PSI - Issue 71

K.M.K. Chowdary et al. / Procedia Structural Integrity 71 (2025) 188–195

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● The creep deformation of IN-RAFM steel is characterized by longer tertiary stage creep with marginal steady state creep regime at 260-240 MPa. Whereas the longer secondary and tertiary creep regimes are observed at 220-200 MPa with limited primary creep stage. ● The Sin-Hyperbolic model successfully predicted the sigmoidal bend in creep curves at primary to secondary transition and secondary to tertiary transition at most of the stress levels. ● The time to reach Monkman-Grant Ductility t MGD and its relationship with rupture life showed dependence on damage tolerance factor. ● The isotropic creep damage formulation in the Novel Sinh model is found to mitigate rapid damage accumulation from the early stages of creep deformation, with damage values reaching to unity or finite value at the rupture. ● Creep strain of the IN-RAFM steel in tertiary regime was predicted accurately by using the coupled FE-CDM analysis based on the damage mechanics equation and Novel Sinh strain rate model. A. Cauvin, R.B. Testa, 1999. Damage mechanics: basic variables in continuum theories. Int J Solids Struct 747–761. Chowdary, K.M.K., Peshwe, D.R., Ballal, A.R., Prasad Reddy, G. V., Vanaja, J., 2024. Comparative assessment of a continuum damage mechanics based creep damage models for India-specific RAFM steel. Materials at High Temperatures 41, 519–530. Haque, M.S., Stewart, C.M., 2019. Comparative analysis of the sin-hyperbolic and Kachanov–Rabotnov creep-damage models. International Journal of Pressure Vessels and Piping 171, 1–9. L. M. Kachanov, 1967. The theory of creep (ed. A. J. Kennedy). National Lending Library, Boston Spa. Laha, K., Saroja, S., Moitra, A., Sandhya, R., Mathew, M.D., Jayakumar, T., Rajendra Kumar, E., 2013. Development of India-specific RAFM steel through optimization of tungsten and tantalum contents for better combination of impact, tensile, low cycle fatigue and creep properties. Journal of Nuclear Materials 439, 41–50. Rabotnov YN, 1969. English Translation. Leckie FA, editor. Creep problems of structural members. Amsterdam: North Holand. Stewart, C., 2013. STARS Electronic Theses and Dissertations 2013 A Hybrid Constitutive Model for Creep, Fatigue, And Creep-fatigue A Hybrid Constitutive Model for Creep, Fatigue, And Creep-fatigue Damage STARS Citation STARS Citation. Vanaja, J., Laha, K., Mythili, R., Chandravathi, K.S., Saroja, S., Mathew, M.D., 2012. Creep deformation and rupture behaviour of 9Cr-1W-0.2V 0.06Ta Reduced Activation Ferritic-Martensitic steel. Materials Science and Engineering: A 533, 17–25. Wen, J.F., Tu, S.T., Gao, X.L., Reddy, J.N., 2014. New model for creep damage analysis and its application to creep crack growth simulations. In: Materials Science and Technology (United Kingdom). pp. 32–37. Y.Liu, S.Murakami, 1998. Damage localization of conventional creep damage models and proposition of a new model for creep damage analysis. JSME Int. J. Ser. A 41, 57–65. Zhao, Y., Xu, X., Liu, Y.L., Yang, K., Liu, S., 2023. The long-term creep behavior and damage mechanism of RAFM steel for fusion reactors. Fusion Engineering and Design 194. References: