The corrosion tests of Inconel 740 H in supercritical water were carried out at 600-700 degrees C and 25 MPa. The weight gain elevated with the rise in exposure time and temperature. The oxidation kinetics follows parabolic law in all cases. The temperature has an enhanced impact on oxide phase composition. Cr2O3 was the major oxide phase and the oxides containing Ti, Ni Co, Fe or Nb were also detected at different temperatures. A marked experiment was performed in (H2O)-O-16/O-16(2) and subsequently in (H2O)-O-16/O-18(2). The oxygen isotope profile showed that oxidation proceeded by outward chromium transport. The related mechanism was discussed.

Nickel-based alloy; SEM; XRD; Oxidation

North China Electric Power University