局部控温局部加载下钛合金功能梯度构件渐变组织的主动调控

Titanium functionally gradient component (TFGC) becomes the key part for developing advanced aircraft because its advantage of integral structure with different microstructures and performance at different positions which greatly satisfies the requirements of significantly varying thermal-mechanical service environment. There is a challenging problem in manufacturing TFGCs that how to achieve gradual change between significantly different microstructures at different positions in order to avoid weak link between these positions. The key to solve this problem is to develop the novel principle and method of active coordination of gradual-changed microstructures through the integral coordination of temperature and deformation by means of local temperature-controlling local loading forming process. In this project, based on the homogenization theory, a hierarchical multiscale-homogenized model will be proposed to synchronously predict forming characteristics and microstructure evolution of TFGCs. By virtue of this model together with experimental study on scaled components, the objective gradual-changed microstructures and their distribution will be defined under the requirements of gradual-change performance of TFGCs. Then, the effect of non-uniformly distributed fields of temperature and deformation on microstructure evolution will be studied. Consequently, the matching mechanism and actively controlling principle and approach of the local temperature-controlling technique, which can be realized through integral preheating followed by local induction treatment, and the local loading technique, which can be realized by die division and multi-pass loading, will be studied and developed. The above expected research results will provide a basis for developing the high-performance precision plastic forming theory and technology of TFGCs, and thus contribute to the progress in advanced manufacturing technology of TFGCs, e.g., the dual-property engine compressor discs, which are urgently required in China aerospace.

钛合金功能梯度构件因其不同部位具备不同组织和性能，可满足热力环境差异显著的服役要求，成为先进飞行器发展的关键构件。如何调控构件不同部位间组织的渐变过渡以避免“弱连接”，是其高性能成形制造面临的挑战性难题。而发展局部控温局部加载创新工艺协同控制成形温度与变形以主动调控构件渐变组织的原理和方法，是解决该难题的关键。本项目基于均匀化理论，研究建立同步预测构件成形与组织性能演化的分阶层多尺度均匀化模型，并与缩比件试验研究相结合，由构件渐变性能要求确定其目标渐变组织分布，进而研究揭示不均匀温度场与变形场耦合作用下的组织演化规律，依此研究电炉整体预热+局部感应加热的局部控温方法与模具分区多道次局部加载方法的匹配机制和渐变组织的主动调控原理与方法。为发展钛合金功能梯度构件高性能精确塑性成形理论和技术提供依据，为推动我国航空发动机迫切需求的钛合金双性能整体叶盘等功能梯度构件先进制造技术的进步做出贡献。

本项目采用局部控温局部加载方法主动调控钛合金功能梯度构件组织渐变，解决了双性能盘过渡区微观组织突变问题。在此过程中围绕“梯度控温梯度变形耦合作用下钛合金微观组织演变机理与规律”、“钛合金功能梯度构件渐变组织局部控温局部加载的主动调控方法”两个科学问题，重点开展了钛合金相组分对性能的影响规律、复杂温度场与变形场下的细-微观多尺度建模、大型构件成形与组织演化的宏-细-微观跨尺度建模、盘坯局部控温局部加载下梯度温度场与变形场的主动调控方法等四个方面的研究。研究取得的进展包括：（1）揭示了钛合金相组分对性能的影响规律，获得了组织与性能之间的关联关系；（2）建立了多尺度数值预测模型，定量描述了动态再结晶、片层析出相变、片层组织球化、晶界损伤与断裂等组织演化行为，揭示了钛合金梯度复杂温度场与变形场条件下的变形与组织演化机理与规律；（3）建立了非均匀温度场和变形场作用下钛合金大型构件成形与组织演化跨尺度建模；（4）提出了钛合金盘坯梯度温度场与变形场调控工艺方案，建立了盘坯局部控温局部加载变形全过程预测模型，揭示了钛合金盘坯温度场和变形场的演化规律，优化了目标梯度温度场与变形场下的工艺参数调控窗口。项目成果在国内外重要学术期刊发表论文18篇，其中包含国际塑性领域TOP1期刊Int J Plasticity上3篇，授权发明专利1项，在国内外重要学术会议作邀请报告4次，以本项目成果为重要支撑，获2020年度陕西省自然科学一等奖（已公示），项目负责人入选青年长江学者，获批陕西省杰青和陕西高校青年创新团队。培养博士生4人、硕士生3人。