Lamellar구조 TiAl 합금의 크리프-피로 상호작용에 미치는 크리프 손상의 영향

초록

Gamma TiAl alloys have been attracted a lot of research interests because of their high specific strength at elevated temperature. Because the studies on the gamma TiAl alloys have been conducted explosively since the alloys were developed, it is very important to know their research trends. In the present study, the research trends were reviewed to classify the published reports on gamma TiAl alloys. Gamma TiAl alloys, designed to be used for light and high-temperature structural materials, are generally used under the creep-fatigue interaction condition. Therefore, the study on the creep-fatigue interaction of the gamma TiAl alloy is necessary. However, most of the investigators have focussed mainly on fatigue crack growth resistance and fatigue fracture behavior under the condition of high cycle fatigue. In the present study, strain-controlled creep-fatigue and continuous low cycle fatigue tests with lamellar structured Ti-46.6Al-1.4Mn-2Mo(at.%) were conducted. At 800oC, fatigue life was reduced drastically in creep-fatigue test condition compared with that of continuous low cycle fatigue test condition and the reduction of the fatigue life in creep-fatigue test was the result of the creep damage during hold time. In addition, the effects of the creep damage on the creep-fatigue interaction were discussed.