BCC结构铁素体不锈钢形变及再结晶过程的织构演变机制和宏-介观建模

Texture is the primary cause for the anisotropy of ferritic stainless steel and other metals. However, the texture formation is sensitive to various factors during processing. Now, most of the available texture controlling techniques are limited to the experimental qualitative analysis. .The objective of this proposal is to study the mechanism and quantitative modeling of the texture evolution of ferritic stainless steel during processing. By introducing the crystalline orientation information to the modeling of deformation and recrystallization process, the mechanism of texture evolution during processing was clarified using experimental investigation, finite element modeling and simulation. The investigations are conducting as follows. 1) The characterization of the evolution of macro and micro texture during rolling and other deformation processes will be investigated. And crystal plasticity finite element method (CPFEM) is being utilized to model the deformation procedure of Fe-Cr based steel with BCC structure. Then the plastic deformation behavior and the mechanism of deformation texture formation will be clarified. 2) The preferential position and orientation of the recrystallization nuclei will be characterized. And the grain boundary mobility characteristic during growth of recrystallization nuclei will be also confirmed. These laws are being introduced to the cellular automata (CA) to simulate the variations of orientation during recrystallization process. The mechanism of recrystallization texture formation will be clarified. 3) Then the macro-meso texture evolution during the whole manufacture process including deformation and recrystallization can be simulated by coupling CPFEM and CA, considering the genetic characteristic of texture evolution. .The achievements of this proposal are of significant theoretical value and application value for enriching the texture formation mechanisms of BCC polycrystalline as well as for developing the new texture controllable techniques.

织构是铁素体不锈钢等多晶体金属材料产生各向异性的主要原因，受加工制备过程中多种因素影响，现有织构调控方法多局限于实验定性分析。本项目拟针对BCC结构铁素体不锈钢，将晶体取向信息引入到形变和再结晶的计算模拟中，结合实验、有限元计算和模拟，研究其在加工制备中的织构演变机制和定量计算方法。具体包括：1)研究轧制等形变过程中宏微观织构演变特征，建立Fe-Cr钢多晶体多系滑移的晶体塑性有限元模型(CPFEM)，揭示形变过程中多晶体塑性变形行为及形变织构形成机制；2)研究再结晶形核的位置、取向及长大过程中的晶界迁移特征，并引入到元胞自动机(CA)中模拟再结晶过程的晶体取向变化，阐明再结晶织构形成机制；3)基于织构演变遗传特性，将CPFEM与CA耦合，实现形变及再结晶加工全过程的宏介观织构演变预测。研究成果对充实BCC多晶体金属的织构形成理论、发展织构可控制备新技术有重要理论意义和应用价值。

铁素体不锈钢等多晶体金属材料在形变及再结晶过程中除发生组织变化外，其晶体取向也将发生改变，而制备过程中产生的织构对其成形性能、各向异性均有重要影响。本项目基于实验研究，分析了铁素体不锈钢晶体塑性变形机理和再结晶取向演化机制，构建了形变及再结晶过程中晶体取向预测的晶体塑性模型和再结晶模型，实现了铁素体不锈钢形变及再结晶过程织构演化的定量预测，具体包括：1研究了冷轧及形变过程中微观组织和晶体取向变化规律，并基于晶体塑性理论，构建了BCC结构多晶体的晶体塑性有限元模型，回归了铁素体不锈钢的晶体塑性参数，对变形过程的取向依赖特性进行了系统分析；2研究了冷轧退火过程中的再结晶织构演化规律，在传统扫描电子显微镜电子背散射（SEM-EBSD）设备中开发了准原位跟踪技术，成功追踪了再结晶微观组织和晶体取向的演化过程；3.构建了含有晶体取向状态变量的再结晶元胞自动机模型，实现了对再结晶过程中的拓扑结构和晶体取向的同时模拟。项目的顺利执行丰富了铁素体不锈钢的织构形成机理，为多晶体金属材料的织构演化提供了一种数值计算方法，对发展金属材料织构可控制备具有重要理论和应用价值。