Evaluating the microstructure and mechanical properties of dissimilar welding between austenitic stainless steel A240-TP. 316 and ferritic low alloy steel A387-Gr. 11

مهندسی متالورژی و مواد

Article 3, Volume 27, Issue 1, March 2016, Pages 23-38   

Document Type: Original Articles

DOI: 10.22067/ma.v27i1.23535

Authors

Seyed Hossein Mirkarimi^* ; khalil ranjbar; mohsen Roshani; Reza Dehmollaei

Shahid Chamran University of Ahwaz

Abstract

Dissimilar joint of low-alloy ferritic steel and austenitic stainless steel has been widely used in industries. In this study, the austenitic stainless steel A240-TP.316 and low-alloy ferritic steel A387-Gr.11 were welded together by gas tungsten arc welding (GTAW) method with constant and pulsed currents. Two types of filler metals, i.e. ER309L and ERNiCr-3, were used in this investigation. The microstructure of the dissimilar weldment was characterized by conventional metallography using optical and scanning electron microscopes and by energy disperse spectroscopy (EDS). The mechanical properties of test samples were evaluated by tension, charpy impact and microhardness experiments. It was found that the samples welded by pulsed current exhibit relatively higher impact energies mainly due to their lower heat input induction and creation of intense mixing in the welding pool. Consequently, the formation of undesirable microstructural features such as carbon depleted zone, transmission region and unmixed zones were reduced in the pulsed current welded specimens. Among all the filler metals used, the nickel based filler metal was found to be suitable since in this case, the migration of carbon into the welding pool was limited and therefore, the risk of transition region formation as compared with other filler metals decreased.

Keywords

Dissimilar joint; Austenitic stainless steel; Ferritic low alloy steel; GTAW; Pulse current; Microstructure of weldment

References

1. Bhaduri, A., et al., "Transition metal joints for steam generators-an overview", International Journal of Pressure Vessels and Piping, Vol. 58(3), PP. 251-265, (1994).
2. Lundin, C., "Dissimilar metal welds-transition joints literature review", Welding Journal, Vol. 61(2), PP. 58-63, (1982).
3. Wang, S., Q. Ma, and Y. Li, "Characterization of microstructure, mechanical properties and corrosion resistance of dissimilar welded joint between 2205 duplex stainless steel and 16MnR", Materials & Design, Vol. 32(2), PP. 831-837, (2011).
4. DuPont, J.N. and R.E. Mizia, "Review of Dissimilar Metal Welding for the NGNP Helical-Coil Steam Generator", Idaho National Laboratory (INL), PP. 1-20, (2010).
5. Wu, Y. and B. Patchett, "Formation of crack-susceptible structures of weld overlay of corrosion resistant alloys", Materials Performance: Sulphur and Energy, PP. 283-295, (1992).
6. Nelson, T., J. Lippold, and M. Mills, "Nature and Evolution of the Fusion Boundary in Ferritic-Austenitic Dissimilar Metal Welds—Part 2: On-Cooling Transformations", Welding Journal, Vol. 79, PP. 267-277, (2000).
7. Yoo, C.Y., S.C. Han, and D.Y. Yoon, "The grain boundary migration in Ag induced by thermal strain", Metallurgical and Materials Transactions A, Vol. 26(11), PP. 3048-3049, (1995).
8. Barnhouse, E. and J. Lippold, "Microstructure/property relationships in dissimilar welds between duplex stainless steels and carbon steels", Welding Journal, Vol. 77, PP. 477, (1998).
9. Pan, C. and Z. Zhang, "Morphologies of the transition region in dissimilar austenitic-ferritic welds", Materials Characterization, Vol. 36(1), PP. 5-10, (1996).
10. Srinivasan, P.B., et al., "Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel", Journal of Materials Engineering and Performance, Vol. 15(6), PP. 758-764, (2006).
11. Naffakh, H., M. Shamanian, and F. Ashrafizadeh, "Interface and Heat-affected Zone Features of Dissimilar Welds between AISI 310 Austenitic Stainless Steel and Inconel 657", International Journal of Iron and Steel Society of Iran, Vol.5, PP. 22-30, (2008).
12. Wang, S.H., et al., "Gamma (γ) phase transformation in pulsed GTAW weld metal of duplex stainless steel", Materials Science and Engineering: A, Vol. 420(1), PP. 26-33, (2006).
13. "Welding Handbook", Vol. 1., 8th ed., PP. 33-35, American Welding Society, (1987).
14. American Society of Mechanical Engineers, "Process Piping, B31.3", PP. 74-76, (2010).
15. American Society for Testing and Materials,"Standard Test Methods and Definitions for Mechanical Testing of Steel Products", A370, p. 5 & 19, (2003).
16. American Welding Society, "Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal", A4.2, (1991).
17. Lippold, J.C. and D.J. Kotecki, "Welding metallurgy and weldability of stainless steels", 3rd ed., PP. 141-212, John Wiley and Sons, (2005).
18. Kou, S., "Welding metallurgy", 2nd ed., PP. 398-403, John Wiley and Sons, (2003).
19. Parker, J. and G. Stratford, "Characterisation of microstructures in nickel based transition joints", Journal of materials science, Vol. 35, PP. 4099-4107, (2000).
20. Maruyama, T., "Arc Welding Technology for Dissimilar Joints", Journal of the Japan Welding Society (Japan), Vol. 71(6), PP. 25-29, (2002).
21. Pan, C. and Z. Zhang, "Morphologies of the transition region in dissimilar austenitic-ferritic welds", Materials Characterization, Vol. 36(1), PP. 5-10, (1996).
22. Baeslack, W.A.I., Lippold, J. C., and Savage, "Unmixed zone formation in austenitic stainless steel weldments", Welding Journal, Vol. 58, PP. 168-176, (1979).
23. Sireesha, M., et al., "A comparative evaluation of welding consumables for dissimilar welds between 316LN austenitic stainless steel and Alloy 800", Journal of Nuclear Materials, Vol. 279(1), PP. 65-76, (2000).
24. Sireesha, M., et al., "Microstructural features of dissimilar welds between 316LN austenitic stainless steel and alloy 800", Materials Science and Engineering: A, Vol. 292(1), PP. 74-82, (2000).
25. American Society of Mechanical Engineers, "Materials-Sec. II-Prat A, PP. 734, (2004).