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通过Gleeble模拟一种高铌微合金管线钢控轧控冷过程,研究了其组织及相变特征和变形对相变过程的影响。由膨胀量变化分析及组织观察,建立了该钢的连续冷却相变CCT曲线。结果表明,铌元素及变形促进了针状铁素体的形成,采用两阶段控轧,当冷速由0.5℃/s增加到50℃/s时,组织由多边形铁素体、准多边形铁素体向针状铁素体转变,但冷速低于5℃/s时,组织转变对冷速变化较敏感,当冷速继续增加时,组织结构变化不明显,而基体中的M/A组元变得更细小、弥散。
Gleeble simulation of a high-niobium microalloyed steel controlled rolling and controlled cooling process, the study of its microstructure and phase transition characteristics and deformation of the phase transition process. By CCT analysis and microstructure observation, the CCT curve of continuous cooling transformation was established. The results show that the formation of acicular ferrite is facilitated by niobium and deformation. Two-stage controlled rolling is adopted. When the cooling rate increases from 0.5 ℃ / s to 50 ℃ / s, the microstructure consists of polygonal ferrite, quasi-polygonal ferrite Body acicular ferrite transformation, but when the cooling rate is lower than 5 ℃ / s, the transformation of the structure is more sensitive to the change of cooling rate. When the cooling rate continues to increase, the structure of the structure changes insignificantly, while the M / A group Yuan becomes smaller and more diffuse.