徐明,孙汝剑,曹子文,邹世坤.激光冲击TC17钛合金叶片的微观组织/应力演变及缺口振动疲劳性能[J].表面技术,2023,52(6):429-438.
XU Ming,SUN Ru-jian,CAO Zi-wen,ZOU Shi-kun.Microstructure/Stress Evolution and Notch Vibration Fatigue Property of Laser Shock Peened TC17 Titanium Alloy Blades[J].Surface Technology,2023,52(6):429-438 |
| 激光冲击TC17钛合金叶片的微观组织/应力演变及缺口振动疲劳性能 |
| Microstructure/Stress Evolution and Notch Vibration Fatigue Property of Laser Shock Peened TC17 Titanium Alloy Blades |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.040 |
| 中文关键词: 激光冲击强化 TC17钛合金 叶片 微观组织 残余应力 缺口疲劳 |
| 英文关键词:laser shock peening TC17 titanium alloy blades microstructure residual stress notch fatigue |
| 基金项目:国家自然科学基金(52101103) |
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| 中文摘要: |
| 目的 提高航空发动机叶片的抗疲劳性能。方法 采用高功率密度短脉冲激光冲击某型发动机TC17钛合金整体叶盘叶片模拟件，并采用飞秒激光在进气边预制缺口。通过扫描电子显微镜和透射电子显微镜表征激光冲击前后的表层微观组织。通过X射线衍射和三坐标测量仪分别测量激光冲击强化过程中的残余应力演变和宏观塑性变形，并由一阶弯曲振动疲劳对激光冲击强化效果进行评价。结果 激光冲击在TC17钛合金叶片表层诱导产生了高密度位错组织，但由于冲击次数的控制，未产生明显的晶粒细化效应。激光冲击叶盆面后，叶盆面呈现压应力状态，残余应力为330.5 MPa，叶背面呈现拉应力状态，其值为55.5 MPa。进一步激光冲击叶背面后，叶背面的拉应力转变为压应力，其值达到了267.0 MPa，叶盆面残余压应力减小，由330.5 MPa变为261.9 MPa。激光冲击叶盆面后，进气边与叶尖交点偏离初始位置0.119 1、0.129 1 mm;冲击叶背面后，位移偏离初始位置减小，分别为0.071 08、0.099 mm。激光冲击强化后，缺口振动疲劳寿命显著提升，平均循环次数由56 696周次增加到199 515周次，出现了明显的裂纹闭合效应。结论 激光冲击强化在TC17钛合金表层引入了高密度位错组织和双面贯穿式残余压应力，并将叶片宏观塑性变形控制在0.1 mm以内，在疲劳性能上获得了显著的提升。 |
| 英文摘要: |
| With the development of new generation aero-engines, the high weight reduction requirement leads to the thin design of blades. Trickily, these blades are vulnerable to complex loads such as rotating centrifugal force, air flow excitation force as well as foreign objects, resulting in deformation, fatigue, and fracture failures, which seriously affect the safety and reliability of aero-engine. In this paper, laser shock peening, an advanced surface modification technique, was employed to treat TC17 titanium alloy manufactured blisk simulated blades. The leading edge, trailing edge, and blade tip of TC17 blade specimens were peened once with a power density of 8.33 GW/cm2 and an overlapping rate of 15%. After peening, a femtosecond laser was employed to introduce the artificial pre-crack on the leading edge of both as-received and laser shock peened TC17 blade specimens. Surface microstructures before and after laser shock peening were characterized by a scanning electron microscope and a transmission electron microscope. Residual stress and macro plastic deformation during the laser shock peening process were measured by X-ray diffraction and coordinate measuring instruments, respectively. The effect of laser shock peening on the first-order bending vibration fatigue was evaluated on an electromagnetic vibration tester. Results showed that dislocation structures, such as dislocation line, dislocation tangle, dislocation wall, and dislocation cell, were introduced into the surface of the TC17 titanium alloy blade even though no obvious grain refinement was detected due to the lower peening times. In addition to the microstructure changes, residual stresses, and macro plastic deformations were also studied. After conducting laser shock peening on the blade basin surface, the surface presented a compressive stress state with an averaged residual stress value of 330.5 MPa, while the other side (blade back) surface exhibited tensile stress with an averaged residual stress value of 55.5 MPa. The subsequent peening on the blade back surface indicated that the former tensile residual stress on the surface turned into compressive stress with a value of 267.0 MPa, and the compressive residual stress on the blade basin surface decreased from 330.5 MPa to 261.9 MPa. Similar changes were found in the macro plastic deformation. The displacement at the intersection of the leading edge and the blade tip was 0.119 1 mm and 0.129 1 mm measured on two separate peened blades after peening on the blade basin surface, and then the corresponding displacement decreased to 0.071 08 mm and 0.099 mm after peening on the blade back surface. Besides, the first-order bending vibration fatigue life illustrated a significant improvement after laser shock peening, which underwent 199 515 fatigue cycles, 2.52 times higher than that of the as-received blades (56 696 cycles). The subsequent scanning electron microscope observations carried out on the fracture surface indicated an obvious feature of crack closure. The current work indicates that laser shock peening is an effective method in introducing high-density dislocation structure and double-sided through-type compressive residual stress on the surface of TC17 titanium alloy manufactured blades, and can control the macro plastic deformation within 0.1 mm off the initial position. Our work seeks to fundamentally understand of shape and property synchronous control of laser shock peened thin wall structures, and provides a theoretical basis and data support for the laser shock peening engineering application in aero-engine blade manufacturing. |
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