博士生许祥研究成果发表在材料加工领域顶刊JMPT
点击次数：
发布时间：2020-07-13
发布时间：2020-07-13
文章标题：博士生许祥研究成果发表在材料加工领域顶刊JMPT
内容：
针对钛合金高速加工过程中的热-力耦合问题引起的工件表面微观组织变化现象，提出了用有限元方法与元胞自动机的综合方法研究由于动态再结晶导致的晶粒细化问题，这种方法的提出对于揭示高速加工零件表面微观组织的演变以及对表面力学性能的影响是一种非常有效和创新的方法。论文发表在材料加工领域的顶级期刊Journal of Materials Processing Technology，论文的详细摘要如下，全文可通过以下链接查看。
https://www.sciencedirect.com/science/article/abs/pii/S092401362030248X
Multiscale simulation of grain refinement induced by dynamic recrystallization of Ti6Al4V alloy during high speed machining
【摘要】During high speed machining (HSM), the strong thermal-mechanical coupling can lead to the microstructure evolution in the deformation zone of workpiece. Grain refinement may occur, which has great effects on the mechanical behavior, and even on the fatigue strength and corrosion resistance of the machined surface. The development of multiscale models to predict the microstructure evolution is gaining rising interest. This study aims to investigate the grain refinement induced by dynamic recrystallization (DRX) occurring in HSM of Ti6Al4V, through finite element (FE) and cellular automata (CA) methods. An orthogonal cutting model for HSM of Ti6Al4V is developed combining a modified Johnson-Cook constitutive model (TANH) and Johnson-Mehl-Avrami-Kolmogorov (JMAK) DRX model. The CA model is proposed considering dislocation density evolution, grain nucleation and growth. The 2D mesoscopic microstructure evolution is simulated successfully by the CA model in which the input deformation parameters come from the FE simulations of the orthogonal cutting process. Finally, the grain size and microstructure morphology calculated by both FE and CA methods are compared with those characteristics obtained experimentally by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Identical microstructure predictions from both CA and FE methods show a reasonable agreement with the TEM results, on the condition that twinning and phase transformation are not considered in the simulations. This work proves that the combination of FE and CA methods is an effective approach to achieve a more comprehensive understanding of the microstructure evolution and its effect on mechanical behavior during HSM. It shows that the rise of both DRX volume fraction and DRX grain size finally results in the slightly decreasing of average grain size of serrated chips with the increase of cutting speed, which leads to the strain softening phenomenon of flow stress.