The Characteristics of Residual Stresses in the Welded Joint of P92 Steel for Fossil Power Plant by the X-ray Diffraction

X-ray 회절을 이용한 화력발전소용 P92 강 용접부의 잔류응력 특성

  • 현중섭 (한국전력공사 전력연구원 수화력발전연구소) ;
  • 유근봉 (한국전력공사 전력연구원 수화력발전연구소) ;
  • 최현선 (한국전력공사 전력연구원 수화력발전연구소)
  • Published : 2008.07.01

Abstract

In the fossil power plant, the reliability of the components which consist of the many welded parts depends on the quality of welding. The residual stress is occurred by the heat flux of high temperature during weld process. This decreases the mechanical properties as the strength of fatigue and fracture or causes the stress corrosion cracking and fatigue fracture. Especially, the accidents due to the residual stress occurred at the weld parts of high-temperature and high-pressure pipes and steam headers. Also, the residual stress of the welded part in the recently constructed power plants has been brought into relief as the cause of various accidents. The aim of this study is the measurement of the residual stress using the x-ray diffraction method. The merits of this are more accurate and applicable than other methods. The materials used for the study is P92 steel for the use of high temperature pipe on super critical condition. The variables of tests are the post-weld heat treatment, the surface roughness and the depth from the original surface. The test results were analyzed by the distributed characteristics of the full width at half maximum intensity (FWHM) in x-ray diffraction intensity curve and by the relation of hardness with FWHM.

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