利用超高周弯曲疲劳试验系统, 对表面带不同轻微损伤和无损伤的TC6钛合金试样, 在20kHz激振频率条件下进行了超高周疲劳试验, 用扫描电镜观察了断口形貌。结果表明: 带轻微损伤与无损伤的TC6钛合金的疲劳寿命均随着应力水平的减小呈连续增大的趋势;循环周次超过107后试样仍会发生疲劳破坏, 不存在传统意义上的疲劳极限;表面的轻微点压损伤会使试样的疲劳寿命降低, 但在低应力水平下表面线划痕则不会对试样的疲劳寿命造成影响;疲劳裂纹萌生于试样表面, 而且表面的点压损伤及线划痕并不影响疲劳源的萌生位置。

Ultra-high cycles fatigue tests of titanium alloy with and without different slight damages on surface was performed using ultra-high cycle bending fatigue system under the condition of 20 kHz excitation frequency, and the fracture images were observed by optical microscopy. The results show that the fatigue life of TC6 alloy without damage and with slight damages increased continuously with the decrease of stress levels. The sample still appeared fatigue failure when the cycles were more than 107, so there was no fatigue limit. Slight point stress damage could decrease the sample′s fatigue life, but the line scratches made little changes under low stress condition. Fatigue cracks initiated on sample surface, and the fatigue source initiation position was not affected by the stress damge and line scratches on samples surface.