Transactions of the Korean Society of Pressure Vessels and Piping (한국압력기기공학회 논문집)

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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Effects of Plastic Deformation on Surface Properties and Microstructure of Alloy 690TT Steam Generator Tube

증기발생기 전열관 Alloy 690TT의 소성변형이 표면특성 및 미세조직에 미치는 영향

  • Soon-Hyeok Jeon ;
  • Ji-Young Han ;
  • Hee-Sang Shim ;
  • Sung-Woo Kim
  • 전순혁 (한국원자력연구원 재료안전기술연구부) ;
  • 한지영 (한국원자력연구원 재료안전기술연구부) ;
  • 심희상 (한국원자력연구원 재료안전기술연구부) ;
  • 김성우 (한국원자력연구원 재료안전기술연구부)
  • Received : 2024.05.20
  • Accepted : 2024.05.30
  • Published : 2024.06.30
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Abstract

Denting of steam generator (SG) tube is defined as the reduction in tube diameter due to the stresses exerted by the corrosion products formed on the outer diameter surface. This phenomenon is mostly observed in the crevices between SG tube and the top-of tubesheet or tube support plate. Despite the replacement of SG tube with Alloy 690, which has better corrosion resistance than Alloy 600, the denting of SG tube still remains a potential problem that could decrease the SG integrity. Deformation of SG tube by denting phenomenon can affect the surface properties and microstructure of SG tube. In this study, the effects of plastic deformation on surface properties and microstructure of Alloy 690 thermally treated (TT) tube was investigated by using the various analysis techniques. The plastic deformation of Alloy 690 increased the surface roughness and area. Many surface defects such as ripped surface and micro-cracks were observed on the deformed Alloy 690TT specimen. Based on the electron backscatter diffraction analysis, the dislocation density of deformed SG tube increased compared to non-deformed SG tube. In addition, the effects of changes in surface properties and microstructure of SG tube on general corrosion behavior were discussed.

Keywords

Acknowledgement

본 연구는 한국연구재단을 통해 과학기술정보통신부 연구개발사업(2021M2E4A1037979, RS-2022-00143316)의 지원을 받아 수행되었음.

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