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0.1191、0.1291 mm;冲击叶背面后,位移偏离初始位置减小,分别为0.07108、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56696周次增加到199515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。
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
作者
徐明
孙汝剑
曹子文
邹世坤
XU Ming;SUN Ru-jian;CAO Zi-wen;ZOU Shi-kun(AVIC Manufacturing Institute,Beijing 100024,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第6期429-438,共10页
Surface Technology
基金
国家自然科学基金(52101103)。
