镍基高温合金线性摩擦焊接头疲劳裂纹扩展动态行为研究

Linear friction welding can be used to manufacture the whole blisk of high temperature superalloy in aerospace and aviation industries. However, the microstructure of the joints and the composition of the oxides formed during the high temperature service process are constantly changing, which leads to the difficulty of predicting and controlling the crack propagation behavior at the joint interface and its vicinity. In addition, the mechanism of failure is not yet clear. This project aims at the urgent need for the reliability and durability of high temperature service on the whole blisk. Taking the GH4169 superalloy linear friction welding joint as the research object, the combined method of multi fields (thermal-mechanical-chemical) coupling numerical model, high cycle fatigue experiments at high temperatures and acoustic emission technique is selected to research the characteristics of deformation and breaking of the GH4169 linear friction welded joint under high temperature and high cycle fatigue conditions. The crack tip stress distribution at the joint interface and its vicinity is studied during high temperature service. The fatigue crack initiation and propagation behavior and its impact mechanism is the focus of research. The internal failure mechanism of joint under high temperature service process is clarified. Thus, the active control of the life prediction and fatigue performance of the joint during the high temperature service are realized. The purpose of this project is to enrich the fatigue fracture mechanisms of joints under high temperature and high cycle fatigue conditions. It has an important theoretical significance for the design, manufacture, high safety and reliable serviceability of the high temperature alloy whole blisk.

线性摩擦焊接可实现航空、航天等领域高温合金整体叶盘构件的制造，但接头在高温服役过程中的微观组织和所形成氧化物的成分均发生不断的变化，导致接头界面及其附近裂纹扩展行为难以预测和控制，且失效机制尚不清楚。本项目针对整体叶盘高温服役可靠性和持久性的迫切需求，以GH4169高温合金线性摩擦焊接头为研究对象，采用多场(热-力-化学)耦合数值模型、高温高周疲劳实验及声发射技术相结合的方法，探索GH4169合金线性摩擦焊接头高温高周疲劳条件下变形及破环特征，研究接头在高温服役过程中焊缝界面及其附近裂纹尖端应力分布情况，重点研究接头疲劳裂纹萌生和扩展行为及其影响机制，阐明接头在高温服役过程中的内在失效机制，实现接头在该过程中的寿命预测与抗疲劳性能的主动控制。本项目的研究旨在丰富高温高循环条件下接头抗疲劳断裂机理，对于高温合金整体叶盘的线性摩擦焊接设计、制造、高安全及可靠服役性具有重要的基础理论意义。

线性摩擦焊接可实现航空、航天等领域高温合金整体叶盘构件的制造，但接头在高温服役过程中的微观组织均发生不断的变化，导致接头界面及其附近裂纹扩展行为难以预测和控制，且失效机制尚不清楚。本项目针对整体叶盘高温服役可靠性和持久性的迫切需求，以GH4169高温合金线性摩擦焊接头为研究对象，采用多场耦合数值模型、高温高周疲劳实验相结合的方法，探索GH4169合金线性摩擦焊接头高温高周疲劳条件下变形及破环特征，研究接头在高温服役过程中焊缝界面及其附近裂纹尖端应力分布情况，重点研究接头疲劳裂纹萌生和扩展行为及其影响机制，阐明接头在高温服役过程中的内在失效机制。本项目的研究旨在丰富高温高循环条件下接头抗疲劳断裂机理，对于高温合金整体叶盘的线性摩擦焊接设计、制造、高安全及可靠服役性具有重要的基础理论意义。.本项目首先进行高温合金线性摩擦焊接实验，分析接头微观组织缺陷并建立接头成形模型。基于以上模型获得应力场分布，计算微缺陷等对接头性能的影响，获得界面微结构对裂纹尖端应力场和裂纹扩展行为的影响规律，计算其疲劳性能，并进行实验以获得高温高循环疲劳应力参数。建立界面及附近裂纹数值模型，分析裂纹几何形状等对疲劳性能的影响规律，分析了裂纹尖端应力场、扩展倾向和扩展路径的规律。通过实验，分析了高温高循环下不同循环次数的接头疲劳失效形貌特征，研究了疲劳裂纹萌生和扩展，确定了微观组织对疲劳循环次数的影响规律。