Abstract In this paper the homogeneity and isotropy of the mechanical hardness of thin-walled Inconel 718 (IN718) alloy samples manufactured by Selective Laser Melting (SLM) were examined using nanoindentation testing. SLM-produced honeycombed samples with wall thicknesses of 0.8, 0.6 and 0.4 mm respectively were studied by measuring the hardness across the wall thickness, and on the planes parallel and perpendicular to the build direction over the range of depths of 10-2000 nm. The average hardness values close to the edges were 4.0-6.5% lower than the areas away from the them. Interestingly the average hardness dropped by 15.2% with reduction in the cell wall thickness from 0.8 mm to 0.4 mm. Average hardness values were reported to be higher on the plane perpendicular to the build direction compared to the parallel plane. A variable material length scale was proposed in this work to describe the size effects of the microstructure. It was evaluated using the nanoindentation hardness test results and a computational model developed in previous studies by the first author and his co-workers.

中文翻译：

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元件壁厚对使用纳米压痕的 SLM IN718 硬度均匀性和各向同性的影响

摘要 本文采用纳米压痕测试方法研究了选择性激光熔化（SLM）制造的薄壁Inconel 718（IN718）合金样品的机械硬度的均匀性和各向同性。SLM 生产的蜂窝状样品的壁厚分别为 0.8、0.6 和 0.4 毫米，通过测量壁厚的硬度以及在 10-2000 纳米深度范围内平行和垂直于构建方向的平面上的硬度进行了研究。靠近边缘的平均硬度值比远离边缘的区域低 4.0-6.5%。有趣的是，随着单元壁厚度从 0.8 毫米减少到 0.4 毫米，平均硬度下降了 15.2%。据报道，与平行平面相比，垂直于构建方向的平面上的平均硬度值更高。在这项工作中提出了一个可变的材料长度尺度来描述微观结构的尺寸效应。使用纳米压痕硬度测试结果和第一作者及其同事在先前研究中开发的计算模型对其进行了评估。