Welding in the World

, Volume 60, Issue 3, pp 459–473 | Cite as

Low heat input gas metal arc welding for dissimilar metal weld overlays part I: the heat-affected zone

  • Julian Frei
  • Boian T. AlexandrovEmail author
  • Michael Rethmeier
Research Paper


Dissimilar metal weld overlays of nickel base alloys on low alloy steel components are commonly used in the oil and gas, petro-chemical, and power generation industries to provide corrosion and oxidation resistance in a wide range of service environments and temperatures. Traditionally, weld overlays are produced using cold or hot wire gas tungsten arc welding (GTAW). Potential advantages of cold metal transfer (CMT) welding, a low heat input gas metal arc welding process, over the conventional GTAW in production of weld overlays were evaluated. Metallurgical characterization was performed on CMT overlays of Alloy 625 filler metal on Grade 11 and Grade 22 steels. Significant grain refinement was found in the high temperature HAZ compared to the traditional coarse-grained HAZ in arc welding. Evidences of incomplete carbide dissolution, limited carbon diffusion, and incomplete transformation to austenite were also found. These phenomena were related to high heating and cooling rates and short dwell times of the high-temperature HAZ in austenitic state. Tempering effects in the steel HAZ were identified, showing a potential for development of CMT temperbead procedures. Based on the results of this study, the steel HAZ regions in CMT overlays were classified as high-temperature HAZ and intercritical HAZ.

Keywords (IIW Thesaurus)

Nickel alloys Low alloy steels GMA Surfacing DIP Transfer Coarse-grained heat-affected zone Microstructure Clad steels 



This study was supported by ExxonMobil and Fronius International by provision of materials, welding equipment, and technical support, and was performed at the Welding Engineering Laboratory of the Ohio State University.


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Copyright information

© International Institute of Welding 2016

Authors and Affiliations

  • Julian Frei
    • 1
  • Boian T. Alexandrov
    • 2
    Email author
  • Michael Rethmeier
    • 3
  1. 1.Department of Joining and Coating TechnologyFraunhofer Institute for Production Systems and Design Technology IPKBerlinGermany
  2. 2.Welding Engineering Program, Department of Material Science and EngineeringThe Ohio State UniversityColumbusUSA
  3. 3.Fraunhofer Institute for Production Systems and Design Technology IPK | BAM - Federal Institute for Materials Research and TestingBerlinGermany

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