Microstructure of low carbon high niobium steel under the conditions of different controlling rolling and cooling parameters was studied by thermomechanical simulator. The results show that the amount of ferrite increased and the amount of bainite decreased with the decrease of temperature and the increase of deformation, and the morphology of the lathe bainite became granular gradually. When the cooling rate was lower than 5℃ ·s*1, the microstructure was constituted by ferrite and pearlite, and when the cooling rate was higher than 5 ℃· s-1 , the amount of bainite increased and the grains were smaller and more uniform. The micro-hardness of tested steel increased with the increase of cooling rate.%利用热模拟试验机研究了低碳高铌钢在不同控轧控冷参数下组织的变化规律.结果表明:随着变形温度的降低和变形量的增加,准多边形铁素体的含量增加,粒状贝氏体的含量减少,贝氏体的形貌逐渐由板条状变为粒状；当冷速低于5℃·s-1时,形成由铁素体和珠光体组成的组织,当冷速高于5℃·s-1时,组织中的贝氏体含量随之增加,晶粒明显更加细小均匀；试样的显微硬度随着冷速的增加而逐渐增大.
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