EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The thermo-fluid simulation of metal transfer and melt pool with gas metal arc heat source gives access to an in-depth understanding of the process. However, to be reliable the computed data must be validated with experimental measurements. The common validation method largely depends on the conformance of the fusion zone profile between the computed and the post-build metallographic cross-sections. Although it provides satisfactory information, by nature it cannot capture the tri-dimensional essence of the process. Therefore, a novel method developed to validate the melt pool free surface geometry with images acquired in real-time is presented and applied in this study. An image acquisition system was set up to extract the melt pool geometry. The edge of the melt pool was identified using an image processing technique to generate the free surface contour. The contours of the melt pool free surface were recalibrated using a checkerboard pattern to undistort the contours. A three-dimensional and transient thermo-fluid model with tracking of the free surface deformation implemented in the CFD software OpenFOAM was applied to simulate the experimental test cases. The three electromagnetic models today in use to determine the Lorentz force in the melt were also tested. The results show that the usual two-dimensional validation along traverse cross-sections can be conveniently achieved while the top view validation of the free surface contour can be extremely difficult. The results highlight the limitations of computational models currently used for the Lorentz force, and of the melt pool models where the arc heat source is simplified via boundary conditions.