PSI - Issue 13

Elena Astafurova et al. / Procedia Structural Integrity 13 (2018) 1129–1134 Elena Astafurova et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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water-quenched from the two solution-treatment temperatures: 1100ºС and 1200ºС, 1h . The following conclusions are drawn from this work: Independently on quenching temperature (QT), steel possesses two-phase composition – high-nitrogen austenite and Cr-,V-based precipitates. Austenite with high lattice parameter a γ ≈3.61Å is the main phase of the steel. Precipitate composition, fraction and size are QT-dependent characteristics. For QT= 1100ºС , the (Cr,V) 2 (N,C) and (V,Cr)(N,C) phases were evaluated using TEM analysis. Increase in quenching temperature from 1100ºС up to 1200ºС provides a dissolution of Cr 2 N precipitates, partial dissolution of (V,Cr)(N,C) particles and increase a solid-solution hardening of the steel. For both treatment schedules (QT=1100°C and QT=1200°C), there is strong temperature dependence of the strength properties and plasticity of the steel. A yield strength and strain-hardening coefficient are QT-dependent characteristic especially in low-temperature deformation regime (below room temperature). Independently on QT and test temperature, steel specimens fracture in ductile transgranular mode except for 77K deformation temperature. For 77K deformation regime, some cleavage components on fracture surfaces of the specimens were evaluated. Decrease in solid solution hardening and increase of particle strengthening effect (due to decrease in QT) partially suppresses brittle fracture during low-temperature deformation: fraction of cleavage components on fracture surfaced changes from 25% for specimens treated at QT= 1200ºС down to 8% for that treated at QT= 1100ºС . Astafurova, E.G., Chumlyakov, Yu.I., Maier, H.J., 2009. The Effect of Aluminum Alloying on Ductile-To-Brittle Transition in Hadfield Steel Single Crystal. International Journal of Fracture 160(2), 143. Astafurova, E.G., Moskvina, V.A., Maier, G.G., Melnikov, E.V., Galchenko, N.K., Astafurov, S.V., Gordienko, A.I., Burlachenko, A.G., Smirnov, A.I., Bataev, V.A., 2018. The Effect of Test Temperature on Deformation Microstructure and Fracture Mechanisms in CrMn High-Nitrogen Steels Alloyed (0-3 wt.%) with Vanadium. Materials Science Forum (accepted for publication). Chumlyakov, Yu.I., Kireeva, I.V., Sehitoglu, H., Litvinova, E.I., Zaharova, E.G., Luzginova, N.V., 1999. High-Strength Single Crystals of Austenitic Stainless Steels with Nitrogen Content: Mechanisms of Deformation and Fracture. Materials Science Forum 318-320, 395. Gavrilyuk, V.G., Berns, H., 1999. High Nitrogen Steels: Structure, Properties, Manufacture, Applications. Springer, Berlin, pp.378. Hwang, B., Lee, T.-H., Kim, S.-J., 2010. Effect of Deformation-Induced Martensite and Grain Size on Ductile-to-Brittle Transition Behavior of Austenitic 18Cr-10Mn-N Stainless Steel, Metals and Materials International 16(6), 905. Hwang, B., Lee, T.-H., Kim, S.-J., 2012. Ductile-to-Brittle Transition Behavior of High-Interstitial Fe-Cr-Mn alloys, Philosophical Magazine Letters 92(2), 93. Lang, Y., Qu H., Chen H., Weng Y., 2015. Research Progress and Development Tendency of Nitrogen-alloyed Austenitic Stainless Steels. Journal of Iron and Steel Research, International 22(2), 91. Liu, S., Liu, S., Liu, D., 2004. Annealing Twin Boundary Cracking in the Low-Temperature Brittle Fracture of a High-Nitrogen Bearing Austenitic Steel. Journal of Materials Science 39, 2841. Mullner, P., 1997. On the Ductile to Brittle Transition in Austenitic Steel. Materials Science and Engineering A 234-236, 94. Tomota, Y., Nakano, J., Xia, Y., Inoue, K., 1998. Unusual Strain Rate Dependence of Low Temperature Fracture Behavior in High Nitrogen Bearing Austenitic Steels. Acta Materialia 46(9) 3099. Tomota, Y., Xia, Y., Inoue, K., 1998. Mechanism of Low Temperature Brittle Fracture in High Nitrogen Bearing Austenitic Steels. Acta Materialia 46(5), 1577. Santi Srinivas, N.C., Kutumbarao, V.V., 1997. On the Discontinuous Precipitation of Cr 2 N in Cr-Mn-N Austenitic Stainless Steels. Scripta Materialia 37 (3), 285. Wang, W., Yan, W., Yang, K., Shan, Y., Jiang, Z., 2010. Temperature Dependence of Tensile Behaviors of Nitrogen-Alloyed Austenitic Stainless Steels. Journal of Materials Engineering and Performance 19, 1214. Acknowledgements This research was supported by the Russian Science Foundation (project No. 17-19-01197). The studies were conducted using the equipment of Institute of Strength Physics and Materials Science SB RAS (NANOTECH center). References