Additively manufactured (AM) materials experience shorter fatigue lives compared to their wrought form. Shorter fatigue life can be related to different effects like defects, residual stresses, surface finish, geometry, size, layer orientation, and heat treatment. One of the main contributors to the shorter fatigue life of AM alloys is their unique and complex microstructure. In this paper, we study this challenge from a novel perspective in which the interaction between the microstructure and fatigue life is explored. Among different microstructural features in the AM alloys, here we focus on the cells which form inside the grains during fabrication. While this microstructural feature is not always the prominent site for the fatigue initiation, it always has a significant role in the fatigue failure, particularly in high cycle fatigue because it occupies a high percentage of the volume in the material. A fatigue damage model is developed and verified to predict the life of cellular microstructures present in the AM metal microstructure. It is shown that the life of a cellular microstructure, which is composed of an arrangement of cells and cell boundaries is lower than a single-phase material without such an arrangement. We investigate how the arrangement if cells can govern the fatigue life, and analyze different cellular geometries to find the best performing cellular microstructure. By changing the geometrical parameters, the considerable variation in life can be as high as 95% in some strain amplitudes. Since the microstructure of cells in AM alloys can be tailored by changing the processing parameters, our results can be used as a guide to additively manufacture alloys with improved fatigue-resistance.

与锻造形式相比，增材制造（AM）材料的疲劳寿命更短。较短的疲劳寿命可能与不同的影响有关，例如缺陷，残余应力，表面光洁度，几何形状，尺寸，层取向和热处理。AM合金较短的疲劳寿命的主要原因之一是其独特而复杂的微观结构。在本文中，我们从新颖的角度研究了这一挑战，其中探讨了微观结构与疲劳寿命之间的相互作用。在AM合金的不同微观结构特征中，我们重点研究制造过程中晶粒内部形成的晶胞。尽管这种微结构特征并非总是引发疲劳的重要部位，但它在疲劳失效中始终起着重要的作用，特别是在高周疲劳中，因为它占据了材料中很大一部分体积。开发并验证了疲劳损伤模型，以预测存在于AM金属微结构中的蜂窝状微结构的寿命。结果表明，由单元和单元边界的排列组成的细胞微结构的寿命比没有这种排列的单相材料的寿命低。我们研究了如果细胞可以控制疲劳寿命的安排，并分析了不同的细胞几何结构以找到性能最佳的细胞微观结构。通过改变几何参数，在某些应变幅度下，寿命的显着变化可高达95％。由于可以通过更改加工参数来调整AM合金中细胞的微观结构，