摘要
研究了T91铁素体耐热钢的相变行为与微观组织。结合热力学计算与差热分析法分析了相变行为;利用光学显微镜、扫描电镜和透射电镜观察了材料的显微组织;用X射线衍射仪检测了材料晶体结构。结果表明,经正火与回火处理的样品,其相变温度Ac1与磁性转变温度分别为856.2、749℃,其中计算的相变平衡转变温度Ae1为820℃,与实验测量的Ac1吻合很好;冷却过程中发生马氏体相变温度为400℃,根据热力学计算,其平衡析出相为MX、M23C6和Z相,MX相和M23C6型碳化物的最高溶解温度分别为1264、866℃。经正火、回火处理的样品基体组织为回火马氏体,析出相为MX、M23C6,由于短时回火与相对较低的Cr含量,所以未发现Z相。
The phase transformation behavior and microstructure of T91 ferritic heat-resistant steel were investigated. The phase transformation behavior was analyzed by combining the thermodynamic calculation with differential thermal analysis; the microstructure was observed by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The results show that the transformation temperature A c1 and magnetic transition temperature is 856.2 ℃ and 749 ℃ for a normalized and tempered sample, respectively. Ac1 shows a reasonable agreement with phase equilibrium temperature Ac1 （820℃ ）. In addition, the martensitic transformation occurs at 400 ℃ during cooling. The major equilibrium phases in T91 steel are MX, M23C6 and Z-phase. The solution temperature of MX and M23C6 is 1264 ℃ and 840 ℃, respectively. The microstructure observation indicates that the matrix is representative tempered martensite and the precipitates are MX and M23C6 after normalizing and tempering, whereas, no Z phase is found due to short-term tempering and relative low Cr content.
出处
《热加工工艺》
CSCD
北大核心
2012年第22期96-98,103,共4页
Hot Working Technology
关键词
相变
差热分析
微观组织
析出相
phase transformation
differential thermal analysis
microstmcture
precipitates
