钛合金同步感应激光成形修复的“本体-热影响区-修复区”组织性能协调控制

The interdisciplinary method combining the metal metallurgy and the structural mechanics was employed to solve the key science problem of coordinated control of the microstructure and mechanical properties in the "base-heat affected zone-repaired zone"during laser forming repair of titanium alloys. A composite induction laser forming repair technology was proposed to expand the thermal behavior regulatory capacity during laser forming repair. Firstly, a finite element model coupling the thermal-force during induction laser repair was established based on the experimental measurement and the finite element analysis. The influences of the composite processing parameters on the thermal behavior and the stress deformation were disclosed and the regulation and control mechanism was established. The influences of the thermal behavior on the microstructure and the mechanical properties were proved and the relationship among the processing parameters, thermal behavior, microstructure and mechanical properties was established based the thermal simulation experiment and the characterization of the microstructure and mechanical properties. A load-bearing model was established, and the stress transfer, regularities of stress distribution and failure mechanism of the "base-heat affected zone-repaired zone" under the loading were studied based on the mechanical analysis and the dynamic analysis of the deforming. Further, the coordinated design and the optimization of the "base-heat affected zone-repaired zone" were proposed based on the optimization of the structural mechanics. Finally, the regulation and control of the microstructure and mechanical properties of the "base-heat affected zone-repaired zone" was realized and the synthesis mechanical properties of the repaired parts were improved. The research will lay a theoretical and technical foundation for the high performance repair of the titanium alloys.

本项目采用金属冶金学与结构力学学科交叉的研究方法，解决钛合金激光成形修复中"本体-热影响区-修复区"体系的组织、性能协调控制的关键问题。利用同步感应辅助的方法，拓展激光成形修复的热行为调控能力。结合实验测量和有限元方法，建立感应-激光成形修复的热-力耦合模型，揭示复合工艺对热行为和应力变形的影响规律并建立调控机制；基于热模拟实验及区域组织、性能表征，探明热行为对修复区、热影响区显微组织及区域性能的影响，建立各区域"工艺-热行为-组织-性能"的关联，并提出控制原理；建立修复件承载模型，基于承载过程力学分析和动态过程观测，揭示载荷作用下"本体-热影响区-修复区"的应力传递、分布规律及失效机理；结合结构力学优化方法，提出"本体-热影响区-修复区"的协调设计原理及优化方案。据此，实现各区域的组织、性能协调控制，提高修复件的综合力学性能。项目研究成果将为钛合金高性能成形修复奠定重要的理论和技术基础。

本项目针对激光成形修复中“本体-热影响区-修复区”组织性能协调控制的难题，发展同步感应激光成形修复技术，拓展激光成形修复的热行为调控能力。项目采用TC4钛合金，建立和改进了同步感应复合激光成形装置，研究复合工艺参数对钛合金成形修复工艺特性的影响规律，建立复合工艺窗口。在此基础上，重点研究了复合工艺下的过程热行为、微观组织性能以及本体-热影响区-修复区承载条件下的力学行为。结合实验测量和有限元方法，建立感应-激光成形修复的过程耦合模型，揭示了感应-激光成形修复双热场耦合作用下成形过程的热行为规律；结合非平衡凝固及固态相变理论，明晰了感应-激光成形修复双热场耦合作用下的热影响区、修复区微观组织形成及演化机理，进而提出了修复区、热影响区显微组织、区域性能的主动调控方法，为激光成形修复中“本体-热影响区-修复区”组织性能协调控制奠定了技术基础；研究结合本体-热影响区-修复区的性能表征，建立了承载条件下“本体-热影响区-修复区”体系承载模型，结合载荷测试，揭示了“本体-热影响区-修复区”体系协同力学行为，进而探讨了修复界面形貌对修复件承载力学行为的影响规律，研究表明， 30°斜界面的界面附近的应力分布最优，凹、平、斜界面最低疲劳寿命依次降低。该研究成果为“本体-热影响区-修复区”组织、区域性能协调优化设计奠定了理论基础。在本项目的资助下，相关研究成果已在国际国内核心期刊上发表具有高水平的研究论文17篇，申请国家专利5项；入选英国皇家学会“牛顿学者(Newton International Fellowships)”1 人，陕西省创新人才推进计划——中青年科技创新领军人才1人，博士3名，硕士6名。项目相关成果正在西安铂力特增材技术股份有限公司进行成果转化，并且项目部分研究成功果支撑西工大增材制造团队牵头成立了陕西省增材制造军民融合产业联盟，建立西工大-空客增材制造联合实验室。