强剪切对单层晶极薄带轧制变形行为的影响

Effect of Strong Shear on Micro-rolling Deformation Behavior of Single Layer Grain Foil

为确定最优的极薄带轧制工艺,本研究深入分析了强剪切对轧制单层晶极薄带微观变形行为和晶体转动演化的影响。采用基于位错滑移机制的晶体塑性有限元模型进行模拟,最大异速比达到1.5。建立了晶粒取向随机分布的单层晶极薄带轧制模型,以探究少晶组织的晶界作用特性。结果表明:强剪切导致单层晶极薄带轧制微观变形和晶体转动表现出显著的局部化。强剪切促进了晶粒的剪切变形,使得晶界的协调变形能力增强。在轧制区施加强剪切变形,可使已启动滑移得到扩展,主滑移带缩窄分散形成新的次滑移带,滑移更加集中和各向异性。变形后晶粒取向主要绕箔材宽度方向发生转动和分散,强剪切使转动角度增大和分散点更加集中稳定。模拟表明强剪切严重影响单层晶极薄带轧制变形的各向异性,进而导致择优取向、滑移局部化以及非均匀应力-应变分布。

The effect of strong shear on the micro-deformation behavior and crystal rotation evolution of rolling single layer crystal foil was deeply analyzed in order to determine the optimal foil rolling process.A crystal plastic finite element model based on dislocation slip mechanism was used for simulation,and the maximum differential speed ratio reached 1.5.A single layer crystal foil rolling model with random grain orientation was established to investigate the grain boundary interaction characteristics of oligocrystalline microstructure.The results show that the micro-deformation and crystal rotation are significantly localized by strong shear.The shear deformation of grain is promoted by strong shear and the coordinated deformation capacity of grain boundary is enhanced.The slip is more concentrated and anisotropic because of initiated slip can be extended and the main slip band shrinks and disperses to form a new secondary slip band by the shear deformation which is strengthened in the rol-ling zone.After foil rolling,the grain orientation mainly rotates and disperses around the width of the foil.The rotation angle increases and the dispersion point becomes more concentrated and stable by strong shear.The simulation results show that the anisotropy of single layer crystal foil rolling deformation is seriously affected by strong shearing,which leads to preferred orientation,slip localization and non-uniform stress-strain distribution.