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CM247LC 초내열합금에서 일방향응고에 따른 응고조직 변화
이정석 ( Jeongseok Lee ),권석환 ( Seokhwan Kown ),윤병관 ( Byunggwan Yoon ),장병문 ( Byungmoon Chang ),정연길 ( Yongil Jung ),이재현 ( Jehyun Lee ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.11
Directional solidification of CM247LC was performed at a constant growth velocity (300 mm/h) using a Bridgman type furnace. Microstructural features, including the number of grains, PDAS, and EBSD IPF map, were investigated with progressive positions from the starter block. As directional solidification proceeded, the number of grains decreased and PDAS increased. These results indicate that the thermal gradient decreases with distance from the starter block. Thermal gradient changes were estimated by dendrite spacing change in the directionally solidified rod. The EBSD IPF map showed that almost all of the grains were close to the < 001 > preferred direction, but with heights of about 300 mm from the starter block, some grains at the center of the specimen exhibited quite different crystallographic directions near the gate instead of the preferred direction. (Received October 5, 2015; Accepted May 24, 2016)
윤정한(Junghan Yun),이정민(Jeong-Min Lee),석창성(Chang-Sung Seok),권석환(Sukhwan Kwon),윤병관(Byoungkwan Yun),장병문(Byungmoon Chang) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.1
Gas turbine, the core equipment of the power plant, is capable of rapid starting operation and has less carbon dioxide emission than coal power plant. So it has the advantage of being eco- friendly. In order to increase the efficiency of these gas turbines, the turbine inlet temperature has steadily increased and to ensure the safety of the gas turbine, means for protecting parts exposed to high temperatures have also been developed. Protective coating technology is one of them, which plays the role of lowering the temperature of the base metal and preventing oxidation and corrosion. In this paper, thermal fatigue test simulating the operation environment was conducted using the Amdry 9951 protective coating powder applied to the HPT Heat Shield for the Alstom GT 24 gas turbine and the performance before and after the thermal fatigue test was evaluated and examined by adhesive strength test and SEM (EDS) analysis.
단결정 CMSX-4의 상온 및 고온 기계적 물성에 관한 연구
김태형(Taehyung Kim),안성철(Sungchul Ahn),홍석우(Seokwoo Hong),윤병관(Byounggwan Yun),안종기(Jongkee Ahn),석창성(Changsung Seok),한착희(Chakheui Han),김기태(Kitae Kim),신동익(Dongick Shin),장병문(Byungmoon Chang),김용련(Yeongryeon Ki 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
Ni기 초내열합금은 고온에서 강도를 유지할 수 있기 때문에 가스터빈 엔진의 블레이드와 같은 고온 부품에 널리 사용된다. 이런 초내열합금 중 단결정 응고를 통해 만들어진 부품은 고온에서 크리프 특성이 우수하여 최근 가스터빈 엔진에 많이 사용된다. CMSX-4는 이런 단결정 소재로 본 연구에서는 단결정 CMSX-4가 가지는 상온 및 고온에서의 기계적 물성을 평가하였다. 인장 강도 평가 결과 800℃ 근방에서 가장 우수한 인장 강도를 보였고 크리프 시험 결과에서는 고응력에서 파단 수명이 급격하게 감소하였다. 이런 결과는 슬립 시스템의 변화로 고온 또는 고응력에서 강도가 급격하게 변화하는 것으로 판단된다. Ni base superalloy is widely used for blade of gas turbine engine, since it has high strength at high temperature. Among superalloys, single-crystal solodified components are much used in recent gas turbine engine. Single-crystal superalloy. has not only high strength but also high creep resistance than equiaxed structured superalloys. CMSX-4 is representative single-crystal materials and we evaluated mechanical properties at room and high temperature. Tensile test results show that strength is highest around 800℃. Creep test results show that rupture-time was much shortened than predicted time. We can conclude that this results are come from variation slip system along temperature and stress.