PSI - Issue 42

Numan Berat Yondu et al. / Procedia Structural Integrity 42 (2022) 1567–1575 Author name / StructuralIntegrity Procedia 00 (2019) 000 – 000

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4. Conclusion In this work load controlled rotating bending fatigue tests are performed under 2 different temperatures and dwell conditions. Additional to that hardness of Vickers measurements, nanoindentation, SEM monitoring, and optical microscopy visualizations are performed. As a result of these works following conclusions can be reached;  Inconel718 pure bending fatigue life is highly affected by temperature, increasing in temperature decreases the fatigue life.  Inconel718 material shows softening under cyclic loadings through the fracture surface. Softening can be affected by temperature.  Dwell application has no decreasing effect to Inconel718 fatigue behavior under bending at 450 o C.  At 450 o C dwell application on Inconel718 material is stress-dependent, dwell sensitivity is observed at lower stress levels.  At room temperature, dwell application at lower stresses showed a reduction in life.  With dwell application fracture characteristics are observed to change from transgranular to mixed feature.  Dwell sensitive stress regions are not favorable for recovery and recrystallization since there is no increase in toughness is observed. In the light of these works, it can be said that unexpectedly the detrimental effects of an increase in temperature and dwell loading have not been observed. Plasticity-induced crack closure is most likely to explain this increase in life. Acknowledgements The present investigation is conducted as a part of thesis program in Istanbul Technical University Material Engineering Masters program under supervision of Prof. Murat Baydoğan. Th e authors would like to thank TUSAS Engine Industry for supplying the material and specimen machining. References M. J. Donachie and S. J. Donachie, “SUPERALLOYS A Technical Guide Second Edition Superalloys: A Technical Guide (#06128G) www.asminternational.org,” 2002. doi: 10.1361/stgs2002p011. G. W. Meetham, “Trace elements in superalloys – an overview,” Metals Technology, vol. 11, no. 1, pp. 414 – 418, Jan. 1984, doi: 10.1179/030716984803275188. “Aerospace materials: past, present and future,” in Introduction to Aerospace Materials, Elsevier, 2012, pp. 15 – 38. doi: 10.1533/9780857095152.15. W. Betteridge and S. W. K. Shaw, “Development of superalloys,” vol. 3, p. 13, 1987. R. E. Smallman and R. J. Bishop, Modern physical metallurgy and materials engineering: science, process, applications, 6th ed. Oxford ; Boston: Butterworth Heinemann, 1999. A. J. Goodfellow, “Strengthening mechanisms in polycrystalline nickel - based superalloys,” Materials Science and Technology, vol. 34, no. 15, pp. 1793 – 1808, Oct. 2018, doi: 10.1080/02670836.2018.1461594. D. K. Ganji and G. Rajyalakshmi, “Influence of Alloying Compositions on the Properties of Nickel - Based Superalloys: A Review,” in Recent Advances in Mechanical Engineering, H. Kumar and P. K. Jain, Eds. Singapore: Springer Singapore, 2020, pp. 537 – 555. doi: 10.1007/978 981-15-1071-7_44. M. Jambor, O. Bokůvka, F. Nový, L. Trško, and J. Belan, “Phase Transformations in Nickel base Superalloy Inconel 718 during C yclic Loading at High Temperature,” Production E ngineering Archives, vol. 15, no. 15, pp. 15 – 18, Jun. 2017, doi: 10.30657/pea.2017.15.04. S. Patel, J. deBarbadillo, and S. Coryell, “Superalloy 718: Evolution of the Alloy from High to Low Temperature Application,” in Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications, E. Ott, X. Liu, J. Andersson, Z. Bi, K. Bockenstedt, I. Dempster, J. Groh, K. Heck, P. Jablonski, M. Kaplan, D. Nagahama, and C. Sudbrack, Eds. Cham: Springer International Publishing, 2018, pp. 23 – 49. doi: 10.1007/978-3-319-89480-5_2. Inconel alloy 718 special metals corporation. (n.d.). https://www.specialmetals.com/documents/technicalbulletins/inconel/inconelalloy718.pdf

T. Nicholas, High cycle fatigue: a mechanics of materials perspective. Oxford: Elsevier, 2006. A. A. Azeez, “MECHANICAL ENGINEERING AND PRODUCTION TECHNOLOGY,” p. 32.