钛合金薄壁筒形件交叉旋压成形机理及性能调控机制

The mechanical properties of different parts of the as-spun cylindrical parts are obvious differences, the circumferential performance of thin-walled cylindrical parts is lower than its axial performance, which restricts the application of spinning cylindrical parts, how to improve the uniformity of the mechanical properties of as-spun cylindrical parts needs further study. The project proposed a new method of cylindrical cross-spinning to form the thin-walled cylindrical parts of titanium alloy, focusing on the cylindrical cross-spinning forming mechanism, cylindrical cross-spinning anisotropy and performance control mechanism. The cross-spinning FE model of the cylindrical part was established to reveal the deformation mechanism of the metal during the cross-spinning. The cross-spinning forming experiment was carried out to analyze the material microstructure evolution during the cross-spinning process, the texture evolution and the rotational rule of crystal orientation. The correlation between the cross-spinning parameters and the mechanical properties of the cylindrical part was clarified, and the technical approaches to improve the axial and circumferential performance of the as-spun part were explored for the properties controlling and bidirectional strengthening of the thin-wall cylindrical part. The research of this project will helpful to establish the theoretical method of cross-spinning of thin-walled cylindrical parts, to realize the optimal control of the microstructure and properties of the thin-walled titanium alloy parts, improved the uniformity of the cylindrical parts, obtained high quality thin-walled spinning parts and promote the application of spinning technology, which has important scientific significance and engineering application value.

强力旋压筒形件的不同部位性能存在较为明显的差异，薄壁筒形件的环向性能低于其轴向性能的问题，一定程度上制约了旋压筒形件的应用，如何提高筒形件的性能均匀性有待深入研究。本项目将以钛合金薄壁筒形件为研究对象，提出一种筒形件交叉旋压新工艺，重点开展筒形件交叉旋压成形机理、筒形件交叉旋压各向异性和性能调控机制研究。建立筒形件交叉旋压有限元模型，揭示其成形过程金属变形流动机理；开展交叉旋压成形试验，分析交叉旋压过程金属微观组织演化规律，揭示筒形件织构演化和晶粒晶体取向转动规律；阐明交叉旋压工艺参数与筒形件性能相关性，探索提高旋压筒形件轴向和环向性能的技术途径，实现钛合金薄壁筒形件性能的调控及双向强化。本项目的研究有助于建立薄壁筒形件交叉旋压成形的理论方法，实现钛合金薄壁筒形件组织性能优化控制，改善筒形件性能均匀性，获得高质量的薄壁旋压件，推动旋压技术的应用范围，具有重要的科学意义和工程应用价值。

旋压筒形件组织性能的各向异性问题制约着薄壁筒形件的应用，提高筒形件环向性能，改善构件性能均匀性，是获得高质量薄壁旋压件的关键。本项目以钛合金薄壁筒形件为研究对象，建立了筒形件多道次交叉旋压弹塑性有限元模型，揭示了关键工艺参数和旋轮几何参数对筒形件旋压接触区变形的影响规律，旋压接触区金属变形流动机理。采用筒形件交叉旋压工艺进行塑性成形，分析了多道次交叉旋压过程微观组织演化规律，揭示了筒形件织构演化和晶粒晶体取向转动规律，阐明了筒形件各向异性产生机理。单向旋压筒形件轴向取样的晶粒滑移系平均施密特因子从0.38逐步降低到0.19，环截面取向获得的平均施密特因子只在前2道次旋压时有少量减小，从0.37减小至约0.32，后续则呈现一定的波动，没有明显的减小，筒形件轴向强化要大于环向强化趋势，导致旋压筒形件各向异性比较明显。随着旋压减薄，初始粗大晶粒逐渐破碎细化，发生伸长变形，多道次旋压后晶粒细化较为明显，微观晶粒平均尺寸从1.69μm逐渐减小到0.57μm；晶粒取向在旋轮压应力作用下发生转动，晶粒c轴的偏转使得晶粒晶体取向逐渐靠近于ND硬位向，多数晶粒的施密特因子明显减小。交叉旋压改变了旋轮接触变形区金属环向流动规律，使较多的晶粒c轴倾向于向难变形的硬取向偏转，促进了环向力学性能的提升，晶粒取向Schmid因子在环向也有明显降低，从0.39减小到0.26，使得环向性能和轴向性能更为接近，旋压件轴向和环向的抗拉强度明显提升约30%。交叉旋压工艺改变了变形区在环向金属塑性流动特点和晶粒晶体取向的转动，实现了晶粒细化和均匀化，调控晶体取向差分布和滑移系施密特因子，进而实现了旋压筒形件性能均匀性调控和双向强化。