基于各向异性冷轧纯钛薄带的屈服行为研究

Yield behavior of cold-rolled pure titanium thin strip based on anisotropy

摘要:

传统冷轧薄带理论中常将轧件假设为理想的各向同性材料，往往以RD-TD面内屈服应力进行轧制计算，而并未考虑薄带存在各向异性的问题。为此基于单轴拉伸试验和晶体粘塑性自洽模型(VPSC)开展了纯钛薄带的屈服行为研究，利用等塑性功和屈服准则构建了以RD拉伸屈服应力为参考的屈服轨迹，并通过冷轧过程模拟探究了各向屈服应力的差异对轧制变形区特征的影响规律。研究结果表明:基面双峰织构纯钛薄带的屈服应力依次为ND最大，TD次之，RD最小，而屈服应力的各向异性导致传统薄带轧制理论的计算结果与实际结果之间存在很大误差。为方便应用以RD拉伸屈服应力为参考，基于Hill48各向异性屈服准则对传统冷轧薄带理论中的Fleck轧制模型进行了修正，计算值与理论值吻合良好。

Abstract:

The rolled piece is assumed to be an ideal isotropic material in the traditional cold-rolled strip theory, and the yield stress in the RD-TD plane is often used for rolling calculation, while the anisotropy of the strip is rarely considered. For this reason, the yield behavior of pure titanium strips was studied based on uniaxial tensile test and crystal viscoplastic self-consistent model (VPSC), and the yield trajectory with RD tensile yield stress as reference was constructed using equal plastic work and yield criterion. The influence of the yield stress difference in each direction on the characteristics of rolling deformation zone was investigated through the cold rolling process simulation. The research results show that the yield stress of the basal bimodal textured pure titanium strip is the largest in ND, the second in TD, and the smallest in RD, and the anisotropy of the yield stress leads to a large error between the traditional theoretical results and the actual results. For the convenience of application, the Fleck rolling model in the traditional cold-rolled strip theory was modified based on the Hill48 anisotropic yield stress with the RD tensile yield stress as a reference, and the calculated values were in good agreement with the theoretical values.