가스터빈 버너용 Inconel 738LC 합금의 작동시간에 따른 열화거동 분석

• Published in: 대한금속·재료학회지, 51(3) Vol. 51; no. 3; pp. 159 - 168
• Main Authors: 홍현욱, Hyun Uk Hong, 박경미, Kyung Mi Park, 김희수, Hee Soo Kim, 김인수, In Soo Kim, 최백규, Baig Gyu Choi, 조창용, Chang Yong Jo, 우타관, Ta Kwan Woo, 이재현, Je Hyun Lee
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 20.03.2013; 대한금속·재료학회
• Subjects: alloys; degradation; gas turbine; intergranular crack; microstructure; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2013.51.3.159

The microstructure and mechanical property degradation of a gas turbine SEV burner made of the nickel-based superalloy Inconel 738LC were investigated with increasing operation times in the range of 24000-65000 equivalent number of operating hours (EOH). The original cuboidal shape of γ? particles with a size of 400-500 nm became spherical with a diameter larger than 1 μm. The γ? coarsening kinetics conformed well to the LSW model suggesting that the variation of r³as a function of exposure time is linear. In the hottest zone of the SEV burner operated for 65000 EOH, a continuous film of carbides along the grain boundaries was observed as a result of the transformation of MC carbide to M_23C_6＋γThis continuous film of M_23C_6 carbides provided a preferential site for intergranular crack initiation and propagation during tensile testing, and reduced accordingly the alloy ductility, whereas it was favorable to tensile strength.