Flow and bead formation characteristics in high power laser welding at different welding positions

Suck-Joo Na, Sang-Woo Han, Muhammad Sohail, Linjie Zhang, Andrey Gumenyuk, Michael Rethmeier, Miikka Karhu, Veli Kujanpää

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

    Abstract

    The numerical simulations of high power laser keyhole welding at different welding positions are performed by using Volume-Of-Fluid (VOF) method. The main material is SS400. The multi-physics phenomenon is considered using several models, such as the heat flux of Gaussian heat source, the recoil pressure with Clausisus-Clapeyron equation, the Marangoni flow considering temperature gradient, the buoyancy force with Boussinesq approximation, the additional shear stress and heat source due to metallic vapor ejected through keyhole entrance, the bubble formation assumed as adiabatic bubble, and the multiple-reflection by solving proper discriminant, are used. To analyze the fluid flow pattern, the concept of streamline formed by reconstructing the value of the velocity vector is applied. Partial and full penetration cases at different welding positions are considered. The welding position seems to have only a minor influence on bead formation characteristics in both cases. This is probably due to the fact that the recoil pressure has a major influence when compared to other driving forces. The flow characteristics and fluid velocity in weld pool are analyzed to compare the gravity direction effect at different welding positions. It is observed that the clockwise flow pattern is mainly formed by the recoil pressure on the keyhole surface in the case of partial penetration. The laser energy can't maintain the whole weld pool when the weld pool size becomes too large. And then the solidification starts from the middle part of weld pool and a necked weld pool shape is formed. In the full penetration welding, the weld pool flow patterns are affected by the leakage of laser power through the full penetration keyhole and also by surface tension. Furthermore, the numerical simulation of full penetration welding with AISI316L is also performed to analyze the effect of material properties. The weld bead shapes obtained by simulations were compared with the corresponding experimental results to confirm the validity of the process models adopted and the CFD simulation tool.
    Original languageEnglish
    Title of host publicationProceedings of the Lasers in Manufacturing Conference 2015
    Number of pages6
    Publication statusPublished - 2015
    MoE publication typeB3 Non-refereed article in conference proceedings
    EventLasers in Manufacturing 2015, LiM 2015 - Munich, Germany
    Duration: 22 Jun 201525 Jun 2015

    Conference

    ConferenceLasers in Manufacturing 2015, LiM 2015
    Abbreviated titleLiM 2015
    CountryGermany
    CityMunich
    Period22/06/1525/06/15

    Keywords

    • macro processing (joining, welding)
    • high power laser keyhole welding
    • numerical simulation
    • different welding position
    • flow pattern
    • weld pool

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    Na, S-J., Han, S-W., Sohail, M., Zhang, L., Gumenyuk, A., Rethmeier, M., Karhu, M., & Kujanpää, V. (2015). Flow and bead formation characteristics in high power laser welding at different welding positions. In Proceedings of the Lasers in Manufacturing Conference 2015 https://www.wlt.de/lim/Proceedings/Stick/PDF/Contribution232_final.pdf