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A Study on Hydrogen Damage in Base Metal of API X70

API X70강 배관 모재부의 수소 손상에 관한 연구

  • LEE, HO JUN (Department of Mechanical Engineering, Graduate School of Chung-Ang University) ;
  • YU, JONG MIN (Department of Mechanical Engineering, Graduate School of Chung-Ang University) ;
  • DAO, VAN HUNG (Department of Mechanical Engineering, Graduate School of Chung-Ang University) ;
  • BAE, JAE HYEON (Department of Mechanical Engineering, Graduate School of Chung-Ang University) ;
  • KIM, WOO SIK (Kores Gas Corporation Gas Institute) ;
  • YOON, KEE BONG (Department of Mechanical Engineering, Chung-Ang University)
  • 이호준 (중앙대학교 기계공학부 대학원) ;
  • 유종민 (중앙대학교 기계공학부 대학원) ;
  • 다오반헝 (중앙대학교 기계공학부 대학원) ;
  • 배재현 (중앙대학교 기계공학부 대학원) ;
  • 김우식 (한국가스공사 가스연구원) ;
  • 윤기봉 (중앙대학교 기계공학부)
  • Received : 2020.04.17
  • Accepted : 2020.06.30
  • Published : 2020.06.30

Abstract

In this study, hydrogen charging was conducted for API X70 steel by the electro-chemical hydrogen charging method. Right after hydrogen was diffused from the specimen surface to the inside of the X70, the small punch tests and hydrogen concentration analysis was conducted within 5 minutes. Hydrogen was analyzed by melting the whole specimen and detect the gas after melting. Mechanical properties were measured by the small punch (SP) testing. Fracture surface and specimen surface were observed using scanning electron microscope. Three tests were repeated for study sensitivity of the SP test results under a same charging condition. It was observed that the variation of the maximum load, SP displacement at failure, hydrogen concentration as the charging period was not much in the case of X70 as the other steel such as Inconel. It can be argued that X70 base metal may have high hydrogen damage resistance and hydrogen diffusion in the base metal would not cause much embrittlement. Limitations of the SP test with 0.5 mm thickness for hydrogen damage test for X70 were discussed.

Keywords

References

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