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    用直流电压降法研究高温下GH3230合金的疲劳裂纹扩展行为

    Fatigue crack growth behavior of GH3230 alloy at high temperature by direct current potential drop method

    • 摘要: 采用直流电压降法对GH3230合金进行了高温下的疲劳裂纹扩展试验,分析了温度及应力强度因子对GH3230合金疲劳裂纹扩展速率的影响,并利用扫描电子显微镜对断口进行分析。结果表明:在相同的应力强度因子下,随着温度的升高,合金的裂纹扩展速率增大;温度从750℃升高到850℃时,裂纹扩展速率明显增大,从850℃升高到950℃时,小应力强度因子下的裂纹扩展速率相差不大,随着应力强度因子的增大和温度的升高,裂纹扩展速率的差距增大;观察断口表面可知,在裂纹扩展区和瞬断区,断口表面呈现典型的疲劳辉纹和韧窝特征,随着温度的升高,断口表面的氧化物颗粒增多,裂纹扩展区的疲劳辉纹不明显。

       

      Abstract: The fatigue crack growth test of GH3230 alloy at high temperature was carried out by direct current potential drop method. The effects of temperature and stress intensity factor on the fatigue crack growth rate of GH3230 alloy were analyzed, and the fracture surface was analyzed by scanning electron microscope. The results show that under the same stress intensity factor, the crack growth rate of the alloy increased with the increase of temperature. When the temperature rose from 750 ℃ to 850 ℃, the crack growth rate increased obviously. When the temperature rose from 850 ℃ to 950 ℃, the difference of crack growth rate under small stress intensity factor was not big. With the increase of stress intensity factor and temperature, the difference of crack growth rate increased. It could be seen from the observation of the fracture surface that in the crack propagation zone and the transient fracture zone, the fracture surface presented typical fatigue striation and dimple characteristics. With the increase of temperature, the oxide particles on the fracture surface increased, and the fatigue striation in the crack propagation zone was less obvious.

       

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