振动时效对结构件材料表面完整性的影响

为揭示平台式振动时效对结构件材料表面完整性性能——表面残余应力、硬度及微观组织的影响，以7075铝合金薄壁件为研究对象，运用ANSYS构建平台式振动时效(vibration stress relief, 简称VSR)有限元模型，通过模态分析获得最佳激振频率和试样装夹位置。在此基础上，将3个薄壁框架件置于平台不同位置进行VSR处理，得到其试样表面应力的松弛效果。结果表明：亚共振频率为112 Hz时，在激振源的中间位置和最大振幅位置处试样应力释放效果最好，其应力释放率最大为27%；电子背散射衍射（electron backscattered diffraction，简称EBSD）电镜观察发现，时效后表面组织晶粒存在明显取向区变化，晶粒成长带来能量的变迁以及位错的增殖，再结晶晶粒的增多提升了表面性能，使得材料表面硬度得到10%~17%的强化。研究表明，平台式振动时效能够改变和优化材料表面完整性。

Effect of VSR on Surface Integrity of Structural Parts

In order to reveal the influence of vibration stress relief (VSR) on the surface integrity including residual stress, hardness and microstructure of structural parts, the 7075 aluminum alloy structural parts is taken as the research object. The software ANSYS is used to build VSR finite element model, the optimum excitation frequency and sample clamping position are obtained by modal analysis. On this basis, three thin-walled components are placed in different positions of the platform for VSR, and the effect of VSR on the surface properties of the samples is obtained. The results show that when the sub resonance frequency is 112 Hz, the stress release rate of the specimen is 27% at the middle position of the excitation source and at the max amplitude position. At the same time, electron backscattered diffraction (EBSD) electron microscope observation shows that there is obvious orientation area change in the surface structure grain after VSR, the change of energy and dislocation proliferation brought by grain growth, and the increase of recrystallization grain improves the surface performance, making the surface hardness of the material promote about 10%~17%. The results show that VSR with platform can change and optimize the surface integrity of materials.