电致塑性辅助微细模压成形介观尺度效应机理与工艺研究

The high aspect ratio micro channel is the key to the high efficiency of the micro channel reactor. Recently, Processing methods such as cutting and milling are of low efficiency and high cost. In the efficient forming process at room temperature, it is difficult to achieve precise forming of high aspect ratio micro channel features because the material is less formable. While hot forming process could result in surface oxidation and low quality product. So that It can not be widely used right now. In this project, a novel forming process is proposed to combine the application of the electroplastic effect with the meso-scale forming process, namely the meso-scale electroplastic forming process. Electric pulse is introduced into the forming process to induce the electroplastic effect and reduce the Joule heating, so as to improve the quality of the micro channel features. Centred on the material deformation behavior and the process control in the meso-scale electroplastic forming process, the influences of the electric pulse parameters on the electroplastic effect and the Joule heating are firstly studied, based on which the precise description scheme for the electroplastic effect is presented, and the meso-scale electroplastic constitutive model is established by taking into account the mutual influence between the scale effect and the electroplastic effect. After that the multi-fields coupling simulation analysis modeling method for the meso-scale electroplastic forming process is established, and the influence of the process parameters on the product quality is investigated. Eventually the optimization method for the forming process is presented.At last, the experimental meso-scale electroplastic forming process prototype system is built to verify the feasibility of the forming process proposed, and to provide a new way for the high-quality, high efficiency production of the micro channel features.

介观尺度微通道是高性能微通道反应器的核心结构。目前采用铣削、刻蚀等加工方法效率低、成本高。微细模压虽可提高效率，但常温条件下材料充模困难；热成形条件下零件表面质量差。制约着微通道反应器大规模运用。.本项目将不锈钢材料电致塑性效应引入介观尺度模压工艺，提出一种电致塑性辅助介观尺度模压成形新方法，降低成形力，改善表面质量。围绕模压过程中材料流变行为的控制，研究电流场引发的材料电致塑性激发机理及热效应抑制机制，定量描述电流对电致塑性效应的影响规律；研究材料电致塑性和介观尺度效应的相互激励行为，建立电流场作用下的介观尺度材料本构模型；研究电致塑性辅助介观尺度模压成形的多场耦合仿真建模方法，揭示成形过程中电流场分布对金属流变行为的影响规律；研究工艺参数波动对成形质量的影响规律，建立微通道模压成形工艺稳健性设计方法。最后，构建电致塑性介观尺度模压成形实验系统，为微通道高效高质量制造提供理论与方法。

带有微细通道特征板式构件是高性能微通道反应器的核心结构。目前采用铣削、刻蚀等加工方法效率低、成本高。微细模压虽可提高效率，但常温条件下材料充模困难，热成形条件下零件表面质量差。本项目将不锈钢材料电致塑性效应引入介观尺度模压工艺，研究了一种电辅助介观尺度模压成形新方法。围绕电流辅成形工艺中高密度电流对引发材料塑性增强效应这一科学问题，在电致塑性成形材料本构、工艺建模及工艺实验开展深入研究。.项目研究了电流作用下，不同晶粒尺度对料性能的影响规律，解耦了电流、焦耳热效应对材料性能的影响；确定了电流对FCC金属位错滑移影响及组织转变的影响，建立了材料本构模型。研究表明，高密度电流对材料的影响分成电流本身的作用，即电致塑性效应，和电流引发的焦耳热作用，即电热塑性效应。对于以F.C.C位错堆垛变形为主的纯铜材料，电致塑性效应在电热效应的基础上，进一步减少了位错的生成（26%）以及加速了位错湮灭于晶界（65%）的过程，降低了在位错在晶粒内部堆垛，使得宏观力学性能出现“软化”现象；此外对于以切变型马氏体相变为主要硬化的不锈钢材料，高密度电流显著降低剪切带的生成，而电热效应则有效的抑制了马氏体相的生成含量（占77%），使得不锈钢材料的“软化”，塑性提高；提出了电-热-力三场耦合的电辅助成形工艺过程分析模型，分析了工艺参数对屈服应力、应变、温度及微观相变的影响规律。针对不锈钢模压工艺过程的仿真表明，高密度电流作用下，变形区电流分布促进材料温度提升，局部接触点塑性变形显著增加，应变抗力明显下降，相同载荷条件下微细特征的高度提升了23%。此外构建了电辅助模压成形实验系统，开展了微细沟槽及微细复杂结构的电辅助成形工艺实验，验证了电辅助成形工艺的优势和可行性。.在项目支持下，共发表英文论文8篇，其中5篇为ASME会刊；培养博士研究生2名。研究结论为电辅助成形工艺的实际工程运用提供了理论参考。.