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Vol.49, No.2, 112 ~ 121, 2011
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| Title |
| Deformation and Failore Behavior during Thermo-Mechanical Fatigue of a Nickel-Based Single Crystal Superalloy |
| 김인수 In Soo Kim , 강정구 Jeong Gu Kang , 조창용 Chang Yong Jo , 홍현욱 Hyun Uk Hong , 강남현 Nam Hyun Kang , 최백규 Baig Gyu Choi |
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| Abstract |
| The out-of-phase thermo-mechanical fatigue (OP TMF) in a <001> 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 <100> 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. |
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| Key Words |
| alloys, fatigue, deformation, twinning, transmission electron microscopy, TEM |
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