一种新型冷轧辊用钢的组织演变

Microstructure evolution of a new type of cold-roller steel

本文以一种新型冷轧辊用钢为研究对象,借助金相显微镜和扫描电子显微镜分析了试验钢在正火、球化退火、淬火、回火过程中的组织演变,研究了碳化物的成分变化和溶解析出行为。结果显示,试验钢正火后得到马氏体+部分颗粒状和少量块状碳化物的显微组织;球化退火后的显微组织为铁素体基体上分布有大量颗粒状碳化物+少量块状碳化物,球化退火组织评定为为2~3级;淬火后的组织为马氏体+部分颗粒状和少量块状碳化物;三次回火后的组织为回火马氏体+部分颗粒状和少量块状碳化物。试验钢中的块状碳化物在整个热处理过程中始终存在,1100℃以下奥氏体化时只发生边缘部分的少量溶解。颗粒状碳化物主要为M23C6型,在热处理过程中存在明显的溶解和析出行为,1100℃以下奥氏体化时部分溶解。

By taking a new type of cold-roller steel as the research object,the microstructure evolution of the steel during normalizing,spheroidizing-annealing,quenching and tempering was analyzed by means of optical microscope and scanning electron microscope,and the composition change,dissolution and precipitation behaviours of carbides were investigated.The results show that the microstructure of the as-normalized steel consists of martensite,some granular carbides and a small amount of blocky carbides.After spheroidizing-annealing,the microstructure is a large amount of granular carbides and a small portion of blocky carbides distributed on the ferrite matrix,which is rated as 2~3 grades.The quenching microstructure of the steel is a mixture of martensite and carbide particles with different morphologies,i.e granular-like and blocky-like.The microstructure after triple-tempering is tempered martensite dipersed with some granular carbides and a small amount of blocky carbides.The blocky carbides in the tested steel is present throughout the heat treatment process;however,only a small portion of the carbides edge will dissolve when austenitizing below 1100℃.The main type of granular carbides is M 23 C 6,which exhibits obvious dissolution and precipitation behavior during heat treatment and partially dissolve during austenitization below 1100℃.