Vilanova Mireia, Taboada Mari Carmen, Martinez-Amesti Ana, Niklas Andrea, San Sebastian Maria, Guraya Teresa
LORTEK Technological Centre, Basque Research and Technology Alliance (BRTA), Arranomendia Kalea 4A, 20240 Ordizia, Spain.
Minning and Metallurgical Engineering and Materials Science Department, University of the Basque Coutry UPV/EHU, Rafael Moreno "Pitxitxi", 2, 48013 Bilbao, Spain.
Materials (Basel). 2021 Sep 30;14(19):5702. doi: 10.3390/ma14195702.
Inconel 738LC (IN738LC) is a nickel-based superalloy specially used in the hot section components of turbine engines. One of its main drawbacks relies on the cracking susceptibility when it is manufactured by laser powder bed fusion (LPBF). This paper analyzes the influence of minor alloying element concentration on cracking tendency of IN738LC superalloy manufactured by LPBF. For that objective, samples were manufactured using two powders, which presented different minor alloying elements concentration (Si, Zr and B). It was shown that the samples crack tendency was very different depending on the powder used for their manufacturing. In fact, the measured crack density value was 2.73 mm/mm for the samples manufactured with the powder with higher minor alloying elements concentration, while 0.25 mm/mm for the others. Additionally, a special emphasis has been put on elemental composition characterization in cracked grain boundaries in order to quantify possible Si or Zr enrichment. It has been also studied the differences of solidification ranges and grain structures between both samples as a consequence of different minor alloying elements concentration in order to analyze their effect on crack susceptibility. In this sense, Scheil-Gulliver simulation results have shown that samples with higher Si and Zr contents presented higher solidification range temperature. This fact, as well as an increase of the presence of high angle grain boundaries (HAGB), leaded to an increment in the crack formation during solidification. Therefore, in this research work, an understanding of the factors affecting crack phenomenon in the LPBF manufactured IN738LC was accomplished.
Inconel 738LC（IN738LC）是一种镍基高温合金，专门用于涡轮发动机的热端部件。其主要缺点之一在于通过激光粉末床熔融（LPBF）制造时的开裂敏感性。本文分析了微量合金元素浓度对通过LPBF制造的IN738LC高温合金开裂倾向的影响。为此，使用两种粉末制造样品，这两种粉末呈现出不同的微量合金元素浓度（硅、锆和硼）。结果表明，根据制造样品所用的粉末不同，样品的开裂倾向差异很大。事实上，使用微量合金元素浓度较高的粉末制造的样品，测得的裂纹密度值为2.73毫米/毫米，而其他样品为0.25毫米/毫米。此外，特别强调了对裂纹晶界处元素组成的表征，以量化可能的硅或锆富集情况。还研究了由于微量合金元素浓度不同，两种样品在凝固范围和晶粒结构上的差异，以分析它们对裂纹敏感性的影响。从这个意义上说，Scheil-Gulliver模拟结果表明，硅和锆含量较高的样品呈现出更高的凝固范围温度。这一事实，以及大角度晶界（HAGB）出现的增加，导致凝固过程中裂纹形成增加。因此，在这项研究工作中，对影响LPBF制造的IN738LC中裂纹现象的因素有了一定的认识。
