The Effect of Surface Condition on Primary Water Stress Corrosion Cracking Initiation of Alloy 600
Stress corrosion cracking (SCC) initiation tests have been conducted on Alloy 600 in simulated PWR primary water (PW) with the aim of understanding the effect of surface condition produced by different machining methods on the time to initiation. Surface roughness, residual stress and cold work were characterised using profilometry, X-ray diffraction (XRD), micro-hardness and electron backscatter diffraction (EBSD). Initiation tests used tensile, button-headed specimens manufactured from 15% cold rolled, low temperature annealed Alloy 600 to relate machining parameters to PWSCC initiation susceptibility. Tests were conducted at 360 °C with active loading corresponding to 1% plastic strain. The onset of initiation was detected by in situ direct current potential drop (DCPD) measurement. Results indicate that residual stress and orientation of the crack plane in relation to cold work are critical parameters for Alloy 600 PWSCC initiation susceptibility. This suggests that knowledge of surface roughness cannot be used as the sole acceptance criteria for surface condition with regard to PWSCC susceptibility.
KeywordsNickel based alloys Stress corrosion cracking SCC initiation testing PWR
- 1.R.A. Etien, E. Richey, D.S. Morton, J. Eager, SCC initiation testing of alloy 600 in high temperature water, in Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, 2011Google Scholar
- 2.ASTM E2860-12, Standard test method for residual stress measurement by X-ray diffraction for bearing steels, in ASTM International, 2012Google Scholar
- 3.M.E. Fitzpatrick, A.T. Fry, P. Holdway, F.A. Kandil, J. Shackleton, L. Suominen, Measurement good practice guide no. 52—determination of residual stresses by X-ray diffraction—issue 2, in National Physical Laboratory, 2005, p. 11Google Scholar
- 4.M.B. Toloczko, M.J. Olszta, Z. Zhai, S.M. Bruemmer, Stress corrosion crack initiation measurements of alloy 600 in PWR Primary water, in Proceedings of the 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, 2015Google Scholar
- 5.Z. Zhai, M.J. Olszta, M.B. Toloczko, S.M. Bruemmer, Precursor corrosion damage and stress corrosion crack initiation in alloy 600 during exposure to PWR primary water, in Proceedings of the 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, 2015Google Scholar