俞延庆,周留成,宫健恩,方修洋,周杰,蔡振兵.GH4169 高温合金激光冲击强化层微观结构和微动疲劳行为研究[J].表面技术,2022,51(10):38-48.
YU Yan-qing,ZHOU Liu-cheng,GONG Jian-en,FANG Xiu-yang,ZHOU Jie,CAI Zhen-bing.Microstructure and Fretting Fatigue Behaviour of GH4169 Superalloy after Laser Shock Peening[J].Surface Technology,2022,51(10):38-48
GH4169 高温合金激光冲击强化层微观结构和微动疲劳行为研究
Microstructure and Fretting Fatigue Behaviour of GH4169 Superalloy after Laser Shock Peening
  
DOI:10.16490/j.cnki.issn.1001-3660.2022.10.005
中文关键词:  GH4169高温合金  激光冲击强化  微观结构  微动疲劳  断口形貌  裂纹扩展
英文关键词:GH4169 superalloy  laser shock peening  microstructure  fretting fatigue  fracture morphology  crack propagation
基金项目:国家科技重大专项(2017-VII-0003-0096-1、J2019-IV-0014-0082);国家自然科学基金(51875574、U2067221);四川省科技项目(22JCQN0111)
作者单位
俞延庆 西南交通大学 机械工程学院,成都 610031 
周留成 空军工程大学 航空工程学院 等离子体动力学重点实验室,西安 710038 
宫健恩 西南交通大学 机械工程学院,成都 610031 
方修洋 西南交通大学 机械工程学院,成都 610031 
周杰 西南交通大学 机械工程学院,成都 610031 
蔡振兵 西南交通大学 机械工程学院,成都 610031 
AuthorInstitution
YU Yan-qing School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China 
ZHOU Liu-cheng Science and Technology on Plasma Dynamic Laboratory, Aeronautics Engineering College, Air Force Engineering University, Xi’an 710038, China 
GONG Jian-en School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China 
FANG Xiu-yang School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China 
ZHOU Jie School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China 
CAI Zhen-bing School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China 
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中文摘要:
      目的 提高GH4169镍基高温合金的微动疲劳寿命。方法 利用激光冲击强化(LSP)技术对GH4169高温合金榫试样进行表面强化处理并研究其微动疲劳性能。借助激光共聚焦显微镜(LCSM)、X射线衍射仪(XRD)、电子背散射衍射(EBSD)、显微硬度计、X射线应力分析仪、光学显微镜(OM)、扫描电子显微镜(SEM)及高频疲劳试验机,对激光冲击强化前后的GH4169高温合金的微观组织、硬度、残余应力、微动疲劳寿命、断口形貌和裂纹扩展情况进行分析。结果 激光冲击强化后表面硬度提高了17.3%,硬化层深度约为0.63 mm,表面残余压应力为331.5 MPa。经激光冲击强化后变形层中晶粒未发生明显细化,表明激光诱导冲击波主要引起GH4169高温合金中位错的形成而不是位错的运动。在20 kN峰值载荷下,尽管强化后的断裂机制没有发生明显的变化,但是强化后榫试样的微动疲劳寿命比未处理的试样提高了827%,裂纹从多疲劳源转变为单疲劳源,裂纹萌生位置从表面转移到距表面234 μm的次表面,激光冲击强化显著提升了GH4169的萌生抗力和扩展速率,扩展区域的疲劳条带间距从未处理的0.50 μm增加到了强化后的1.01 μm,这可能与残余应力的突变与松弛有关。结论 在激光冲击强化后获得硬化层和残余应力场共同影响下,GH4169高温合金榫试样的微动疲劳寿命得到了显著提升。
英文摘要:
      To improve the fretting fatigue lifetime of GH4169 Ni-based superalloy, in this paper, laser shock peening (LSP) was performed on the surface of GH4169 dovetail structure. The laser energy of 5 J, the pulse duration of 20 ns, the spot diameter of 2.2 mm, the overlap rate of 50%, the repetition of 1 Hz, and the scan number of 1 cycle were adopted in this study. The laser scanning confocal microscope (LSCM) was used to obtain the 3D surface morphology and 2D profile after LSP. The X-ray diffractometer (XRD) was evaluated to analyze the phase composition change before and after LSP. The micro-hardness and residual stress were measured by the vickers hardness tester and X-ray stress analyzer, respectively. The fretting fatigue performance of GH4169 superalloy was performed on the high-frequency fatigue testing machine with a maximum load of 20 kN and stress ratio of 0.1. The fretting fatigue lifetime and crack propagation were collected to analyze the difference before and after LSP. The optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the fracture morphology. The results indicate that the surface hardness of LSPed sample is increased by 17.3% compared to the untreated sample. The hardened layer is about 0.63 mm. The surface compressive residual stress is 331.5 MPa. The surface roughness (Sa) is increased from 1.62 μm to 13.89 μm after LSP. The grain size of LSPed sample in the deformed layer has no obvious refinement, which indicates the formation of dislocation rather than the motion of dislocation in the surface layer of GH4169 superalloy under the action of the laser shock wave. Similar to the untreated sample, the fracture mechanism changes from the quasi-cleavage fracture to the ductile fracture with a fatigue stripe along with the crack propagation. However, after LSP, the number of crack sources decreases from multiple fatigue sources to single fatigue sources. Besides, the crack initial site is also changed from the surface to the sub-surface, which is 234 μm from the surface. The overall fatigue lifetime of LSPed sample is increased by 827% compared to the untreated sample under the maximum load of 22 kN, which is primarily provided by the enhancement of crack initiation lifetime. The formed hardened layer can improve the surface wear resistance and reduce the micro-crack initiation probability. The formed compressive residual stress field can reduce the average stress. Therefore, LSP can significantly increase the initial resistance of GH4169 superalloy. However, the propagation lifetime of the untreated sample accounts for about 54.4% of the overall lifetime, while that of LSPed sample accounts for about 0.3% of the overall lifetime. The spacing of fatigue stripe is also increased from 0.50 μm to 1.01 μm after LSP. The spacing of fatigue stripe represents the distance of a single cycle, indicating that a shorter spacing leads to a faster propagation rate. The faster propagation rate after LSP may be ascribed to the sudden change and relaxation of residual stress below the compressive residual stress field. The fretting fatigue performance of GH4169 superalloy dovetail structure is significantly improved under the combined action of hardened layer and compressive residual stress field induced by LSP.
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