Metallography, Microstructure, and Analysis

, Volume 8, Issue 1, pp 23–31 | Cite as

Effect of Applied Energy on the Microstructure, Texture, and Mechanical Properties of Short-Circuit Metal Inert Gas-Welded Modified Cr-Mo Steel Joints

  • S. MadhavanEmail author
  • M. Kamaraj
  • B. Arivazhagan
Technical Article


Modified 9Cr-1Mo is a ferritic-martensitic steel widely used in steam generators of fast breeder reactors in the nuclear industry due to their enhanced creep resistance. In the present investigation, P91 steel was welded without preheat using three different heat inputs by pulsed short-circuit metal inert gas welding process using a ER90S-B9 wire electrode for the first time. The microstructural developments were characterized by using optical and electron microscopy, while the residual stresses were measured by X-ray diffraction using the sin2ψ method. The grain size variation in the fusion zone/heat-affected zone was effectively studied using electron backscattered diffraction to bring out the changes quantitatively. The weld zone had a consistent texture, while the heat-affected zone was random. The grain size tends to increase with the increase in heat input which leads to reduced joint strength. It is evident that at highest heat input, the weld microstructure shows substantial precipitation of M23C6-type carbides. The residual stresses were near compressive in the weld-HAZ, while maximum tensile stresses were found for the highest heat input.


9Cr-1Mo steel Microstructure Texture Joint strength Residual stress 


  1. 1.
    J. Xue, C. Zhou, J. Peng, Creep stress analyses affected by defect geometries on P91 pipe with local wall thinning under high temperature. In: 18th International Conference on Nuclear Engineering, vol. 5. ASME Proceedings; 2010, pp. 523–528Google Scholar
  2. 2.
    J. Blach, L. Falat, P. Ševc, Fracture characteristics of thermally exposed 9Cr-1Mo steel after tensile and impact testing at room temperature. Eng. Fail. Anal. 16, 1397–1403 (2009)CrossRefGoogle Scholar
  3. 3.
    J.A. Francis, G.M.D. Cantin, W. Mazur et al., Effects of weld preheat temperature and heat input on type IV failure. Sci. Technol. Weld. Join. 14(5), 436–442 (2009)CrossRefGoogle Scholar
  4. 4.
    K.K. Coleman, W.F. Newell, P91 and beyond. Weld. J. 86, 29–33 (2007)Google Scholar
  5. 5.
    S.S.M. Tavares, J.M. Pardal, G.C. Souza et al., Study of cracks in the weld metal joint of P91 steel of a super heater steam pipe. Eng. Fail. Anal. 56, 464–473 (2015)CrossRefGoogle Scholar
  6. 6.
    M. Kondo, M. Tabuchi, S. Tsukamoto et al., Suppressing type IV failure via modification of heat affected zone microstructures using high boron content in 9Cr heat resistant steel welded joints. Sci. Technol. Weld. Join. 11, 216–223 (2006)CrossRefGoogle Scholar
  7. 7.
    B. Arivazhagan, M. Vasudevan, A comparative study on the effect of GTAW processes on the microstructure and mechanical properties of P91 steel weld joints. J. Manuf. Process. 16, 305–311 (2014)CrossRefGoogle Scholar
  8. 8.
    B. Shanmugarajan, G. Padmanabham, H. Kumar et al., Autogenous laser welding investigations on modified 9Cr-1Mo (P91) steel. Sci. Technol. Weld. Join. 16, 528–534 (2011)CrossRefGoogle Scholar
  9. 9.
    W.F. Newell, Guidelines for Welding P91 (W.F. Newell & Associates, Mooresville, 1991)Google Scholar
  10. 10.
    A. Kundu, P.J. Bouchard, S. Kumar et al., Residual stresses in P91 steel electron beam welds. Sci. Technol. Weld. Join. 18, 70–75 (2013)CrossRefGoogle Scholar
  11. 11.
    J.A. Francis, W. Mazur, H.K.D.H. Bhadeshia, Type IV cracking in ferritic power plant steels. Sci. Technol. Weld. Join. 22, 1387–1395 (2006)Google Scholar
  12. 12.
    P.K. Ghosh, S.R. Gupta, A.K. Pramanick, Effect of pulse current on shrinkage stress and distortion in multipass GMA welds of different groove sizes. Weld. J. 89, 43–53 (2010)Google Scholar
  13. 13.
    P.K. Ghosh, K. Devakumaran, H.S. Randhawa, Characteristics of a pulsed-current, vertical-up gas metal arc weld in steels. Metall. Mater. Trans. A 31A, 2247–2259 (2000)CrossRefGoogle Scholar
  14. 14.
    S. Krishnan, D.V. Kulkarni, A. De, Probing pulsed current gas metal arc welding for modified 9Cr-1Mo steel. J. Mater. Eng. Perform. 24, 1462–1470 (2014)CrossRefGoogle Scholar
  15. 15.
    K. Devakumaran, P.K. Ghosh, Thermal characteristics of weld and HAZ during pulse current gas metal arc weld bead deposition on HSLA Steel Plate. Mater. Manuf. Process. 25, 616–630 (2010)CrossRefGoogle Scholar
  16. 16.
    P. Kamal, K.P. Surjya, Effect of pulse parameters on weld quality in pulsed gas metal arc welding: a review. J. Mater. Eng. Perform. 20, 918–931 (2011)CrossRefGoogle Scholar
  17. 17.
    K. Sawada, H. Kushima, M. Tabuchi, K. Kimura, Microstructural degradation of Gr.91 steel during creep under low stress. Mater. Charact. 101, 106–113 (2015)CrossRefGoogle Scholar
  18. 18.
    M. Yoshino, Y. Mishima, Y. Toda, H. Kushima, K. Sawada, K. Kimura, Phase equilibrium between austenite and MX carbonitride in a 9Cr-1Mo-V-Nb steel. ISIJ 45, 107–115 (2005)CrossRefGoogle Scholar
  19. 19.
    B. Arivazhagan, G. Srinivasan, S.K. Albert et al., A study on influence of heat input variation on microstructure of reduced activation ferritic martenistic steel weld metal produced by GTAW process. Fusion Eng. Des. 86, 192–197 (2011)CrossRefGoogle Scholar
  20. 20.
    J.E. Burke, The formation of annealing twins. J. Mater. 2, 1324–1328 (1950)Google Scholar
  21. 21.
    ASM International, Metals Handbook, Volume 12: Fractography (ASM International, 1987), pp. 18–20Google Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature and ASM International 2018

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringSRM Institute of Science and TechnologyKattankulathur, ChennaiIndia
  2. 2.Department of Metallurgical and Materials EngineeringIndian Institute of Technology MadrasChennaiIndia
  3. 3.Materials Development and Technology DivisionIndira Gandhi Centre for Atomic ResearchKalpakkamIndia

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