Journal of Welding and Joining

The Korean Welding and Joining Society (대한용접접합학회)
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Heat Treatment Effect on Super Duplex Stainless Steel UNS S32750 FCA Multipass Welds

슈퍼 듀플렉스 스테인리스강 UNS S32750의 FCA 다층 용접부의 용접 후 열처리 영향

  • Jang, Bok-Su (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Moon, In-June (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Lim, Myung-Jin (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Kim, Se-Cheol (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Kim, Soo-Sung (Research Reactor Development Division, Korea Atomic Energy Research Institute) ;
  • Lee, Jung-Won (Research Reactor Development Division, Korea Atomic Energy Research Institute) ;
  • Park, Hai-Woong (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Koh, Jin-Hyun (School of Energy.Materials.Chemical, Korea University of Technology and Education)
  • 장복수 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 문인준 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 임명진 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 김세철 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 김수성 (한국원자력원구원 연구로개발부) ;
  • 이정원 (한국원자력원구원 연구로개발부) ;
  • 박해웅 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 고진현 (한국기술교육대학교 에너지.신소재.화학공학부)
  • Received : 2014.01.28
  • Accepted : 2014.02.25
  • Published : 2014.04.30
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Abstract

This study was carried out to investigate the effect of postweld heat treatment(PWHT, 930, 1080, $1230^{\circ}C$) on the microstructure, phase formation, pitting corrosion and mechanical properties such as hardness, tensile strength and impact values of super duplex stainless steel(UNS S32750) multipass welds. Based on the microstructural examination and X-ray diffraction analysis, it was found that the ${\sigma}$ phase was formed in the welds heat treated at $930^{\circ}C$ in which the ferrite content greatly decreased into 5~10% in the welds. The secondary austenite was formed in the reheated zone of welds and redissolved into ferrite with increasing heat treatment temperatures. The tensile strength and impact values of welds heat treated at $930^{\circ}C$ were the lowest and revealed the brittle fracture surface. The weight loss by pitting corrosion increased with test temperatures. It was confirmed that pitting corrosion occurred mainly in secondary austenite of reheated zones. The postweld heat treatment temperature is recommended to be in the range of $1050{\sim}1150^{\circ}C$.

Keywords

References

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