The effect of specimen size on the fatigue performance of additively manufactured (AMed) Ti-6Al-4V is investigated in this paper. The fatigue tests of Ti-6Al-4V specimens made by laser powder bed fusion were conducted via ultrasonic axial cycling up to very-high-cycle regime with stress ratio = –1. The - data of five group specimens show an evident size effect, that is, with the increase of specimen size, the fatigue life or fatigue strength decreasing gradually. A new probabilistic control volume scheme is developed to evaluate the fatigue life of large sized specimens by the tested data of small sized specimens. The applicability of the proposed model is validated by the present data and those of our previous investigation. Moreover, a general form of probabilistic control volume model is derived to show the original and present models are the special cases for conventional cast and AMed alloys.

中文翻译：

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一种新的概率控制体积方案来解释样品尺寸对增材制造钛合金疲劳寿命的影响

本文研究了试样尺寸对增材制造（AMed）Ti-6Al-4V 疲劳性能的影响。通过激光粉末床熔合制成的 Ti-6Al-4V 样品的疲劳测试是通过超声轴向循环进行的，直至应力比 = –1 的极高循环状态。五组试件的数据显示出明显的尺寸效应，即随着试件尺寸的增大，疲劳寿命或疲劳强度逐渐降低。开发了一种新的概率控制体积方案，通过小尺寸试件的测试数据来评估大尺寸试件的疲劳寿命。目前的数据和我们之前的调查数据验证了所提出模型的适用性。此外，推导了概率控制体积模型的一般形式，以表明原始模型和现有模型是传统铸造和 AMed 合金的特殊情况。