Journal of Materials Science

, Volume 51, Issue 10, pp 4864–4879

Metallurgical characterization of coupled carbon diffusion and precipitation in dissimilar steel welds

  • Fanny Mas
  • Catherine Tassin
  • Nathalie Valle
  • Florence Robaut
  • Frédéric Charlot
  • Miguel Yescas
  • François Roch
  • Patrick Todeschini
  • Yves Bréchet
Original Paper

DOI: 10.1007/s10853-016-9792-z

Cite this article as:
Mas, F., Tassin, C., Valle, N. et al. J Mater Sci (2016) 51: 4864. doi:10.1007/s10853-016-9792-z

Abstract

The complex microstructures developed during post-welding heat-treatment in the vicinity of the fusion line between a ferritic and austenitic steel were examined in the case of submerged arc welded 18MND5/309L dissimilar joints. Quantitative measurements of the carbon distribution in the as-welded and post-weld heat-treated conditions were performed by both wavelength dispersive spectrometry and secondary ion mass spectrometry. The extent of carbon diffusion was confirmed by hardness profiles performed by nanoindentation. On the low-alloy ferritic side, decarburization resulted in cementite dissolution allowing the evolution of the bainitic structure toward a large-grained ferritic region. In the weld metal, the carbon content reached unusually high levels and an intense precipitation of chromium-rich carbides was observed in both the interfacial martensitic layer and the austenitic weld metal. The evolution of the precipitation as a function of the distance from the interface was analyzed in terms of crystallography, chemistry, volume fractions, and size distributions. Automated crystal orientation mapping in a transmission electron microscope allowed identification of the precipitates extracted on carbon replicas from both the martensitic and austenitic matrices. A 3D reconstruction of the carbides population in the martensitic layer was performed by serial cutting with a focused ion beam: M7C3 and M23C6 were found to coexist in the two carburized regions, but displayed different sizes, compositions, and morphologies, depending on their location with respect to the fusion line. This evolution in terms of precipitation was analyzed taking into account the local microstructure and composition.

Funding information

Funder NameGrant NumberFunding Note
Areva
    EDF R&D

      Copyright information

      © Springer Science+Business Media New York 2016

      Authors and Affiliations

      • Fanny Mas
        • 1
        • 2
      • Catherine Tassin
        • 1
        • 2
      • Nathalie Valle
        • 3
      • Florence Robaut
        • 4
      • Frédéric Charlot
        • 4
      • Miguel Yescas
        • 5
      • François Roch
        • 5
      • Patrick Todeschini
        • 6
      • Yves Bréchet
        • 1
        • 2
      1. 1.Université Grenoble Alpes, SIMAPGrenobleFrance
      2. 2.CNRS, SIMAPGrenobleFrance
      3. 3.Centre Public Gabriel LippmannBelvauxLuxembourg
      4. 4.Consortium des Moyens Technologiques CommunsGrenoble-INPSt. Martin d’HèresFrance
      5. 5.AREVA NPParis La DéfenseFrance
      6. 6.EDF R&DMoret-Sur-LoingFrance

      Personalised recommendations