摘要
采用宏观与微观结合的方法以及大型疲劳试验机和光学显微镜研究了压力容器用钢16MnR在低周疲劳下微孔(φ40~200μm)的裂纹萌生与扩展规律。结果表明:裂纹的萌生机制为滑移带启裂,由剪应力起主要作用,微观缺陷尺寸、应力水平对疲劳寿命有显著影响,当应力水平较低时,微孔尺寸对疲劳寿命的影响明显;当应力水平较高时(超过屈服强度),孔径对疲劳寿命的影响不敏感;在同一应力水平下,微缺陷尺寸d存在临界值dt,当d>dt时,疲劳寿命下降很多。
A fatigue test for micro-crack development was performed with a microscope and a large fatigue testing machine,combined with macro-analysis and microscopic examination.The crack initiation and propagation of small holes and the size effects of small defects on low cyclic fatigue of steel bar were investigated.The specimens chosen was 16MnR steel,normally for fabricating pressure vessels in China,with drilled holes of different sizes from 40 to 200 in diameter.It has been observed that one type of crack init...
出处
《机械工程材料》
CAS
CSCD
北大核心
2008年第2期18-20,48,共4页
Materials For Mechanical Engineering
关键词
微孔
低周疲劳
裂纹萌生
裂纹扩展
crack initiation
crack propagation
small crack
low cycle fatigue
