摘要
在双轴向疲劳载荷作用下,16MnR、45~#及1Cr18Ni9Ti钢试件的Ⅱ型裂纹快速分支转型。分支点处的断口上出现了一条无光泽的“沟”,分支裂纹断口发生倾斜,它在微观上表现为疲劳斑片和台阶;LY12CZ材料的Ⅱ型裂纹沿着原裂纹面向前扩展,其断口粗糙不平,微观形貌以“碎屑”、“长线窝”及致密氧化膜为特征,长线窝的形成可以由微孔聚集模型予以解释。
Under biaxial fatigue loading, a mode I crack of specimens for 16MnR, 45~# or 1Cr18Ni9Ti steels bifurcates quickly into two symmetric branch cracks. At the bifurcation point three is a 'groove' on the fracture surface and with the propagation of the branch crack the fracture surface becomes increasingly slant to the surface of the specimen. The slant fracture surface under SEM consists of fatizue batches and steps. But under the same loading for LY12CZ material the mode Ⅱ crack propagates in the direction of the orizinal crack. The fracture surface is characterized by 'broken bits','long-shallow dimples'and oxidic film. The formation of the long-shallow dimples can be interpreted by the model of microvoid coalescence.
关键词
疲劳
载荷
断口形貌
裂纹扩展
金属
biaxial fatigue loading
mode Ⅱ crack
fractographic analysis
microvoid coalescence
