Corrosion of 12Kh18AG18Sh steel in contact with copper

The anodic dissolution rate of 12Kh18AG18Sh steel increases due to its contact with copper at temperatures of 65–100°C. The difference-effect coefficient is 0.375 at 75°C. A copper cathode is almost twice as efficient as a steel one, and an increase in its area results in a sharp increase in the corrosion current density of steel. We established experimentally that, in the temperature range 85–100°C, the formation of a galvanic element with copper leads to pitting corrosion of 12Kh18AG18Sh steel owing to polarization to a more positive potential than the pitting-formation one. But, at temperatures below 65°C, a protective effect caused by polarization to a more negative potential than the steady-state potential is observed. In this case, the current of anodic dissolution of copper grows insignificantly. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 64, pp. 101–104, November–December, 1999.