冷却孔周りの過渡的熱応力がおよぼすクリープ疲労き裂進展速度への影響

抄録

Recently, land-based gas turbine has strongly required to play a role in electric power adjustment by introducing renewable energy system. The gas turbine blade is subjected to superimposing of high cycle thermal fatigue load generated by adjustment in addition to the low cycle fatigue load generated by starting and shut-down. In order to study the failure behavior around the cooling holes introduced in gas turbine blade, the crack propagation tests were performed under waveform conditions that the high cycle fatigue load due to thermal transient stress was superimposed on a low cycle fatigue load assuming start and shutdown. As the results, it was shown that the fracture mode was changed depending on the condition of stress amplitude and temperature. The crack propagation behavior could be evaluated via the stress intensity factor range under the condition of fatigue-dominant and the creep J-integral range under the condition of creep-dominant, respectively. Based on the above findings, a method for predicting creep-fatigue fracture modes initiating from the cooling hole was proposed.