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7449合金高周疲劳及裂纹萌生行为
发布人：上海艾荔艾金属材料有限公司www.shailiai.com
更新时间：2015-10-22
研究7449-T7951合金的高周疲劳及裂纹萌生行为。在室温下，采用光滑及缺口试样进行疲劳寿命测试，应力比(R)分别为0.5和−1.0。采用金相显微镜、扫描电镜及透射电镜对该合金的微观组织及疲劳试样断口进行分析，以揭示其疲劳裂纹萌生机理与合金微观组织之间的关系。
7449合金高周疲劳及裂纹萌生行为High-cycle fatigue and crack initiation behavior of 7449 alloy
研究7449-T7951合金的高周疲劳及裂纹萌生行为。在室温下，采用光滑及缺口试样进行疲劳寿命测试，应力比(R)分别为0.5和−1.0。采用金相显微镜、扫描电镜及透射电镜对该合金的微观组织及疲劳试样断口进行分析，以揭示其疲劳裂纹萌生机理与合金微观组织之间的关系。结果表明：7449-T7951合金具有优异的疲劳性能；应力比为0.5和−1.0时，光滑试样的疲劳寿命极限(σN)分别为349和134 MPa，而缺口试样的σN(缺口系数Kt=3.0)分别为138和70 MPa。其裂纹萌生行为受合金中粗大第二相、析出相、晶界和位错(滑移带)的共同影响。
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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