镁合金构件开口凸模旋转挤压成形新工艺及其机制研究

How to manufacture magnesium alloy components with high properties and low cost is an significant and urgent demand to expand the applications of magnesium. Research on it has become one of important and challengeable issues in the plastic processing field of magnesium alloy. Thus, this project proposed a new method to form magnesium alloy parts by rotating extrusion with opening die in order to realize the unity of severe plastic deformation and component forming. Therefore it is urgent to research and resolve the coupling force field and cooperative control, the formability and macro or micro defects control, Structure and design of open punch，which is a key scientific and technical issue. By means of combining the process experiments and the method innovation, constitutive model modeling, numerical simulation, forming mechanism analysis, this project will reveal the composite loading mechanism of extrusion and torsion. The formation mechanism of continuous accumulation severe plastic deformation in the opening punch micro-field can be revealed. On this basis, the formability and the forming limit could be investigated under the effect of high pressure shear stress on magnesium alloy, deformation macro or micro defects will be predicted under the effect of controlled multi-movement and force calculation approach and mold designing standard are proposed for rotating extrusion process with opening punch. In the end, the new theory and new methods of rotating extrusion forming with opening punch were established. The research results are significant to fabricate the magnesium alloy parts of high performance with controlled shape and quality in low cost and to expand the engineering applications of magnesium alloy.

如何实现镁合金构件的高性能低成本制造是扩大镁合金应用重大而迫切的问题，其研究已成为镁合金塑性加工领域重要和挑战性课题。为此研究提出开口凸模旋转挤压成形新方法，实现镁合金剧烈塑性变形与构件成形的统一。而旋转挤压过程中的力场耦合与协同控制、成形性与宏微观缺陷调控、开口凸模结构及设计是其中急需研究解决的关键科学技术问题。因此，本项目拟通过工艺实验与方法创新、本构模型建模、数值仿真计算和成形机理分析结合等方法，揭示挤压和扭转复合加载力场耦合与协同控制机理，解析镁合金强压剪应力作用下的成形性能和成形极限，预测控制多运动作用下的成形宏微观缺陷，提出开口凸模旋转挤压成形力能计算方法和模具设计准则，建立开口凸模旋转挤压成形新理论和新方法。其结果对镁合金构件的成形成性低成本制造和扩大镁合金的工程化应用具有重要意义。

项目开展了镁合金构件开口凸模旋转挤压成形新工艺及其机制研究，理论分析、数值模拟与试验研究相结合，分析了开口凸模旋转挤压成形应力应变场量分布特征、金属流动规律和成形力能变化，揭示了挤压和扭转复合加载力场耦合与协同控制机理；研究了镁合金开口凸模旋转挤压成形性能和内部空洞型缺陷演变规律，阐明了镁合金强压剪应力作用下的空洞闭合条件和强韧化机制；研究了镁合金在不同开口凸模结构以及变形温度、旋转圈数下的组织性能演化规律，提出了开口凸模旋转挤压模具结构和热力加载条件设计准则；开口凸模旋转挤压成形理论与技术应用于镁合金舱段类、轮盘类构件的成形制造，实现了镁合金剧烈塑性变形与构件成形的统一。进一步丰富了镁合金塑性加工理论，促进了剧烈塑性变形技术的应用与发展，为高性能镁合金构件的成形成性低成本制造奠定了理论基础，为航空航天、交通运输等领域装备轻量化提供了技术支撑。