A new process involving ultra-fast cooling (UFC) and on-line tempering (OLT) was proposed to displace austempering process, which usually implements in a salt/lead bath and brings out serious pollution in the industrial application. The optimization of the new process, involving the evolution of the microstructure of medium-carbon steel during various cooling paths, was studied. The results show that the cooling path affected the final microstructure in terms of the fraction of pearlite, grain size and distribution of cementite in pearlite. Increasing the cooling rate or decreasing the OLT temperature contributes to restraining the transformation from austenite to ferrite, and simultaneously retains more austenite for the transformation of pearlite. It is also noted that bainite was observed in the microstructure at the cooling rate of 45°C/s and the OLT temperature of 500°C. Through either increasing the cooling rate or decreasing the OLT temperature, the distribution of cementite in pearlite is more dispersed and grain is refined. Taking the possibility of industrial applications into account, the optimal process of cooling at 45°C/s followed by OLT at 600°C after hot rolling was determined, which achieves a microstructure containing nearly full pearlite with an average grain size of approximately 7 μm and a homogeneously dispersed distribution of cementite in pearlite.
Abstract
A new process involving ultra-fast cooling (UFC) and on-line tempering (OLT) was proposed to displace austempering process, which usually implements in a salt/lead bath and brings out serious pollution in the industrial application. The optimization of the new process, involving the evolution of the microstructure of medium-carbon steel during various cooling paths, was studied. The results show that the cooling path affected the final microstructure in terms of the fraction of pearlite, grain size and distribution of cementite in pearlite. Increasing the cooling rate or decreasing the OLT temperature contributes to restraining the transformation from austenite to ferrite, and simultaneously retains more austenite for the transformation of pearlite. It is also noted that bainite was observed in the microstructure at the cooling rate of 45°C/s and the OLT temperature of 500°C. Through either increasing the cooling rate or decreasing the OLT temperature, the distribution of cementite in pearlite is more dispersed and grain is refined. Taking the possibility of industrial applications into account, the optimal process of cooling at 45°C/s followed by OLT at 600°C after hot rolling was determined, which achieves a microstructure containing nearly full pearlite with an average grain size of approximately 7 μm and a homogeneously dispersed distribution of cementite in pearlite.
关键词
medium-carbon steel /
ultra-fast cooling /
on-line tempering /
phase transformation kinetics
{{custom_keyword}} /
Key words
medium-carbon steel /
ultra-fast cooling /
on-line tempering /
phase transformation kinetics
{{custom_keyword}} /
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1]F. Fang, X.J. Hu, S.H. Chen, Z.H. Xie, J.Q. Jiang.Revealing microstructural and mechanical characteristics of cold-drawn pearlitic steel wires undergoing simulated galvanization treatment[J].Materials Science and Engineering A, 2012, 547(-):51-54
[2]T. Waterschoot, K. Verbeken, B.C. De Cooman.Tempering Kinetics of the Martensitic Phase in DP Steel[J].ISIJ International, 2006, 46(1):138-146
[3]D.S. Zhou, G.J. Shiflet.Ferrite: Cementite Crystallography in Pearlite[J].Metallurgical Transactions A, 1992, 23(4):1259-1269
[4]F. Fang, X.J. Hu, B.M. Zhang, Z.H. Xie, J.Q. Jiang.Deformation of dual-structure medium carbon steel in cold drawing[J].Materials Science and Engineering A, 2013, 583(-):78-83
[5]C.S. Zheng, L.F. Li, Y.D. Wang, W.Y. Yang, Z.Q. Sun.Micromechanical behavior of eutectoid steel quantified by an analytical model calibrated by in situ synchrotron-based X-ray diffraction[J].Materials Science and Engineering A, 2015, 631(-):181-188
[6]L. Storojeva, D. Ponge, R. Kaspar, D. Raabe.Development of microstructure and texture of medium carbon steel during heavy warm deformation[J].Acta Materialia, 2004, 52(8):2209-2220
[7]H.L. Yi.L. Yi, Mater. Sci. Eng. A 527 (2010) 7600-7604.[J].Full pearlite obtained by slow cooling in medium carbon steel, 2010, 527(-):7600-7604
[8]G.A. Thomas, J.G. Speer, D.K. Matlock.Quenched and Partitioned Microstructures Produced via Gleeble Simulations of Hot-Strip Mill Cooling Practices[J].Metallurgical and Materials Transactions A, 2011, 42A(12):3652-3659
[9]S.N. Prasad, A. Saxena, M.M.S. Sodhi, P.N. Tripathi.Influence of different heat treatment parameters on microstructure and mechanical properties of C-Mn strapping quality steels[J].Materials Science and Engineering A, 2008, 476(-):126-131
[10]A. Saxena, S.N. Prasad, S. Goswami, J. Subudhi, S.K. Chaudhuri.Influence of austempering parameters on the microstructure and tensile properties of a medium carbon-manganese steel[J].Materials Science and Engineering A, 2006, 431(-):53-58
[11]J. Chen, S. Tang, Z. Y. Liu, G.D. Wang.Microstructural characteristics with various cooling paths and the mechanism of embrittlement and toughening in low-carbon high performance bridge steel[J].Materials Science and Engineering A, 2013, 559(-):241-249
[12]J. Chen, M.Y. Lv, S. Tang, Z.Y. Liu, G.D. Wang.Low-Carbon Bainite Steel with High Strength and Toughness Processed by Recrystallization Controlled Rolling and Ultra Fast Cooling (RCR plus UFC)[J].ISIJ International, 2014, 54(12):2926-2932
[13]S. Tang, Z.Y. Liu, G.D. Wang, R.D.K. Misra.Microstructural evolution and mechanical properties of high strength microalloyed steels: Ultra Fast Cooling (UFC) versus Accelerated Cooling (ACC)[J].Materials Science and Engineering A, 2013, 580(-):257-265
[14]J. Trzaska, L.A. Dobrzański.Trzaska, L.A. Dobrzański, J. Mater. Process. Technol. 192-193 (2007) 504-510.[J].Journal of Materials Processing Technology, 2007, 192-193(-):504-510
[15]W.C. Jeong.Microstructural aspects of quasi-polygonal and granular bainitic ferrites in an ultra-low-carbon interstitial-free high-strength steel[J].Metallurgical and Materials Transactions A, 2003, 34A(9):2025-2026
[16]L. Ryde.Application of EBSD to analysis of microstructures in commercial steels[J].Materials Science and Technology, 2006, 22(11):1297-1306
[17]J.P. Houin, A. Simon, G. Beck.Relationship between structure and mechanical properties of pearlite between 0.2% and 0.8%C[J].Transactions of the Iron and Steel Institute of Japan, 1981, 21(10):726-731
[18]Y.V. Leeuwen, M. Onink, J. Sietsma, S.V.D. Zwaag.The γ–αTransformation Kinetics of Low Carbon Steels under Ultra-fast Cooling Conditions[J].ISIJ International, 2001, 41(9):1037-1046
[19]M. Tong, D. Li, Y. Li.Modeling the austenite–ferrite diffusive transformation during continuous cooling on a mesoscale using Monte Carlo method[J].Acta Materialia, 2004, 52(5):1155-1162
[20]C.L. Magee, R.G. Davies.On the volume expansion accompanying the f.c.c. to b.c.c. transformation in ferrous alloys[J].Acta Metallurgica, 1972, 20(8):1031-1043
[21]F.G. Caballero, H.K.D.H. Bhadeshia.Very strong bainite[J].Current Opinion in Solid State and Materials Science, 2004, 8(-):251-257
[22]F.G. Caballero, M.K. Miller, S.S. Babu, C. Garcia-Mateo.Atomic scale observations of bainite transformation in a high carbon high silicon steel[J].Acta Materialia, 2007, 55(1):381-390
[23]K. Hasegawa, K. Kawamura, T. Urabe, Y. Hosoya.Effects of Microstructure on Stretch-flange-formability of 980 MPa Grade Cold-rolled Ultra High Strength Steel Sheets[J].ISIJ International, 2004, 44(3):603-609
[24]Y. Funakawa, T. Shiozaki, K. Tomita, T. Yamamoto, E. Maeda.Development of High Strength Hot-rolled Sheet Steel Consisting of Ferrite and Nanometer-sized Carbides[J].ISIJ International, 24, 44(11):1945-1951
[25]B. Wang, Z.Y. Liu, X.G. Zhou, G.D. Wang.Improvement of Hole-Expansion Property for Medium Carbon Steels by Ultra Fast Cooling After Hot Strip Rolling[J].Journal of Iron and Steel Research International, 2013, 20(6):25-32
[26]D.W. Tian, L.P. Karjalainen, B.N. Qian, X.F. Chen.Nonuniform distribution of carbonitride particles and its effect on prior austenite grain size in the simulated coarse-grained heat-affected zone of thermomechanical control-processed steels[J].Metallurgical and Materials Transactions A, 1996, 27(12):4031-4038
[27]Y. Tian, T. S. Tang, B.X. Wang, Z.D. Wang, G.D. Wang.Development and industrial application of ultra-fast cooling technology[J].SCIENCE CHINA-Technological Sciences, 2012, 55(6):1566-1571
[28]S. Tsuyama.Thick Plate Technology for the Last 100 Years: A World Leader in Thermo Mechanical Control Process[J].ISIJ International, 2015, 55(1):67-78
{{custom_fnGroup.title_cn}}
脚注
{{custom_fn.content}}
基金
the Key Projects in the National Science & Technology Pillar Program;the State Natural Science Fund Projects of China;the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning;China Postdoctoral Science Foundation
{{custom_fund}}
PDF(3945 KB)
