The Research Of Oxidizing Behavior Of T122Steel

The"four tubes" filure in the boilers can lead to a lot of halt accidents in the thermal generator sets. So studying and grasping the discipline of oxide and rusty of the steel used in the boilers is proactive in ensuring the operating of generator sets and increasing the economic benefits. It also plays a guiding role in predicting the boilers lives of serving, which reduces the unnecessary losses caused by "four tubes" filure.In this article the author makes a research of oxide behavior of T122steel in different contents of (Ar+H2O) atmosphere at550℃and650℃. The study shows that the rate of oxidation is obviously increasing along with the oxidizing temperature when T122steel is oxidized in the (Ar+H2O) atmosphere. The oxidation kinetics followed parabolic law at550℃, but two stage parabolic law at650℃. The variation turn up after4hours’oxidation. The oxidation activation energy was identified as157.2kJ/mol according to Arrhenius equation. Meanwhile, water vapor can also affect oxidation kinetics-the rate of oxidation increased with the amount of water vapor. When oxidation happens in the air, it has the lower rate at the beginning. Serious oxidation of T122happens in the state of550℃48h and650℃72h. Comparing the oxidation of T122in the air with in the (Ar+H2O) atmosphere, we find it much slighter.We have made the deeper study of the filams by means of XR、SEM. The result is that the multi-structured filams are formed in both conditions of air and vapor. The oxide scale with threee-layer microstructure was composed of Fe3O4、Fe2O3、and (Fe,Cr)3O4in the order from the top layer to the inner layer. Meanwhile the internal oxidations was also observed, the corresponding internal oxide was FeO and CrO3、in the (Ar+H2O) atmosphere at550℃, but it is opposite in the air. At the same time, the author studies the crazing and peeling of the filams and makes the discussion in the antistrip performance of it and some influencing factors. From all these analysis, the oxidation mechanism of T122steel are drawn as a conclusion in both (Ar+H2O) atmosphere and air.