High-temperature corrosion data and mechanisms for T122, Super304H and HR3C after 15 years in 1000MW ultra-supercritical power plant

The high-temperature corrosion of heat-resistant steels T122, Super304H and HR3C used for the inlet of a header in a 1000 MW ultra-supercritical power plant for 15 years was investigated. The steam temperature and pressure were about 610 degrees C and 28 MPa, respectively. The morphology and phase compositions of the corrosion products formed on the investigated tubes were analysed using X-ray diffraction and a scanning electron microscope with an energy dispersive spectroscopy detector. The results showed that the thickness of the corrosion products on the tube fireside was larger than that on the steam-side of the investigated tubes, which was due to the sulphur in the flue gas. The thickness rank of the corrosion products on the investigated steels was T122 > Super304H > HR3C. Defects including micro-cracks and voids were found in the corrosion products on both sides of the three tubes, which led to the breakaway of corrosion products.