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Nondestructive Evaluation for Mechanical Degradation of Ultrasuper-Critical Heat-Resistance Steel by Reversible Permeability

가역투자율를 이용한 초초임계압 내열강의 기계적 열화에 관한 비파괴평가

  • Ahn, SeongBin (Department of Materials Science and Engineering, Chosun UNIV.) ;
  • Kim, JaeJin (Department of Materials Science and Engineering, Chosun UNIV.) ;
  • Seo, DongMin (Department of Materials Science and Engineering, Chosun UNIV.) ;
  • Kim, ChungSeok (Department of Materials Science and Engineering, Chosun UNIV.)
  • 안성빈 (조선대학교 재료공학과) ;
  • 김재진 (조선대학교 재료공학과) ;
  • 서동민 (조선대학교 재료공학과) ;
  • 김정석 (조선대학교 재료공학과)
  • Received : 2018.09.10
  • Accepted : 2018.10.02
  • Published : 2018.12.31

Abstract

Nondestructive evaluation for mechanical degradation of ultrasuper-critical (USC) heat-resistance steel, which is attractive to the next generation of power plants is studied by magnetic reversible permeability. The interrelationship between reversible permeability and high-temperature mechanical degradation has been investigated by precise measurement of permeability nondestructively. Also, the effects of microstructural variation on reversible permeability are discussed. Isothermal aging was observed to coarsen the tempered carbides ($Cr_{23}C_6$), generated the intermetallic phases ($Fe_2W$), and grow rapidly during aging. The dislocation density also decreases steeply within lath interior. The peak to peak interval (PPI) of reversible permeability profile decreased drastically during the initial 500 h aging period, and was thereafter observed to decrease only slightly. The variation in PPI is closely related to the decrease in the number of pinning sites and the degradation in tensile strength.

Keywords

References

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