Serrano-Munoz Itziar, Mishurova Tatiana, Thiede Tobias, Sprengel Maximilian, Kromm Arne, Nadammal Naresh, Nolze Gert, Saliwan-Neumann Romeo, Evans Alexander, Bruno Giovanni
, Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205, Berlin, Germany.
Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24/25, 14476, Potsdam, Germany.
Sci Rep. 2020 Sep 4;10(1):14645. doi: 10.1038/s41598-020-71112-9.
The effect of two types of scanning strategies on the grain structure and build-up of Residual Stress (RS) has been investigated in an as-built IN718 alloy produced by Laser Powder Bed Fusion (LPBF). The RS state has been investigated by X-ray diffraction techniques. The microstructural characterization was performed principally by Electron Backscatter Diffraction (EBSD), where the application of a post-measurement refinement technique enables small misorientations (< 2°) to be resolved. Kernel average misorientation (KAM) distributions indicate that preferably oriented columnar grains contain higher levels of misorientation, when compared to elongated grains with lower texture. The KAM distributions combined with X-ray diffraction stress maps infer that the increased misorientation is induced via plastic deformation driven by the thermal stresses, acting to self-relieve stress. The possibility of obtaining lower RS states in the build direction as a consequence of the influence of the microstructure should be considered when envisaging scanning strategies aimed at the mitigation of RS.
在激光粉末床熔融（LPBF）制备的IN718合金中，研究了两种扫描策略对晶粒结构和残余应力（RS）积累的影响。通过X射线衍射技术研究了RS状态。微观结构表征主要通过电子背散射衍射（EBSD）进行，其中应用测量后细化技术能够分辨小角度取向差（<2°）。与织构较弱的拉长晶粒相比，择优取向的柱状晶粒的内核平均取向差（KAM）分布表明其包含更高水平的取向差。KAM分布与X射线衍射应力图相结合推断，热应力驱动的塑性变形会诱导取向差增加，从而起到自消除应力的作用。在设想旨在减轻RS的扫描策略时，应考虑由于微观结构的影响而在构建方向上获得较低RS状态的可能性。
