Material- and process oriented non-destructive testing of additively manufactured components by computed tomography

选择性激光熔化(简写为SLM)是一种添加剂制造工艺(缩写AM)，其中金属结构部件可以通过逐渐施加和熔化粉末层来生产。这些部件的高度几何复杂性导致近年来AM在许多工业领域被研究并测试其适用性。然而，在SLM的快速发展中，出现了大量与材料有关的问题和问题，这些问题是这项新技术及其生产的部件的应用和鉴定的基础。例如，对于大多数材料来说，安全使用结构部件所必需的可控和可重复的孔隙率是不能保证的。同时，材料力学行为的各向异性是由LayerWise制造工艺引起的定向凝固组织造成的。由于这些特性和缺陷的不可避免地出现，对成品零件的材料分析和质量保证以及与制造参数和零件几何形状的相关性问题仍处于研究的初级阶段。无损检测是迈向全面显微组织分析和成分鉴定的重要一步。因此，本项目的目的是基于X射线显微断层扫描方法，研究显微组织和由此产生的力学性能与工艺参数和成分几何形状的关系，从而改善对孔洞减少和演化的工艺控制。为此，我们将研究在SLM中广泛使用的铝合金AlSi10 Mg在不同的工程几何形状和建造方向下，在不同的激光速度、激光功率和舱口间距下的变化。这允许评估过程-结构-属性。在这项任务的范围内，将主要根据关于SLM微观结构特征的X射线显微断层摄影数据，开发自动化的材料相学评价方法。这第一次允许三维可视化的工艺参数和部件形状与微观结构特征和机械部件性能之间的可能联系。这为真正的过程控制和基于材料建模的组件行为预测开辟了道路。基于在样品和类部件几何形状中提取的这些相关性，对测试几何形状进行了现场测试中的力学性能建模的验证。

Selective laser melting (Abbr. SLM) is an additive manufacturing process (Abbr. AM), in which metallic structural components can be produced by the incremental application and melting of powder layers. The high geometric complexity of such components has led to the AM being investigated in many industrial fields in recent years and tested for their applicability. Within this rapid development of SLM, however, a large number of material-related questions and problems arise which are fundamental in the application and qualification of this new technology and the components produced with it. For example, a controllable and reproducible porosity, which is necessary for a safe use in structural components, cannot be guaranteed for most materials. At the same time, the anisotropy in the mechanical material behavior due to the directionally solidified microstructure is caused by the layerwise manufacturing process. Due to the inevitable occurrence of such characteristics and imperfections, the question of the material analysis and quality assurance of finished components and the correlation to the manufacturing parameters and component geometries is still at the beginning of research. Non-destructive testing represents an important step on the way to comprehensive microstructure analysis and component qualification.The aim of this project is therefore to investigate the relationships between microstructure and resulting mechanical properties to the process parameters and the component geometry based on X-ray microtomographic methods and thus to improve the process control with regard to the reduction and evolution of the porosity. For this purpose, the aluminium alloy AlSi10Mg, which is widely used in SLM, will be investigated under variation of laser speed, laser power and hatch spacing for various engineering geometries and build directions. This allows evaluation of process-structure-property. Within the scope of this task, automated, materialographic evaluation methods are to be developed mainly on the basis of X-ray microtomographic data for microstructural features in SLM. For the first time, this allows for a possible linking of the three-dimensionally visualized process parameters and the component shape with the microstructural characteristics and the mechanical component properties. This opens the way for a real process control and a prediction of the component behavior based on material modeling. On the basis of these extracted correlations in samples and component-like geometries, a validation of the modeling of mechanical properties in an in-situ test is carried out on a test geometry.