Electrochemical Characteristics of Main Materials of Dissimilar Metal Weld A508III-52M-316L in High Temperature Water Environments

The electrochemical characteristics in simulated high temperature primary water environments of three main materials machined from dissimilar metal weld A508III-52M-316L used for new pressurized water reactor nuclear power plants like AP1000 were studied experimentally, mainly on the effects of temperature, impurities chloride and sulfate in water and dissolved oxygen on the polarization curves and characteristic parameters, in order to provide fundamental data for relevant research and development. The obtained polarization curve and characteristic parameter data such as the corrosion current density at corrosion potential, passivity related critical passive current density and passivation potential as well as passive current density in various conditions were given in this paper. The results showed that with the rise of temperature from 160 ℃ to 290 ℃, the tendency to corrosion at anodic condition of 52M and 316L increased but that of A508III did not change apparently. Adding chloride and sulfate into the water caused the rise of the corrosion tendency of all the three materials. The rise of the dissolved oxygen led to the rise of the open-circuit potentials and also the rise of the tendency to corrosion of all the materials.