Effect of Oxygenation Treatment on Steam Side Oxide Film of TP347H Steel Tube

Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction were used to analyze the oxide film on the internal surface of super-heater tubes made of TP347H material of a boiler and its exfoliation. The microscopic characteristics and mechanism of oxidation in oxygenation treatment environment were studied. The results show that the oxide film on the internal surface of TP347H steel tubes after oxygenation treatment mainly consisted of two layers, an inner layer and an outer layer. The inner layer was heterosphere and was composed of (Cr,Fe)₂O₄ and NiO, while the outer layer was composed of Fe₂O₃ and Fe₃O₄. The oxygenation treatment changed the steam-side oxidation mechanism and characterization, increased the oxygen content in oxide film, the outer layer became loose, porous and fine granular structure, and the inner oxide layer was rich in pores, which promoted the oxidation mass transfer process and accelerated the oxidation of metal matrix