THE MODIFIED RATE APPROACH METHOD TO EVALUATE FATIGUE LIFE UNDER SYNCHRONOUSLY CHANGING TEMPERATURE AND STRAIN RATE IN ELEVATED TEMPERATURE WATER IN AUSTENITIC STAINLESS STEEL

摘要

Hie fatigue life of steel of light water reactor (LWR) in elevated temperature water is affected by the composition of die environmental water, decreasing strain rate and increasing temperature. The effects of these parameters on fatigue life reduction have been investigated experimentally. One problem to be discussed is the fact that the previous studies which leaded main results on the environmental effects were generally executed by experimental parameters constant. On the other hand, in an actual plant, such parameters as temperature and strain rate are changing transient In order to evaluate fatigue damage in an actual plant on the basis of experimental results under constant temperature and constant strain rate conditions, the modified rate approach method was developed. The study has conducted as a part of the EFT project in order to evaluate the applicability of the modified rate approach to the case that LWR environment The applicability of a modified rate approach method to the case where temperature and strain rate varied simultaneously was discussed in the previous paper. In order to confine the applicability under extended condition, the tests of which conditions were different from those of the previous study were conducted. The accuracy of modified rate approach is same level of the result of previous paper.