Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Effect of Dissolved Oxygen on the Stress Cor rosion Cracking Behavior of 3.5NiCrMoV Steels in High Temperature Water

  • Lee, J.H. (Nuclear Materials R&D. Korea Atomic Energy Research Institute) ;
  • Maeng, W.Y. (Nuclear Materials R&D. Korea Atomic Energy Research Institute) ;
  • Kim, U.C. (Nuclear Materials R&D. Korea Atomic Energy Research Institute)
  • Published : 2003.08.01
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Abstract

Slow Strain Rate Tests (SSRT) were carried out to investigate the effect of environmental factors on the Stress Corrosion Cracking (SCC) susceptibility of 3.5NiCrMoV steels used in discs for Low-Pressure (LP) steam turbines in electric power generating plants. The influences of dissolved oxygen on the stress corrosion cracking of turbine steel were studied, For this purpose, specimens were strained at variously oxygenated conditions at $150^{\circ}C$ in pure water. When the specimen was strained with $1{\times}10^{-7}s^{-1}$ at $150^{\circ}C$ in pure water, increasing concentration of dissolved oxygen decreased the elongation and the UTS. The corrosion potential and the corrosion rare increased as the amounts of dissolved oxygen increased. The increase of the SCC susceptibility of the turbine steel in a highly dissolved oxygen environment is due to the non protectiveness of the oxide layer on the turbine steel surface and the increase of the corrosion current. These results clearly indicate that oxygen concentration increases Stress Corrosion Cracking susceptibility in turbine steel at $150^{\circ}C$.

Keywords

Acknowledgement

Supported by : Ministry Science and Technology of Korea

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