PSI - Issue 37

E. Entezari et al. / Procedia Structural Integrity 37 (2022) 145–152 E.Entezari et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Based on the results, an increase in quenching temperature raised the amount of residual austenite. Increasing the volume fraction of residual austenite can enhance the toughness of the Q-P treated specimens by increasing the ductility at the crack tip, but it may not be the only reason. Avishan et al. (2012) observed that the bainite plate size plays a significant role in enhancing the toughness of nanostructured bainitic steel as compared with the amount of residual austenite. As shown in Table 1, the bainitic plate size decreased by decreasing the quenching temperature; therefore, finer bainitic sheaves with various crystallographic orientations may be a contributing factor to increase further the toughness of the test specimens quenched at 260 °C. 4. Conclusion In summary, the Q-P treatment of low carbon steel can produce a good combination of strength and ductility and increase fracture toughness by decreasing the quenching temperature. It was observed that decreasing quenching temperature from 300 to 260 °C increased the volume fraction of tempered martensite and martensite microblocks and produced finer bainitic plates with various crystallographic orientations. These microstructural characteristics enhance the mechanical properties by hard phases mixture and fine size of the second phases as strengthening mechanisms. Acknowledgments The Sahand University of Technology financially supports the present research. J.L. González-Velázquez acknowledges the financial support of IPN and Conacyt of Mexico. References Schmitt, J.H. and Iung, T., 2018. New developments of advanced high-strength steels for automotive applications. Comptes Rendus Physique, 19(8), pp.641-656. Edmonds, D.V., He, K., Rizzo, F.C., De Cooman, B.C., Matlock, D.K. and Speer, J.G., 2006. Quenching and partitioning martensite-A novel steel heat treatment. Materials Science and Engineering: A, 438, pp.25-34. Tsuchiyama, T., Tobata, J., Tao, T., Nakada, N. and Takaki, S., 2012. Quenching and partitioning treatment of a low-carbon martensitic stainless steel. Materials Science and Engineering: A, 532, pp.585-592. Gouné, M., Danoix, F., Allain, S. and Bouaziz, O., 2013. Unambiguous carbon partitioning from martensite to austenite in Fe-C-Ni alloys during quenching and partitioning. Scripta Materialia, 68(12), pp.1004-1007. Shen, Y.F., Qiu, L.N., Sun, X., Zuo, L., Liaw, P.K. and Raabe, D., 2015. Effects of retained austenite volume fraction, morphology, and carbon content on strength and ductility of nanostructured TRIP-assisted steels. Materials Science and Engineering: A, 636, pp.551-564. Avishan, B., Yazdani, S. and Nedjad, S.H., 2012. Toughness variations in nanostructured bainitic steels. Materials Science and Engineering: A, 548, pp.106-111. Mandal, G., Ghosh, S.K., Bera, S. and Mukherjee, S., 2016. Effect of partial and full austenitisation on microstructure and mechanical properties of quenching and partitioning steel. Materials Science and Engineering: A, 676, pp.56-64. Mousalou, H., Yazdani, S., Avishan, B., Ahmadi, N.P., Chabok, A. and Pei, Y., 2018. Microstructural and mechanical properties of low-carbon ultra-fine bainitic steel produced by multi-step austempering process. Materials Science and Engineering: A, 734, pp.329-337. Entezari, E., Avishan, B., Mousalou, H. and Yazdani, S., 2018. Effect of Electro Slag Remelting (ESR) on the microstructure and mechanical properties of low carbon bainitic steel. Kovove Mater, 56, pp.253-263. S.R.S.B.D. Cullity., 2001. Elements of X-Ray Diffraction, 3rd ed. Prentice Hall, New York. Wang, L. and Speer, J.G., 2013. Quenching and partitioning steel heat treatment. Metallography, Microstructure, and Analysis, 2(4), pp.268-281. Xiong, X.C., Chen, B., Huang, M.X., Wang, J.F. and Wang, L., 2013. The effect of morphology on the stability of retained austenite in a quenched and partitioned steel. Scripta Materialia, 68(5), pp.321-324. Kocatepe, K., Cerah, M. and Erdogan, M., 2006. Effect of martensite volume fraction and its morphology on the tensile properties of ferritic ductile iron with dual matrix structures. Journal of materials processing technology, 178(1-3), pp.44-51. Lee, S., Kang, S.H., Nam, J.H., Lee, S.M., Seol, J.B. and Lee, Y.K., 2019. Effect of tempering on the microstructure and tensile properties of a martensitic medium-Mn lightweight steel. Metallurgical and Materials Transactions A, 50(6), pp.2655-2664. Langford, G. and Cohen, M., 1970. Calculation of cell-size strengthening of wire-drawn iron. Metallurgical and Materials Transactions B, 1(5), pp.1478-1480. González-Velázquez, J.L., 2019. Mechanical behavior and fracture of engineering materials. Springer.