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为使X70HD管线钢中的铁素体晶粒得到细化,在轧制过程中产生一定比例的形变诱导铁素体,并尽量避免先共析铁素体生成,本文制定了2种仅第二阶段变形温度、应变速率不同的两阶段大变形的热压缩工艺,研究了热形变参数对形变诱导铁素体含量及晶粒尺寸的影响,对热压缩后的试样采取不同的冷却工艺,分析得出压缩变形后以25℃/s的速度冷却至终冷温度350℃时晶粒大小及微观组织构比较合理可实现晶粒细化。随冷却速度的增大,形变诱导铁素体晶粒平均直径逐渐变小,贝氏体形态也更加理想,对改善组织构成具有重要意义。
In order to refine the ferrite grains in the X70HD pipeline steel, a certain proportion of deformation-induced ferrite was produced during the rolling process and the pro-eutectoid ferrite formation was avoided as much as possible. In this paper, Stage deformation temperature and strain rate of the two stages of large deformation of the hot compression process to study the thermal deformation parameters of the deformation induced ferrite content and grain size of the hot compression of the sample to take a different cooling process, The result shows that the grain size and microstructure are reasonable when the temperature is 25 ℃ / s and the final cooling temperature is 350 ℃. With the increase of cooling rate, the average diameter of deformation-induced ferrite grains becomes smaller and the morphology of bainite is more ideal, which is of great significance to improve the tissue composition.