Microstructural study on retained austenite in advanced high-strength multiphase 3Mn-1.5Al and 5Mn-1.5Al steels

• Autorzy: Grajcar A. , Kwaśny W.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The aim of the paper is to describe crystallographic and morphological features of retained austenite in thermomechanically processed bainite-martensite multiphase steels containing 3 and 5% Mn. Design/methodology/approach: Two groups of steels were designed and investigated: 3Mn-1.5Al and 5Mn-1.5Al were reference steels, whereas next two steels were microalloyed with niobium. The steels were thermomechanically processed using the Gleeble simulator. The isothermal holding temperature to enrich austenite in carbon was between 350 and 450°C. Metallographic investigations were carried out using light (LM) and scanning electron microscopy (SEM). The retained austenite amount and its carbon concentration was evaluated by X-ray analysis. Findings: Manganese addition results in the high hardenability of steels leading to bainitic-martensitic microstructures. A high-Al concept and isothermal holding of steel in a bainitic transformation range allow to obtain a high fraction of retained austenite as a result of an incomplete bainitic transformation phenomenon. New complex bainitic morphologies like degenerate upper and lower bainite were identified using SEM. The microstructure and retained austenite characteristics were correlated with the carbon content in y phase. Research limitations/implications: Further investigations (TEM, EBSD) to describe in detail the identified structural constituents and the effect of Nb microalloying on microstructure and mechanical properties are needed. Practical implications: The knowledge of the influence of the isothermal holding temperature on the microstructure and hardness of thermomechanically processed steels are of primary importance for hot rolling of these multiphase high-strength steels. Originality/value: A problem of the stabilization of retained austenite in advanced high-strength multiphase Nb-free and Nb-microalloyed steels with increased Mn content is discussed.

Słowa kluczowe

EN

metallic alloys; TRIP steel; retained austenite; Nb microalloying; thermomechanical processing; X-ray quantitative analysis

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2012
• Tom: Vol. 54, nr 2
• Strony: 168--177
• Opis fizyczny: Bibliogr. 33 poz., rys., tab.

Twórcy

autor

Grajcar A.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

autor

Kwaśny W.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

Bibliografia

• [1] A.K. Lis, B. Gajda, Modelling of the DP and TRIP microstructure in the CMnAlSi automotive steel, Journal of Achievements in Materials and Manufacturing Engineering 15 (2006) 127-134.
• [2] J. Adamczyk, A. Grajcar, Heat treatment and mechanical properties of low-carbon steel with dual-phase microstructure, Journal of Achievements in Materials and Manufacturing Engineering 22/1 (2007) 13-20.
• [3] W. Shi, L. Li, Ch. Yang, R.Y. Fu, L. Wang, P. Wollants, Strain-induced transformation of retained austenite in low-carbon low-silicon TRIP steel containing aluminum and vanadium, Materials Science and Engineering A 429 (2006) 247-251.
• [4] A. Grajcar, Morphological features of retained austenite in thermo-mechanically processed C-Mn-Si-Al-Nb-Ti multiphase steel, Journal of Achievements in Materials and Manufacturing Engineering 39/1 (2010) 7-18.
• [5] D. Krizan, B.C. De Cooman, Analysis of the strain-induced martensitic transformation of retained austenite in cold rolled micro-alloyed TRIP steel, Steel Research International 79/7 (2008) 513-522.
• [6] L.A. Dobrzański, W. Borek, Hot-working of advanced high-manganese austenitic steels, Journal of Achievements in Materials and Manufacturing Engineering 43/2 (2010) 507-526.
• [7] T. Bator, Z. Muskalski, S. Wiewiórkowska, J.W. Pilarczyk, Influence of the heat treatment on the mechanical properties and structure of TWIP steel in wires, Archives of Materials Science and Engineering 28/6 (2007) 337-340.
• [8] L.A. Dobrzański, W. Borek, Hot deformation and recrystallization of advanced high-manganese austenitic TWIP steels, Journal of Achievements in Materials and Manufacturing Engineering 46/1 (2011) 71-78.
• [9] M. Opiela, A. Grajcar, W. Krukiewicz, Corrosion behaviour of Fe-Mn-Si-Al austenitic steel in chloride solution, Journal of Achievements in Materials and Manufacturing Engineering 33/2 (2009) 159-165.
• [10] L.A. Dobrzański, A. Grajcar, W. Borek, Microstructure evolution of high-manganese steel during the thermomechanical processing, Archives of Materials Science and Engineering 37/2 (2009) 69-76.
• [11] A.J. DeArdo, J.E. Garcia, M. Hua, C.I. Garcia, A new frontier in microalloying. Advanced high strength, coated sheet steels, Materials Science Forum 500-501 (2005) 27-38.
• [12] M.J. Merwin, Microstructure and properties of cold rolled and annealed low-carbon manganese TRIP steels, Iron and Steel Technology 5/10 (2008) 66-84.
• [13] S.J. Kim, Effects of manganese content and heat treatment condition on mechanical properties and microstructure of fine-grained low-carbon TRIP-aided steels, Materials Science Forum 638-642 (2010) 3313-3318.
• [14] P.J. Gibbs, E. De Moor, M.J. Merwin, B. Clausen, J.G. Speer, D.K. Matlock, Austenite stability effects on tensile behaviour of manganese-enriched-austenite transformation-induced plasticity steel, Metallurgical and Materials Transactions A 42 (2011) 3691-3702.
• [15] A. Grajcar, E. Kalinowska-Ozgowicz, M. Opiela, B. Grzegorczyk, K. Gołombek, Effects of Mn and Nb on the macro- and microsegregation in high-Mn high-Al content TRIP steels, Archives of Materials Science and Engineering 49/1 (2011) 5-14.
• [16] S. Lee, S.J. Lee, S. Santhosh Kumar, K. Lee, B.C. De Cooman, Localized deformation in multiphase, ultra-fine-grained 6 pct Mn transformation-induced plasticity steel, Metallurgical and Materials Transactions A 42 (2011) 3638-3651.
• [17] A. Grajcar, R. Kuziak, Dynamic recrystallization behaviour and softening kinetics in 3Mn-1.5Al TRIP steels, Advanced Materials Research 287-290 (2011) 330-333.
• [18] G.A. Thomas, J.G. Speer, D.K. Matlock, Quenched and partitioned microstructures produced via Gleeble simulations of hot-strip mill cooling practices, Metallurgical and Materials Transactions A 42 (2011) 3652-3659.
• [19] F.G. Caballero, J. Chao, J. Cornide, C. Garcia-Mateo, M.J. Santofimia, C. Capdevila, Toughness deterioration in advanced high strength bainitic steels, Materials Science and Engineering A 525 (2009) 87-95.
• [20] J. Lis, A.K. Lis, Austenite formation during intercritical annealing, Journal of Achievements in Materials and Manufacturing Engineering 29/1 (2008) 83-90.
• [21] A. Kurc, E. Kalinowska-Ozgowicz, The influence of the martensite a’ phase occurring in the structure of cold rolled austenitic Cr-Ni steel on its mechanical properties, Archives of Materials Science and Engineering 37/1 (2009) 21-28.
• [22] A. Kokosza, J. Pacyna, Mechanical stability of retained austenite in unalloyed structural steels of various carbon content, Archives of Metallurgy and Materials 55/4 (2010) 1001-1006.
• [23] S.J. Pawlak, H.J. Krztoń, Cold worked high alloy ultra highstrength steels with aged martensite structure, Journal of Achievements in Materials and Manufacturing Engineering 36/1 (2009) 18-24.
• [24] I.B. Timokhina, P.D. Hodgson, E.V. Pereloma, Effect of deformation schedule on the microstructure and mechanical properties of a thermomechanically processed C-Mn-Si transformation-induced-plasticity steel, Metallurgical and Materials Transactions A 34 (2003) 1599-1609.
• [25] A. Grajcar, H. Krztoń, Effect of isothermal bainitic transformation temperature on retained austenite fraction in C-Mn-Si-Al-Nb-Ti TRIP-type steel, Journal of Achievements in Materials and Manufacturing Engineering 35/2 (2009) 169-176.
• [26] A. Grajcar, R. Kuziak, Effects of Nb microaddition and thermomechanical treatment conditions on hot deformation behavior and microstructure of Mn-Al TRIP steels, Advanced Science Letters, 2012 (in press).
• [27] B.L. Averbach, M. Cohen, X-Ray determination of retained austenite by integrated intensities, Transactions A.I.M.E. 176 (1948) 401-408.
• [28] Z.C. Wang, S.J. Kim, C.G. Lee, T.H. Lee, Bake-hardening behaviour of cold-rolled CMnSi and CMnSiCu TRIP-aided steel sheets, Journal of Materials Processing Technology 151 (2004) 141-145.
• [29] S. Zajac, V. Schwinn, K.H. Tacke, Characterisation and quantification of complex bainitic microstructures in high and ultra-high strength linepipe steels, Materials Science Forum 500-501 (2005) 387-394.
• [30] H.K.D.H. Bhadeshia, Bainite in steels, The Institute of Materials, The University Press, Cambridge, 1992
• [31] I.B. Timokhina, H. Beladi, X.Y. Xiong, Y. Adachi, P.D. Hodgson, Nanoscale microstructural characterization of a nanobainitic steel, Acta Materialia 59 (2011) 5511-5522.
• [32] K. Sugimoto, N. Usui, M. Kobayashi, S. Hashimoto, Effects of volume fraction and stability of retained austenite on ductility of TRIP-aided dual-phase steels, ISIJ International 32 (1992) 1311-1318.
• [33] M. Takahashi, H.K.D.H. Bhadeshia, A model for the microstructure of some advanced bainitic steels, Materials Transactions of the Japan Institute of Metals 32 (1991) 689-696.