Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters

2
Reset filters

Settings
Now showing 1 - 2 of 2
No Thumbnail Available
Publication

Elucidation of the Bulging Effect by an Improved Ray-Tracing Algorithm in Deep Penetration Wire Feed Laser Beam Welding and its Influence on the Mixing Behavior

2022 , Bachmann, M. , Meng, X. , Artinov, A. , Rethmeier, Michael

Herein, an improved ray-tracing routine using a virtual mesh refinement approach is adopted in a 3D transient multiphysics computational fluid dynamics model for deep penetration wire feed laser beam welding. In a previous study, it was shown that the improved localization of the reflection points of the subrays within the keyhole leads to a more realistic development of the keyhole depth being validated with experimental results. Another effect investigated in detail herein is a drastic change in the flow behavior in the weld pool, which promotes the occurrence of a necking area in the solidification line and subsequent bulging under specific circumstances. This has a detrimental effect on the filler material element transport in the weld pool, leading to an inhomogeneous dilution of the added material. The numerical observations are backed up by experimentally obtained data, allowing to provide a clear physics-based explanation of the reduced mixing behavior of the filler wire in the melt pool.

View
No Thumbnail Available
Publication

A study of the magnetohydrodynamic effect on keyhole dynamics and defect mitigation in laser beam welding

2022 , Meng, X. , Bachmann, M. , Artinov, A. , Rethmeier, Michael

In this paper, the highly transient keyhole dynamics, e.g., laser absorption, keyhole geometry, and fluctuation, etc., under a magnetic field are investigated using an experimental approach and multi-physical modeling. The model provides accurate predictions to the variation of penetration depth and weld pool profiles caused by the MHD effect, which is validated by the measurements of optical micrographs and in-situ metal/glass observation. The micro-X-ray computed tomography shows a remarkable reduction of keyhole-induced porosity with the magnetic field. The correlation between the porosity mitigation and the weld pool dynamics influenced by the magnetic field is built comprehensively. It is found that the magnetic field gives a direct impact on the laser energy absorption at the keyhole front wall by changing the protrusion movement. The porosity mitigation comes from multiple physical aspects, including keyhole stabilization, widening of the bubble floating channel, and the electromagnetic expulsive force. Their contributions vary according to the bubble size. The findings provide a deeper insight into the relationship between electromagnetic parameters, keyhole dynamics, and suppression of keyhole-relevant defects.

View