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Alternative TitleStudy on High Temperature Failure Mechanism and Stabilization Method of Laser Shock Peening
Thesis Advisor乔红超
Keyword温激光冲击强化 GH4169合金 热稳定性 残余应力 微观组织结构
Degree Discipline机械制造及其自动化
Degree Name硕士
Degree Grantor中国科学院沈阳自动化研究所
Place of Conferral沈阳
Other AbstractIn this thesis, a nickel-based superalloy GH4169 material was used as the research object, and a temperature laser shock strengthening experimental platform was designed , and the thermal stability of LSP and WLSP were compared by microhardness, surface roughness, residual stress and TEM. The main results obtained are as follows: (1) A warm laser shock enhancement experimental platform was designed and fabricated. Taking the functional requirements of the experimental platform as the starting point, and then formulating the corresponding solutions by consulting relevant materials, and finally processing the parts and building the platform. The platform is mainly equipped with heating and temperature control function, anti-oxidation function of sample surface, confining layer stable output and loop function and quick positioning and clamping function. (2) The thermal stability of LSP GH4169 alloy was studied. Firstly, the LSP effect of different laser energies (3J, 4J, 5J, 6J, 7J) and different impact times (1, 2, 3, 4 times) was studied by using the surface microhardness as a characterization index. The results show that when the laser energy is 7J and the impact is 2 times, the microhardness of the sample surface is 476.9HV, which is 26.7% higher than the matrix hardness (376.3HV), so 7J and 2 times are selected as the optimal experimental parameters for subsequent thermal stability studies. The thermal stability of GH4169 alloy of different aging temperatures (600 °C, 650 °C, 700 °C) and different aging time (1h, 3h, 5h, 10h, 30h, 100h) was studied by using the changes of surface residual stress and microstructure as indicators. The results show that with the increase of aging time and aging temperature, the residual stress relaxation on the surface of LSP samples increases gradually, the dislocation density decreases gradually, and the γ phase gradually aggregates and becomes coarse and transforms into δ phase. (3) The thermal stability of WLSP GH4169 alloy was studied. Firstly, the WLSP effect of different process temperatures (100 °C, 150 °C, 200 °C, 250 °C, 300 °C, 350 °C) was studied by using the surface microhardness, surface roughness and surface residual stress as indicators. The results show that the strengthening effect is best when the process temperature is 200 °C. After the sample is processed by WLSP (200 °C), high-density entanglement is formed inside the material, which forms a complex dislocation structure such as dislocation network and dislocation cell. Then the thermal stability of WLSP GH4169 alloy under different aging temperature and aging time was studied by using surface residual stress and microstructure change as indicators. The results show that compared with LSP, the surface residual stress relaxation and relaxation rate of WLSP samples are smaller; the internal dislocation density of materials is higher and more uniform, and there is no obvious δ phase precipitation , which has higher thermal stability.
Contribution Rank1
Document Type学位论文
Recommended Citation
GB/T 7714
胡太友. 激光冲击强化高温失效机理与稳固方法研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2019.
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