Abstract

In the nuclear power plant industry, Cr-Mo ferritic steels are indispensable due to their high-temperature tensile strength, creep strength, and resistance to stress corrosion cracking. This study evaluated and analyzed the mechanical properties and metallurgical behavior of indigenously developed filler (over matched with base metal) manual metal arc welded Cr-Mo ferritic steel (hereafter referred as P91 steel). The analysis revealed that the ultimate tensile properties of the weld joint exceed those of the unwelded metal, being 6% higher than the base metal. Consequently, the joint efficiency for the weld joint is 106%. However, the impact toughness of the weld pad is significantly lower compared to the unwelded metal, nearly 2.5 times less than the base metal. The weld metal region’s microstructure is characterized by untempered lath martensite pinned with dense dislocations, which is attributed to rapid cooling from the liquidus range. Furthermore, a distinct Heat-Affected Zone (HAZ) was identified adjacent to the weld metal region, which results from the elevated temperature experienced in this area.

Keywords

P91 steel, Manual Metal Arc Welding, Microstructure, Mechanical Properties,

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References

  1. A.K. Bhaduri, S. Venkadesan, P. Rodriguez, P.G. Mukunda, Transition metal joints for steam generators-An overview. International Journal of Pressure Vessels and Piping, 58(3), (1994) 251–265. https://doi.org/10.1016/0308-0161(94)90061-2
  2. A.K. Bhaduri, K. Laha, Development of Improved Materials for Structural Components of Sodium-Cooled Fast Reactors. Procedia Engineering, 130, (2015) 598–608. https://doi.org/10.1016/j.proeng.2015.12.276
  3. J.C. Lippold, (2014) Welding Metallurgy and Weldability, Wiley. https://doi.org/10.1002/9781118960332
  4. M. Sireesha, S.K. Albert, V. Shankar, S. Sundaresan, A comparative evaluation of welding consumables for dissimilar welds between 316LN austenitic stainless steel and Alloy 800. Journal of Nuclear Materials, 279(1), (2000) 65–76. https://doi.org/10.1016/S0022-3115(99)00275-5
  5. E.I. Samuel, B.K. Choudhary, K.B.S. Rao, Influence of post-weld heat treatment on tensile properties of modified 9Cr-1Mo ferritic steel base metal. Materials Science and Technology, 23(8), (2007) 992–999. https://doi.org/10.1179/174328407X161295
  6. R.K. Shiue, K.C. Lan, C. Chen, Toughness and austenite stability of modified 9Cr-1Mo welds after tempering. Materials Science and Engineering A, 28(1), (2000) 10–16. https://doi.org/10.1016/S0921-5093(00)00831-5
  7. K.S. Chandravathi, K. Laha, K.B.S. Rao, S.L. Mannan, Microstructure and tensile properties of modified 9Cr-1Mo steel (grade 91). Materials Science and Technology, 17(5), (2001) 559–565. https://doi.org/10.1179/026708301101510212
  8. B. Adhithan, C. Pandey, Study on effect of grain refinement of P92 steel base plate on mechanical and microstructural features of the welded joint. International Journal of Pressure Vessels and Piping, 192 (2021) 104426. https://doi.org/10.1016/j.ijpvp.2021.104426
  9. S. Kumar, C. Pandey, A. Goyal, A microstructural and mechanical behavior study of heterogeneous P91 welded joint. International Journal of Pressure Vessels and Piping, 185, (2020) 104128. https://doi.org/10.1016/j.ijpvp.2020.104128
  10. C. Pandey, M.M. Mahapatra, P. Kumar, N. Saini, Some studies on P91 steel and their weldments. Journal of Alloys and Compounds, 743, (2018) 332–364. https://doi.org/10.1016/j.jallcom.2018.01.120
  11. S. Sirohi, A. Sauraw, A. Kumar, S. Kumar, T. Rajasekaran, P. Kumar, R.S. Vidyarthy, N. Kumar, C. Pandey, Characterization of Microstructure and Mechanical Properties of Cr-Mo Grade P22/P91 Steel Dissimilar Welds for Supercritical Power Plant Application. Journal of Materials Engineering and Performance, 31, (2022) 7353–7367. https://doi.org/10.1007/s11665-022-06747-y
  12. K. Karthick, S. Malarvizhi, V. Balasubramanian, Evolution of Microstructure at the Interface Region Between Parent Metal (Modified 9Cr–1Mo Steel) and Buttering Layer (Alloy 182) in Dissimilar Joints. Journal of Advanced Microscopy Research, 12(3), (2017) 167–172.
  13. K. Karthick, S. Malarvizhi, V. Balasubramanian, Microstructural characterization of dissimilar weld joint between ferritic steel and stainless steel. Materials Science and Technology, 37(15), (2021) 1–13. https://doi.org/10.1080/02670836.2021.1992949
  14. K. Karthick, S. Malarvizhi, V. Balasubramanian, Mechanical properties and microstructural characteristics of rotary friction welded dissimilar joints of rolled homogeneous armor steel and medium carbon steel. Journal of the Mechanical Behavior of Materials, 30(1), (2021) 171–178. https://doi.org/10.1515/jmbm-2021-0017
  15. K. Karthick, S. Malarvizhi, V. Balasubramanian, A. Gourav Rao, Tensile Properties Variation Across the Dissimilar Metal Weld Joint Between Modified 9Cr–1Mo Ferritic Steel and 316LN Stainless Steel at RT and 550 °C. Metallography, Microstructure, and Analysis, 7, (2018) 209–221. https://doi.org/10.1007/s13632-018-0430-9
  16. K. Karthick, S. Malarvizhi, V. Balasubramanian, S.A. Krishnan, G. Sasikala, S.K. Albert, Microstructural Characteristics and Mechanical Properties of Dissimilar Joints of AISI 316LN Austenitic Stainless Steel and Modified 9cr-1Mo Steel. Indian Welding Journal, 50(4), (2017) 39–46.
  17. K. Karthick, S. Malarvizhi, V. Balasubramanian, S.A. Krishnan, G. Sasikala, S.K. Albert, Tensile properties of shielded metal arc welded dissimilar joints of nuclear grade ferritic steel and austenitic stainless steel. Journal of the Mechanical Behavior of Materials, 25(5-6), (2016) 171–178. https://doi.org/10.1515/jmbm-2017-0005
  18. B. Karthick, L. Shrihari, M. Sakthivel, S. Shriram, V. Silambarasan, Effect of Heat Input on the Microstructure and Mechanical Properties of Gas Tungsten Arc Welded AISI 316 Stainless Steel Joints. International Research Journal on Advanced Science Hub, 2(08), (2020) 23-27.
  19. R. Ashok Kumar, K. Karthick, R. Jayasuriya, J. Aswin Kumar, V. Balaji Karthik, Tribological Behaviour of Aluminum Metal Matrix Composites - A Review. IOP Conference Series: Materials Science and Engineering, 923, (2020) 1–12. https://doi.org/10.1088/1757-899X/923/1/012055
  20. K. Karthick, S. Malarvizhi, V. Balasubramanian, S.A. Krishnan, G. Sasikala, S.K. Albert, Tensile and impact toughness properties of various regions of dissimilar joints of nuclear grade steels. Nuclear Engineering and Technology, 50(1), (2018) 116–125. https://doi.org/10.1016/j.net.2017.10.003
  21. K. Karthick, D. Bharathidhasan, R. Ashok Kumar, F. Mohamed Jaffarsha, M. Sreeraam, K. Surya Prakash, Investigation on Mechanical Properties of Aluminum Metal Matrix Composites - A Review. IOP Conference Series: Materials Science and Engineering, 923, (2020) 012058. https://doi.org/10.1088/1757-899X/923/1/012058
  22. Y. Wang, R. Kannan, L. Li, Correlation between Intercritical Heat-Affected Zone and Type IV Creep Damage Zone in Grade 91 Steel. Metallurgical and Materials Transactions A, 49, (2018) 1264–1275. https://doi.org/10.1007/s11661-018-4490-x
  23. A.K. Bhaduri, K. Laha, V. Ganesan, T. Sakthivel, M. Nandagopal, G.V.P. Reddy, J.G. Kumar, V.D. Vijayanand, S.P. Selvi, G. Srinivasan, C.R. Das, A. Nagesha, S. Ravi, P. Parameswaran, R. Sandhya, S.K. Albert, Advanced materials for structural components of Indian sodium-cooled fast reactors. International Journal of Pressure Vessels and Piping, 139–140 (2016) 123-136. https://doi.org/10.1016/j.ijpvp.2016.02.027
  24. T. Jayakumar, M.D. Mathew, K. Laha, High temperature materials for nuclear fast fission and fusion reactors and advanced fossil power plants. Procedia Engineering, 55, (2013) 259–270. https://doi.org/10.1016/j.proeng.2013.03.252
  25. G. Dak, C. Pandey, A critical review on dissimilar welds joint between martensitic and austenitic steel for power plant application. Journal of Manufacturing Processes, 58, (2020) 377–406. https://doi.org/10.1016/j.jmapro.2020.08.019
  26. C. Pandey, A. Giri, M.M. Mahapatra, Evolution of phases in P91 steel in various heat treatment conditions and their effect on microstructure stability and mechanical properties. Materials Science and Engineering A, 664(10), (2016) 58–74. https://doi.org/10.1016/j.msea.2016.03.132
  27. P. Parameswaran, K. Laha, Role of microstructure on creep rupture behaviour of similar and dissimilar joints of modified 9Cr-1Mo steel. Procedia Engineering, 55, (2013) 438–442. https://doi.org/10.1016/j.proeng.2013.03.277
  28. S. Nagaraju, J. GaneshKumar, P. Vasantharaja, M. Vasudevan, K. Laha, Evaluation of strength property variations across 9Cr-1Mo steel weld joints using automated ball indentation (ABI) technique. Materials Science and Engineering A, 695, (2017) 199–210. https://doi.org/10.1016/j.msea.2017.04.021
  29. D.W. Rathod, S. Pandey, P.K. Singh, S. Kumar, Microstructure-dependent fracture toughness (J IC) variations in dissimilar pipe welds for pressure vessel system of nuclear plants. Journal of Nuclear Materials, 493, (2017) 412–425. https://doi.org/10.1016/j.jnucmat.2017.06.038
  30. F.C. Liu, T.W. Nelson, S.L. McCracken, Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Dissimilar Metal Weld Used in Power Plants. Metallurgical and Materials Transactions A, 50, (2019) 2826–2834. https://doi.org/10.1007/s11661-019-05223-y