Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    A study on shielded metal arc welding of 9%Ni steel using non-conventional ferritic welding electrode for LNG facilities
    ( 2018)
    Siayah, A.
    ;
    El-Batahgy, A-M.
    ;
    Khafagi, S.
    ;
    Gumenyuk, A.
    ;
    Gook, S.
    ;
    Rethmeier, M.
    The present research work aims at clarification of the effect of the welding electrode type on the mechanical properties of SMA welded joints of 9%Ni steel plates. Properties of produced SMA welded joints were evaluated using different non-destructive and destructive investigation methods. In comparison with the conventionally used Ni-based welding electrode ENiCrMo-3 (AWS A5.11), an experimentally produced non-conventional ferritic welding electrode with 11%Ni (ENi11-Company specification) has resulted in a better combination of the mechanical properties of SMA welded joints of this steel type for critical cryogenic applications. Besides, a positive economic impact for the experimentally produced non-conventional ferritic welding electrode, due to its lower cost, could be another attractive aspect.
  • Publication
    Effect of laser-beam and hybrid-laser-arc welding parameters and filler metal on microstructure and mechanical properties of thick heat-treated steel X8Ni9+QT640 for cryogenic service
    ( 2018)
    El-Batahgy, A-M.
    ;
    Gook, S.
    ;
    Gumenyuk, A.
    ;
    Rethmeier, M.
    The present research work encloses results of experimental investigations of the interaction between welding process parameters for laser-beam and hybrid-laser-arc as well as type of the filler metal and the achievable mechanical properties of the weld joints on steel grade X8Ni9+QT640 for cryogenic service containing 9% nickel. The results obtained contribute to the development and conversion in the industrial practice a new laser beam-based welding technology for the automated manufacturing of facilities for the liquefaction, storage and the transport of natural gases (LNG facilities). The results show, that the martensitic microstructure of the laser weld metal including low amount of retained austenite not exceeding 3.5% leads to the relatively low V-notch impact energy. The remarkable heterogeneity in the chemical composition of the weld metal through the weld thickness could be recognized in the case of hybrid-laser-arc welding with ERNiCrMo-3 austenitic filler metal, what also led to insufficient impact toughness of the weld metall. The most promising results could be achieved by using 11%Ni filler wire, which is similar to the base metal and provides a homogeneous microstructure with uniform distribution of Ni through the weld seam. It is remarkable, that a correlation between Charpy impact toughness and wire feeding speed and respectively process heat input exists. The highest toughness values were 134±58 J at -196 °C. The both laser as well as laser-hybrid welds passed the tensile test. The failure stress of 720±3 MPa with a fracture location in the base material was achieved for all samples tested.