Effect of Surface Roughness on Corrosion Behavior of 800H Alloy in Supercritical Water Environment

The effect of surface roughness on general corrosion behavior of 800H alloy in supercritical water environment at 650℃ and 25 MPa was studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscattering diffraction (EBSD). The results showed that the corrosion mass increase rate of rough grinding sample was significantly lower than that of mechanical polishing sample. After immersion for 1 000 h, the corrosion mass of mechanical polishing sample increased 20 times as much as that of rough grounding sample. A double-layer oxide film rich in iron and chromium was formed on the surface of vibration polishing sample, and a single-layer oxide film rich in chromium was formed on the surface of rough grounding sample, and obvious chromium-rich slip band appeared under the oxide film.