Abstract
The microstructural features and grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels were investigated using optical microscopy, scanning electron microscopy, and electron backscattering diffraction. The coarse-grained region of the heat-affected zone consists of predominantly bainite and a small proportion of acicular ferrite. Bainite packets are separated by high angle boundaries. Acicular ferrite laths or plates in the coarse-grained region of the heat-affected zone formed prior to bainite packets partition austenite grains into many smaller and separate areas, resulting in fine-grained mixed microstructures. Electron backscattering diffraction analysis indicates that the average crystallographic grain size of the coarse-grained region of the heat-affected zone reaches 6–9 μm, much smaller than that of austenite grains.
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References
H.K.D.H. Bhadeshia and R.W.K. Honeycombe, Steels Microstructures and Properties, 3rd ed., Elsevier Ltd., Oxford, 2006, p.152.
V. Pancholi, M. Krishnan, I.S. Samajdar, et al., Self-accommodation in the bainitic microstructure of ultra-high-strength steel, Acta Mater., 56(2008), p.2037.
I.A. Yakubtsov, P. Poruks, and J.D. Boyd, Microstructure and mechanical properties of bainitic low carbon high strength plate steels, Mater. Sci. Eng. A, 480(2008), p.109.
M. KarlÍka, P. Haušilda, C. Prioulb, and M. Stöger-Pollachc, Microstructure of low alloyed steel close to the fracture surface, Mater. Sci. Eng. A, 462(2007), p.183.
A.M. Guo, S.R. Li, J. Guo, et al., Effect of zirconium addition on the impact toughness of the heat affected zone in a high strength low alloy pipeline steel, Mater. Charact., 59(2008), p.134.
K.M. Wu, Z.G. Li, A.M. Guo, et al., Microstructure evolution in a low carbon Nb-Ti microalloyed steel, ISIJ Int., 46(2006), p.161.
K.M. Wu, M. Kagayama, and M. Enomoto, Kinetics of ferrite transformation in an Fe-0.28mass%C-3mass%Mo alloy, Mater. Sci. Eng. A, 343(2003), p.143.
M. Enomoto, N. Maruyama, K.M. Wu, and T. Tarui, Alloying element accumulation at ferrite/austenite boundaries below the time-temperature-transformation diagram bay in an Fe-C-Mo alloy, Mater. Sci. Eng. A, 343(2003), p.151.
H. Mabuchi, R. Uemori, and M. Fujioka, The role of Mn depletion in intragranular ferrite transformation in the heat affected zone of welded joints with large heat input in structural steels, ISIJ Int., 36(1996), p.1406.
J.M. Gregg and H.K.D.H. Bhadeshia, Solid-state nucleation of acicular ferrite on minerals added to molten steel, Acta Mater., 45(1997), p.739.
J.H. Shim, Y.W. Cho, S.H. Chung, et al., Nucleation of intragranular ferrite at Ti2O3 particle in low carbon steel, Acta Mater., 47(1999), p.2751.
J.H. Shim, Y.J. OH, J.Y. Suh, et al., Ferrite nucleation potency of non-metallic inclusions in medium carbon steels, Acta Mater., 49(2001), p.2115.
M. Enomoto, Nucleation of phase transformations at intragranular inclusions in steel, Met. Mater. Int., 4(1998), p.115.
S. Zhang, N. Hattori, M. Enomoto, and T. Tarui, Ferrite nucleation at ceramic/austenite interfaces, ISIJ Int., 36(1996), p.1301.
Z. Zhang and R.A. Farrar, Role of nonmetallic inclusions in formation of acicular ferrite in low alloy weld metals, Mater. Sci. Technol., 12(1996), p.237.
M. Enomoto, K.M. Wu, Y. Inagawa, T. Murakami, and S. Nanba, Three-dimensional observation of ferrite pate in low carbon steel weld, ISIJ Int., 45(2005), p.756.
K.M. Wu, Y. Inagawa, and M. Enomoto, Three-dimensional morphology of ferrite formed in association with inclusions in low-carbon steel, Mater. Charact., 52(2004), p.121.
X.L. Wan, R. Wei, and K.M. Wu, Effect of acicular ferrite formation on grain refinement in the coarse-grained region of the heat-affected zone, Mater. Charact., 61(2010), p.726.
K.M. Wu, Three-dimensional analysis of acicular ferrite in a low-carbon steel containing titanium, Scripta Mater., 54(2006), Spec. Iss., p.569.
L. Cheng and K.M. Wu, New insights into intragranular ferrite in a low-carbon low-alloy steel, Acta Mater., 57(2009), p.3754.
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This work was financially supported by the National Natural Science Foundation of China (No.50734004).
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Wei, R., Shang, Cj. & Wu, Km. Grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels. Int J Miner Metall Mater 17, 737–741 (2010). https://doi.org/10.1007/s12613-010-0382-9
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DOI: https://doi.org/10.1007/s12613-010-0382-9