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罗思海,聂祥樊,王学德,王波,李靖,何卫锋.无保护层激光冲级强化提高K24镍基合金疲劳强度试验研究[J].稀有金属材料与工程(英文),2017,46(12):3682~3687.[Luo Sihai,Nie Xiangfan,Wang Xuede,Wang Bo,Li Jing and He Weifeng.Experiment study on improving fatigue strength of K24 nickel based alloy by laser shock processing without coating[J].Rare Metal Materials and Engineering,2017,46(12):3682~3687.]
Experiment study on improving fatigue strength of K24 nickel based alloy by laser shock processing without coating
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Received:December 26, 2015  Revised:April 22, 2016
Key words: Laser shock processing without coating  K24 nickel based alloy  high-cycle fatigue  fatigue fracture  residual stress  strengthening mechanism
Foundation item:国家自然科学基金项目(面上项目,重点项目,重大项目);国家重点基础研究发展计划(973计划);
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Luo Sihai,Nie Xiangfan,Wang Xuede,Wang Bo,Li Jing and He Weifeng  
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      Laser shock processing without coating (LSPwC) is a novel surface treatment, which can effectively increase the fatigue strength of metal materials by introducing compressive residual stress and microstructural changes. The objective of this work is to improve the fatigue resistance of K24 nickel based alloy by LSPwC. Firstly, high cycle vibration fatigue experiment was adopted to verify the LSPwC strengthening effect. Compared to the untreated samples, the results of the vibration fatigue experiments showed that the fatigue strength of K24 alloy was enhanced and improved from 282MPa to 328MPa after LSPwC. Secondly, the effects of multiple impacts on mechanical properties and fatigue fracture morphologies were investigated, which were observed and measured by scan electron microscope (SEM), X-ray diffractometer and microhardness tester. The results indicated that residual stress presented compressive state on the superficial layer with about 150μm depth and the maximum value reaches -595MPa. The microhardness is about 526 HV0.5 with about 100 μm depth from the top surface after three impacts. The fracture observation indicated that the flatness area was larger in the FCI after LSPwC, meanwhile, the growth rate of fatigue crack was decreased. Lastly, the strengthening mechanism of LSPwC on the fatigue resistance was discussed based on the experimental results.