報告書番号

T99024

タイトル（和文）

Ni基一方向凝固超合金の高温強度評価法の開発 -第1報：高温引張特性と結晶成長方向のクリープ疲労寿命-

タイトル（英文）

Development of high temperature strength evaluation method for nickel-based directionally solidified superalloy (1st report : High temperature tensile properties and creep-fatigue life of solidified direction)

概要 （図表や脚注は「報告書全文」に掲載しております）

Ni基一方向凝固超合金の高温強度特性を把握するため、クリープ疲労試験を実施した。ひずみ保持の導入によって破損寿命が低下した。圧縮保持条件下では保持に伴うピーク応力の移動、引張保持条件では保持中のクリープキャビティ損傷によって寿命が低下するものと考えられた。ピーク応力の移動およびクリープキャビティ損傷を考慮した非線型累積損傷速度則によって、本材料のクリープ疲労寿命を精度良く推定することができた。

概要 （英文）

In order to clarify the high temperature strength property of a directionally solidified Nickel-based superalloy, a series of the fatigue and creep-fatigue tests were carried out at 870℃. The failure life was reduced by introducing a strain hold period. The life reduction under the compressive strain hold condition is seemed to be caused by the peak stress shift which took place by the unidirectional accumulation of creep strain during the hold period. In the case of tensile strain hold condition, the creep cavities are initiated by the creep effect during the hold period, and they contribute the reduction of the creep-fatigue life.A non-linear damge accumulation model was applied to the creep-fatigue life prediction. Here, the creep damage caused by cavities was considered to accelerate the fatigue damage which was obtained by the relationship between the maximum tensile stress and the fatigue life in order to consider the mean stress effect. By using the model, the creep-fatigue lives were well predicted and all of the results were fallen into the range of a factor of 2 on life.

報告者

キーワード