摘要
基于位移循环加载试验,对反应堆压力容器密封元件Inconel 718合金O形环短管试样变形幅控制下进行了常温和300℃高温低周疲劳试验研究.结果表明,在循环加载中试样发生接触力松弛,当位移压缩比峰值不低于8%且压缩比幅值超过0.6%时试样会产生低循环疲劳失效.采用弹塑性接触有限元方法对引发疲劳裂纹的试样危险局部的应力应变进行了分析,给出了位移压缩比幅值与危险局部应变幅值的短管疲劳寿命估算式.疲劳试样断口微观分析表明,在初始大变形引起的裂纹萌生区,断口微观形貌表现为晶体滑移与解理撕裂,而在裂纹扩展区表现为解理撕裂与疲劳辉纹共生的混合型裂纹扩展.
Under radial displacement cycling at RT and elevated temperature 300℃, a series of low cycle fatigue （LCF） tests on small specimens of Inconel 718 alloy tube used to make O-ring seal elements of nuclear pressure vessel were performed. The test results show that, as the peak of compressing ratio of radial displacement loading on a specimen is not lower than 8 % and the amplitude of compressing ratio is between 0.6% and 1. 44%, the cycling leads the specimen to LCF failure, and the relationship between the ampli- tudes of the compressing ratio or amplitudes of the contacting force and twice lives of specimens is in accord with power law. Furthermore, by an elastic-plastic finite element analysis （FEA） method with contact elements, the stress and the strain of the material at crack initiation area of the specimen under cycling of radial displacement were investigated, and estimated equations of fatigue life based on the compressing ratio amplitude and local strain amplitude were given. Finally, some microcosmic properties on fracture surface of the specimens were investigated.
出处
《上海交通大学学报》
EI
CAS
CSCD
北大核心
2007年第6期1003-1007,共5页
Journal of Shanghai Jiaotong University
