Nowadays many materials such as steels, aluminium and titanium alloys can be realised by powder bed solutions melting subsequently powder layers by means of a laser or electron beam (Laser Beam Melting -LBM and Electron Beam Melting -EBM). The microstructure realised by layer-by-layer solidification having high cooling rate cannot be considered isotropic. Therefore, the mechanical properties could be influenced by the building direction. Regarding maraging steel, the study of the influence of the building direction and the heat treatment on the static and axial fatigue strength has been investigated in a previous contribution. A large scatter of the fatigue test results was found because of the presence of detrimental surface and subsurface defects. The aim of this contribution is to present additional axial fatigue test results of maraging steel characterized by different build orientation and providing an analysis of the defects observed at the crack initiation area of the fracture surface.
Materials and methods
Material and specimen's geometryMATEC Web of Conferences 165, 02005 (2018)
In the near future, combustion engineers will shape the burner according to the flame, and not the opposite way anymore. In this contribution, this idea is explored with the help of additive manufacturing (AM). The focus is put on the design and the production of swirlers using advanced materials with the least possible efforts in terms of manufacturing. The material chosen for this study is Inconel 718. There are three motivations to this project. The first one is to design new shapes and assess these in comparison to conventional ones. The second motivation is to be able to manufacture them using additive manufacturing, and to gather know-how on selective laser melting. The third motivation is to elaborate a methodology involving engineering, research and education to promote — only if and when this is desirable — the production of series of premium parts such as high-end components of gas turbine combustor using AM. First-of-a-kind swirler shapes are explained and designed. These are unlikely to be produced using conventional manufacturing. They are then successfully produced in Inconel 718 using AM. The raw parts are directly submitted for testing with no surface post-processing. The paper states why at current state-of-the-art the raw surface quality still needs improvement, and highlights the benefits of the new swirler shape versus conventional.
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