Liang Zhiyuan, Zhao Qinxin
Key Laboratory of Thermal Fluid Science and Engineering of MOE, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2019 Feb 14;12(4):577. doi: 10.3390/ma12040577.
Steam oxidation of austenitic heat-resistant steels TP347H and TP347HFG at 650⁻800 °C was investigated. Comprehensive micro-characterization technologies containing Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) were employed to observe and analyze the oxidation products. Results show that breakaway oxidation behaviors were observed on TP347H at 700 °C and 800 °C. The oxidation kinetics of TP347HFG at 650⁻800 °C followed a parabolic law. The oxide scales formed on TP347HFG were composed of MnCr₂O₄ and Cr₂O₃. A thin and protective Cr-rich oxide scale was replaced by Fe₂O₃ nodules due to the insufficient outward migration of metallic ions, including Cr and Mn at the subsurface of coarse-grain TP347H. Smaller grain of TP347HFG promoted the formation of the compact Cr-rich oxide scales. At higher temperatures, the incubation period for breakaway oxidation of the Cr-rich oxide scale was much shorter because of quick evaporation of the Cr₂O₃ oxide scale and the slower outward diffusion of metallic ions via the grain boundaries.
研究了奥氏体耐热钢TP347H和TP347HFG在650⁻800 °C下的蒸汽氧化。采用了包括扫描电子显微镜（SEM）、能量色散X射线光谱仪（EDS）、X射线衍射仪（XRD）和X射线光电子能谱仪（XPS）在内的综合微观表征技术来观察和分析氧化产物。结果表明，在700 °C和800 °C下，TP347H出现了剥落氧化行为。TP347HFG在650⁻800 °C下的氧化动力学遵循抛物线规律。TP347HFG上形成的氧化皮由MnCr₂O₄和Cr₂O₃组成。由于粗晶粒TP347H亚表面的Cr和Mn等金属离子向外迁移不足，一层薄的富Cr保护氧化皮被Fe₂O₃结核所取代。TP347HFG较小的晶粒促进了致密富Cr氧化皮的形成。在较高温度下，由于Cr₂O₃氧化皮的快速蒸发以及金属离子沿晶界向外扩散较慢，富Cr氧化皮的剥落氧化孕育期要短得多。
