Ti2AlNb alloy is one of the candidate high strength titanium alloy materials under consideration for compressor disc, which will endure dwell loading at high peak stress level during service. In this work, low cycle fatigue (LCF) and low cycle dwell fatigue (LCDF) deformation behaviors and damage mechanism of Ti2AlNb alloy with lamellar microstructure under high loading level were investigated. The results show that fatigue life is highly dependent on the peak stress (σpeak) and dwell time (tdwell). With increasing the σpeak, the LCF life decreases gradually since higher loading stress can accelerate plastic strain accumulation and lead to faster crack propagation. When at the same σpeak, the LCDF life is lower than the LCF life due to greater plastic strain accumulation caused by dwell effect, indicating a dwell life debit of the Ti2AlNb alloy. Moreover, dwell fatigue sensitivity exhibits an increasing trend as the tdwell increases. Under different loading waveforms, the fractography shows remarkably different features. Crack source of LCF appears on sample surface, while crack source of LCDF appears on surface and sub-surface of sample. The research of LCDF behavior is relevant to aviation industry to prevent premature failure of rotating components made of Ti2AlNb alloys.

中文翻译：

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峰值应力和停留时间对层状显微组织Ti-22Al-23Nb-2（Mo， Zr）合金疲劳损伤行为的影响


Ti2AlNb 合金是正在考虑用于压缩机盘的候选高强度钛合金材料之一，该材料在运行期间将承受高峰值应力水平的驻留载荷。本工作研究了高载荷水平下具有层状微观结构的 Ti2AlNb 合金的低周疲劳 （LCF） 和低周驻留疲劳 （LCDF） 变形行为和损伤机制。结果表明，疲劳寿命高度依赖于峰值应力 （σpeak） 和停留时间 （tdwell）。随着 σpeak 的增加，LCF 寿命逐渐缩短，因为较高的加载应力会加速塑性应变的积累并导致更快的裂纹扩展。当处于相同的 σpeak 时，由于驻留效应引起的塑性应变积累更大，LCDF 寿命低于 LCF 寿命，表明 Ti2AlNb 合金的驻留寿命借记。此外，随着 tdwell 的增加，驻留疲劳敏感性呈增加趋势。在不同的加载波形下，断口分析表现出截然不同的特征。LCF 的裂纹源出现在样品表面，而 LCDF 的裂纹源出现在样品的表面和近表面。LCDF 行为的研究与航空工业相关，以防止由 Ti2AlNb 合金制成的旋转部件过早失效。