2A12铝合金超声疲劳试验研究
首发时间:2006-05-31
摘要:本文利用超声疲劳试验的原理,采用光滑试样,宏观观测与细观测试相结合,研究了2A12铝合金的超长寿命疲劳性能。超声疲劳试验在频率f=20kHz, 应力比R=-1,室温下进行到109。结果表明,对于实验材料,不存在所谓的“疲劳极限”,其S-N曲线表现为分段连续下降的特征。材料性能在低应力超高周疲劳条件下发生了改变。用扫描电镜(SEM)观察实验材料的疲劳断口,发现裂纹萌生于试件表面。
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Experimental Investigation on Ultrasonic Fatigue of 2A12 Al-alloy
Abstract:In the present paper, the smooth specimens made of 2A12 aluminum alloy were employed to study very high cycle fatigue properties of the material, both from the macro and micro points view. Ultrasonic Fatigue tests up to 109 have been conducted at the loading frequency of 20 KHZ , under R=-1 conditions and in the ambient air. It is found that the S-N curve of the material displayed a sectional continuum-wise feature, without a “fatigue limit” as indicated in the conventional fatigue test curve. The curve falls swiftly in high stress segment, while slows down in low stress segment. It looks like that the properties of the material have been changed in low stress and very high cycle fatigue conditions. Fractography showed that most of the fatigue cracks initiated from the defect at the surface of the specimen.
Keywords: Ultrasonic fatigue Fatigue crack 2A12 aluminum alloy Very high cycle
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No.6876446801149046****
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