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Corrosion Fatigue Crack Propagation Behaviour of TMCP Steel Plate at Ballast Tank of Ship Structure under the Condition of Cathodic Overprotection

선체구조 Ballast Tank 고장력 TMCP강판의 과방식중 부식피로균열 전파거동

  • Kim, Won-Beom (Department of Naval Architecture and Ocean Engineering, School of Digital Mechanics, Ulsan College)
  • 김원범 (울산과학대학교 디지털기계학부 조선해양전공)
  • Received : 2012.03.26
  • Accepted : 2012.06.07
  • Published : 2012.06.30

Abstract

For the steel structures those are used in harsh sea environments, corrosion fatigue is a challenging issue in connection with design life. In this research, in order to investigate the influence of cathodic overprotection on the corrosion fatigue crack propagation behavior, corrosion fatigue crack propagation test under the condition of -950mV vs SCE was conducted by using of high tensile TMCP steel plate and the relationships between da/dN-${\Delta}K$ were obtained. At this test, when ${\Delta}K$ is low, the crack propagation rates were accelerated compared to those of seawater condition, however, when ${\Delta}K$ is high, the crack propagation rates were lower than those of seawater condition. As the cause for the acceleration and deceleration of corrosion fatigue crack propagation rates under the condition of cathodic overprotection, the role of hydrogen and calcareous deposits are discussed.

선박이나 심해저 해양플랜트와 같이 가혹한 해양환경에서 사용되는 강구조물에서 부식피로는 설계수명과 관련하여 해결을 요하는 중요한 문제이다. 본 연구에서는 전기방식중 과도한 전기방식이 부식피로균열 전파거동에 미치는 영향을 고찰하기 위하여 근래 사용이 확대되고 있는 고장력 TMCP에 대하여 합성해수중 -950mV vs. SCE의 과방식 인가전압 환경에서 부식피로균열 전파시험을 실시하고 da/dN-${\Delta}K$ 선도를 구하였다. 이 선도에서 저 ${\Delta}K$ 영역에서는 해수중 전파속도보다 빠른 균열전파속도를 나타내었으나, 고 ${\Delta}K$영역으로 갈수록 해수중 보다 늦은 균열전파속도를 나타내었다. 부식피로균열 전파속도에 영향을 미치는 인자로서 가속요인과 감속요인으로 나누고 각각 수소기체와 석회질생성물의 역할에 대하여 고찰하였다.

Keywords

References

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