Ti6Al4V切削过程中动态再结晶模拟

Simulation of Dynamic Recrystallization in Ti6Al4V Cutting Process

零件的力学和物理性能很大程度上取决于材料的微观组织和化学成分,针对钛合金在机加工过程中会发生严重的塑性变形和较高的温度下所触发的动态再结晶(DRX)以及动态回复现象成为了微观组织演化的一种机制,通过建立有限元-元胞自动机(FE-CA)耦合的DRX预测模型,该模型包括位错密度模型、晶粒形核模型、晶粒长大模型,目的是为了研究车削钛合金过程中的微观组织演化机制,在不同进给量下温度、应变、应变率对DRX的影响规律,结果表明:温度的增大有利于DRX行为的发生,较高的应变有利于DRX晶粒的长大,较大的应变率增强了形核率的发生而抑制了晶粒的长大;随着进给的增大,切屑更容易发生DRX,切屑晶粒细化程度增强,而已加工表面细化程度减弱,刀具后刀面磨损更易触发已加工表面的DRX。

The mechanical and physical properties of parts are largely determined by the microstructure and chemical composition of the material.For titanium alloys,dynamic recrystallization(DRX),dynamic recovery triggered by higher temperatures and severe plastic deformation during machining have become a mechanism of microstructure evolution.A dynamic recrystallization prediction model coupled with finite element-cellular automata(FE-CA)is established,which includes a dislocation density model,a grain nucleation model,and a grain growth model.The purpose is to study the microstructure evolution mechanism in the process of turning titanium alloy,and the influence of temperature,strain and strain rate on dynamic recrystallization under different feed rates.The results show that the increase in temperature is beneficial to the occurrence of dynamic recrystallization behavior.The higher strain is beneficial to the growth of dynamic recrystallized grains,the larger strain rate enhances the occurrence of nucleation rate and inhibits the growth of grains;With the increase of feed,the chips are more prone to DRX,the degree of chip grain refinement is enhanced,and the degree of refinement of the machined surface is weakened,and it is easier to trigger DRX of the machined surface by tool flank wear.