对TC4-DT钛合金的高周疲劳性能及断口形貌进行了研究.结果表明:TC4-DT钛合金的S-N曲线(应力比R=-1)不出现呈水平线的疲劳极限,10 7次不被破坏的条件疲劳极限为550 MPa,置信度为95％；疲劳裂纹源均出现在试样的表面,疲劳裂纹扩展区较大说明材料具有较高的断裂韧度；疲劳裂纹扩展区由许多解理小刻面组成,解理面上可见疲劳条带及二次裂纹,以解理断裂为主；断裂区断口表面由许多互相连接的凹坑所组成,主要表现为韧窝断裂.%The high circle fatigue properties and fractography of TC4-DT titanium alloy were studied. Results show that when the confidence is 95% , the S-N curve of TC4-DT titanium alloy (R =-1) does not show the level fatigue limit and the conditional fatigue limit for 107 cycles is 550 Mpa. Macrographs of fatigue fractography show that fatigue crack initiation is under the surface of specimens and the larger fatigue crack growth region displays that the material has higher fracture toughness. Micrographs of fatigue fractography reveals that fatigue crack growth region is composed of many small cleavage facet planes on which fatigue striations and crack braching are observed and the mode of fracture is cleavage fracture, fracture region consists of a lot of dimples and the mode of fracture is dimple fracture.
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