铝锂合金板材冷-热复合模成形新方法与强化机理

To enhance the effective carrying capacity of heavy lift launch vehicles, it is very urgent to realize the weight reduction by using of Al-Li alloy. However, its application for forming tank gore panel is limited due to the high spring-back and low dimensional accuracy in the traditional forming process. Meanwhile, thermal distortion is easily caused during solution heat treatment. In order to solve these problems, new integrated process of hot forming-quenching with cold-hot dies is proposed, combining hot forming and heat treatment together in one operation. Heated dies are used to heat the sheet or avoid rapid temperature decrease of heated sheet. Water-cooled dies are used to accomplish quenching and limit thermal distortion. It is flexible to control the material flow and quenching by combining hot and cold dies. In this project, the forming behavior and strengthening mechanism of Al-Li alloy sheet in the integrated process of forming-quenching with cold-hot dies will be investigated. The cooperative control mechanism of shape and performance under the non-uniform temperature field condition will be revealed. The corresponding microstructure and performance evolutions will be clarified. The aim is to realize the integrated control of dimensional precision and performance of the tank gore panel, providing the theoretical basis for its application in heavy lift launch vehicles. This research can provide a new idea for the large size Al-Li alloy gore panel forming, and promote the application of the new process by cooperative control of shape and performance in aerospace.

重型运载火箭箭体结构迫切需要采用铝锂合金来实现轻量化，以提高有效运载能力。为解决大尺寸铝锂合金曲面板件传统成形方法存在易开裂、尺寸精度差和热处理变形大的难题，提出冷-热复合模成形新方法。其核心思想是将热处理和热成形相结合，在成形的同时控制性能。利用热模加热或减缓板材温度下降，利用冷模实现快速冷却和限制热畸变，灵活控制材料流动和淬火效果。通过铝锂合金曲面板件冷-热复合模成形时的变形规律和强化机理研究，揭示非均匀温度场下的形性协同调控机制及组织性能演变规律，实现贮箱瓜瓣等曲面板件形状精度-性能一体化控制，为在重型运载火箭上的应用提供理论基础。该项目的研究可为大尺寸铝锂合金箭体结构精密成形提供新思路，并推动“成形”-“成性”一体化新工艺在航空航天领域的应用。

针对铝锂合金曲面板件传统成形方法存在易开裂、尺寸精度差及热处理变形大的难题，提出冷-热复合模成形新方法，研究了铝锂合金曲面板件冷-热复合模成形时的变形规律和强化机理，揭示了非均匀温度场下构件形性协同调控机制及组织性能演变规律，实现曲面板件形状精度-性能一体化控制，建立的铝合金曲面件热变形-淬火复合成形技术，已应用于国防高端装备关键构件研制。作为重要组成部分，获得2020年国家技术发明二等奖和2019年黑龙少省技术发明一等奖。