CAJ | 학술논문

采用一种真实的多晶集合体模型和晶体塑性有限元模型，研究异步轧制纯铜箔塑性变形晶粒统计效应。考虑局部硬化耗散作用，根据取向分布函数在取向空间中的分布规律将晶体取向分配给各个晶粒的单元积分点，建立弹塑性大变形条件下的相关多晶体塑性模型，并将其引入隐式有限元法。对非均匀材料流动、铜箔厚度一定时接触压力和轧制力随晶粒尺寸增加而降低的变形行为进行研究。结果表明，在箔材厚度方向上只有少数几个晶粒时，晶粒尺寸、形貌和取向不再均匀分布于箔材中，材料的变形行为主要受到单个晶粒变形行为的影响，从而导致非均匀变形及模拟和实验结果更加离散。研究变形过程中滑移系的启动过程，晶粒取向对滑移系的启动和滑移带的形成具有重要影响，预测结果与表面层模型一致。随着晶粒尺寸的增加，表层晶粒效应增大，更加有利于降低轧制力和激活表层晶粒内滑移系的开动。通过箔材轧制实验和模拟，可以更加深入地理解异步轧制极薄带微塑性变形的机理。
채용일충진실적다정집합체모형화정체소성유한원모형，연구이보알제순동박소성변형정립통계효응。고필국부경화모산작용，근거취향분포함수재취향공간중적분포규률장정체취향분배급각개정립적단원적분점，건립탄소성대변형조건하적상관다정체소성모형，병장기인입은식유한원법。대비균균재료류동、동박후도일정시접촉압력화알제력수정립척촌증가이강저적변형행위진행연구。결과표명，재박재후도방향상지유소수궤개정립시，정립척촌、형모화취향불재균균분포우박재중，재료적변형행위주요수도단개정립변형행위적영향，종이도치비균균변형급모의화실험결과경가리산。연구변형과정중활이계적계동과정，정립취향대활이계적계동화활이대적형성구유중요영향，예측결과여표면층모형일치。수착정립척촌적증가，표층정립효응증대，경가유리우강저알제력화격활표층정립내활이계적개동。통과박재알제실험화모의，가이경가심입지리해이보알제겁박대미소성변형적궤리。
The grain statistics effect was investigated through asymmetric rolling of pure copper foil by a realistic polycrystalline aggregates model and crystal plasticity element finite model. A polycrystalline aggregate model was generated and a crystal plasticity-based finite element model was developed for each grain and the specimen as a whole. The crystal plasticity model itself is rate dependent and accounts for local dissipative hardening effects and the original orientation of each grain was generated based on the orientation distribution function (ODF). The deformation behaviors, including inhomogeneous material flow, decrease of contact press and roll force with the increase of grain size for the constant size of specimens, were studied. It is revealed that when the specimens are composed of only a few grains across thickness, the grains with different sizes, shapes and orientations are unevenly distributed in the specimen and each grain plays a significant role in micro-scale plastic deformation and leads to inhomogeneous deformation and the scatter of experimental and simulation results. The slip system activity was examined and the predicted results are consistent with the surface layer model. The slip band is strictly influenced by the misorientation of neighbor grain with consideration of slip system activity. Furthermore, it is found that the decrease of roll force and the most active of slip system in surface grains are caused by the increase of free surface grain effect when the grain size is increased. The results of the physical experiment and simulation provide a basic understanding of micro-scaled plastic deformation behavior in asymmetric foil rolling.