報告書番号

T99069

タイトル（和文）

疲労およびクリープ疲労条件下におけるNi基単結晶超合金のき裂発生および伝ぱ寿命の定量的評価

タイトル（英文）

Quantitative evaluation of crack initiation and propagation life of Ni-based single crystal superalloy under fatigue and creep-fatigue conditions

概要 （図表や脚注は「報告書全文」に掲載しております）

Ni基単結晶超合金における疲労寿命のばらつきおよび圧縮保持クリープ疲労条件における顕著な寿命低下の要因を明らかにするため、疲労および圧縮保持クリープ疲労条件でき裂伝ぱ試験を実施した。試験結果を元にき裂伝ぱ解析を行うことにより疲労寿命のばらつきの下限界値を予測した。また、クリープ疲労条件におけるき裂発生・伝ぱ寿命を定量的に明らかにした。

概要 （英文）

Scatter of the fatigue life and remarkable reduction of the creep-fatigue life under the compressive hold condition are important problems for in life assessment of gas-turbine blades due to the absence of high-accuracy life prediction method for them. Although the quantitative evaluation of the crack initiation and propagation life is important to know the main cause of the scatter or the life reduction, they have not been clarified sufficiently because of the difficulty of the experiments. A series of fatigue and creep-fatigue tests were carried out at 1173K to clarify the scatter and the life reduction characteristics. Naturally introduced crack propagation tests were also carried out under the fatigue and compressive hold creep-fatigue conditions and the crack initiation and propagation characteristics were clarified quantitatively. The lower bound of fatigue scatter band can be successfully predicted by crack propagation simulation for the maximum eutectic γ' phase in the specimen. Several important causes of the creep-fatigue life reduction were pointed out quantitatively.

報告者

キーワード