Tensile Properties Variation Across the Dissimilar Metal Weld Joint Between Modified 9Cr–1Mo Ferritic Steel and 316LN Stainless Steel at RT and 550 °C
In liquid metal cooled fast breeder reactors (LMFBR), modified 9Cr–1Mo ferritic steel (P91 or Grade 91) is a preferred material for constructing steam generators due to its creep strength and stress corrosion cracking resistance. The austenitic stainless steels (SS 316LN and SS 304LN) are widely used for primary and secondary piping systems because of its oxidation resistance and excellent creep strength. So, the dissimilar metal weld joint (DMWJ) between P91 and SS 316LN is inevitable. Nickel-based consumables (Alloy 82 and Alloy 182) are preferred to join these materials. The DMWJ will experience the temperature up to 550 °C. For accurate integrity assessment, the mechanical properties of individual regions are to be evaluated at room temperature (RT) and 550 °C. Hence, the present investigation is focused on evaluating the mechanical properties of various regions of DMWJ at RT and 550 °C. From this investigation, it is understood that the tensile properties are heterogeneous across the DMWJ at RT and 550 °C. The high-temperature (550 °C) tensile properties are significantly lower with respect to the RT properties. The development of complex microstructures at the interfaces will alter the mechanical properties across the DMWJ.
KeywordsP91-ferritic steel SS 316LN stainless steel Dissimilar metal weld joint Tensile properties Microstructures Microhardness
The authors are grateful to UGC-DAE CSR (Kalpakkam node) for providing financial assistance (Project No. CSR-KN/CRS-56/2013-14/655) to carry out this investigation. Authors wish to record their sincere thanks to M/s. Mailam India Pvt. Limited, Pondicherry, for the consumables supply. Authors are also thankful to The Director, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, for providing base metals for carrying out this investigation. Authors are thankful to Director, Naval Materials Research Laboratory (NMRL), Ambernath, for providing hot tensile test facility. The technical supports rendered by Mr. S. A. Krishnan, Scientist-E and Dr. G. Sasikala, Scientist-H+ from IGCAR, Kalpakkam, are gratefully acknowledged.
- 6.T. Sarikka, M. Ahonen, R. Mouginot, P. Nevasmaa, P. Karjalainen-Roikonen, U. Ehrnstén, H. Hänninen, Microstructural, mechanical, and fracture mechanical characterization of SA 508-alloy 182 dissimilar metal weld in view of mismatch state. Int. J. Press. Vessel. Pip. 145, 13–22 (2016). https://doi.org/10.1016/j.ijpvp.2016.06.004 CrossRefGoogle Scholar
- 7.S. Kumar, P.K. Singh, K.N. Karn, V. Bhasin, Experimental investigation of local tensile and fracture resistance behaviour of dissimilar metal weld joint: SA508 Gr.3 Cl.1 and SA312 type 304LN. Fatigue Fract. Eng. Mater. Struct. 40, 190–206 (2017). https://doi.org/10.1111/ffe.12484 CrossRefGoogle Scholar
- 12.M. Sireesha, S.K. Albert, S. Sundaresan, Influence of high-temperature exposure on the microstructure and mechanical properties of dissimilar metal welds between modified 9Cr–1Mo steel and alloy 800. Metall. Mater. Trans. A 36, 10–12 (2005). https://doi.org/10.1007/s11661-005-0241-x CrossRefGoogle Scholar
- 18.T. Böllinghaus, H. Herold, Hot Cracking Phenomena in Welds (Springer, 2005), https://books.google.co.in/books?id=OveDQzH5fPwC
- 19.J.N. DuPont, S.W. Banovic, A.R. Marder, Microstructural evolution and weldability of dissimilar welds between a super austenitic stainless steel and nickel-based alloys. Weld. J. 82(6), 125–135 (2003)Google Scholar
- 26.S. Kou, Welding Metallurgy, (Wiley, 2003), https://books.google.co.in/books?id=FQSEfRigyNUC
- 29.C.F. Etienne, D.V. Rossum, F. Roode, in Proceedings of the International Conference on Engineering Aspects of Creep, University of Sheffield, vol. 2 (1980), pp. 113–121Google Scholar
- 33.K. Laha, K.S. Chandravathi, P. Parameswaran, K.B.S. Rao, S.L. Mannan, Characterization of microstructures across the heat-affected zone of the modified 9Cr–1Mo weld joint to understand its role in promoting type IV Cracking. Metall. Mater. Trans. A Phys. Metall. Mater. Sci. 38(1), 58–68 (2007)CrossRefGoogle Scholar
- 34.G.E. Dieter, D. Bacon, Mechanical Metallurgy, (McGraw-Hill, 1988), https://books.google.co.in/books?id=hlabmB3e8XwC