This paper presents a multi-level viscoplastic self-consistent (VPSC) model for correlated structures (CS-VPSC). A polycrystalline aggregate response is homogenized over inclusions, which are linearized using the generalized affine scheme. Response of the inclusions is that of either a single grain or a correlated structure of multiple single crystals. The single crystal response is a strain rate adjusted power-law viscoplastic formulation, which considers not only the driving force in the glide direction but also the two orthogonal shear and three normal components of the driving force. The resistance to slip is grain size sensitive and based on the evolution of dislocation density. Furthermore, the resistances of prismatic and basal slip systems are adjusted based on the geometry of slip transfer between adjacent correlated structures. The overall model linking the single crystal micro-scale to a correlated structure meso‑scale to an aggregate macro-scale response is also coupled with the implicit finite elements (FE-CS-VPSC). The model is used for modeling strain rate sensitive mechanical response and microstructural evolution of additively manufactured Ti-6Al-4 V (Ti64) alloy in two conditions. As-built and stress-relived (SR) microstructure consisted of correlated α-lath/lamellar structures, while thermo-hydrogen refined microstructure (THRM) consisted primarily of α- and $\beta$-globular structures and some correlated α-lath/lamellar structures. Electron backscatter diffraction data, neutron diffraction data, and mechanical data were used to initialize, calibrate, and validate the model. To this end, the flow stress and texture evolution of the materials in tension and compression under quasi-static and high strain rate deformations were predicted using CS-VPSC, while the texture evolution during rolling and impact was simulated using FE-CS-VPSC. Good predictions of the texture evolution and mechanical response including the tension/compression asymmetry allowed us to discuss the roles of correlated structures, slip system activation stresses, size effects, strain partitioning between phases, and slip activities in such predictions.

本文提出了一种用于相关结构 (CS-VPSC) 的多级粘塑性自洽 (VPSC) 模型。多晶聚集体响应在夹杂物上均匀化，夹杂物使用广义仿射方案线性化。夹杂物的响应是单个晶粒或多个单晶的相关结构。单晶响应是应变率调整的幂律粘塑性公式，它不仅考虑了滑动方向的驱动力，还考虑了驱动力的两个正交剪切和三个法向分量。抗滑移对晶粒尺寸敏感并且基于位错密度的演变。此外，棱柱和基底滑移系统的阻力根据相邻相关结构之间的滑移传递几何形状进行调整。将单晶微尺度与相关结构中观尺度与聚合宏观尺度响应联系起来的整体模型也与隐式有限元 (FE-CS-VPSC) 耦合。该模型用于模拟增材制造的 Ti-6Al-4 V (Ti64) 合金在两种条件下的应变率敏感机械响应和微观结构演变。竣工和应力消除 (SR) 微观结构由相关的组成α-板条/层状结构，而热氢精制微观结构 (THRM) 主要由α-和$\beta$-球状结构和一些相关的α -板条/层状结构。电子背散射衍射数据、中子衍射数据和机械数据用于初始化、校准和验证模型。为此，使用 CS-VPSC 预测了准静态和高应变率变形下材料在拉伸和压缩下的流变应力和织构演变，同时使用 FE-CS-VPSC 模拟了滚动和冲击过程中的织构演变。对纹理演化和机械响应（包括拉伸/压缩不对称）的良好预测使我们能够讨论相关结构、滑移系统激活应力、尺寸效应、相间应变分配和滑移活动在此类预测中的作用。