Skip to main content Accessibility help

The influence of fine ferrite formation on the γ/α interface, fine bainite and retained austenite in a thermomechanically-processed transformation induced plasticity steel

  • Ilana B. Timokhina (a1), Michael K. Miller (a2), Hossein Beladi (a3) and Peter D. Hodgson (a3)


An Fe–0.26C–1.96Si–2Mn with 0.31Mo (wt%) steel was subjected to a novel thermomechanical processing route to produce fine ferrite with different volume fractions, bainite, and retained austenite. Two types of fine ferrites were found to be: (i) formed along prior austenite grain boundaries, and (ii) formed intragranularly in the interior of austenite grains. An increase in the volume fraction of fine ferrite led to the preferential formation of blocky retained austenite with low stability, and to a decrease in the volume fraction of bainite with stable layers of retained austenite. The difference in the morphology of the bainitic ferrite and the retained austenite after different isothermal ferrite times was found to be responsible for the deterioration of the mechanical properties. The segregation of Mn, Mo, and C at distances of 2–2.5 nm from the ferrite and retained austenite/martensite interface on the retained austenite/martensite site was observed after 2700 s of isothermal hold. It was suggested that the segregation occurred during the austenite-to-ferrite transformation, and that this would decrease the interface mobility, which affects the austenite-to-ferrite transformation and ferrite grain size.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All
1.Hodgson, P.D.: The evolution of ferrite grain size in structural steels. Mater. Forum 23, 105 (1999).
2.Beladi, H., Kelly, G.L., and Hodgson, P.D.: Ultrafine grained structure formation in steels using dynamic strain induced transformation processing. Int. Mater. Rev. 52, 14 (2007).
3.Bhadeshia, H.K.D.H.: Large chunks of very strong steel. Mater. Sci. Technol. 21, 1293 (2005).
4.Caballero, F.G. and Bhadeshia, H.K.D.H.: Very strong bainite. Curr. Opin. Solid State Mater. Sci. 8, 251 (2004).
5.Timokhina, I.B., Beladi, H., Xiong, X., Adachi, Y., and Hodgson, P.D.: Nanoscale microstructural characterization of a nanobainitic steel. Acta Mater. 59, 5511 (2011).
6.Zackay, V.F., Parker, E.R., Fahr, D., and Bush, R.: The enhancement of ductility in high strength steels. Trans. ASM 60, 252 (1967).
7.Speich, G.R., Demarest, V.A., and Miller, R.L.: Formation of austenite during intercritical annealing of DP steel. Metall. Mater. Trans. 12, 1419 (1981).
8.Gerberich, W.W., Hemmings, P.L., Merz, M.D., and Zackay, V.F.: Preliminary toughness results on TRIP steels. Trans. ASM 61, 843 (1968).
9.Ludwigson, D.C. and Berger, J.A.: Plastic behaviour metastable austenitic stainless steels. J. Iron Steel Inst. 207, 63 (1969).
10.Antolovich, S.D.: Fracture toughness and strain-induced phase transformation. Metall. Soc. AIME Trans. 242, 2371 (1968).
11.Antolovich, S.D. and Singh, S.: On the toughness increment associated with the austenite to martensite phase transformation. Metall. Mater. Trans. 2, 2135 (1971).
12.Tamura, I.: Deformation-induced martensitic transformation and transformation-induced plasticity in steels. Metal Sci. 16, 245 (1982).
13.Bhandarkar, V.F., Zackay, V.F., and Parker, E.R.: Stability and mechanical properties of some metastable austenitic steels. Metall. Mater. Trans. 3, 2619 (1972).
14.Lecroisey, F. and Pineau, A.: Martensitic transformations induced by plastic deformation in the Fe–Ni–Cr–C system. Metall. Mater. Trans. 3, 387 (1972).
15.Olson, B.G. and Cohen, M.: Kinetics of strain-induced martensitic nucleation. Metall. Mater. Trans. 6, 791 (1975).
16.Olson, B.G. and Cohen, M.: Stressed-assisted isothermal martensitic transformation: Application to TRIP steels. Metall. Mater. Trans. 13, 1907 (1982).
17.Krauss, G.: Deformation and fracture in martensitic carbon steels tempered at low temperature. Metall. Mater. Trans. 32, 205 (2001).
18.Toji, Y., Matsuda, H., Herbig, M., Choi, P.P., and Raabe, D.: Atomic-scale analysis of carbon partitioning between martensite and austenite by atom probe tomography and correlative transmission electron microscopy. Acta Mater. 65, 215 (2014).
19.Wang, M.M., Tasan, C.C., Ponge, D., Dippel, A.C., and Raabe, D.: Nonalaminate transformation-induced plasticity-twinning induced plasticity steel with dynamic strain partitioning and enhanced damage resistance. Acta Mater. 85, 216 (2015).
20.Zhu, K., Chen, H., Masse, J.P., Bouaziz, O., and Gachet, G.: The effect of prior ferrite formation on bainite and martensite transformation kinetics in advanced high-strength steels. Acta Mater. 61, 6025 (2013).
21.Waterschoot, T., De, A.K., Vandeputte, S., and De Cooman, B.C.: Static strain aging phenomena in cold-rolled dual-phase steels. Metall. Mater. Trans. 34, 781 (2003).
22.Timokhina, I.B., Hodgson, P.D., and Pereloma, E.V.: Transmission electron microscopy characterization of the bake-hardening behaviour of the transformation induced plasticity and dual phase steels. Metall. Mater. Trans. 38, 2442 (2007).
23.Akben, M.G., Bacroix, B., and Jonas, J.J.: Effect of vanadium and molybdenum addition on high temperature recovery, recrystallisation and precipitation behaviour of niobium-based microalloyed steels. Acta Metall. 31, 161 (1983).
24.Wada, T., Wada, H., Elliot, J.F., and Chipman, J.: Activity of carbon and solubility of carbides in the FCC Fe–Mo–C, Fe–Cr–C and Fe–V–C alloys. Metall. Trans. 3, 2856 (1972).
25.Bhadeshia, H.K.D.H.: Bainite in Steels, 2nd ed. (IOM Communications Ltd; The Institute of Materials, London; Cambridge, 2001); p. 454.
26.Li, M.V., Niebuhr, D.V., Meekisho, L.L., and Atteridge, D.G.: A computational model for the prediction of steel hardenability. Metall. Mater. Trans. 29, 661 (1998).
27.Andrews, K.W.: Empirical formulae for the calculation of some transformation temperatures. J. Iron Steel Inst. July, 721 (1965).
28.Grange, R.A.: Estimating the hardenability of carbon steels. Metall. Trans. 4, 2231 (1973).
29.Bhadeshia, H.K.D.H.: Theoretical analysis of changes in cementite composition during the tempering of bainite. Mater. Sci. Technol. 5, 131 (1989).
30.Song, R., Ponge, D., and Raabe, D.: Influence of Mn Content on the microstructure and mechanical properties of ultrafine grained C–Mn steels. ISIJ Int. 45, 1721 (2005).
31.Calcagnotto, M., Pongo, D., and Raabe, D.: On the effect of Mn on grain size stability and hardenability in ultrafine-grained ferrite/martensite dual-phase steels. Metall. Mater. Trans. 43, 37 (2012).
32.Beladi, H., Timokhina, I.B., Xiong, X.Y., and Hodgson, P.D.: A novel thermomechanical approach to produce a fine ferrite and low-temperature bainitic composite microstructure. Acta Mater. 61, 7240 (2013).
33.Adachi, Y., Wakita, M., Beladi, H., and Hodgson, P.D.: The formation of ultrafine ferrite through static transformation in low carbon steels. Acta Mater. 55, 4925 (2007).
34.Eghbali, B., Abdollah-Zadeh, A., Beladi, H., and Hodgson, P.D.: Characterization on ferrite microstructure evolution during large strain warm torsion testing of plain low carbon steel. Mater. Sci. Eng., A 435–436, 499 (2006).
35.Beladi, H., Timokhina, I.B., Mukherjee, S., and Hodgson, P.D.: Ultrafine ferrite formation through isothermal static phase transformation. Acta Mater. 59, 4186 (2011).
36.Timokhina, I.B., Pereloma, E.V., and Hodgson, P.D.: Effect of microstructure on the stability of retained austenite in transformation-induced-plasticity steels. Metall. Mater. Trans. 35, 2331 (2004).
37.Shen, Y.F., Qiu, L.N., Sun, X., Zuo, L., Liaw, P.K., and Raabe, D.: Effcts of retained austenite volume fraction, morphology and carbon content on strength and ductility of nanostructured TRIP assisted steels. Mater. Sci. Eng. 636, 551 (2015).
38.Seol, J.B., Raabe, D., Choi, P.P., Im, Y.R., and Park, C.G.: Atomic scale effects of alloying, partitioning, solute drag and austempering on the mechanical properties of high-carbon bainitic-austenitic TRIP steels. Acta Mater. 60, 6183 (2012).
39.Dmitrieva, O., Ponge, D., Inden, G., Millan, J., Choi, P., Sietsma, J., and Raabe, D.: Chemical gradient across phase boundaries between martensite and austenite in steel studied by atom probe tomography and simulation. Acta Mater. 59, 364 (2011).
40.Caballero, F.G., Miller, M.K., Babu, S.S., and Garcia-Mateo, C.: Atomic scale observations of bainite transformation in a high carbon high silicon steel. Acta Mater. 55, 381 (2007).
41.Ryde, L.: Application of EBSD to analysis of microstructures in commercial steels. Mater. Sci. Technol. 22, 1297 (2006).
42.Petrov, R., Kestens, L., Wasilkowska, A., and Houbaert, Y.: Microstructure and texture of a lightly deformed TRIP-assisted steel characterized by means of the EBSD technique. Mater. Sci. Eng. 447, 285297 (2007).
43.Zaefferer, S., Romano, P., and Friedel, F.: EBSD as a tool to identify and quantify bainite and ferrite in low-alloyed Al-TRIP steels. J. Microsc. 230, 499508 (2008).
44.Cullity, B.D.: Elements of X-Ray Diffraction (Addison-Wesley, New York, 1978); p. 555.
45.Miller, M.K.: Atom Probe Tomography (Springer, New York, 2000).
46.Tsuzaki, K., Kodai, A., and Maki, T.: Formation mechanism of bainitic ferrite in an Fe-2 PctSi-0.6 pct C alloy. Metall. Mater. Trans. 25, 2009 (1994).
47.Sandvik, B.P.J.: The bainite reaction in Fe-Si-c alloys: Secondary stage. Metall. Trans. 13, 789 (1982).
48.Malet, L., Barnett, M.R., Jacques, P.J., and Godet, S.: Variant selection during the γ-to-αb phase transformation in hot-rolled bainitic TRIP-aided steels. Scr. Mater. 61, 520 (2009).
49.Gong, W., Tomota, Y., Koo, M.S., and Adachi, Y.: Effect of ausforming on nanobainite steel. Scr. Mater. 63, 819 (2010).
50.Quidort, D. and Brechet, Y.J.M.: Isothermal growth kinetics of bainite in 0.5% C steels. Acta Metall. 49, 4161 (2001).
51.Hashimoto, S., Sudo, M., Mimura, K., and Hosoda, T.: Effect of microstructure on mechanical properties of C-Mn high strength hot rolled sheet steel. Trans. Iron Steel Inst. Jpn. 26, 985 (1986).
52.Gilmour, J.B., Purdy, G.R., and Kirdalky, J.S.: Partition of Mn during the proeutectoid ferrite transformation in steel. Metall. Mater. Trans. 3, 3213 (1972).
53.Wada, T., Wada, H., Elliott, J.F., and Chipman, J.: Thermodynamics of the FCC Fe–Mn–C and Fe–Si–C alloys. Metall. Mater. Trans. 3, 1657 (1972).
54.Bradley, J.R. and Aaronson, H.I.: Growth kinetics of grain boundary ferrite allotrimorphs in Fe–C–X alloys. Metall. Mater. Trans. 12, 1729 (1981).
55.Capdevila, C., Cornide, J., Tanaka, K., Nakanishi, K., and Urones-Garrote, E.: Kinetic transition during ferrite growth in Fe–C–Mn medium carbon steel. Metall. Mater. Trans. 42, 3719 (2011).
56.Guo, H., Purdy, G.R., Enomoto, M., and Aaronson, H.I.: Kinetic transitions and substitutional solute (Mn) fields associated with later stages of ferrite growth in Fe–C–Mn–Si. Metall. Mater. Trans. 37, 1721 (2006).
57.Zurob, H.S., Hutchinson, C.R., Béhé, A., Purdy, G.R., and Bréchet, Y.J.M.: A transition from local equilibrium to paraequilibrium kinetics for ferrite growth in Fe–C–Mn: A possible role of interfacial segregation. Acta Mater. 56, 2203 (2008).
58.Thuillier, O., Danoix, F., Gounbé, M., and Blavette, D.: Atom probe tomography of the austenite–ferrite interphase boundary composition in a model alloy Fe–C–Mn. Scr. Mater. 55, 1071 (2006).
59.Guo, H., Yang, S.W., Shang, C.J., Wang, X.M., and He, X.L.: A quantitative analysis of Mn segregation at partitioned ferrite/austenite interface in a Fe-C-Mn-Si alloy. J. Mater. Sci. Technol. 25, 383 (2009).
60.Bouet, M., Fillipine, R., Essadiqi, E., Root, J., and Yue, S.: The effect of Mo in Si–Mn Nb bearing TRIP steels. Mater. Sci. Forum 284, 319 (1998).
61.Humphreys, E.S., Fletcher, H.A., Hutchins, J.D., Garratt-Reed, A.J., Reynolds, W.T. Jr., Aaronson, H.I., Purdy, G.R., and Smith, G.D.W.: Molybdenum accumulation at ferrite: Austenite interfaces during isothermal transformation of an Fe-0.24 pct C-0.93 pct Mo alloy. Metall. Trans. 35, 1223 (2004).
62.Fridberg, J., Torndahl, L.E., and Hillert, M.: Diffusion in iron. Jernkont. Ann. 153, 263 (1969).


Related content

Powered by UNSILO

The influence of fine ferrite formation on the γ/α interface, fine bainite and retained austenite in a thermomechanically-processed transformation induced plasticity steel

  • Ilana B. Timokhina (a1), Michael K. Miller (a2), Hossein Beladi (a3) and Peter D. Hodgson (a3)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.