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X-ray 회접을 이용한 화력발전소용 P92 강 용접부의 잔류응력 특성
현중섭(Jung Seob Hyun),유근봉(Keun Bong Yoo),최현선(Hyun Sun Choi) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.7
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.
현중섭(J. S. Hyun),송기욱(G. W. Song),박정현(J. H. Park),하정수(J. S. Ha) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8
The piping system of fossil power plant is subject to a severe thermal range and usually operates well into the creep range. Cyclic operation of the plant subjects the piping system to mechanical and thermal fatigue mechanisms and poor or defective support assemblies can impose massive loads onto the system. In order to prevent the serious damage and failure of the critical pipe system in fossil power plants, 3-dimensional displacement measurement system was developed for the on-line monitoring. Two types displacement measurement systems were developed with LVDT type sensor and rotary encoder type sensors. These systems were installed and operated on the piping system of fossil power plant successfully.
현중섭(Jung Seob Hyun),이영신(Young Shin Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.6
Most domestic fossil power plants have exceeded 100,000 hours of operation with the severe operating condition. Among the critical components of fossil power plant, high temperature steam pipe systems have had a many problems and damage from unstable displacement behavior because of frequent start up and shut down. In order to prevent the serious damage and failure of the critical pipe system in fossil power plants, 3-dimensional displacement measurement system was developed for the on-line monitoring. Displacement measurement system was developed with a use of a LVDT type sensor and two rotary encoder type sensors. This system was installed and operated on the real power plant successfully.
현중섭(Jung Seob Hyun),송기욱(Gee Wook Song),이영신(Young Shin Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.12
The rotating components such as turbine rotors in service are generally subjected to multiaxial cyclic loading conditions. The prediction of fatigue life for turbine rotor components under complex multiaxial loading conditions is very important to prevent the fatigue failures in service. In this paper, axial and torsional low cycle fatigue tests were preformed for 3.5NiCrMo steels serviced low pressure turbine rotor of nuclear power plant. Several methods to predict biaxial fatigue life such as Tresca, von Mises and Brown & Miller's critical plane approach were evaluated to correlate the experimental results for serviced NiCrMoV steel. The fracture mode and fatigue characteristics of NiCrMoV steel were discussed based on the results of fatigue tests performed under the axial and torsional test conditions. In particular, the Brown and Miller's critical plane approach was found to best correlate the experimental data with predictions being within a factor of 2.