Abstract: Through SEM observation, EDS analyses, the effect of dual thermal cycle on microstructure of 2.25Cr1Mo steel was analyzed. The results show that dual thermal cycle results in the formation of bainite. However, grain boundary of coarse prior austenite resulted from first thermal cycle does not become finer and still appears to maintain the original forms of it even though subjected second thermal cycle. EDS analyses indicate that micro zone composition are uniformly distributed which means that austernitizing homogenization is completed more sufficiently after subjected second thermal cycle. Micro zone Cr content of granular structure increases compared with matrix. It is assumed that carbides mainly composed of Fe, Cr element are formed among granular structure.

Key words: 2.25Cr1Mo steel, Thermal Cycle, Microstructure, Peak Temperature, Grain Size

摘要： 通过扫描电镜（ＳＥＭ）、能谱（ＥＤＳ）分析方法，对２．２５Ｃｒ１Ｍｏ钢经受二次热循环后的组织进行了分析。结果表明，经过二次热循环作用，获得贝氏体组织。但经第一次峰值温度热循环作用所形成的粗大原奥氏体晶界，并未在第二次热循环作用后产生细化，仍然保持第一次热循环所形成的粗大的原奥氏体晶界形态。能谱分析结果表明，微区成分比较均匀，说明试样经受第二次热循环作用后，奥氏体均质化进行得较为充分。颗粒状组织微区成分与基体相比，铬元素含量增高，可推测颗粒状组织形成了以Ｆｅ，Ｃｒ为主的第二相碳化物。

关键词: ２．２５Ｃｒ１Ｍｏ钢 , 热循环 , 组织 , 峰值温度 ,  晶粒尺寸