A Novel Method for Improving Weld Seam Properties through Inline Coupling of Welding and Forming

High heat input during welding leads to transformations of the microstructure in the area subjected to welding, mostly resulting in an inhomogeneous microstructure and an overall deterioration of the mechanical properties. To restore these properties, post treatment processes which are typically separated from the welding process are state of the art. The present work focusses on recrystallization phenomena and shows the new methodology, WeldForming, which intends to eliminate subsequent treatment processes. The new inline process combination harnesses the synergies of a welding and a rolling process to ultimately prevent the typical zone formation of the heat affected zone. This is done by stimulating recrystallization and recovery processes. The development of the process is based on numerical simulations. A new aspect is the first time coupling of both processes in a single simulation model. The required material models were generated with the aid of thermophysical simulations. A novel approach is shown for creating a material model for the filler metal G4Si1 with the typical directed solidification microstructure. On the basis of the gained knowledge out of thermomechanical and numerical simulation, a process window was identified and a test setup was developed which gave the functional prove of the WeldForming process.