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-  2018 

压下率对轧制单层晶极薄带晶界滑移特性的影响

DOI: 10.11951/j.issn.1005-0299.20170311

Keywords: 极薄带轧制,单层晶,晶体塑性,滑移系,轧制压下率
foil
,rolling,single,layer,grain,crystal,plasticity,slip,systems,rolling,reduction

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Abstract:

采用退火态单层晶轧制铜箔为原料,进行不同压下率的箔轧.以多晶体位错滑移及塑性流动机制为基础,建立了考虑潜在硬化和晶格转动效应的率相关晶体滑移本构模型,分析了压下率对轧制单层晶极薄带晶界附近区域变形分布特性、取向演化和滑移系激活规律的影响,并探讨其机理.确定了合理的材料本构参数,铜箔拉伸实验与晶体塑性有限元模拟得到的应力-应变曲线一致.所建立的晶体塑性有限元模型,可很好的模拟最大压下率达到80%时轧制单层晶铜箔的变形过程.结果表明:1)由于晶粒形状、晶界及晶粒取向的作用导致晶内-晶间变形分布非均匀性;2)由于晶粒间复杂的相互作用导致晶粒取向主要绕横向(TD)进行旋转,且旋转角度和取向分散度随压下率的增加而增大;3)在晶内-晶间不同区域的滑移系启动存在显著差异,启动滑移系随压下率的增加而增多,当压下率小于等于60%时,在晶粒表层和晶界处,滑移系成对发生启动,当压下率达到80%时,表层和晶界处为多滑移系启动情形;4)滑移最先从晶粒表层和晶界处开始,然后向晶粒内部延伸.
The rate-dependent crystal slipping constitutive model incorporating both latent hardening and lattice rotation was implemented to analyze the influence of rolling reduction on the deformation behavior, crystallographic orientation development and the activity of slip systems around grain boundary during single layer grain ultra-thin strip cold rolling based on mechanisms of polycrystal dislocation motion and plastic flow. The reasonable constitutive parameters were established on the premise of consistency of experimental and simulated stress-strain curves.Simulations were successfully carried out using a crystal plasticity finite element method (CPFEM) model with the highest reduction of 80%. The simulation results showed that: 1) the intra-intergranular deformation distribution was inhomogeneous due to the influence of grain geometry, grain boundary and grain orientation; 2) the rotation of crystallographic orientation mainly was around the transverse direction attributing to the complex intergranular interaction, and the growth of rotation angle and dispersion degree increased with increasing cold rolling reduction; 3) the activity of slip system was significantly different in the intra-intergranular area, and the activity of slip systems increased with increasing rolling reduction. When the reduction was less than or equal to 60%, the slip system was activated in pairs at the grain surface and grain boundary, when the reduction reached 80%, the multi-slip systems were activated; 4) the slip was likely initialed at the grain surface and grain boundary first, and then extended to the interior of grain. The simulation results were compared with the experimental results and they were in good agreement in roll force and deformation, winch validated the correctness of the proposed model.

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