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| 激光冲击强化对FGH4098合金疲劳裂纹萌生和扩展影响研究 |
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于泽1,2，江荣1,2，章敬鹏1,2，罗思海3，尤超1,2，刘建涛4，张义文4，宋迎东1,2,5
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1.南京航空航天大学 能源与动力学院 航空发动机热环境与热结构工业和信息化部重点试验室，江苏 南京 210016;2.南京航空航天大学 能源与动力学院 江苏省航空动力系统重点试验室，江苏 南京 210016;3.空军工程大学 等离子体动力学重点实验室，陕西 西安 710038;4.钢铁研究总院 高温材料研究所，北京 100081;5.南京航空航天大学 能源与动力学院 机械结构力学及控制国家重点试验室，江苏 南京 210016
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| 摘要: |
| 金属材料表面进行激光冲击强化（LSP）对其疲劳裂纹萌生和扩展性能具有显著影响。本文对粉末高温合金FGH4098进行激光冲击强化，测定了强化层的显微硬度、残余应力、微观结构，结合室温三点弯曲疲劳试验和应力强度因子计算，研究了LSP前后粉末高温合金FGH4098在不同载荷下的疲劳裂纹萌生和扩展行为。结果表明：LSP可以明显提高FGH4098疲劳寿命，不同载荷水平下，LSP处理后的试样疲劳寿命分别提高40%和476%，且在较低水平载荷下抗疲劳效果更加明显；LSP改变了FGH4098合金疲劳裂纹萌生和扩展机制，裂纹萌生位置和扩展方向明显变化；LSP明显提高了FGH4098合金的疲劳裂纹萌生寿命，但残余应力松弛和LSP引起的加工硬化可能导致了疲劳小裂纹扩展速率加快。 |
| 关键词: 激光冲击强化 粉末高温合金 裂纹萌生 小裂纹扩展 残余应力 |
| DOI：10.13675/j.cnki.tjjs.210797 |
| 分类号:TG132.3+2 |
| 基金项目:国家科技重大专项（2017-VI-0008-0078）；国家自然科学基金（51805251；11872204）；江苏省自然科学基金（BK20180434）。 |
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| Effects of Laser Shock Peening on Mechanisms of Fatigue Crack Initiation and Propagation of FGH4098 Alloy |
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YU Ze1,2, JIANG Rong1,2, ZHANG Jing-peng1,2, LUO Si-hai3, YOU Chao1,2, LIU Jian-tao4, ZHANG Yi-wen4, SONG Ying-dong1,2,5
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1.Key Laboratory of Aero-Engine Thermal Environment and Structure，Ministry of Industry and Information Technology， College of Energy and Power Engineering，Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China;2.Jiangsu Province Key Laboratory of Aerospace Power System，College of Energy and Power Engineering， Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China;3.Science and Technology on Plasma Dynamics Laboratory，Air Force Engineering University，Xi’an 710038，China;4.High Temperature Material Institute，Central Iron and Steel Research Institute，Beijing 100081，China;5.State Key Laboratory of Mechanics and Control Mechanical Structures，College of Energy and Power Engineering， Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China
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| Abstract: |
| Laser shock peening on the surface of metal materials has a significant effect on its fatigue crack initiation and propagation properties. Therefore，the powder metallurgy superalloy FGH4098 was strengthened by LSP in this study， the microhardness and residual stress of the strengthened layer were measured， and the microstructure was characterized. At the room temperature， three-point bending and stress intensity factor were used to study the fatigue crack initiation and propagation behaviour of FGH4098 alloy processed by LSP in comparison to unpeened samples under different loads. The results show that the fatigue life of the LSP sample can increase by 40% and 476% under the two investigated loading conditions respectively， and the strengthening effect of LSP is more evident at a relatively lower level of load. The fatigue crack initiation and growth mechanism of the sample are changed by LSP， and the crack initiation site and growth direction are changed obviously. LSP obviously increases the fatigue crack initiation life of the sample， but it may accelerate the small crack growth rate of the LSP sample due to residual stress relaxation under the fatigue loading and the work hardening effects inherent from LSP process. |
| Key words: Laser shock peening Powder metallurgy superalloy Crack initiation Small crack propagation Residual stress |
