Journal of Materials Science

, Volume 44, Issue 1, pp 257–265 | Cite as

Effectiveness of Ni-based diffusion barriers in preventing hard zone formation in ferritic steel joints

  • R. Anand
  • C. Sudha
  • T. Karthikeyan
  • A. L. E. Terrance
  • S. SarojaEmail author
  • M. Vijayalakshmi


A numerical procedure based on finite difference method was used to simulate the formation of ‘hard’ and ‘soft’ zones, in dissimilar weldments of 9Cr–1Mo and 2¼Cr–1Mo steels during high temperature exposure. Kinetic analysis of the calculated diffusion profiles showed that the activation energy for carbon diffusion in Cr–Mo steels is marginally higher than that in Fe–C system. Calculations were extended to incorporate the effect of Ni-based interlayers between 2¼Cr–1Mo and 9Cr–1Mo ferritic steels. The presence of a diffusion barrier was found to reduce the propensity for formation of hard and soft zones, which is related to the interaction parameter \( \varepsilon_{\rm C}^{\rm M}. \) Thickness of the interlayer required to suppress the formation of hard zone was optimized by the calculations. Transition joints of ferritic steels with Inconel 182 as the interlayer of thickness close to that predicted by the computations were fabricated and exposed to elevated temperature. Microstructural studies and hardness measurements further confirmed the effectiveness of Ni-based interlayers in preventing hard zone formation.


PWHT Ferritic Steel Diffusion Profile Weld Interface Soft Zone 



The authors thank Dr. Baldev Raj, Director, IGCAR, and Dr. P. R. Vasudeva Rao, Director, Metallurgy and Materials Group, for their support and encouragement for this project. The authors also thank Dr. S. K. Albert and Dr. K. Laha, Scientific Officers, MMG, IGCAR, for their help and useful suggestions.


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • R. Anand
    • 1
  • C. Sudha
    • 1
  • T. Karthikeyan
    • 1
  • A. L. E. Terrance
    • 1
  • S. Saroja
    • 1
    Email author
  • M. Vijayalakshmi
    • 1
  1. 1.Physical Metallurgy DivisionMetallurgy and Materials Group, Indira Gandhi Centre for Atomic ResearchKalpakkamIndia

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