Temperature Dependence of Oxidation Behaviour of a Ferritic–Martensitic Steel in Supercritical Water at 600–700 °C

Abstract

Oxidation tests on a ferritic–martensitic steel were carried out in deaerated supercritical water at 600–700 °C under 25 MPa pressure. The oxidation kinetics followed near-parabolic rate law at 600 °C and obeyed near-cubic rate law at 650–700 °C. The deviations from parabolic behaviour may have been related to the development of growth stresses within the oxide. The oxidation rate did not always increase significantly with increasing temperature. The oxidation rates at 650 and 700 °C were approximately equal. The reason for this may be attributed to the formation of large pores at the interface between oxide scale and substrate at 700 °C. The influence of temperature on the microstructure of oxide scale and oxidation kinetics is discussed.