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6867 |
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Wednesday, March 10, 2021, Hall 1 2:30 PM Special Materials |
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Electron beam welding of the conventionally casted and directionally solidified superalloy Alloy-247 LC |
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Aleksej Senger* / The Welding and Joining Institute of the RWTH Aachen University , Germany Uwe Reisgen / Welding and Joining Institute of the RWTH Aachen University, Germany Torsten Jokisch/ Siemens AG, Gas and Power, Germany Timm Evers/ Welding and Joining Institute of the RWTH Aachen University, Germany Thomas Krichel/ Welding and Joining Institute of the RWTH Aachen University, Germany Simon Olschok / Welding and Joining Institute of the RWTH Aachen University, Germany |
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Gas turbine technology plays a decisive role in power generation. The most important parts of the gas turbine in terms of efficiency and environmental emissions are the components in the hot gas path. These components have to maintain their functionality under extreme conditions such as high thermo-mechanical load with simultaneous oxidation and corrosion attack at temperatures over long service life. To achieve these technical conditions, components for the hot gas path are manufactured from high-temperature Ni-based alloys and with special casting processes (directionally solidified). The aim is to increase the operating temperature of the materials. Alloy-247 LC has been developed for use at high temperatures. In addition, the alloy can be cast both conventionally and directionally solidified. Due to its high hot cracking sensitivity, however, the material is classified as non-weldable. Improved weldability would create new possibilities, especially for corrective maintenance and the development of hybrid turbine blades of conventionally cast and directionally solidified. In this thesis, the potential of electron beam welding of precipitation hardening nickel base superalloy Alloy-247 LC is investigated. For this purpose, the crack sensitivity as a function of the applied temperature regime was investigated and evaluated by using metallographic and radiographic investigations. To validate the results, hybrid joints were welded with crack-optimized parameters and examined for creep resistance. |