利用OM(光学显微镜)、SEM(扫描电子显微镜)对激光沉积TA15钛合金疲劳裂纹扩展行为进行研究。结果表明: 由于激光沉积自身特性, 沉积试样具有较强的组织敏感性, 疲劳裂纹易起源于气孔且裂纹源区有明显的α/β片层撕裂特征并伴随有与α单个片层或α集束尺寸相当的解理断裂平面。疲劳裂纹扩展稳定期路径曲折, 这与片层组织中α集束位向不同有关。一定区域内疲劳裂纹平行α片层或近似垂直α片层扩展, 裂纹扩展遇到α相时主要切过α片层向前扩展, 并伴有二次裂纹的出现; 裂纹稳定扩展期是以疲劳条带机制为主, 也伴随解理断裂机制。

Fatigue crack growth behavior of laser deposited TA15 titanium alloy was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The results showed that the deposited specimen had strong microstructure sensitivity because of the laser deposition’s own characteristic. The fatigue crack source generally originated from the pore and the crack initiation region was characterized by obvious α/β lamellar tearing pattern and crystallographic cleavage facets of them. The crack tended to propagate tortuously, which was related to different orientations of α lamellar. Its propagation direction in certain areas was parallel or approximately perpendicular to α lamellar. The fatigue crack propagated not only round the α lamellar but also splitting ahead of it with secondary cracks emerging. The cracks in the stable spreading region propagated by strip mechanism with some regions of micro-cleavage fracture.