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机械工程学报

机械工程学报 ›› 2016, Vol. 52 ›› Issue (20): 66-75.doi: 10.3901/JME.2016.20.066

• 材料科学与工程 • 上一篇    下一篇

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室温和650 ℃下晶粒尺寸对GH4169合金疲劳
小裂纹萌生和扩展行为的影响

吴楠1, 张显程1, 涂善东1, 钱夏夷2, 王一宁2   

  1. 1. 华东理工大学承压系统与安全教育部重点实验室 上海 200237；
    2. 国家压力管道元件质量监督检验中心 南京 211100
  • 出版日期:2016-10-20 发布日期:2016-10-20
  • 作者简介:

    吴楠，男，1991年出生。主要研究方向为疲劳小裂纹萌生和扩展行为。

    E-mail：13012890735@163.com

    张显程(通信作者)，男，1979年出生，博士，教授，博士研究生导师。主要研究方向为高温装备的长寿命设计、预测及提升。

    E-mail：xczhang@ecust.edu.cn

Grian Size Effect on the Initiation and Propagation of Small Fatigue Crack of GH4169 Alloy at Room Temperature and 650 ℃

WU Nan1, ZHANG Xiancheng1, TU Shantung1, QIAN Xiayi2, WANG Yining2   

  1. 1. Key Laboratory of Pressure Systems and Safety of Ministry of Education，East China University of Science and Technology，Shanghai 200237
    , 2. National Quality Supervision and Inspection Center of Pressure Pipe Components， Nanjing 211100
  • Online:2016-10-20 Published:2016-10-20

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摘要：

在室温和650 ℃条件下，研究晶粒尺寸对GH4169合金疲劳小裂纹萌生机理和扩展行为的影响。通过在960 ℃、 1 010 ℃、1 020 ℃、1 050 ℃条件下，各保温1 h来改变试样晶粒尺寸。通过光学显微镜来观察不同热处理后的微观组织。利用覆膜法监测小裂纹扩展过程。结果表明，两种温度下疲劳小裂纹萌生机理和扩展模式在细晶组织和粗晶组织间均会发生转变。室温和650 ℃条件下，裂纹扩展速率在小裂纹阶段近似恒定。室温下，平均晶粒尺寸变化对小裂纹扩展速率几乎没有影响。650 ℃下，随着平均晶粒尺寸增加，小裂纹扩展速率增大。无论哪种温度下，一旦表面裂纹长度达到一定临界尺寸，小裂纹会加速扩展，进入长裂纹阶段。室温下不同平均晶粒尺寸试样临界裂纹长度基本相同，650 ℃下随着平均晶粒尺寸增加临界裂纹长度增加。

关键词: 650 ℃, GH4169, 晶粒尺寸, 疲劳, 室温, 小裂纹

Abstract:

Addressing grain size effect on the initiation and propagation behavior of small fatigue crack of GH4169 alloy at room temperature and 650 ℃. Changing the grain size of specimen by solid solution heat treated at 960 ℃、1 010 ℃、1 020 ℃、1 050 ℃ about 1 h. The microstructures after different heat treatments are investigated by optical microscope(OM). The replica method is used to measure the crack length. Results show that there are transition of fatigue crack initiation mechanism and crack propagation mode between fine-grained material and coarse-grained material at both room temperature and 650 ℃. Crack propagation rates are almost constant in small crack stages at both room temperature and 650 ℃. The variations of average grain size have almost no effect on the small crack rates at room temperature. But at 650 ℃ small crack propagation rates increase with the increase of average grain size. Once the length of surface cracks reach a critical size, the cracks propagate quickly. At room temperature the critical sizes of surface crack of specimens with different average grain size are almost uniform. However the critical size of surface cracks increase with the increase of average grain size.

Key words: 650 ℃, fatigue, GH4169, grain size, room temperature, small crack

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