Investigation of the combined process chain based on SLM and LMD

近年来，随着快速成型、快速模具和快速制造的应用，增材制造（AM）变得越来越重要。这将缩短产品开发时间和制造时间。AM提供了巨大的优势，如自由几何设计以及特征集成，例如冷却通道或轻量化结构。以目前的技术水平，不可能同时生产复杂而精细的结构，同时实现高建造率。粉末为基础的应用，如选择性激光熔化（SLM）允许建立非常复杂的结构。然而，由于低建造速度，它往往是不经济可行的系列或大规模生产。此外，部件的最大尺寸受工艺室尺寸的限制。由于物料在粉床中的位置，在选定的位置组合不同的物料是不可能的。相比之下，激光金属沉积（LMD）是一种具有高构建速率的增材技术。零件尺寸不受限制，材料的变化很容易实现。然而，这个过程只能建立粗略的结构。SLM和LMD的组合过程链为结合各自方法的优势提供了巨大的潜力。这个项目的目的是了解过程链SLM-LMD的基本原理和影响。这些研究的结果是增加了增材制造零件的功能。在这个组合工艺链中，SLM用于复杂结构的生产。LMD负责生产巨大且更大的几何形状。过程中灵活的材料变化为扩展过程链的功能提供了额外的机会。为了对工艺组合有一个基本的了解，有必要进行调查，以确定以下LMD材料应用对SLM结构的影响程度，以及在连接区域以及整个试样中发生的影响和性能。最后，将从这两个过程的技术研究中得出所选功能属性的经验模型。研究结果为复合增材工艺链的进一步应用提供了理论基础。由于高耐腐蚀性，优异的高温性能以及与涡轮机生产部件的相关性，Inconel 718将用作整个项目的基础材料。

Additive manufacturing (AM) has become more important in recent years with applications in Rapid Prototyping, Rapid Tooling and Rapid Manufacturing. This leads to shorter product development times as well as shorter manufacturing times. AM offers tremendous advantages such as free geometric design as well feature-integration, e.g. cooling channels or lightweight structures. With the current state of the art, it is not possible to produce complex and fine structures while achieving high build rates at the same time. Powder based applications such as selective laser melting (SLM) allow the build-up of very complex structures. However, due to low build speed it is often not economically viable in series or mass production. In addition, the maximum size of the components is limited by the size of the process chamber. Due to the material position in a powder bed, a combination of different materials at selected locations is not yet possible. In contrast, laser metal deposition (LMD) is an additive technology with high build rates. The part size is not limited and a change of materials is easily implemented. However, the process can only build rough structures. A combined process chain of SLM and LMD offers great potential to combine the advantages of the individual methods.The aim of this project is to understand the fundamentals and effects in the process chain SLM-LMD. Increased functionality of additive manufactured parts is a result of these investigations. In this combined process chain, SLM is used for the production of complex structures. LMD is responsible for the production of the massive and bigger geometries. The flexible material change in process offers additional opportunities to extend the functionality of the process chain. For a basic understanding of the process combination, an investigation is necessary to determine the extent in which SLM structures are affected by the following LMD material application, and what effects and properties occur in the connection zone as well in the entire specimen. Finally, empirical models for selected functional properties will be derived from the technological studies for both processes. The results should provide a knowledge base for further applications of the combined additive process chain. Inconel 718 will be used as a basic material for the whole project, due to the high corrosion resistance, excellent high-temperature properties and relevance for components in turbine production.