环形铸坯热辗扩成形微观组织演变规律研究

Study on Rule of Microstructure Evolution during Hot Rolling Process of Annular Casting Blank

建立了铸态42CrMo钢的微观组织演变模型和环件热辗扩三维刚塑性有限元模型。基于DEFORM-3D软件平台,对微观组织演变和宏观热力学行为进行了耦合模拟,研究了环形铸坯热辗扩成形过程中芯辊进给速度对动态再结晶晶粒尺寸和体积分数分布的影响规律。结果表明,在变形量比较大的环件外层和内层容易发生动态再结晶,晶粒尺寸细化明显;适当增大芯辊的进给速度,有利于扩大动态再结晶区域和获得细小均匀的再结晶晶粒,能够改善环件微观组织的大小和分布。

The microstructure evolution model of as—cast 42CrMo ring steel and the three—dimensional rigid-plastic finite element model during thermal rolling have been established by DEFORM—3D software platform.The influence discipline of various feed rate of idle roll on grain size and volume fraction distribution of dynamic recrystallization during ring slab hot rolling process have been studied by the coupled simulation of microstructure and macroscopic thermodynamic behavior.The results show that dynamic recrystallization easily occurs on outer and inner rings of the ring with larger deformation degree,and the refinement of grain size is obvious.Besides,the increased feed rate of idle roll can helps to enlarge the dynamic recrystallization region and obtain the fine and homogeneous recrystallization grain,which will finally improve the grain size and distribution of circular slab microstructure.