A Study on Hot Ductility Behavior of Ni-based Superalloys

니켈기 초내열합금의 고온연성거동에 관한 연구

  • Lee, Choung-Rae (Division of Materials Science and Engineering, Hanyang University) ;
  • Um, Sang-Ho (Division of Materials Science and Engineering, Hanyang University) ;
  • Kim, Sung-Wook (Division of Materials Science and Engineering, Hanyang University) ;
  • Choi, Cheol (Power Generation Lab., Korea Electric Power Research Institute) ;
  • Lee, Chang-Hee (Division of Materials Science and Engineering, Hanyang University)
  • 이청래 (한양대학교 신소재공학부) ;
  • 엄상호 (한양대학교 신소재공학부) ;
  • 김성욱 (한양대학교 신소재공학부) ;
  • 최철 (한전 전력연구원 기술정책실 신기술센터) ;
  • 이창희 (한양대학교 신소재공학부)
  • Published : 2004.04.01

Abstract

Plasma transferred arc welding (PTAW) has been taken into consideration for repairing Ni-based superalloy components used gas turbine blades. Various cracks has been generally reported to be found in the base metal heat affected zone(HAZ) along grain boundary. Thus, hot cracking susceptibility of Ni-based superalloys was evaluated according to heat treatments. Hot ductility test was conducted on specimens with solution treated at 112$0^{\circ}C$ for 2 hours and aging treated at 845$^{\circ}C$ for 24hours after solution treatment. The results of the hot ductility test appeared that solution treated specimens were the highest ductility recovery rate among three conditions. The loss of ductility at high temperature in Ni-based superalloy was mainly controlled by the degree of pain boundary wetting due to constitutional liquation of MC carbide precipitates. Meanwhile, the highest ductility recovery rate in solution-treated alloys seems to be lack of M23C6, which can be dissolved during heating and then result in the local enrichment of Cr in the vicinity of the grain boundary.

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