This study investigates the effects of build orientation and laser-energy density on the pore structure, microstructure, and tensile properties of Inconel 718 manufactured by laser powder bed fusion. Three different build conditions were selected for comparison based on previous research (namely, the conditions that resulted in the worst and best fatigue lifetimes): 0° build orientation and 38 J/mm³ laser-energy density, 0° build orientation and 62 J/mm³ laser-energy density, and 60° build orientation and 62 J/mm³ laser-energy density. Differences in porosity were measured between each build condition. In terms of microstructure, all three conditions exhibited a predominantly 〈001〉 texture in the build direction, grains elongated in the build direction, and a sub-grain structure oriented with the build direction that consisted of dislocation networks decorated with nano-scale precipitates. Build orientation (0° versus 60° with respect to the build plate) produced a difference in yield strength due to anisotropic grain morphology and effective grain size. The low laser-energy density specimens showed a significant decrease in all mechanical properties compared to the high laser-energy density specimens because the amount (6.91% by volume) and size of the lack-of-fusion porosity (from insufficient melting) surpassed a level at which microstructure (the grain and sub-grain structure) no longer governs quasi-static mechanical properties. This work provides insight that could enable the tunability of structure-property relationships in as-built Inconel 718 by optimizing laser-energy density and build orientation.

这项研究调查了构造方向和激光能量密度对通过激光粉末床熔合制造的Inconel 718的孔结构，微结构和拉伸性能的影响。根据先前的研究（即导致最坏和最佳疲劳寿命的条件）选择了三种不同的构建条件进行比较：0°生成方向和38 J / mm ³激光能量密度，0°生成方向和62 J / mm ³激光能量密度，60°构建方向和62 J / mm ³激光能量密度。测量每种构造条件之间的孔隙率差异。就微观结构而言，所有三个条件在构造方向上均表现出主要的<001>织构，晶粒在构造方向上伸长，并且以构造方向取向的亚晶粒结构由以纳米级析出物装饰的位错网络组成。由于各向异性的晶粒形态和有效的晶粒尺寸，构建方向（相对于构建板为0°相对于60°）产生了屈服强度的差异。与高激光能量密度样品相比，低激光能量密度样品显示出所有机械性能均显着下降，因为量（6。91％（按体积计）和缺乏熔融孔隙的尺寸（由于熔融不足）超过了微观结构（晶粒和亚晶粒结构）不再控制准静态机械性能的水平。这项工作提供了见识，可以通过优化激光能量密度和构建方向来实现Inconel 718的结构-属性关系的可调性。