T91钢显微组织变化趋势的定量分析

Microstructure variation tendency of T91-steel based on quantitative analysis

用扫描电镜(SEM)、背散射电子显微镜(EBSD)及X射线衍射(XRD)等方法对不同运行阶段的T91钢管受热面析出碳化物颗粒度、亚结构及位错密度进行了定量测试分析。研究结果表明,在运行前期,随着组织老化程度的增加,T91钢析出碳化物颗粒的数量呈现出明显的上升趋势,运行后期到寿命末期(爆管失效),碳化物颗粒出现明显的聚集长大;T91钢运行前期位错密度下降明显,伴随着前期位错运动的结果是亚结构出现初期兼并,促成亚结构略有粗化;运行后期到失效阶段,T91钢位错密度基本上趋于稳定,亚结构快速兼并,亚晶界密度显著减少。

Carbide size,substructure and dislocation density of T91-steel in different service stage were investigated quantitatively by scanning electron microscopy（SEM）,electron backscattered diffraction microscope（EBSD）and X-ray diffraction（XRD）.The results show that the quantity of the carbide particle precipitates increases obviously with the microstructure deterioration of T91 steel at early service stage,however,the carbide particles grows obviously by aggregation at later service stage.During early service stage,the density of dislocation reduces distinctively and the substructure merges due to the movement of dislocation.The movement of dislocation also induces substructure coarsening.During the later service stage,the density of dislocation keeps stability approximately while the substructure merges quickly which causes the density of sub-grain boundary decreases notablely.