【摘要】 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。更多还原

【Abstract】 To produce a certain proportion of deformation induced ferrite in the process of rolling for X70 HD pipeline steel,two kinds of thermal compression processes with different deformation temperature and different deformation rate in second rolling process were developed,and the influence of thermal deformation parameters on deformation induced ferrite content and grain size was studied. The different cooling processes were adopted for the hot compressed samples and it is found that the fine grain size and more reasonable microstructure can be realized after cooling at a speed of 25 ℃ / s to the final cooling temperature 350 ℃. Along with the increase of cooling rate,the average grain diameter of deformation induced ferrite became smaller and the bainite morphology is more ideal. That is of great significance to the improvement of microstructure.更多还原