Nickel-based designed materials manufactured via laser-based powder bed fusion of metals for high-temperature applications

Large gas turbines (LGTs) are an essential part of the energy infrastructure of today. Moreover, they are essential as we increase the use of renewable energy sources, particularly during times of peak demand, lulls, or low sun exposure. To emit less climate-damaging byproducts, more ecologically friendly fuels must be used, or the already high efficiency must be further increased. Future LGT generations are probably going to have higher hot gas temperatures in both scenarios. As a result, hot gas components must become more temperature resistant, for example by using high-temperature alloys or cutting-edge cooling techniques. Using open-porous structures made from superalloys for transpiration cooling is one of these approaches. The additive manufacturing technology, laser-based powder bed fusion of metals (PBF-LB/M) can create parts from high temperature alloys. According to research, PBF LB/M process modifications can make it possible to fabricate open-porous structures that are geometrically undefined and hence ideal for transpiration cooling. These structures can be referred to as designed materials (DMs). However, it is not proven whether this production technique can satisfy the criteria that are necessary for the application in LGTs. In this thesis, scientific studies are conducted to determine whether the production of geometrically undefined open-porous structures by means of PBF-LB/M can be realized using the nickel-based superalloys Haynes 282 and Inconel 625. The key requirements of repeatable and adjustable properties are also under investigation. It is resolved here whether scatter is determinable and if process parameter adaptations can be used to pre-print-predict the properties of DMs. Furthermore, a methodical understanding of the interaction of morphological, microstructural, functional, and mechanical properties is generated. Finally, advanced DMs and complex LGT prototypes demonstrate DM’s applicability in LGTs. Process limits are investigated by sequentially varying the laser power, scan speed, hatch distance, and layer thickness to gather in-depth knowledge about the mechanisms governing the manufacturability of DMs. Within the established process constraints, the repeatability of DM’s properties is examined. The repeatability evaluation of morphological properties concentrates on variations between different lasers and build jobs in similar regions and on positional changes to create tolerance equations. Investigations are also conducted into how position affects mechanical, microstructural, and functional characteristics. The configurability of DM’s morphological, microstructural, mechanical, and functional properties is examined by altering the process variables, and consequently line and volume energy. Further research on hierarchical DMs, which are DMs combined with lattice structures, reveals that such a combination enhances mechanical strength. The flexibility of design and the combinability of bulk and DMs within a part are shown by a variety of component designs.

Author dc:creator

• Albert, Johannes

Advisor dc:contributor.advisor

• Fleck, Claudia

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

en

Identifier URI

https://doi.org/10.14279/depositonce-18437

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/19638