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采用激光沉积修复技术对铣切沟槽损伤的TA15钛合金锻件进行修复,研究了修复件的疲劳裂纹萌生和扩展特性。采用光学显微镜和扫描电子显微镜分析了试样疲劳断口以及纵截面。结果表明,修复后试样均断裂于修复区,其疲劳行为具有很强的组织敏感性,疲劳源区有与α片层集束尺寸和形貌相同的解理断裂面和撕裂特征。稳定扩展区的裂纹沿着α片层边界扩展,有的垂直于α片层,有的平行于α片层;固溶时效热处理后,组织敏感尺寸达到了单个片层尺寸的细小组织个体,表现为沿不同滑移方向分离的单个α/β片层撕裂和α′片层清晰排列的痕迹。细小、取向更多的片层集束使裂纹更容易偏转,增加了裂纹扩展路径的长度,从而消耗更多的裂纹扩展能量。
The TA15 titanium alloy forging damaged by milling groove was repaired by laser deposition technique, and the fatigue crack initiation and propagation characteristics of the repaired part were studied. The fatigue fracture and longitudinal section of the specimen were analyzed by optical microscope and scanning electron microscope. The results show that the repaired samples are all fractured in the repair area, and their fatigue behavior is highly susceptible to microstructure. The fatigue source area has the same cleavage fracture surface and tearing characteristics as the alpha sheet cluster. The crack in the stable extension zone extends along the boundary of the α sheet, some perpendicular to the α sheet and some parallel to the α sheet. After the solution heat treatment, the sensitive tissue size of the individual tissue reaches the individual size of the fine tissue. A single α / β sheet tearing along different slip directions and a clear alignment of the α ’sheet. Small, more oriented lamellar bundles make the crack easier to deflect, increasing the length of the crack propagation path, thereby consuming more crack propagation energy.