GH4169合金自然萌生小裂纹扩展行为的试验研究
收稿日期: 2014-02-27
修回日期: 2014-05-05
网络出版日期: 2015-03-31
基金资助
国家级项目
Experimental investigation on the growth behavior of naturally- initiated small cracks in superalloy GH4169
Received date: 2014-02-27
Revised date: 2014-05-05
Online published: 2015-03-31
Supported by
National Level Project
为了研究镍基GH4169高温合金自然萌生小裂纹的扩展行为,采用单边缺口拉伸(SENT)试样进行了室温下应力比R=0.1, 0.5的小裂纹扩展试验。在长裂纹近门槛值区域,观察到明显的小裂纹效应,疲劳小裂纹扩展寿命占全寿命的大部分。利用扫描电子显微镜(SEM)和能谱分析仪(EDS)对试样断口表面进行微观分析,结果表明, 疲劳小裂纹起始于合金中的夹杂(Ti(C, N)或Nb(C, N)),并且倾向于以半圆形向试样内部扩展。试样的断裂模式存在由晶体学小平面断裂向疲劳条带断裂的转变,该断裂模式转变处对应小裂纹扩展速率曲线上裂纹加速扩展前的急速降低点。
张丽 , 吴学仁 , 黄新跃 . GH4169合金自然萌生小裂纹扩展行为的试验研究[J]. 航空学报, 2015 , 36(3) : 840 -847 . DOI: 10.7527/S1000-6893.2014.0087
The growth behavior of naturally-initiated small cracks in single edge notched tensile (SENT) specimens of nickel-based superalloy GH4169 is studied. Fatigue experiments are conducted under constant amplitude loading with the stress ratios R of 0.1 and 0.5 at room temperature. A significant small crack effect is evident in this alloy, and the major part of total fatigue life is consumed in small crack propagation phase. Fracture mode under cyclic loading is established by scanning electron microscopy (SEM) and energy dispersive spectra (EDS) analysis on specimen fracture surfaces. Small cracks initiate from material inclusions, namely Ti(C, N) or Nb(C, N). A transition of fracture mode from faceted, crystallographic fracture to classical striation type of fracture occurs, corresponding to the minimum growth rate at small crack growth rate curve before crack growth acceleration.
Key words： superalloy; small crack effect; fracture mode; inclusion; scatter
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