DETECTION OF STRUCTURAL CHANGES IN HEAT-RESISTANT STEELS AFTER HEAT AND CREEP STRAIN USING ELECTROCHEMICAL METHODS

This work is focused on evaluation of material changes of heat and creep strained steel Cr-W (P92) using electrochemical methods. Samples were exposed at temperatures 600 - 650 degrees C for different times (up to 20,000 h) and by application of various strain. Structural changes were evaluated by polarization methods, structure of steels was characterized using light and scanning electron microscope. On measured polarization curves significant local peaks in the passive / transpassive area were observed. Correlation between curve characteristic parameters and time of heating was determined. It is also shown, that electrochemical method could be used for detection of structural instability and creep damage of material.