冲击载荷下高温合金整体叶盘焊接接头的力学行为及机制

The mechanical behavior of the dissimilar welded joint of single crystal/polycrystal superalloy under the impact loading directly affects the service reliability of the welded components of the blisk. The project aims to investigate the essential relationship between the microstructural change and microhardness distribution of the welded joint and determine the tensile properties and strain rate dependent failure location under the high temperature and impact load based on the combination of experimental test and theoretical analysis. The strain distribution and evolution of the welded joint under various strain rates and micro-mechanism for the failure location offset under high strain rates will be clarified using the experimental and simulation results. And the deformation and fracture mechanism model of the single crystal/polycrystal superalloy welded joint under the high temperature and impact load will be set up. The results of the study will enrich the basic theory for the mechanical behavior of the superalloy under the high temperature and transient load and deformation and fracture behavior of the welded components under the impact load. It will also provide scientific basis for structural design of the superalloy blisks based on the mechanical behavior evaluation under the impact loading.

单晶/多晶高温合金焊接接头在冲击载荷下的力学行为直接影响整体叶盘焊接构件的服役可靠性。本项目拟通过实验测试与理论分析相结合的方式，系统研究接头的组织分布与硬度变化空间不对称性规律的本质联系，确定高温冲击载荷下接头拉伸力学性能、断裂位置与应变速率的关系；以实验和计算模拟结果为依据，阐明在不同应变速率下变形时接头的微区应变分布及演化过程，揭示高应变速率下接头断裂失效部位发生迁移的微观机制，并构建高温冲击载荷下单晶/多晶高温合金焊接接头的损伤及断裂机理模型。该研究结果不仅能够丰富对于“高温、瞬态冲击载荷”下高温合金力学行为及理论的认知、推进冲击载荷下焊接结构变形及断裂的基础理论，还可以为“以冲击载荷力学行为评价为基础”的高温合金整体叶盘结构设计提供切实的科学依据。

高温合金异质熔化焊接结构在冲击载荷下的力学行为直接影响熔焊连接整体叶盘、涡轮叶片激光修复焊接构件的服役可靠性。本项目通过实验测试与理论分析相结合的方式，系统研究接头的组织分布与硬度变化空间不对称性规律的本质联系，确定高温冲击载荷下接头拉伸力学性能、断裂位置与应变速率的关系；以实验和计算模拟结果为依据，阐明在不同应变速率下变形时接头的微区应变分布及演化过程，揭示高应变速率下接头断裂失效部位发生迁移的微观机制，并构建高温冲击载荷下单晶/多晶高温合金焊接接头的损伤及断裂机理模型。项目实施过程中，针对DD407/IN718单晶/多晶、DZ125L/IN718定向凝固/多晶高温合金进行了激光熔焊连接，获得了优化焊接工艺指导方案；在此基础上系统进行了接头熔合区、热影响区在凝固过程中及热处理过程中组织结构的演化行为及控制机制的研究，提出了单晶/多晶异质熔焊接头的动态服役薄弱环节为熔合区，建立了接头熔合区高温变形过程中的微裂纹萌生机制及强韧化调控模型。项目的研究结果不仅能够丰富对于“高温、瞬态冲击载荷”下高温合金力学行为及理论的认知、推进冲击载荷下焊接结构变形及断裂的基础理论，还可以为“以冲击载荷力学行为评价为基础”的高温合金整体叶盘熔焊连接结构设计提供切实的科学依据。