Compression fatigue behavior of Ti-6Al-4V mesh arrays fabricated by electron beam melting
Compression fatigue behavior of Ti-6Al-4V mesh arrays fabricated by electron beam melting
复制标题
电子束熔炼Ti-6Al-4V网状阵列的压缩疲劳行为
DOI：
10.1016/j.actamat.2011.10.051
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发表时间：
2012-02-01
期刊：
影响因子：
9.4
通讯作者：
Wicker, R. B.
中科院分区：
文献类型：
--
作者：
Li, S. J.;Murr, L. E.;Wicker, R. B.
本文研究了采用电子束熔化增材制造技术制备的高孔隙率为60-85%的Ti-6Al-4V网格阵列的压缩疲劳性能。结果表明：试件的疲劳寿命主要取决于整个试件的均匀变形，其破坏特征为应变快速积累和与循环加载方向成45度角的严重挤压带；相对疲劳强度和相对密度之间的关系可以用著名的Gibson-Ashby模型来评价，其指数因子n为2.7，高于铝泡沫和镍泡沫的报告数据，几乎是随机开孔泡沫理想值（n = 1.5）的两倍。疲劳失效的潜在机制是循环棘轮与疲劳裂纹萌生和扩展的相互作用，而循环棘轮对疲劳寿命起主导作用。透射电镜观察发现，位错沿α′相界面产生，随着相对密度的增加，位错的产生更加明显。这将有助于延缓循环棘轮，提高疲劳强度。(C) 2011材料学报Elsevier Ltd.出版。版权所有。
This paper focuses on the compression fatigue behavior of Ti-6Al-4V mesh arrays with high porosities of similar to 60-85%, which were fabricated by an additive manufacturing technique using electron beam melting. The results show that their fatigue lives are mainly determined by uniform deformation through the entire specimens, while their failures are characterized by rapid strain accumulation and a severe crush band at an angle of 45 degrees to the cyclic loading direction. The relation between the relative fatigue strength and relative density can be evaluated by the well-known Gibson-Ashby model with the exponential factor n being 2.7, which is higher than the reported data for aluminum and nickel foams, and almost double the idealized value (n = 1.5) of a stochastic open cellular foam. The underlying mechanism of fatigue failure appears to be interaction between cyclic ratcheting and fatigue crack initiation and propagation, while the former plays a dominant role in fatigue life. TEM observations found that dislocations are generated along the interface of the alpha' phase and their generation becomes more evident with an increase in the relative density. This would contribute to the retardation of cyclic ratcheting and an improvement in the fatigue strength. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.