In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel

Abstract

In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100°C for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100°C, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.

Keywords

bainitic steel / austenite / grain growth / kinetics / bainitic transformations

References

[1] Miranda RM, Fortes MA. Austenite grain growth, microstructure and hardness in the heat-affected zone of a 2.25 Cr-1Mo steel. Mater. Sci. Eng. A, 1989, 108, 1.

[2] Akselsen OM. HAZ grain growth mechanisms in welding of low carbon microalloyed steels. Acta Metall., 1986, 34(9): 1807.

[3] Feltham P. Grain growth in metals. Acta Metall., 1957, 5(2): 97.

[4] Higgins GT. Grain-boundary migration and grain growth. Met. Sci., 1974, 8(1): 143

[5] Staśko R, Adrian H, Adrian A. Effect of nitrogen and vanadium on austenite grain growth kinetics of a low alloy steel. Mater. Charact., 2006, 56(4–5): 340

[6] Maity J, Mondai DK. Isothermal grain growth of austenite in hypoeutectoid and hypereutectoid plain carbon steels. J. Iron Steel Res. Int., 2010, 17(7): 38.

[7] Lee SJ, Lee YK. Prediction of austenite grain growth during austenitization of low alloy steels. Mater. Des., 2008, 29(9): 1840.

[8] Zheng L, Yuan ZX, Song SH, Xi TH, Wang Q. Austenite grain growth in heat affected zone of Zr-Ti bearing microalloyed steel. J. Iron Steel Res. Int., 2012, 19(2): 73.

[9] Maalekian M, Radis R, Militzer M, Moreau A, Poole WJ. In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel. Acta Mater., 2012, 60(3): 1015.

[10] Ray A, Ray SK, Mediratta SR. Effect of carbides on the austenite grain growth characteristics in 1Cr-1C and 6Cr-1Mo-1C steels. J. Mater. Sci., 1990, 25(12): 5070.

[11] Xu G, Liu F, Wang L, Hu HJ. A new approach to quantitative analysis of bainitic transformation in a superbainite steel. Scripta Mater., 2013, 68(11): 833.

[12] Li W, Xia K. Kinetics of the α grain growth in a binary Ti-44Al alloy and a ternary Ti-44Al-0.15Gd alloy. Mater. Sci. Eng. A, 2002, 329–331, 430.

[13] Gavard L, Montheillet F, Coze JL. Recrystallization and grain growth in high purity austenitic stainless steels. Scripta Mater., 1998, 39(8): 1095.

[14] Zhao YL, Shi J, Cao WQ, Wang MQ, Xie G. Kinetics of austenite grain growth in medium-carbon niobium-bearing steel. J. Zhejiang Univ. Sci. A, 2011, 12(3): 171.

[15] Manohadr PA, Dunne DP, Chandra T, Killmore CR. Grain growth predictions in microalloyed steels. ISIJ Int., 1996, 36(2): 194.

[16] Uhm S, Moon J, Lee C, Yoon J, Lee B. Prediction model for the austenite grain size in the coarse grained heat affected zone of Fe-C-Mn steels: considering the effect of initial grain size on isothermal growth behavior. ISIJ Int., 2004, 44(7): 1230.

[17] Xu YW, Tang D, Song Y, Pan XG. Prediction model for the austenite grain growth in a hot rolled dual phase steel. Mater. Des., 2012, 36, 275.

[18] Illescas S, Fernández J, Guilemany JM. Kinetic analysis of the austenitic grain growth in HSLA steel with a low carbon content. Mater. Lett., 2008, 62(20): 3478.

[19] Sellars CM, Whiteman JA. Recrystallization and grain growth in hot rolling. Met. Sci., 1979, 13(3–4): 187