Analysis of Electrochemical Processes near the Tip of a Corrosion-Mechanical Crack at High Temperatures

We describe some results of our electrochemical investigations of a model of the renewed surface–passivated surface galvanic couple for 15Kh2NMFA steel in borate-buffered reactor water with pH8 under the action of high temperatures (up to 300°C) and pressures. On the basis of studying the kinetics of potential and current in this galvanic couple and their temperature dependences, we conclude that the galvanic couple significantly affects the acceleration of the growth of a corrosion-mechanical crack. Using the results of our investigations and data available in literature, we analyze the electrochemical situation at the tip of a corrosion-mechanical crack and propose a possible mechanism describing the effect of a high-temperature aqueous medium on the crack growth.