Study on Corrosion Characteristics and Stress Corrosion Cracking of the Weldment for HT-60 Steel in Synthetic Seawater

  • Na, Eui-Gyun (Institute of Machinery and Automotive Technology, Kunsan National University) ;
  • Koh, Seung-Ki (Institute of Machinery and Automotive Technology, Kunsan National University) ;
  • Oh, Seok-Hyung (Institute of Machinery and Automotive Technology, Kunsan National University)
  • Published : 2000.02.01

Abstract

The contents of this paper include the evaluation of corrosion characteristics and the behaviour of stress corrosion cracking (SCC) for the weldment and post weld heat treatment (PWHT) specimen and parent of HT -60 steel using a slow strain rate test (SSRT) in synthetic seawater. Corrosion characteristics were obtained from the polarization curves by potentiostat, and SCC phenomena were evaluated through the parameters such as reduction of area and time to failure by comparing the experimental results in corrosive environment with those obtained in air. Corrosion rate of the weldment was the fastest, followed by parent and PWHT specimen. SCC phenomena between the weldment of HT-60 steel and synthetic seawater were shown. Besides, SCC was dependent upon the pulling speed greatly. Maximum severity of SCC was obtained at a speed of $10^{-6}mm/min$, whereas SCC could not be seen almost at $10^{-4}mm/min$. The resistance to SCC for PWHT specimen was improved considerably compared that of the weldment at $10^{-6}mm/min$. In case of SCC failure, it was verified from SEM examination that brittle mode and lots of pits could be seen at the fractured region near the surface of the specimen.

Keywords

References

  1. Ann, Y. T., 1998, 'Study on the Characteristics of Stress Corrosion Cracking for the Welded Zone of High Strength Steel using a Slow Strain Rate Test Method,' Kunsan National Univ., Korea
  2. ASTM D 1141-86, 1986, Standard Specification for Substitute Ocean Water
  3. ASTM G5-72, 1984, 'Standard Recommended Practice for Standard Reference Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements,' Annual Book of ASTM Standards, Vol. 03.02
  4. Brown, B. F., 1972, 'A Preface to the Problem of Stress Corrosion Cracking,' ASTM STP 518, pp. 3-15
  5. Lee, J. I., 1988, 'About the Damage of Power Plant Installation,' Journal of Korean Corrosion, Vol. 17, pp. 172-181
  6. Na, E. G., 1987, 'Effect of PWHT on Corrosion Fatigue in Weld HAZ of Steels,' Chonbuk National Univ.
  7. Shreir, L. L., 1979, Corrosion, Vol. 1. pp. 12-13
  8. Son, U. T., 1980, Corrosion Science of Metals, pp. 108-109
  9. Stephen Tait, W., 1994, 'An Introduction to Electrochemical Corrosion Testing for Practicing Engineers and Scientists,' Ohio State University, pp. 53-62
  10. Theus, G. J. and Cels, J. R., 1975, 'Slow Strain Rate Technique to Stress Corrosion Cracking Studies,' Corrosion, Vol. 20, No.8, pp. 221-226