T22锅炉钢奥氏体晶粒长大和马氏体转变行为的原位观察

In-Situ Observation of Austenite Grain Growth and Martensite Transformation Behaviors of T22 Boiler Steel

采用高温激光共聚焦显微镜(LSCM)对SA213-T22锅炉钢的奥氏体晶粒长大和马氏体转变的动态特性进行了原位观察研究。结果表明:①在950～1 200℃,T22钢的奥氏体平均晶粒尺寸(D)与加热温度(T)之间的定量关系可近似地用Arrhenius方程描述,奥氏体晶界迁移的激活能(Q)约为140. 5 kJ/mol;②奥氏体晶粒通过晶界的迁移和扩张、多个小晶粒合并成一个大晶粒以及分割和吞并邻近晶粒而长大;③马氏体在奥氏体的晶界和晶内形核并迅速长大,计算得出的马氏体板条束的长大速度约为282.7μm/s。

In-situ observations of dynamic behaviors of austenite grain gro\Wh and martensite transformation in SA213-T22 boiler steel were carried out by the use of a high temperature laser scanning confocal microscope (LSCM). The results are as follows:① the quantitative dependence of average size (D) of austenite grains in the steel on temperature ( T) may be described approximately by Arrhenius equation in the range of 950 to 1 200 ℃,and the average activation energy (Q) for gain boundary migration is about 140. 5 k//mol;② the austenite grain grows through migration and expansion of grain boundaries,combination of some smaller grains into a larger grain,as well as through parting and merging nearby grains;③ the martensite nucleates and then rapidly grows at grain boundaries and in grain interiors of austenite, and calculated gowth rate of martensite lath is as geat as about 282. 7 μm/s.