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Abstract In this paper, the thermal-cycling creep of Ni-based superalloy DZ125 is investigated at very high temperature. Experiments were conducted with various parameters including overheating duration, applied stress, temperature interval… Click to show full abstract
Abstract In this paper, the thermal-cycling creep of Ni-based superalloy DZ125 is investigated at very high temperature. Experiments were conducted with various parameters including overheating duration, applied stress, temperature interval and heating/cooling frequency. Microscopic observation has revealed a modified thermodynamic equilibrium with lower γ’ content in comparison to isothermal creep situation. This phenomenon is discussed on the basis of Johnson-Mehl-Avrami-Kolmogorov law and pre-existing theoretical assumptions of dislocation density evolution during thermal transients. A linear relationship between overheating numbers and equilibrium γ’ content is obtained to develop a phenomenological life model of thermal-cycling creep. Life prediction results of proposed method are in good agreement with experimental ones.
Journal Title: Scripta Materialia
Year Published: 2021
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