高温合金闪光焊接界面再结晶行为与热影响区组织性能演变规律研究

Flash butt welded superalloy rings are important components to meet the manufacturing of the aeroengines. Due to the mechanism of flash butt welding are poorly understood, and lack of research results on relationship between the microstructure and properties of weldment. The quality of flash butt welded component varies widely, and has no mechanical property standards. And the applied scope of flash butt welded parts was limited. The study about flash butt welding finds that flash butt welding is heated by flash process and completed welding by upset deformation. And the dynamic recrystallization on the interface has an important influence on the formation of welding seam according to the microstructure of welding seam. Thermal deformation simulation method is used to simulate the welding process in this work. The specimens with interface are used, and the effect of temperature, compression degree and rate on the dynamic recrystallization on the interface will be researched. Forming conditions of welding seam will be studied. Then the flash butt welding test of GH4169 is performed according to the conditions of simulation experiments. The establishing of flash butt welding temperature field will be studied. The weldment characteristics under different deformation conditions, and the relationship between microstructure and mechanical properties of their heat affected zone will be researched. According to the boundary conditions of flash butt welding, which can fulfill quality requirement of weldment. The flash butt welding processing map will be established, which can describe the temperature and the upset deformation condition of flash butt welded GH4169 alloy. The results of this research will meet the technical requirements for the manufacture of flash butt welded rings for aviation, and provide reference for the application development of flash butt welding technology.

高温合金闪光焊环件是能满足航空发动机制造的重要构件。由于对高温合金闪光焊接机理认识不清晰，焊接组织与性能关系规律研究缺乏，导致闪光焊接环件质量波动大，性能控制缺乏标准，限制了其应用范围。申请人根据闪光焊接是通过闪光加热+顶锻变形完成焊接的特点，结合对焊缝微观结构研究结果，得出焊接界面上的动态再结晶对焊缝形成具有重要影响。提出采用热变形模拟方法对闪光焊接过程进行模拟。采用带界面试样，研究温度、压缩变形速率和变形量对界面上发生动态再结晶的影响规律，获得焊缝形成条件。根据模拟实验所得条件开展GH4169闪光焊接实验，研究闪光焊接温度场形成规律，顶锻变形参数变化对焊缝组织的影响规律，认清焊缝与热影响区组织性能关系。获得满足质量要求的闪光焊接边界条件，由此建立一种闪光焊接加工图，描述GH4169合金完成闪光焊接所需温度及顶锻变形条件范围。研究成果将对闪光焊应用于航空环件提供新的思路和技术支撑。

燃气涡轮发动机中，高温合金钛合金环形件是各级燃烧室中最基础的零部件。闪光焊接是环形件制造高效、经济的技术方案，在国外民用航空发动机中已经广泛应用，但相关焊接机制与制造技术无从查询，这类难变形材料闪光焊接机理认识不清晰，焊接组织与性能关系规律研究缺乏，导致这类高性能要求闪光焊接环件质量波动大，性能控制缺乏标准，限制了其应用范围。本研究中申请人根据闪光焊接闪光加热+顶锻变形完成焊接的特点，结合对焊缝微观结构研究结果，得出焊接界面上的动态再结晶对焊缝形成具有重要影响。.（1）通过对各焊接参数GH4169闪光焊接试样的性能对比分析，焊接温度形成源于端面微区短路接触爆破，通过热传导形成梯度温度场，顶端过程在焊接端面上的动态再结晶是形成焊缝的主要机制，认识了焊接温度来源与分布特点，焊缝形成机制，证实了闪光焊是固态焊接的本质，并在具有同素异构转变的Ti6242合金上成功开展了闪光焊接实验，证实了该焊接机制。.（2）通过焊接性能测试认识到热影响区宽度对GH4169焊接组织性能具有重要影响。结合顶锻变形对梯度温度场宽度的影响，提出通过满足焊接端面动态再结晶的温度与变形条件，来满足焊接成形与热影响区宽度控制。由此提出焊接参数需要满足将任意焊接件低硬度区控制在10-15mm左右，硬度过渡区小于2mm的组织控制原来来满足高性能GH4169焊接件制造。.（3）根据焊缝形成的组织结构特点，研究焊缝残留应变对不同固溶温度下组织尺寸的影响规律，合理的焊后组织在980℃进行固溶，会得到从焊缝到热影响区晶粒尺寸梯度分布的组织特点，这种非均匀的焊接组织会促进变形过程几何必须位错的增值，焊接试样拉伸强塑性均高于同热处理条件下的母材。.针对燃气轮机用难变形合金闪光焊接研究，本课题系统探索了闪光焊接成形机制，组织性能控制方法，相关研究结果在GH4169与Ti6242环形件零部件制造中得到应用，支撑了低成本焊接环件的制造技术与方法的发展，相关研究工作发表了科技论文12篇，获批发明专利4件。