2013 年 62 巻 10 号 p. 648-653
Creep damage assessment methods considering the effect of stress multiaxiality are discussed in order to evaluate creep crack initiation from stress concentrating fields such as notch roots. Creep tests using notched specimens were performed and damaging features around the notch root were investigated. Micro damages such as small creep cracks were mainly observed around several hundred micro-meters below the surface. Inelastic analyses taking primary creep into account were also performed. The area of high stress multiaxiality obtained from the analyses coincides with the area where micro damages were observed. Creep damage evaluation methods are also discussed. The strain based method was in good agreement with experimental results. Stress multiaxiality should be considered in evaluation of creep damage in stress concentrating fields.