This study investigated the effect of cooling rate on the formation of carbide bands in hot-rolled SUJ2 steel after spheroidization. The metallographic microstructure was observed under an optical microscope and a scanning electron microscope with an electron backscatter diffractometer, and the distribution of the chemical composition was analyzed using a field emission electron probe. Experimental results show the formation of carbide banding and the effect of cooling rate. Cr segregation occurs in carbide banding, in which C content increases after austenitization and spheroidization. The area fraction of carbide in the band region is larger than that in the normal region. Increasing the cooling rate can restrain the diffusion of C into the Cr microsegregation band. The formation of carbide banding can be avoided at a high cooling rate. This phenomenon may aid in quantifying the processing parameter of the cooling rate to improve the quality and the lifetime of bearings for bearing steels.

本研究研究了冷却速率对球化后热轧SUJ2钢中碳化物带形成的影响。在光学显微镜和具有电子背散射衍射仪的扫描电子显微镜下观察金相组织，并使用场发射电子探针分析化学成分的分布。实验结果表明了碳化物带的形成和冷却速率的影响。Cr偏析发生在碳化物带中，其中奥氏体化和球化后，C含量增加。带状区域的碳化物的面积率比通常区域大。提高冷却速率可以抑制C扩散到Cr微偏析带中。在高冷却速率下可以避免碳化物带的形成。