching a pair of split collars of the same material. The dissolved oxygen (DO) concentration was varied from 10 ppb to 4000 ppb. The fatigue life was found longer for creviced specimens than that for no creviced ones, especially for low strain range. The same trend was observed at low DO concentration levels. In case of no creviced specimen, fatigue life was notably reduced for DO concentrations higher than 1000 ppb. It can be concluded that the extention of fatigue life of the creviced specimens is due to the reduction of DO concentraion in the crevice.