Microstructure and Mechanical Properties of 9Cr-1Mo Steel Weld Fusion Zones as a Function of Weld Metal Composition

  • B. Arivazhagan
  • Ranganath Prabhu
  • S. K. Albert
  • M. KamarajEmail author
  • S. Sundaresan


Modified 9Cr-1Mo steel, designated as P91, is widely used in the construction of power plants and other sectors involving temperatures higher than 500 °C. Although the creep strength is the prime consideration for elevated temperature applications, notch toughness is also important, especially for welded components, as it is essential to meet the pressure test and other requirements at room temperature. P91 steel weld fusion zone toughness depends on factors such as welding process, chemical composition, and flux composition. Niobium and vanadium are the main alloying elements that significantly influence the toughness as well as creep strength. In the current work, weld metals were produced with varying amounts of niobium and vanadium by dissimilar joints involving P9 and P91 base metals as well as filler materials. Microstructural studies and Charpy V-notch impact testing were carried out on welds to understand the factors influencing toughness. Based on the results, it can be concluded that by reducing vanadium and niobium weld metal toughness can be improved.


9Cr-1Mo steel chemical composition hardness microstructure toughness weld metal 


  1. 1.
    A. Barnes, “The Influence of Composition on Microstructural Development and Toughness of Modified 9%Cr-1%Mo Weld Metals,” Report 509/1995, TWI, Abington, UK, 1995Google Scholar
  2. 2.
    R.W. Vanstone, Advanced (“700°C”) PF Power Plant, Proceedings of the 3rd Conference on Advances in Materials Technology for Fossil Power Plants, The Institute of Materials, London, 2001, p 7–14Google Scholar
  3. 3.
    S. Dittrich, V. Gross, and H. Heuser, Optimized and Advanced P (T) 91 Filler Metals, Proceedings of National Welding Seminar, India, 1994, p 4R2/1–4R2/4Google Scholar
  4. 4.
    T. Onizawa, T. Wakai, M. Ando, and K. Aoto, Effect of V and Nb Contents on Mechanical Properties of High Cr Steel, ECCC Creep Conference, London, 2005, p 130–142Google Scholar
  5. 5.
    F. Abe and S. Nakazawa (1992) The Effect of Tungsten on Creep, Metall. Trans. A, 23, 3025–3033CrossRefGoogle Scholar
  6. 6.
    M Sireesha, S K Albert, S Sundaresan (2001) Microstructure and Mechanical Properties of Weld Fusion Zones in Modified 9Cr-1Mo Steel. J. Mater. Eng. Perform., 10(3), 320–330CrossRefGoogle Scholar

Copyright information

© ASM International 2009

Authors and Affiliations

  • B. Arivazhagan
    • 1
  • Ranganath Prabhu
    • 1
  • S. K. Albert
    • 2
  • M. Kamaraj
    • 1
    Email author
  • S. Sundaresan
    • 1
  1. 1.Indian Institute of Technology MadrasChennaiIndia
  2. 2.Indira Gandhi Centre for Atomic ResearchKalpakkamIndia

Personalised recommendations