低碳钢表面FeO层空气条件下等温转变行为的研究

采用热模拟试验机研究了不同温度和等温时间条件下低碳钢表面形成的FeO层的等温转变行为。试验结果发现,在600℃时,FeO只发生先共析反应而无共析反应发生。在650℃时,无任何析出反应发生。FeO层的等温转变遵循着"C"曲线规律,450~550℃为FeO分解反应的"鼻尖"温度范围。FeO的等温转变分为两个阶段,即析出先共析Fe3O4的第一阶段和后续发生的共析反应(FeO→Fe+Fe3O4)阶段。在350℃时形成的共析反应产物的片间距最小。通过热力学分析和FeO层中氧的贫化与富集分别解释了FeO的先共析和共析反应行为。

Isothermal Eutectic Decomposition of FeO Formed on a Low Carbon Steel in Air

The isothermal decomposition behavior of FeO formed on low carbon steels was studied by using a ther mal-simulator at different oxidation temperatures for different isothermal holding times. The results showed that FeO only underwent proeutectoid reaction at 600 ℃, and no eutectoid reaction occurred at 650 ℃. The isothermal time-temperature-transformation curve for the FeO decomposition was found to be in a "C" shape, with the "nose" temperature being in the range of 450-550 ℃. The isothermal transformation of FeO was divided into two stages, or the occurrence of proeutectoid precipitation of Fe_3O_4 followed by the eutectoid transformation of FeO→Fe+ Fe_3O_4. The interlamellar spacing for the eutectoid transformation products at 350 ℃ is the smallest. The proeu-tectoid and eutectoid transformation behaviors of FeO were discussed in terms of thermodynamics and oxygen de-pletion or enrichment in FeO, respectively.