Multi-laser scan strategies for enhancing creep performance in LPBF
Multi-laser scan strategies for enhancing creep performance in LPBF
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DOI：
10.1016/j.addma.2021.101948
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发表时间：
2021-05-01
影响因子：
11
通讯作者：
Clare, A. T.
中科院分区：
文献类型：
--
作者：
Sanchez, Salome;Hyde, C. J.;Clare, A. T.
激光粉末床融合（LPBF）可以制造复杂的结构，这对可以实现增强服务性能的行业具有吸引力。然而，LPBF的构建时间可能比传统制造工艺慢，特别是对于更大批量的零件。多激光机床有可能显著缩短加工时间，但人们对隔行扫描策略如何影响机械性能知之甚少。这项工作的结果表明，多激光扫描策略对LPBF合金718在不同构建方向的蠕变性能没有不利影响，证明了使用多激光策略在不影响机械性能的情况下实现更快构建速率的潜力。事实上，对于垂直构建的样品（即构建方向平行于加载方向），多激光样品优于其单激光对应物，并且具有与锻造合金相似的蠕变寿命和二次蠕变速率（差异1%）。水平构建的单激光和多激光样品（即构建方向垂直于加载方向）和45？从加载方向的表现相似，所有失败后不久，第三蠕变开始。还发现，组件的故障不能归因于多激光加工所使用的交错扫描策略，而是构建方向及其对相对于加载方向和样品的应力状态的晶粒取向的影响。然而，扫描策略、激光器的数量、固化层的分数面积、层下的粉末和层间旋转意味着层本身以及样品是不均匀的。尽管如此，任何给定样品的蠕变寿命在其重复试验的73小时（即17%）内，使结果具有可信度。因此，有可能，作为这项工作的结果，了解多激光扫描策略的影响，特别是激光对激光界面LPBF微观结构。多激光扫描策略被证明对蠕变性能没有不利影响，同时将构建时间缩短一半以上。
Laser Powder Bed Fusion (LPBF) enables complex structures to be manufactured, which is attractive to industries where augmented service performance can be achieved. However, the build time of LPBF can be slower than traditional manufacturing processes, especially for higher volumes of parts. Multi-laser machines have the potential to significantly reduce process time, but there is little understanding of how interlaced scan strategies impact upon mechanical properties. The results of this work show that multi-laser scan strategies have no adverse effects on the creep properties of LPBF alloy 718 at different build orientations, demonstrating the potential of using multi-laser strategies for faster build rates without compromising the mechanical properties. Indeed, it is shown that for samples built vertically (i.e. where the build direction is parallel to the loading direction), multi-laser samples outperformed their single-laser counterparts and had a similar creep life and secondary creep rate to wrought alloy (1% difference). The single and multi-laser samples built horizontally (i.e. with the build direction perpendicular to the loading direction) and at 45? from the loading direction performed similarly and all failed soon after the onset of tertiary creep. It was also found that the failure of components could not be attributed to the interlacing scan strategies used with multi-laser processing, but rather to the build orientation and its effect on the grain orientation with respect to the loading direction and the stress state of the sample. However, the scan strategy, number of lasers, fraction area of solidified layer, powder underneath the layer and the interlayer rotation meant that the layers themselves as well as the samples were heterogenous. Despite this, the creep life for any given sample was within 73 h (i.e.17%) of its repeats, giving confidence in the results. It is therefore possible, as a result of this work, to understand the effects of multi-laser scan strategies, particularly the laser-to-laser interfaces on LPBF microstructure. Multi-laser scan strategies are shown to have no detrimental effects on the creep performance, while cutting the build time by more than half.