EVALUATION OF EXFOLIATION ISSUES IN THE FOSSIL-FUELED POWER PLANT

摘要

The supercritical water conditions impose great requirements on the constructional materials properties. Under these conditions some of regularly used stainless steels suffer from exfoliation which could lead to clogging of steam generators pipes and sequentially to the failure of the whole steam generation complex. Nowadays in some fossil-fueled power plants where the supercritical regime is introduced the X6CrNiMo17-13-2 austenitic stainless steel suffers severe exfoliation issues. According to the newest trends in material engineering this steel is being currently replaced by shot peened X10CrNiCuNb18-9-3 steel. In order to evaluate the differences in corrosion behavior and the susceptibility to exfoliation, these two steels were exposed at supercritical water conditions (600°C, 25 MPa). Such behavior of these steels was evaluated and compared. The nature of oxide scales formed on their surface was evaluated by SEM-WDS, XPS, Raman spectroscopy and impedance measurements.