楔横轧不同变形阶段的微观组织演变分析

Analysis of microstructural evolution during different stages of cross wedge rolling

运用三维刚塑性有限元DEFORM-3D软件对GH4169合金零件的楔横轧成形进行变形、传热、微观组织演变的耦合数值模拟,揭示轧件在楔横轧成形过程中各个变形阶段(楔入段、展宽段和精整段)微观组织的演变规律,分析轧件平均晶粒尺寸在不同变形阶段变化的具体原因。结果表明,楔横轧成形GH4169合金轧件时,虽然温度低、应变率高,但楔横轧特有的大变形仍能使动态再结晶发生并完成,从而得到细小均匀的晶粒组织;轧件晶粒的细化程度随断面收缩率的增大而增大;轧件在高温下主要发生晶粒长大,因此减小精整段的长度以及缩短进入下道工序的时间,可以避免粗晶的产生,提高成形件的综合力学性能。

Through the rigid-plastic finite element software DEFORM-3D,the thermo-mechanical coupled microstructure simulation was carried out.Then the law of microstructure evolution during cross wedge rolling（CWR） was revealed in every stage,including knifing stage,spreading stage and sizing stage.The reason for the change of average grain size was analyzed.The results show that when the product made of GH4169 alloy is formed by CWR process,the large deformation may be helpful to the occurrence and accomplishment of dynamic recrystallization and the fine and homogeneous grain may be obtained even under lower temperature and higher roll speed.The effect of grain refining gradually increases with the increase of area reduction.The grain growth is inclined to occur under high temperature.So it would be better to reduce the distance of sizing stage and the time entering the next process to avoid generating coarse grain,and improve the comprehensive mechanical properties of the final product.