控制变形和温度制造钛合金双性能件时微观组织的协调演化机制

Dual-property components with gradually changed microstructure have an extensive application prospect in aviation and aerospace industries. Controlling deformation and dual microstructure heat treatment processes are used to manufacture dual property components of titanium alloys. It is very urgent to acquire the collaborative mechanisms of microstructure during the manufacturing of dual-property components. In this study, the formation mechanisms of alpha and beta phases and its relationship are investigated. The collaborative deformation between the two phases or among polycrystalline grains and its effect on the microstructure evolution are analyzed. The collaborative mechanisms of polycrystalline grains are acquired on the basis of experimental and theoretical analysis during the controlling deformation and dual microstructure heat treatment processes. Moreover, a quantitative assessment method is proposed to describe the morphology of mixed crystal structure. The effect of deformation degree and gradient temperature on the microstructure of different regions is investigated. The relationship between the forming manufacturing parameters and gradient microstructure is acquired. Finally, the optimal the forming manufacturing parameters are confirmed to obtain goal microstructure. Present study lays a foundation for developing precise manufacturing technique for dual property components of titanium alloys.

具有渐变微观组织的双性能件在航空航天领域的应用前景广阔。采用控制变形量的锻造方法和控制温度梯度的热处理方法复合可制造出高性能的钛合金双性能件，其成形制造过程中微观组织的协调演化机制是急需解决的关键基础问题。本项目拟采用试验与理论相结合的方法，研究钛合金α相与β相的形变机理及其关联性，获得不同组成相、不同晶粒互相协调变形对微观组织演变行为的影响规律，揭示控制变形和温度下钛合金的多晶协调演化机制；提出钛合金混晶表征方法，将微观组织形态表征与数值模拟相结合，研究变形和梯度热处理工艺参数对钛合金不同区域微观组织的影响规律，揭示钛合金渐变微观组织与成形制造参数的关联特性，确定目标组织下钛合金变形和梯度热处理工艺参数的极限范围，为钛合金双性能件精密制造技术发展奠定理论基础。

本项目采用试验与理论相结合的方法，研究了钛合金α相与β相的形变机理及其关联性，获得不同组成相、不同晶粒互相协调变形对微观组织演变行为的影响规律，揭示控制变形和温度下钛合金的多晶协调演化机制；提出钛合金混合组织定量分析方法，将微观组织形态表征与数值模拟相结合，研究变形和梯度热处理工艺参数对钛合金不同区域微观组织的影响规律，揭示钛合金微观组织演化与成形制造参数的关联特性，确定目标组织下钛合金变形和梯度热处理工艺参数的极限范围。研究结果表明：TC17合金高温变形与热处理时交织的组织形态有利于片层球化，发明的交织程度定量方法有效地描述了不同工艺条件下网篮组织的交织程度，而且等轴组织TC17合金在变形温度930℃、应变速率0.01 s-1、等效应变值0.51时进行锻造，再经过适当的热处理后获得的TC17合金的网篮组织状态最佳，在此基础上开展840℃等温锻造和炉内温度梯度大于60℃的热处理试验，可以获得目标渐变组织，为钛合金双性能件精密制造技术发展奠定理论基础。