TY - JOUR A1 - Frei, J. A1 - Alexandrov, B. T. A1 - Rethmeier, Michael T1 - Low heat input gas metal arc welding for dissimilar metal weld overlays part II: the transition zone N2 - Dissimilar metal weld overlays (DMWOL) of nickel base alloys on low alloy steel components are commonly used in the oil and gas, petrochemical, and power generation industries to provide corrosion and oxidation resistance in a wide range of service environments and temperatures. Traditionally, dissimilar weld overlays are produced using cold or hot wire gas tungsten arc welding. This study aims to identify and evaluate potential advantages of low heat input gas metal arc welding processes over the conventional gas tungsten arc welding in the production of dissimilar weld overlays. In order to evaluate the quality of these overlays regarding resistance against hydrogen-assisted cracking, their transition zone region is investigated in this part of the publication series. Metallurgical characterization, including energy-dispersive x-ray spectroscopy, is performed on Alloy 625/grade 22 steel overlays. The transition zone is characterized by a narrow planar growth zone and steep compositional gradients from the fusion boundary towards the weld metal. Evidence of low carbon contents in the planar growth zone, as well as for carbide precipitation in the cellular growth zone was found. The microstructure in the transition zone region of the fusion zone shows characteristics known to be suitable for good resistance against hydrogen embrittlement. KW - Low heat input Gma welding KW - Dissimilar metal weld overlays KW - Coarse grained heat affected zone KW - Grain size KW - Microstructure KW - Fusion zone, nickel alloys PY - 2018 U6 - https://doi.org/10.1007/s40194-017-0539-5 VL - 62 IS - 2 SP - 317 EP - 324 PB - Springer CY - Heidelberg, Germany AN - OPUS4-44721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -