Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
  • Publication
    Optimierung von Verzug und Eigenspannungen beim Schweißen dickwandiger Bauteile
    (Verlag und Vertriebsgesellschaft m.b.H., 2011)
    Heinze, C.
    ;
    Schwenk, C.
    ;
    Rethmeier, M.
  • 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.
  • Publication
    Welding residual stresses depending on solid-state transformation behaviour studied by numerical and experimental methods
    ( 2011)
    Heinze, C.
    ;
    Kromm, A.
    ;
    Schwenk, C.
    ;
    Kannengiesser, T.
    ;
    Rethmeier, M.
    The development of high-strength structural steels with yield strengths up to 1000 MPa results in the requirement of suitable filler materials for welding. Recently designed low transformation temperature (LTT) alloys offer appropriate strength. The martensitic phase transformation during welding induces compressive residual stress in the weld zone. Therefore, the mechanical properties of welded joints can be improved. The present paper illustrates numerical simulation of the residual stresses in LTT-welds taking into account the effect of varying Ms/Mf-temperatures, and therefore different retained austenite contents, on the residual stresses. Residual stress distributions measured by synchrotron diffraction are taken as evaluation basis. A numerical model for the simulation of transforma tion affected welds is established and can be used for identification of appropriate Ms-temperatures considering the content of retained austenite.