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Evaluation on the Characteristics of Stress Corrosion Cracking for the Weldment of HT-60 Steel under Applied Potentials

인가전위 하에서 HT-60강 용접부의 SCC특성 평가

  • Na, Ui-Gyun (Faculty of Mechanical Engineering, Kunsan National University)
  • 나의균 (군산대학교 기계공학부)
  • Published : 2002.05.01

Abstract

The susceptibility of SCC for the weldment and PWHT specimens of HT-60 steel was evaluated using a slow strain rate method under applied potential by means of the potentiostat in synthetic seawater. In case of the parent, anodic polarization voltage was inappropriate in elongating the time to failure(TTF). -0.8V corresponding to cathodic protection range is most effective in improving the SCC resistance against corrosive environment. In case of the weldment, the values of reduction of area(ROA) and TTF at -0.68V corresponding to cathodic polarization value were 45.2% and 715,809sec which were the largest and longest life among other applied potentials. Those were vise versa at -1.1V. In case of the PWHT specimens, TTF and ROA at -0.68V was longest and largest like the weldment. Besides, PWHT is effective in prolonging the time to failure of the welded off-shore structure due to softening of effect. Regardless of the weldment and PWHT specimen, as corrosion rate gets higher, TTF becomes shorter and deformation behaviour for the weldment and PWHT specimen at -1.1V was shown to be irregular. Finally, it was found that specimens showed brittle fracture at -1.1V, but more ductile fracture accompanying the micro-cracks at applied potential of -0.68V.

Keywords

Stress Corrosion Cracking;Weldment;Applied Potential;Post Weld Heat Treatment;Anodic;Cathodic;Polarization;Time to Failure;Reduction of Area;Softening;Potential;Ductility;Brittlement

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