论文部分内容阅读
用宏观与微观相结合的方法,研究16MnR钢在低周疲劳下微裂纹的萌生与扩展规律。试样上分别钻有40—200μm的微孔,研究了微裂纹启裂、扩展和微缺陷尺寸对疲劳寿命的影响。结果认为,孔边裂纹启裂机理有两种方式:滑移带启裂和疏松带启裂。前者是由剪应力起主要作用,后者是正应力起主要作用。而滑移带的局部性和裂纹开叉是低周疲劳下微裂纹的两大典型现象。且微缺陷尺寸对疲劳寿命有显著影响,该影响随应力水平的增加而减小。
The combination of macroscopic and microscopic methods was used to study the initiation and propagation of micro-cracks in 16MnR steel under low cycle fatigue. The samples were respectively drilled with 40-200μm micropores, and the effects of crack initiation, propagation and micro-defect size on fatigue life were studied. The results show that there are two ways of crack initiation on the edge of the hole: slip zone cracking and loosen zone cracking. The former is the main role played by the shear stress, the latter is the main role of normal stress. However, the localization of slip band and crack opening are two typical phenomena of microcracks under low cycle fatigue. And micro-defect size has a significant impact on fatigue life, the impact decreases with increasing stress levels.