基于复杂应变路径效应的镁合金温热拉深成形机理研究

Magnesium alloy sheet is under multiaxial stress states and complex strain paths during warm deep drawing process. However, it is still unclearr that the effect of deformation mechanisms such as slip, twinning and detwinning on the mechanical properties and formability of magnesium alloys under complex strain paths at warm temperature. In this project, the physical simulation of warm deep drawing is combined innovatively with in-situ EBSD tracing technique to analyze the grain morphology and texture evolution of magnesium alloy sheet during warm deep drawing process. The activation conditions of slip, twinning, detwinning and their evolution mechanism will be systematically researched. Therefore, the deformation mechanism of magnesium alloy sheet under complex strain paths will be revealed. To accomplish above aims, macro-finite element model and crystal plasticity finite model will be used in conjunction with multi-scale simulation on the deep drawing process. Then, the microstructure and mechanical property prediction model of deep drawing magnesium alloy parts will be built based on comprehensive analysis of physical simulation results and numerical simulation results. This project will be hopeful to reveal the deformation mechanism of deep drawing for magnesium alloy sheet, which provides theoretical basis for the optimizing deep drawing process, as well as promoting the application of magnesium alloy sheet deformation area.

合金复杂构型零件在温热拉深过程中，板材处于多向应力、复杂应变路径状态。然而，镁合金板材在温热条件和复杂应变路径下，滑移、孪生以及织构演变等微观变形机制对板材力学性能、成形性能的影响规律和机理还未明确。本项目创新性地结合镁合金温热拉深成形物理模拟实验和EBSD原位跟踪方法，分析具有不同织构和晶粒尺寸的板材在温热拉深过程中晶粒形貌及织构演化，系统研究镁合金板材拉深过程中滑移、孪生、退孪生的开动条件、扩展规律，揭示复杂应变路径下镁合金板材的变形机理；通过宏观有限元与晶体塑性有限元多尺度模拟建立拉深成形镁合金零件组织、力学性能及冲压成形性能预测模型。本项目有助于揭示镁合金板材温热拉深变形机理，为优化温热拉深成形工艺提供理论依据，促进温热拉深成形在镁合金板材成形领域的应用。

在板材塑性成形工艺中，拉深成形工艺是成形薄壁空心零部件的重要成形工艺，因此，对镁合金拉深成形工艺的研究得到了广泛的关注。镁合金板材在真实的室温及温热拉深过程中，板材处于多向应力、复杂应变路径状态。然而，镁合金板材在室温及温热条件和复杂应变路径下，滑移、孪生以及织构演变等微观变形机制对板材力学性能、成形性能的影响规律和机理还未明确。本项目创新性地结合镁合金室温及温热拉深成形物理模拟实验和EBSD方法，分析镁合金板材在拉深过程中晶粒形貌及织构演化，通过多尺度模拟系统研究镁合金板材拉深过程中滑移、孪生、退孪生的开动条件、扩展规律，揭示复杂应变路径下镁合金板材的变形机理。本项目有助于揭示镁合金板材室温及温热拉深变形机理，为优化拉深成形工艺提供理论据，促进拉深成形在镁合金板材成形领域的应用。