Microstructure- and defect-controlled damage tolerance evaluation of lattice structures at room temperature and 650 °C based on the E-PBF processed Ni-based alloy Inconel 718

基于 E-PBF 处理的镍基合金 Inconel 718 进行室温和 650 °C 晶格结构的微观结构和缺陷控制损伤容限评估

• 批准号: 379213719
• 负责人: Professor Dr.-Ing. Thomas Niendorf
• 金额: --
• 依托单位: Lehrstuhl für Werkstoffprüftechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/379213719?language=en
• 关键词: Microstructure; defect; controlled; damage; tolerance

The main objective of the project is the establishment of a profound understanding of the structural behavior as well as the microstructural and mechanical properties of lattice structures based on the E-PBF processed Inconel 718 (IN718) alloy. In particular, it will be investigated how far material properties and surface roughness can systematically be adjusted by process parameters and subsequent post-processing (surface and heat treatment). Regarding the surface finish, alternative approaches are focused, since conventional grinding and polishing are only partially suitable for additively manufactured lattice structures. Besides wet chemical treatments such as chemical etching or electrochemical polishing (ECP), mechanical processes such as vibratory finishing and ball-polishing are considered. It has to be ensured that uniform material removal takes place in the near-surface and in the center of the specimen. In order to evaluate the different approaches, resulting surface roughness will be measured using confocal microscope and computer tomography (µ-CT). In addition to 2D/3D pore analysis, supplementary mircostructural investigations will be carried out by means of scanning- (SEM) and transmission electron microscopy (TEM) as well as hardness measurements in the near-surface and the center area of the specimens in order to quantify the influence of subsequent heat treatments (solution annealing + quenching, HIP + solution annealing + quenching). The different material conditions will be investigated by means of quasi-static and cyclic tests up to 107 cycles, using application-oriented measurement techniques such as a direct/alternating current potential drop (DC-/ACPD) system, infrared camera and Optimizer4D sensor. In addition to the tests at room temperature (RT), the relevant high-temperature range of 650 °C will further be investigated in order to determine the high temperature properties of IN718 lattice structures. However, especially the adaption of the different measurement techniques is challenging. For a profound understanding of the material, additional damage evolution tests will be carried out to enable in-depth conclusions on the damage accumulation and propagation, respectively, in additively manufactured lattice structures. In summary, microstructural, computed tomographic as well as mechanical investigations will be correlated with the results of fatigue testing. Based on these correlations process-geometry-microstructure-property relationships will be qualitatively and quantitatively established.

该项目的主要目标是建立对基于E-PBF处理的Inconel 718（IN 718）合金的晶格结构的结构行为以及微观结构和机械性能的深刻理解。特别是，它将调查多远的材料性能和表面粗糙度可以系统地调整工艺参数和随后的后处理（表面和热处理）。关于表面光洁度，关注替代方法，因为常规研磨和抛光仅部分适用于增材制造的晶格结构。除了湿法化学处理，如化学蚀刻或电化学抛光（ECP），机械加工，如振动抛光和球抛光被认为是。必须确保在样品的近表面和中心均匀地去除材料。为了评估不同的方法，将使用共聚焦显微镜和计算机断层扫描（µ-CT）测量所得的表面粗糙度。除了2D/3D孔隙分析外，还将通过扫描（SEM）和透射电子显微镜（TEM）以及样品近表面和中心区域的硬度测量进行补充微观结构研究，以量化后续热处理（固溶退火+淬火，HIP +固溶退火+淬火）的影响。不同的材料条件将通过准静态和循环测试进行研究，最多107个循环，使用面向应用的测量技术，如直流/交流电位降（DC-/ACPD）系统，红外摄像机和Optimizer 4D传感器。除了在室温（RT）下的测试外，还将进一步研究650 °C的相关高温范围，以确定IN 718晶格结构的高温性能。然而，特别是不同测量技术的适应是具有挑战性的。为了深入了解材料，将进行额外的损伤演化测试，以分别深入了解增材制造晶格结构中的损伤累积和传播。总之，微观结构、计算机断层扫描以及力学研究将与疲劳试验结果相关。基于这些相关性，将定性和定量地建立工艺-几何-显微结构-性能的关系。