Project Details
Projekt
Macro-mechanical prediction of the prevention of solidification cracks during laser beam welding
Applicant
Professor Dr.-Ing. Michael Rethmeier
Subject Area
Joining and Separation Technology
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 434946896
Solidification cracking remains a significant challenge in the laser beam welding (LBW) of nickel based alloys. This sub project focuses on the macromechanical prediction and prevention of solidification cracks in LBW, utilizing multi laser beam technology A comprehensive approach combining experimental investigations and numerical simulations is employed to gain an in depth understanding of the phenomenon. In WP1, in close collaboration with SP2, the welding process is characterized by systematically varying key parameters such as laser power and welding speed. Metallographic analysis and non destructive testing methods are employed, enabling SP3, SP4, SP5, and SP6 to conduct a detailed investigation into microstructural evolution and crack formation. In WP2, the ductility capacity in the mushy zone is experimentally assessed through programmable deformation rate tests (PVR). Advanced measurement techniques(thermography, pyrometry, etc.) are applied to accurately capture the temperature distribution during welding. Parrallely, finite element method (FEM) simulations in WP3 of the PVR tests provide insights into the local strain distribution and critical boundary conditions that lead to solidification cracking, which is crucial for SP4, SP5 and SP6. These simulations also integrate more precise material behavior data from the simulations of SP4. Subsequently, a strategy to minimize solidification cracking is developed by utilizing defocused laser beams to redistribute stress and temperature around the mushy zone. To reduce experimental costs and effort, the optimal setup is designed in WP4, using FEM simulations combined with a gradient based optimization method (SP7). Finally, this optimal setup is experimentally validated to confirm its effectiveness in WP5.
DFG Programme
Research Units
