涡轮盘模锻过程中微观组织演变的模拟分析

Microstructural Simulation and Analysis of Turbine Disk During Hot Forging

针对涡轮盘微观组织精确调控需求,通过有限元法研究应变速率突增条件下微观组织的演变规律及其调控策略。首先在有限元软件中建立典型涡轮盘材料GH4169合金的应力应变模型、动态再结晶模型以及亚动态再结晶模型,然后分别模拟了圆柱试样的热压缩过程以及涡轮盘单道次和多道次模锻过程。研究结果表明,应变速率突增后,临界应变突增,动态再结晶速度有所减缓。有限元法在微观组织模拟方面尚存不足,无法全面地描述应变速率突增条件下的微观组织演变。涡轮盘轮芯区域更容易达到目标晶粒组织要求,单道次模锻成形中应注意避免关键点处出现应变速率突增,多道次模锻成形有助于提高模锻结束时的再结晶程度。

Aiming at the accurate microstructural control of turbine disk during hot forging,the evolution of microstructure under sudden increase of strain rate was investigated by finite element method.The constitutive models for flow stress,dynamic recrystallization and metadynamic recrystallization of a turbine disk material were implemented into finite element software.Then the hot compression of a cylindrical sample and single and multi-pass forging of a turbine disk were simulated.The results show that the sudden increase of strain rate can induce the occurrence of pseudometadynamic resrytallization.i.e.,the suspension of dynamic recrystallization as a consequence of nucleation inhibition.The finite element method may have some shortcomings in microstructural prediction under sudden increase of strain rate.It is easier to achieve the target grain structure in the core area of turbine disk.The sudden increase of strain rate at key area should be avoided during single pass forging.The degree of recrystallization can be improved by multi-pass forging.