Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters

2
2
Reset filters

Settings
Now showing 1 - 2 of 2
  • Publication
    The effect of tack welding on numerically calculated welding-induced distortion
    ( 2012)
    Heinze, C.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
    A single-layer pulsed gas metal arc weld of structural steel S355J2+N with a thickness of 5 mm is experimentally and numerically investigated. Two tack welds are considered in the numerical simulation into two different ways. First, the tack welds are represented by elements belonging to the initial material. This implies that the "tack weld material" was not exposed to any thermal load or phase transformation before actual welding was performed. The weld seam is shortened and there is an influence on the stiffness of the whole structure affecting the calculation result. Secondly, the tack welds were simulated as conducted in the experimental welding procedure. The cases considering tack welding are compared to a simulation neglecting tack welding and to the experimental results. The influence of tack welds on the calculated welding-induced distortion is clarified and a contribution to an improved simulation-based prediction of welding-induced distortion is possible by modeling tack welding according to the realistic fabrication procedure.
  • Publication
    Numerical sensitivity analysis of welding-induced residual stress depending on variations in continuous cooling transformation behavior
    ( 2011)
    Heinze, C.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
    ;
    Caron, J.
    The usage of continuous cooling transformation (CCT) diagrams in numerical welding simulations is state of the art. Nevertheless, specifications provide limits in chemical composition of materials which result in different CCT behavior and CCT diagrams, respectively. Therefore, it is necessary to analyze the influence of variations in CCT diagrams on the developing residual stresses. In the present paper, four CCT diagrams and their effect on numerical calculation of residual stresses are investigated for the widely used structural steel S355J2 + N welded by the gas metal arc welding (GMAW) process. Rather than performing an arbitrary adjustment of CCT behavior, four justifiable data sets were used as input to the numerical calculation: data available in the Sysweld database, experimental data acquired through Gleeble dilatometry tests, and TTT/CCT predictions calculated from the JMatPro and Edison Welding Institute (EWI) Virtual Joining Portal software. The performed numerical analyses resulted in noticeable deviations in residual stresses considering the different CCT diagrams. Furthermore, possibilities to improve the prediction of distortions and residual stress based on CCT behavior are discussed.