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7449合金高周疲勞及裂紋萌生行為
發布人：上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間：2015-10-22
研究7449-T7951合金的高周疲勞及裂紋萌生行為。在室溫下，采用光滑及缺口試樣進行疲勞壽命測試，應力比(R)分別為0.5和?1.0。采用金相顯微鏡、掃描電鏡及透射電鏡對該合金的微觀組織及疲勞試樣斷口進行分析，以揭示其疲勞裂紋萌生機理與合金微觀組織之間的關系。
7449合金高周疲勞及裂紋萌生行為High-cycle fatigue and crack initiation behavior of 7449 alloy
研究7449-T7951合金的高周疲勞及裂紋萌生行為。在室溫下，采用光滑及缺口試樣進行疲勞壽命測試，應力比(R)分別為0.5和?1.0。采用金相顯微鏡、掃描電鏡及透射電鏡對該合金的微觀組織及疲勞試樣斷口進行分析，以揭示其疲勞裂紋萌生機理與合金微觀組織之間的關系。結果表明：7449-T7951合金具有優異的疲勞性能；應力比為0.5和?1.0時，光滑試樣的疲勞壽命極限(σN)分別為349和134 MPa，而缺口試樣的σ-N(缺口系數Kt=3.0)分別為138和70 MPa。其裂紋萌生行為受合金中粗大第二相、析出相、晶界和位錯(滑移帶)的共同影響。
The high-cycle fatigue and crack initiation behavior of 7449-T7951 alloy were investigated. The fatigue-life tests were carried out over a range of stress amplitudes with the stress ratio (R) of 0.5 and ?1.0 at room temperature for both smooth and notch specimens, respectively. Further researches were performed with the help of optical microscopy, scanning electron microscopy and transmission electron microscopy, in order to reveal the relationship between microstructure and fatigue crack initiation behavior of this alloy. The results show that 7449-T791 alloy has an excellent fatigue property. The fatigue limit (σN) of smooth specimens is 349 MPa for R=0.5 and 134 MPa for R=?1.0. While it still remains 138 MPa for R=0.5 and 70 MPa for R=?1.0 by using notch specimens with the notch factor (Kt) of 3.0. The crack initiation behavior of this alloy can be related to the result of a joint influence of inclusions, precipitations, grain structures and their interactions with dislocations or persistent slip bands.
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