Exploring the duality of powder adhesion and underlying surface roughness in laser powder bed fusion processed Ti-6Al-4V
Exploring the duality of powder adhesion and underlying surface roughness in laser powder bed fusion processed Ti-6Al-4V
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DOI：
10.1016/j.jmapro.2022.06.057
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发表时间：
2022-09-01
影响因子：
6.2
通讯作者：
Cox, Sophie C.
中科院分区：
文献类型：
--
作者：
Carter, Luke N.;Villapun, Victor M.;Cox, Sophie C.
建成后的表面粗糙度仍然是广泛采用激光粉床融合(LPBF)的一个重要障碍。要克服这一障碍，首先必须了解这一表面的结构。该研究探索了LPBF表面的二重性，包括：1)由粘结粉末主导的表观表面和2)由完全固结的材料定义的底层轮廓。利用LPBF制作了不同轮廓扫描参数的立方体样品阵列，以研究它们对垂直壁面的影响。首次利用光学图像分析技术对粉末颗粒表面附着的程度和尺寸分布进行了定量研究。切片样品的扫描电子显微镜照片结合第二种新的图像处理技术被用来研究下表面轮廓。研究人员利用这些方法来研究工艺参数和两种表面形貌之间的关系。表面光洁度(S-a)、粉末附着力和底层粗糙度随着能量的输入而降低，直到观察到轮廓熔化轨迹不稳定和不连贯的点(类似于0.1J/mm)。最光滑的试件(S-a，10.9微米)比对照(S-a，13.6微米)的Sa减少了19.9%。结果表明，在大部分实验范围内，工艺室内的横流都会影响底层粗糙度R-a，上游平均比下游低4.0微米。与原料相比，附着的颗粒尺寸分布更细小(D-50表面积=20.8微米；D-50原料=32.9微米)。因此，进一步的研究比较了用粗(筛至36微米，D-50=42.8微米)和细(筛至
As-built surface roughness remains a significant barrier to widespread uptake of Laser Powder Bed Fusion (LPBF). To overcome this barrier, it is first necessary to understand the structure of this surface. This research explores the duality of the LPBF surface consisting of: 1) an apparent surface dominated by adhered powder and 2) the underlying profile defined by the fully consolidated material.An array of cuboidal specimens were produced by LPBF with varying contour scan parameters to study their influence on the vertical wall surface. For the first time, optical image analysis was used to quantify the extent and size distribution of surface adhered powder particles. SEM micrographs of the sectioned specimens were used in conjunction with a second novel image processing technique to study the underlying surface profile. Researchers utilised these methods to study the relationship between process parameters and both surface topographies. These results were compared against traditional line of sight roughness measurements.Surface finish (S-a), powder adhesion, and underlying roughness decreased with energy input to a point where the contour melt track was observed as unstable and incoherent (similar to 0.1 J/mm). A 19.9 % reduction in Sa was demonstrated by the smoothest specimen (S-a, 10.9 mu m) when compared to the control (S-a, 13.6 mu m). Argon crossflow within the process chamber was shown to influence the underlying roughness, R-a, with upstream values 4.0 mu m lower on average than downstream over most of the experimental range.Adhered particle size showed a finer distribution compared with the feedstock (D-50 Surface = 20.8 mu m; D-50 Feedstock = 32.9 mu m). Consequently, a further study comparing specimens built using coarse (sieved to >36 mu m, D-50 = 42.8 mu m) versus fine (sieved to