高强铝合金拼焊板电磁辅助渐进成形塑性流动规律及组织性能遗传演化机制

In order to solve the problems of the difficulty in forming the structure and controlling the performance for the large thin-wall curved surface components of high-strength aluminum alloy, for example, the bottom components of the fuel storage tank for the heavy-duty rocket, this project proposes a new manufacturing scheme of integral forming: welded blank of aluminum alloy→ heat treatment→electromagnetic pulse-assisted incremental stamping. The effects of the process parameters of the post-welding heat treatment on the properties, interface structure and microstructure of the friction stir welding (FSW) joints are investigated in order to obtain the high formability FSW welding plate. The constitutive model of electromagnetic field-stress field-temperature field is established and the plastic flow behavior of aluminum alloy FSW blank is analyzed by numerical simulation and process experiments. The genetic evolution of microstructure and properties of aluminum alloy FSW joints is revealed under the condition of complex strain path and strain rate history. An integrated ‘process-structure-performance’ control method for electromagnetic pulse-assisted incremental stamping of high strength aluminum alloy FSW blank is established. The feasibility of the whole forming process scheme and the control method of properties and microstructure is verified by the experiments of shrinkage parts. The research results of this project are of great significance for illuminating the deformation law of electromagnetic pulse-assisted incremental stamping of aluminum alloy welded components, constructing the method for regulating the microstructure and properties, and improving the manufacturing level of large thin-wall curved surface components of aerospace in China.

针对大推力重型火箭燃料贮箱箱底类高强铝合金大型薄壁曲面构件结构难成形和性能难控制等问题，本项目提出整体成形成性制造新方案：铝合金拼焊板→热处理→电磁辅助渐进成形。研究焊后热处理参数对2219铝合金摩擦搅拌焊（FSW）接头宏观性能、界面结构与微观组织的影响，得到高成形性铝合金FSW拼焊板；构建电磁场-应力场-温度场耦合作用下的本构模型，通过数值模拟和工艺实验分析铝合金FSW拼焊板在电磁辅助冲压渐进成形条件下的塑性流动行为；揭示铝合金FSW拼焊接头在电磁辅助渐进成形复杂应变路径及应变率历史条件下组织与性能遗传演化规律；建立高强铝合金FSW拼焊板电磁辅助渐进成形“工艺-组织-性能”一体化调控方法；开展缩比件实验，验证整体成形工艺方案与宏微观调控方法的可行性。本项目研究成果对于阐明铝合金拼焊构件电磁辅助渐进成形变形规律、构建组织性能调控方法，以及提高我国航天大型薄壁曲面构件制造水平具有重要意义。

针对大推力重型火箭燃料贮箱箱底类高强铝合金大型薄壁曲面构件结构难成形和性能难控制等问题，本项目基于整体成形成性制造新方案：铝合金拼焊板耦合固溶时效、电磁辅助冲压渐进成形的工艺方案开展相关基础研究。研究了搅拌摩擦焊（FSW）焊接参数对拼焊板力学性能和微观组织的影响；探索了2219铝合金搅拌摩擦焊的最佳焊接参数。阐明了铝合金FSW拼焊板常规/形变热处理工艺及其对宏微观性能的影响机制。基于Arrhenius模型扩展的本构模型对铝合金宽应变率和温阈范围塑性流动行为进行研究，并通过实验数据拟合和常用四种本构模型对比的两个维度对新建立的本构模型进行验证。探明高强铝合金在电磁成形及电磁处理条件下的组织与性能的演化规律；综合考虑应变率、应变量、温度因素的影响，系统地阐明了2219铝合金在脉冲电磁力作用下的强化机制。围绕不同工艺路线展开研究，揭示了铝合金FSW拼焊板在准静态-电磁渐进成形条件下组织与性能遗传演化规律；阐明不同应变路径及应变率历史条件下铝合金FSW接头特征组织(晶粒、位错、第二相)遗传演化规律，明晰第二相与位错的交互作用及其强化机理；建立了2219铝合金FSW拼焊板的力学性能、成形性能与微观组织演变之间的联系；基于缩比件实验，探索了高强铝合金拼焊板“工艺-组织-性能”一体化调控方法。本项目研究成果对于阐明铝合金拼焊构件在电磁场-应力场-温度场多物理场耦合作用下变形规律及组织遗传演化机制，以及提高我国航空航天大型薄壁曲面构件制造水平具有重要意义。