PSI - Issue 71

P.K. Sharma et al. / Procedia Structural Integrity 71 (2025) 126–133

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● The yield strength and ultimate tensile strength for specimen tested at 800 °C and 900 °C in air environment reduces from 180 to 82.5 and 186 to 90 MPa respectively. ● There is continuous decrease in ductility with the increase in exposure duration to molten glass environment. However, the decrease in strength has saturating behavior with increase in exposure time. ● After exposure of 95 hrs under molten glass environment, the ductility gets reduced by 33% and 78% at 800 °C and 900 °C, respectively and the corresponding strength reduced by 8% and 22%. ● There is some effect of stress on the mechanical properties of alloy 690 material exposed to air environment however, the effect of molten glass environment is significantly higher than stress exposure. ● The cause for such a change in mechanical properties is determined using statistical distribution of defect size. The defect size distribution follows a lognormal distribution with changing value of mean defect size and standard deviation under different test conditions. ● Large number of defects were observed due to inter-granular attack by corrosive glass environment along whole periphery of the specimen as opposite to air environment tests where defect were lesser. ● The higher the exposure time, stress level and temperature, more will be depth of attack by the molten glass. Due to the higher defect size, the degradation in mechanical properties will increase subsequently. References ASTM Standard E8-22. Standard Test Methods for Tension Testing of Metallic Materials. Day, D.E., Kim, C.W., 2005. Reaction Of Inconel 690 And 693 In Iron Phosphate Melts: Alternative Glasses For Waste Vitrification. Office of Biological and Environmental Research. U.S. Department of Energy, Project ID: 0010255. Design and Operation of High Level Waste Vitrification and Storage Facilities. Technical Reports Series No. 339, International Atomic Energy Agency Vienna, 1992. Gan, H., Buechele, A.C., Kim, C.W., Huang, X., Mohr, R.K., Pegg., I.L. 1999. Corrosion Of Inconel-690 Electrodes In Waste Glass Melts. Mat. Res. Soc. Symp. Proc., 556 Materials Research Society. Guo, Y., Wang, T., Yang, Z., Wang, S., (2023). Intergranular corrosion and oxidation kinetics in Ni-Cr-Fe alloys exposed to molten salts. Corrosion Science 216, 111110. Halder, R., Sengupta, P., Abraham, G., Kaushik, C.P., Dey, G.K., 2016 Interaction of Alloy 693 with Borosilicate Glass at High Temperature. Materials Today: Proceedings (ARRMA) 3, 3025 – 3034. Kaushik, C.P., Mishra, R.K., Sengupta, P., Kumar, A., Das, D., Kale, G.B., 2006. Barium borosilicate glass - a potential matrix for immobilization of sulfate bearing high-level radioactive liquid waste. Journal of Nuclear Materials 358, 129-138. Kaushik, C.P., 2013. Indian Program for Vitrification of High Level Radioactive Liquid Waste. Procedia Materials Science, 16 – 22. Li, J., Gao, Y., Zhang, J., Chen, Q., (2021). Microstructure evolution and corrosion resistance of Ni-based alloys in molten salt environments. Journal of Alloys and Compound 854, 157216. Olson, L., Sridharan, K., Anderson, M., Allen, T., 2010. Intergranular corrosion of high temperature alloys in molten fluoride salts. Materials At High Temperatures 27, 145 – 149. Samantaroy, P.K., Suresh, G., Paul, R., Mudali, U.K., Raj, B., 2011. Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium. Journal of Nuclear Materials 418, 27 – 37. Sengupta, P., Kaushik, C.P., Kale, G.B., Das, D., Raj, K., Sharma, B.P., 2009. Evaluation of alloy 690 process pot at the contact with borosilicate melt pool during vitrification of high-level nuclear waste, Journal of Nuclear Materials 392, 379 – 385. Sengupta, P., Mittra, J., Kale. G.B., 2006. Interaction between borosilicate melt and Inconel. Journal of Nuclear Materials 350, 66 – 73. Sharma, P.K., Samal, M.K., Syed, A., Chattopadhyay. J., 2024. Evaluation of fracture resistance behavior of Alloy 690 materia l upto 1000˚C. Procedia Structural Integrity 60, 335 – 344. Tan, J., Wu, X., Han, E.H., Ke W., Liu, X., Meng, F., Xu, X., 2014. Corrosion fatigue behavior of Alloy 690 steam generator tube in borated and lithiated high temperature water. Corrosion Science 89, 203 – 213. Xie, H., Zhang, Y., Liu, Y., Wang, L., (2022). Corrosion behavior of Ni – Cr based superalloys in molten glass-forming salts: Role of microstructure and alloying elements. Electrochimica Acta 426, 140801. Zhu, D., Kim, C.W., Day, D.E., 2005. Corrosion behavior of Inconel 690 and 693 in an iron phosphate melt. Journal of Nuclear Materials 336, 47 – 53.