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분말야금 및 주조형 니켈기 초내열합금 크리프 신뢰성의 초음파 모니터링
최찬양,송진헌,오세웅,김정석,권숙인,오승탁,현창용,변재원,Choi, Chan-Yang,Song, Jin-Hun,Oh, Se-Ung,Kim, Chung-Seok,Kwun, Sook-In,Oh, Sung-Tag,Hyun, Chang-Yong,Byeon, Jai-Won 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.3
An attempt was made to evaluate creep reliability of two commercial Ni-based superalloys by using ultrasonic wave. The materials include fine-grained PM alloy fabricated by mechanical alloying and subsequent hot isostatic pressing, and IN738LC cast alloy with a grain size of a few cm. Microstructural parameters (fraction of creep cavity and size of ${\gamma}^{\prime}$ precipitates) and ultrasonic parameters (velocity, attenuation) were measured to try to find relationships between them. Ultrasonic velocity decreased with creep cavity formation in PM alloy. On the other hand, no distinct changing trend of ultrasonic velocity was observed for IN738LC alloy. Ultrasonic attenuation was found to have a linear correlation with the size of ${\gamma}^{\prime}$ precipitates and was suggested as a potential parameter for monitoring creep reliability of IN738LC alloy.
초음파현미경을 이용한 Co 기 초내열 합금 열화재의 비파괴평가
김정석(Chung Seok Kim),송진헌(Jin Hun Song),권숙인(Sook In Kwun),임재생(Jea Seang Lim),박익근(Ik Keun Park) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
This research investigates the feasibility of ultrasonic microscope for nondestructive assessment of thermal degradation in artificially aged commercial Co-base superalloy, FSX414. This alloy has been used for high temperature structure applications such as stationary gas turbine blade and nozzle chamber in fossil plant. Microstructural change was found that the fine carbides became coarser and spheroidized in matrix as aging time increased. The leaky surface acoustic wave velocity gradually decreases by a maximum of 4.7% with increasing aging time up to 4,000hours. However, the longitudinal wave velocity has a little change. Also, it has a good correlation between leaky surface acoustic wave velocity and Vickers hardness. Consequently, LSAW can be used to examine the degree of degradation in thermally aged Co-base superalloy.