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Development of Evaluation Technique of High Temperature Creep Characteristics by Small Punch-Creep Test Method (I) - Boiler Superheater Tube -

SP-Creep 시험에 의한 고온 크리프 특성 평가 기술 개발(I) - 보일러 과열기 튜브 -

  • Baek, Seung-Se (Dept.of Precision Mechanical Engineering, Graduate School of Chonbuk National University) ;
  • Na, Seong-Hun (Dept.of Precision Mechanical Engineering, Graduate School of Chonbuk National University) ;
  • Na, Ui-Gyun (Faculty of Mechanical Engineering, Kunsan National University) ;
  • Yu, Hyo-Seon (Automotive New Technology Research Center, Dept.of Mechanical Engineering, Chonbuk National University)
  • 백승세 (전북대학교 대학원 정밀기계공학과) ;
  • 나성훈 (전북대학교 대학원 정밀기계공학과) ;
  • 나의균 (군산대학교 기계공학부) ;
  • 유효선 (전북대학교 기계공학부, 자동차 신기술 연구소)
  • Published : 2001.12.01

Abstract

In this study, a small punch creep(SP-Creep) test using miniaturized specimen(10${\times}$10${\times}$0.5mm) is described to develop the new creep test method for high temperature structural materials. The SP-Creep test is applied to 2.25Cr-lMo(STBA24) steel which is widely used as boiler tube material. The test temperatures applied for the creep deformation of miniaturized specimens are between 550∼600$^{\circ}C$. The SP-Creep curves depend definitely on applied load and creep temperature, and show the three stages of creep behavior like in conventional uniaxial tensile creep curves. The load exponent of miniaturized specimen decreases with increasing test temperature, and its behavior is similar to stress exponent behavior of uniaxial creep test. The creep activation energy obtained from the relationship between SP-Creep rate and test temperature decreases as the applied load increases. A predicting equation or SP-Creep rate for 2.25Cr-lMo steel is suggested. and a good agreement between experimental and calculated data has been found.

Keywords

2.25Cr-lMo Steel;Small Punch Test;Miniaturized Specimen;SP-Creep Test;Equivalent Fracture Strain($\varepsilon$$_{}$ qfo;SP-Creep Rate($\varepsilon$$_{}$ qf-ss;Creep Rupture Life;Load Exponent;Activation Energy(Q$_{}$ SPC;Boiler Superheater tube;Initial Strain($\varepsilon$$_{}$ qfo

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