Abstract In the present study, the mechanism of fatigue and dwell-fatigue crack initiation was investigated in Ti-6Al-4V with a bi-modal microstructure. While substantial dwell-fatigue life debit was evidenced, microstructural configurations associated with crack nucleation are similar and suggest a unique mechanism for fatigue and dwell-fatigue loadings. Pairs of α grains well oriented for basal slip and separated by a (0001) twist grain boundary were found to be critical configurations for crack initiation. Intense slip is localized at the boundary and precedes crack formation along this boundary. Data from a prior fatigue study was revisited and supports the occurrence of this mechanism.

中文翻译：

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Ti-6Al-4V 疲劳和驻留疲劳裂纹萌生机理研究

摘要 在本研究中，研究了具有双峰显微组织的 Ti-6Al-4V 的疲劳和驻留疲劳裂纹萌生机制。虽然证明了大量的驻留疲劳寿命借记，但与裂纹成核相关的微观结构配置是相似的，并表明疲劳和驻留疲劳载荷的独特机制。发现为基底滑移定向良好并由 (0001) 扭曲晶界分隔的成对 α 晶粒是裂纹萌生的关键配置。强烈的滑移位于边界处，并在沿该边界形成裂纹之前。重新审视了先前疲劳研究的数据，并支持这种机制的发生。