采用电化学方法研究了AP1000等新型压水堆核电站用异材焊接件A508III-52M-316L的三种主要材料在模拟主回路高温水环境中的电化学特性。主要是考察温度、水中杂质氯离子和硫酸根离子以及溶解氧对极化曲线及特征参数的影响, 为这类异材焊接件的研发应用提供基础数据。给出了试样在各种条件下的极化曲线和测得的特征参数数据如自腐蚀电位处的腐蚀电流密度、钝化相关的致钝电流密度和致钝电位以及维钝电流密度。结果表明, 当温度从160 ℃升到290 ℃, 52M和316L在阳极极化条件下的腐蚀倾向增大, 但A508III的腐蚀倾向变化不大。水中加入氯离子和硫酸根离子后, 三种试样的腐蚀倾向明显增大。水中溶解氧浓度增高导致自腐蚀电位升高, 阳极极化条件下的腐蚀倾向性增大。

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.