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Micro-structural Characteristics and High-temperature Performance of IN718 Nickel-based Alloy Treated by Laser Peening
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School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University,School of Mechanical Engineering,Jiangsu University

Clc Number:

TG249

Fund Project:

National Natural Science Foundation of China (51175424, 51210008); NPU Foundation for Fundamental Research (JC201238, JC201239); Graduate Starting Seed Fund of Northwestern Polytechnical University (Z2014012)

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    Abstract:

    The aim of this study was to investigate the effects of laser peening (LP) on the micro-structural characteristics and high-temperature performance of IN718 nickel-based alloy. Firstly, LP process was performed on the standard tensile specimens at ambient temperature, then the treated specimens were exposed at 700 ℃ for 300 min. As comparison, we detected the surface residual stress and nano hardness on the untreated, LPed and heat-exposure specimens respectively. The corresponding micro-structures were also observed. The results indicate that high amplitude compressive residual stress distributed in the LP treated surface, the maximum value was -706 MPa, appearing in the central region of the LP area. LP process significantly increased nano hardness of treated surface, the average nano hardness was enhanced by 67.4%. Both the residual stress and nano hardness decreased after heat exposure, however, the strengthening effect still existed while compared with untreated specimens. An obvious “layer-seperating” phenomenon on the grain morphology in the depth direction was observed after laser peening. The grain size in the plastic deforming layer refined greatly, the affecting depth of which reached a value of 80 μm. The precipitated δ phase was found in the grain boundaries for the heat-exposure samples. A further observation verified that the interaction of mechanical twins and dislocation resulted in the grain refinement. After heat exposure, the single- directional-distributed dislocation array in the grain well verified the dislocation activities, which indicates that LP can inhibit the grain growing of IN718 alloy at high temperature.

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[Huang Shu, Sheng Jie, Zhou Jianzhong, Wang Zuowei, Zhang Haifeng, Xu Suqiang, Lu Jinzhong. Micro-structural Characteristics and High-temperature Performance of IN718 Nickel-based Alloy Treated by Laser Peening[J]. Rare Metal Materials and Engineering,2016,45(12):3284~3289.]
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History
  • Received:October 28,2015
  • Revised:March 31,2016
  • Adopted:April 26,2016
  • Online: February 06,2017
  • Published: