Microstructure Evolution and Stress Corrosion Cracking Susceptibility of 12Cr Martensitic Steel Upon Long-Term Service in Power Plants

  • Z. ZhangEmail author
  • Z. F. Hu
  • P. M. Singh
  • X. Li
  • S. Xiong
  • X. X. Fang


After 230,000-h long-term service at 550 °C/13.7 MPa, the microstructure of a kind of 12Cr martensitic steel was investigated using scanning electron microscopy, backscattering electron microscope and x-ray diffraction analysis. The results show that the precipitation and coarsening of carbides at grain/lath boundaries are the main cause of microstructure degradation. The static immersion tests and the slow strain rate test coupled with electrochemical impedance spectroscopy were conducted on the served steel in 1.0% NaCl solution, and it turns out that the pitting corrosion resistance and repassivation ability of the steel are significantly reduced as a result of microstructure degradation. The stress corrosion cracking susceptibility of the steel was also studied. Fracture morphology analysis shows that the secondary crack in conjunction with slip lines is a result of the coalescence of micro-cracks nucleated from the pits.


12Cr martensitic steel microstructure pitting corrosion stress corrosion cracking 



The authors are grateful for the financial support from the Natural Science Foundation of China (No. 51801098), Natural Science General Program of Jiangsu Province (No. 18KJB130003) and High-level Scientific Research Foundation of Nanjing Institute of Technology (No. YKJ201708).


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Copyright information

© ASM International 2019

Authors and Affiliations

  • Z. Zhang
    • 1
    • 2
    Email author
  • Z. F. Hu
    • 3
  • P. M. Singh
    • 4
  • X. Li
    • 1
    • 2
  • S. Xiong
    • 1
    • 2
  • X. X. Fang
    • 1
    • 2
  1. 1.School of Materials Science and EngineeringNanjing Institute of TechnologyNanjingChina
  2. 2.Jiangsu Key Laboratory of Advanced Structural Materials and Application TechnologyNanjingChina
  3. 3.School of Materials Science and EngineeringTongji UniversityShanghaiChina
  4. 4.School of Materials Science and EngineeringGeorgia Institute of TechnologyAtlantaUSA

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