Abstract Micro scratch with depth and width of micron expresses a significant influence on fatigue life. However, little literature is available on modelling the effect of micro scratch on the fatigue life of TC17 titanium alloy. In this paper, the geometric characteristics of micro scratch, especially depth and width, were obsevered and measured. Then, fatigue experiment was conducted to obtain the corresponding fatigue test data. Result shows the presence of micro scratches dramatically reduced the fatigue life from very high cycle fatigue (VHCF) to the high cycle fatigue (HCF) regime. According to the geometrical characteristics of micro scratch, two principles of no obvious influence of scratch direction and length on fatigue life was proposed based on Murakami theory. A new parameter area Δ is proposed to describe fatigue damage quantitatively caused by micro scratches, which is defined as the square root of triangle area of scratch section. An HCF life model of TC17 with the consideration of micro scratches is established by the combined application of area Δ and Paris formula. The validity of the model is confirmed by a good agreement between predicted and experimental results.

中文翻译：

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基于微划痕的TC17钛合金疲劳寿命预测

摘要 微米级深度和微米级宽度的微划痕对疲劳寿命影响显着。然而，关于微划痕对 TC17 钛合金疲劳寿命影响的建模文献很少。本文对微划痕的几何特征，特别是深度和宽度进行了观察和测量。然后进行疲劳试验，得到相应的疲劳试验数据。结果表明，微划痕的存在显着降低了从非常高周疲劳 (VHCF) 到高周疲劳 (HCF) 状态的疲劳寿命。根据微划痕的几何特征，基于村上隆理论，提出划痕方向和长度对疲劳寿命无明显影响的两条原则。提出了一个新的参数面积Δ来定量描述微划痕引起的疲劳损伤，定义为划痕截面三角形面积的平方根。结合面积Δ和巴黎公式，建立了考虑微划痕的TC17的HCF寿命模型。预测结果和实验结果之间的良好一致性证实了模型的有效性。