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pISSN : 1598-706X / eISSN : 2288-8381


(논문)연구논문

한국주조공학회지 (41권6호 505-515)

Temperature Dependent Creep Properties of Directionally Solidified Ni-based Superlloy CM247LC

일방향 응고 니켈기 초내열 합금 CM247LC의 온도에 따른 크리프 특성

Baig-Gyu Choi†, Jeonghyeon Do, Joong Eun Jung, Woo-Young Seok, Yu-Hwa Lee and In Soo Kim

Korea Institute of Materials Science

DOI : http://dx.doi.org/10.7777/jkfs.2021.41.6.505

Abstract

Creep properties of directionally solidified Ni-based superalloy CM247LC under various temperature and stress conditions have been investigated. In the heat-treated specimen, some portion of eutectic γ-γ' remained, and uniform cubic γ' was observed in the dendrites. At low temperature (750℃) and high stress condition, a large amount of deformation occurred during the primary creep, while the tertiary creep region accounted for most of the creep deformation under high temperature and low stress condition. γ' particles are sheared by dislocation dissociated into super lattice partial dislocations separated by stacking faults at 750℃. No stacking faults in γ' were found at and above 850℃ due to the temperature dependence of the stacking fault energy. Raft structure of γ' was found after creep test at high temperature of 950℃ and 1000℃. At 850℃, the deformation mechanism was shown to be dependent on the stress condition, and so rafting was observed only under low stress condition.

Keywords

Ni-based superalloy, Directional solidification, CM247LC, Creep and Deformation mechanism