Abstract
Oxide scale exfoliation is a major concern in fossil fuel power generation because it can cause tube blockages and erode valves and steam turbine components downstream. There is still considerable scientific and commercial interest to improve the mechanistic understanding of oxide failures by developing models to predict exfoliation and the extent of tube blockage as a function of operating conditions and component geometries. Tensile testing inside a scanning electron microscope was conducted on ferritic鈥搈artensitic and austenitic steel specimens with the steam side (Fe,Cr)-rich oxides grown after exposures for up to 1000鈥塰 in steam with ~100鈥塸pb O2 at 276鈥塨ar and 550掳C. Multiple oxide layer cracks and delamination events were observed and analyzed in detail during the tests. Results from the testing agreed well with earlier observations that had identified the failure location at the outer鈥搃nner oxide layer for all tested materials. Calculated adhesion energies identified the outer鈥搃nner oxide interface of alloy 347HFG as the weakest interface.
