열기계적 피로에 따른 단결정 니켈기 초내열합금의 변형 및 파괴거동

• Published in: 대한금속·재료학회지, 49(2) Vol. 49; no. 2; pp. 112 - 120
• Main Authors: 김인수, In Soo Kim, 강정구, Jeong Gu Kang, 조창용, Chang Yong Jo, 홍현욱, Hyun Uk Hong, 강남현, Nam Hyun Kang, 최백규, Baig Gyu Choi
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 20.02.2011; 대한금속·재료학회
• Subjects: alloys; deformation; fatigue; TEM; transmission electron microscopy; twinning; 재료공학
• ISSN: 1738-8228; 2288-8241

The out-of-phase thermo-mechanical fatigue (OP TMF) in a oriented single crystal nickelbased superalloy CMSX-4 has been studied. OP TMF life was less than a half of low cycle fatigue(LCF) life in spite of a small hysteresis loop area of OP TMF compared to that of LCF. The failure was caused by the initiation of a crack at the oxide-layered surface followed by its planar growth along the γ channel in both LCF and OP TMF. However, deformation twins appeared near the major crack of OP TMF. The multiple groups of parallel twin plates on {111} planes provided a preferential path for crack propagation, which caused a significant decrease in OP TMF life. Additionally, the analysis on the surface crack morphology revealed that the tensile strain at the minimum temperature of OP TMF was found to accelerate the crack propagation.