Effect of Mo, Nb and V on Hot Deformation Behaviour, Microstructure and Hardness of Microalloyed Steels


Article Preview

Three novel low carbon microalloyed steels with various additions of Mo, Nb and V were investigated after thermomechanical processing simulations designed to obtain ferrite-bainite microstructure. With the increase in microalloying element additions from the High V- to NbV- to MoNbV-microalloyed steel, the high temperature flow stresses increased. The MoNbV and NbV steels have shown a slightly higher non-recrystallization temperature (1000 °C) than the High V steel (975 °C) due to the solute drag from Nb and Mo atoms and austenite precipitation of Nb-rich particles. The ambient temperature microstructures of all steels consisted predominantly of polygonal ferrite with a small amount of granular bainite. Precipitation of Nb-and Mo-containing carbonitrides (>20 nm size) was observed in the MoNbV and NbV steels, whereas only coarser (~40 nm) iron carbides were present in the High V steel. Finer grain size and larger granular bainite fraction resulted in a higher hardness of MoNbV steel (293 HV) compared to the NbV (265 HV) and High V (285 HV) steels.



Main Theme:

Edited by:

R. Shabadi, Mihail Ionescu, M. Jeandin, C. Richard and Tara Chandra




N. Singh et al., "Effect of Mo, Nb and V on Hot Deformation Behaviour, Microstructure and Hardness of Microalloyed Steels", Materials Science Forum, Vol. 941, pp. 3-8, 2018

Online since:

December 2018




* - Corresponding Author

[1] X. Chen, Y. Huang, Hot deformation behavior of HSLA steel Q690 and phase transformation during compression. J. Alloy Compd. 619 (2015) 564-571.

[2] X. Kong, et al., Optimization of mechanical properties of high strength bainitic steel using thermo-mechanical control and accelerated cooling process, J. Mater. Process. Tech. 217 (2015) 202-210.

DOI: https://doi.org/10.1016/j.jmatprotec.2014.11.016

[3] G.W. Yang, et al., Ultrafine grained austenite in a low carbon vanadium microalloyed steel, J. Iron Steel Res. Int. 20(4) (2013) 64-69.

DOI: https://doi.org/10.1016/s1006-706x(13)60084-9

[4] D.B. Park, et al., Strengthening mechanism of hot rolled Ti and Nb microalloyed HSLA steels containing Mo and W with various coiling temperature, Mater. Sci. Eng. A 560 (2013) 528-534.

DOI: https://doi.org/10.1016/j.msea.2012.09.098

[5] C.Y. Chen, et al., Precipitation hardening of high-strength low-alloy steels by nanometer-sized carbides, Mater. Sci. Eng. A 499(1-2) (2009) 162-166.

[6] Y.F. Shen, C.M. Wang, X. Sun, A micro-alloyed ferritic steel strengthened by nanoscale precipitates, Mater. Sci. Eng. A 528(28) (2011) 8150-8156.

DOI: https://doi.org/10.1016/j.msea.2011.07.065

[7] M. Cabibbo, et al., Effect of thermo-mechanical treatments on the microstructure of micro-alloyed low-carbon steels, J. Mater. Sci. 43(21) (2008) 6857-6865.

DOI: https://doi.org/10.1007/s10853-008-3000-8

[8] A.G. Kostryzhev, O.O. Marenych, C.R. Killmore, E.V. Pereloma, Strengthening mechanisms in thermomechanically processed NbTi-microalloyed steel, Metal. Mater. Trans. A 46(8)(2015)3470-3480.

DOI: https://doi.org/10.1007/s11661-015-2969-2

[9] Y. H. Bae, J. S. Lee, J.-K. Choi, W.-Y. Choo, S. H. Hong, Effects of austenite conditioning on austenite/ferrite phase transformation of HSLA steel, Mater. Trans. 45(1) (2004) 137-142.

DOI: https://doi.org/10.2320/matertrans.45.137

[10] R. Kaspar, U. Lotter, C. Biegus, The influence of thermomechanical treatment on the transformation behaviour of steels, Steel Res. Int. 65 (1994) 242–247.

DOI: https://doi.org/10.1002/srin.199401065

[11] M.-C. Zhao, K. Yang, F.-R. Xiao, Y.-Y. Shan, Continuous cooling transformation of undeformed and deformed low carbon pipeline steels, Mater. Sci. Eng. A 355 (2003) 126-136.

DOI: https://doi.org/10.1016/s0921-5093(03)00074-1

[12] W. P. Sun, M. Militzer, D. Q. Bai, J. J. Jonas, The effects of precipitation on recrystallization under multipass deformation conditions, Acta Metal. Mater. 41(12) (1993) 3595-3604.

DOI: https://doi.org/10.1016/0956-7151(93)90240-s

[13] Z.H. Zhang, et al., The effect of Nb on recrystallization behavior of a Nb micro-alloyed steel. Mater. Sci. Eng. A 474(1-2) (2008) 254-260.

[14] S. Vervynckt, K. Verbeken, P. Thibaux, M Liebeherr, Y. Houbaert, Austenite recrystallization–precipitation interaction in niobium microalloyed steels, ISIJ Int. 49(6) (2009) 911–920.

DOI: https://doi.org/10.2355/isijinternational.49.911

[15] M. G Akben, B. Bacroix, J.J. Jonas, Effect of vanadium and molybdenum addition on high temperature recovery, recrystallization and precipitation behaviour of niobium-based microalloyed steels, Acta Metal. 31 (1983) 161-174.

DOI: https://doi.org/10.1016/0001-6160(83)90076-7

[16] H.L. Andrade, M.G. Akben, J.J. Jonas, Effect of molybdenum, niobium, and vanadium on static recovery and recrystallization and on solute strengthening in microalloyed steels, Metal. Trans. A 14(10) (1983) 1967–(1977).

DOI: https://doi.org/10.1007/bf02662364

[17] T. Schambron, L. Chen, T. Gooch, A. Dehghan-Manshadi, E.V. Pereloma, Effect of Mo concentration on dynamic recrystallization behavior of low carbon microalloyed Steels, Steel Res. Int. 84(12) (2013) 1191-1195.

DOI: https://doi.org/10.1002/srin.201300035

[18] J.F. Siciliano, et al., Mathematical modeling of the mean flow stress, fractional softening and grain size during the hot strip rolling of C-Mn steels, ISIJ Int. 36(12) (1996) 1500-1506.

DOI: https://doi.org/10.2355/isijinternational.36.1500

[19] Y. Chen, D. Zhang, Y. Liu, H. Li, D. Xu, Effect of dissolution and precipitation of Nb on the formation of acicular ferrite/bainite ferrite in low-carbon HSLA steels. Mater. Charact. 84(2013)232-239.

DOI: https://doi.org/10.1016/j.matchar.2013.08.005

[20] N. Khodaie, D.G. Ivey, H. Henein, Extending an empirical and a fundamental bainite start model to a continuously cooled microalloyed steel, Mater. Sci. Eng. A 650 (2016) 510-522.

DOI: https://doi.org/10.1016/j.msea.2015.10.016

[21] H. Yada, Y. Matsumura, T. Senuma, Proc. 1st Conf. Physical Metallurgy of Thermomechanical Processing of Steels and Other Metals (THERMEC-88), ed. by I. Tamura, ISIJ, Tokyo, 1988, 200.

[22] J. J. Jonas, C. Ghosh, V. V. Basabe, Effect of dynamic transformation on the mean flow stress, Steel Res. Int. 84(3) (2013) 253-258.

DOI: https://doi.org/10.1002/srin.201200166

[23] C. Ghosh, V. V. Basabe, J. J. Jonas, Determination of the critical strains for the initiation of dynamic transformation and dynamic recrystallization in four steels of increasing carbon contents, Steel Res. Int. 84 (2013) 490-494.

DOI: https://doi.org/10.1002/srin.201200188

[24] S. Zajac, B. Jansson, Thermodynamics of the Fe-Nb-CN system and the solubility of niobium carbonitrides in austenite, Metal. Mater. Trans. B 29(1) (1998) 163-176.

DOI: https://doi.org/10.1007/s11663-998-0019-9

[25] K. Junhua, et al., Influence of Mo content on microstructure and mechanical properties of high strength pipeline steel, Mater Des. 25(8) (2004) 723-728.

DOI: https://doi.org/10.1016/j.matdes.2004.03.009

[26] H.I. Aaronson, W.T. Reynolds Jr., G.R. Purdy, The incomplete transformation phenomenon in steel, Metal. Mater. Trans. A 37 (2006) 1731-1745.

[27] J. Kong, C. Xie, Effect of molybdenum on continuous cooling bainite transformation of low-carbon microalloyed steel, Mater. Des. 27 (2006) 1169–1173.

DOI: https://doi.org/10.1016/j.matdes.2005.02.006

[28] Y.-K. Lee, J.-M. Hong, C.-S. Choi, J.-K. Lee, Continuous cooling transformation temperatures and microstructures of niobium bearing microalloyed steels, Mater. Sci. Forum 475-479(2005) 65-68.

DOI: https://doi.org/10.4028/www.scientific.net/msf.475-479.65