In this work, the effects of hot deformation on continuous cooling transformation of a high-Nb steel were investigated on a Gleeble 3500 thermal simulator. The amounts of dissolved Nb were determined by inductively coupled plasma-atomic emission spectrometry. Furthermore, the effects of hot deformation and Nb precipitation on phase transformation were discussed. Results showed that high-Nb steel is suitable for acicular ferrite pipeline steels because the acicular ferrite microstructure can be obtained in a wide cooling rate range. Hot deformation strongly accelerates the polygonal ferrite transformation and increases the critical cooling rate to obtain a full acicular ferrite microstructure. Moreover, hot deformation markedly refines the final microstructure and improves the mechanical properties of acicular ferrite obtained at a high cooling rate. However, hot deformation can also promote Nb precipitation during holding and even cooling at low rates after hot deformation. Nb precipitation dramatically promotes the polygonal ferrite, weakens the effect of Nb in solution on phase transformation and strengthening, and decreases the microhardness.
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References
1.
ZhaoM.-C.YangK.XiaoF.-R.ShanY.-Y.: ‘Continuous cooling transformation of undeformed and deformed low carbon pipeline steels’, Mater. Sci. Eng. A, 2003, 355, 126–136. doi: 10.1016/S0921-5093(03)00074-1
2.
StalheimD. G.: ‘The use of high temperature processing (HTP) steel for high strength oil and gas transmission pipeline application’, Iron Steel (Chinese), 2005, 40, (Supplement), 699–704.
3.
ZhengL.GaoS.ZhangC. G.ZhangB.LiY. F.: ‘Development of high Nb X80 grade pipeline steel wide-thick plate used in the second west to east gas pipeline project’, Welded Pipe Tube, 2009, 32, 25–29(in Chinese).
4.
StalheimD. G.JanstoS. G.: The role of niobium in high strength oil and gas transmission line pipe steels. Proceedings of the biennial international pipeline conference, IPC, ASME, 3 (Part A), 99–106; 2007.
5.
SicilianoF.StalheimD. G.BordignonP.GrayJ. M.: Modern high strength steels for oil and gas transmission pipelines Proceedings of the biennial international pipeline conference, IPC, v 3, 187–195; 2009.
6.
CaoY.-B.XiaoF.-R.QiaoG.-Y.ZhangX.-B.LiaoB.: ‘Quantitative research on effects of Nb on hot deformation behaviors of high-Nb microalloyed steels’, Mater. Sci. Eng. A, 2011, 530, 277–284. doi: 10.1016/j.msea.2011.09.086
7.
MiaoC. L.ShangC. J.ZhangG. D.SubramanianS. V.: ‘Recrystallization and strain accumulation behaviors of high-Nb-bearing line pipe steel in plate and strip rolling’, Mater. Sci. Eng. A, 2010, 527, 4985–4992. doi: 10.1016/j.msea.2010.04.039
8.
XiaoF.-R.LiaoB.ShanY.-Y.QiaoG.-Y.ZhongY.ZhangC.-L.YangK.: ‘Challenge of mechanical properties of an acicular ferrite pipeline steel’, Mater. Sci. Eng. A, 2006, 431, 41–52. doi: 10.1016/j.msea.2006.05.029
9.
Sanchez-MouriñoN.PetrovR.BaeJ.-H.KimK.KestensLeo A. I.: ‘Microstructural changes after control rolling and interrupted accelerated cooling simulations in pipeline steel’, Steel Res. Int., 2011, 82, 352–361. doi: 10.1002/srin.201000222
10.
JiF. Q.WangG. D.: ‘Effects of cooling processes on microstructure evolution of X80 pipeline steel’, Mater. Sci. Forum, 2014, 788, 378–383. doi: 10.4028/www.scientific.net/MSF.788.378
11.
SmithY. E.ColdrenA. P.CrydermanR. L.: ‘High-strength, ductile Mn–Mo–Nb steels with a structure of acicular ferrite’, Met. Sci. Heat Treat., (English translation of Metallovedenie i Termicheskaya Obrabotka Metallov)1976, 18, (12), 59–65.
12.
XiaoF. R.LiaoB.RenD. L.ShanY. Y.YangK.: ‘Acicular ferritic microstructure of a low-carbon Mn–Mo–Nb microalloyed pipeline steel’, Mater Charact., 2005, 54, 305–314. doi: 10.1016/j.matchar.2004.12.011
13.
ArakiT.KozasuI.TankechiH.ShibataK.EnomotoM.TamehiroH.: Atlas for bainitic microstructures. Continuous-cooled Zw microstructures of low-carbon steel, Vol. 1, 4–5; 1992, Tokyo 7, ISIJ.
14.
WangY. C.LiY. S.ZhaoM. C.YangK.: ‘Improved processing for microstructures and mechanical properties of a commercial pipeline steel’, Acta Metall. Sinica (Eng. Lett.), 2005, 18, (2), 121–128.
15.
StalheimD. G.MuralidharanG.: The role of continuous cooling transformation diagrams in material design for high strength oil and gas transmission pipeline steels. Proceedings of the biennial international pipeline conference, IPC, 3 (Part A), 231–238; 2007.
16.
CaoY. B.XiaoF. R.QiaoG. Y.HuangC. J.ZhangX. B.WuZ. X.LiaoB.: ‘Strain induced precipitation and static softening behaviors of high Nb microalloyed steels’, Mater. Sci. Eng. A, 2012, 552, 502–513. doi: 10.1016/j.msea.2012.05.078
17.
NöhrerM.ZambergerS.LeitnerH.: ‘Strain-induced precipitation behavior of a Nb-Ti-V steel in the austenite phase field’, Steel Res. Int., 2013, 84, 827–836. doi: 10.1002/srin.201200257
18.
ChenY.ZhangD. T.LiuY. C.LiH. J.XuD. K.: ‘Effect of dissolution and precipitation of Nb on the formation of acicular ferrite/bainite ferrite in low-carbon HSLA steels’, Mater. Charact., 2013, 84, 232–239. doi: 10.1016/j.matchar.2013.08.005
19.
SubramanianS. V.ZengX.CollinsL. E.BucholtzM.KosticM.: ‘Effect of Nb on the transformation behaviour of Nb-Ti microalloyed steels.’ International symposium on low-carbon steels for the 90′s, (ed. RAaG Tither), 313–322; 1993, Pittsburgh.
20.
YakubtsovI. A.PoruksP.BoydJ. D.: ‘Microstructure and mechanical properties of bainitic low carbon high strength plate steels’, Mater. Sci. Eng. A, 2008, 480, 109–116. doi: 10.1016/j.msea.2007.06.069
21.
GomezM.VallesP.MedinaS. F.: ‘Evolution of microstructure and precipitation state during thermomechanical processing of a X80 microalloyed steel’, Mater. Sci. Eng. A, 2011, 528, 4761–4773. doi: 10.1016/j.msea.2011.02.087
22.
KimW. K.JungH. G.ParkG. T.KohS. U.KimK. Y.: ‘Relationship between hydrogen-induced cracking and type I sulfide stress cracking of high-strength line pipe steel’, Scripta Mater., 2010, 62, 195–198. doi: 10.1016/j.scriptamat.2009.10.028
23.
YuQ. B.WangZ. D.LiuX. H.WangG. D.: ‘Effect of microcontent Nb in solution on the strength of low carbon steels’, Mater. Sci. Eng. A, 2004, 379, 384–390. doi: 10.1016/j.msea.2004.03.022
24.
SobralM. D. C.MeiP. R.KestenbachH. J.: ‘Effect of carbonitride particles formed in austenite on the strength of microalloyed steels’, Mater. Sci. Eng. A, 2004, 367, 317–321. doi: 10.1016/j.msea.2003.10.280
