A carbide-free bainitic steel with high-ductility by dynamic transformation during coiling process

A new hot-rolled alloy of carbide-free bainite has been proposed for heavy trucks frames. It involves dynamic bainite transformation during the prolonged cooling of the coiling process after hot-rolling. The new hot-rolled Fe-0.5C-2.9Mn-2.3Al (in wt-%) steels exhibit tensile strength of 1110 MPa with a combined total elongation of 35%. The alloy has been re-heat-treated with one step and two steps isothermal bainitic transformation to study the effect of microstructure evolution and microstructure-property relationship. The transformation-induced plasticity (TRIP) effect of retained austenite has been discussed and revealed as the main contributor for the high ductility of bainitic steels. The formation of the cracks at fracture regions after tensile deformation, which is associated with the austenite stability and morphology, has been observed and discussed.

[1]  Miao‐yong Zhu,et al.  Behavior of V-Ti Elements in Warm-Rolled Transformation-Induced Plasticity Steel with Medium Manganese Content , 2020 .

[2]  K. Shimizu,et al.  Mechanical properties of carbide-free lower bainite in complex-alloyed constructional steel: Effect of bainitizing treatment parameters , 2020 .

[3]  Zhao-dong Wang,et al.  The Role of Intercritical Annealing in Enhancing Low-temperature Toughness of Fe-C-Mn-Ni-Cu Structural Steel , 2019, Metallurgical and Materials Transactions A.

[4]  R. Misra,et al.  Kinetics of Carbon Partitioning during Non‐Isothermal Treatment and Mechanical Properties of the First Industrial Coils of Hot Rolled Quenched and Partitioned Steel , 2019, steel research international.

[5]  X. Zhao,et al.  Effects of nucleation site and morphology of carbide-free bainite on microstructures and properties of bainite/martensite multi-phase steels , 2019, Materials Science and Engineering: A.

[6]  H. Yi,et al.  Challenges in the formability of the next generation of automotive steel sheets , 2018 .

[7]  A. Ceguerra,et al.  Yield Strength Enhancement by Carbon Trapping in Ferrite of the Quenching and Partitioning Steel , 2017, Metallurgical and Materials Transactions A.

[8]  G. Yuan,et al.  Microstructure and partitioning behavior characteristics in low carbon steels treated by hot-rolling direct quenching and dynamical partitioning processes , 2016 .

[9]  S. Sangal,et al.  Super strong and highly ductile low alloy multiphase steels consisting of bainite, ferrite and retained austenite , 2016 .

[10]  J. Yang,et al.  Mechanical behavior and microstructural evolution of nanostructured bainite under high-strain rate deformation by Hopkinson bar , 2016 .

[11]  A. Zhao,et al.  Quenching and partitioning steel produced through hot rolling, direct quenching and annealing , 2016 .

[12]  W. Xu,et al.  Effect of the Cr Content and Coiling Temperature on the Properties of Hot Rolled High Strength Lower Bainitic Steel , 2015 .

[13]  Chong-xiang Huang,et al.  Characterization of Microstructures and Mechanical Properties of Cold-rolled Medium-Mn Steels with Different Annealing Processes , 2015 .

[14]  T. Wang,et al.  Characterisation of microstructure and mechanical properties in two different nanostructured bainitic steels , 2015 .

[15]  Y. Tsai,et al.  Microstructural characterization of Charpy-impact-tested nanostructured bainite , 2015 .

[16]  Young Kook Lee,et al.  Current opinion in medium manganese steel , 2015 .

[17]  D. Suh,et al.  Austenite in Transformation-Induced Plasticity Steel Subjected to Multiple Isothermal Heat Treatments , 2014, Metallurgical and Materials Transactions A.

[18]  H. Roelofs,et al.  Complex Microstructural Banding of Continuously Cooled Carbide-Free Bainitic Steels , 2014 .

[19]  H. Bhadeshia,et al.  Optimizing the Morphology and Stability of Retained Austenite in a δ-TRIP Steel , 2014, Metallurgical and Materials Transactions A.

[20]  F. Hu,et al.  Multi-step isothermal bainitic transformation in medium-carbon steel , 2014 .

[21]  Di Wu,et al.  Effect of partitioning procedure on microstructure and mechanical properties of a hot-rolled directly quenched and partitioned steel , 2014 .

[22]  Z. Fucheng,et al.  Low-temperature bainite in low-carbon steel , 2014 .

[23]  Hao Yu,et al.  Microstructure development and mechanical properties of quenching and partitioning (Q&P) steel and an incorporation of hot-dipping galvanization during Q&P process , 2013 .

[24]  J. Speer,et al.  Effect of Testing Temperature on Retained Austenite Stability of Cold Rolled CMnSi Steels Treated by Quenching and Partitioning Process , 2013 .

[25]  Bing Chen,et al.  The effect of morphology on the stability of retained austenite in a quenched and partitioned steel , 2013 .

[26]  Kebing Zhang,et al.  A new effect of retained austenite on ductility enhancement in high strength bainitic steel , 2012 .

[27]  J. Yang,et al.  Low-alloy duplex, directly quenched transformation-induced plasticity steel , 2011 .

[28]  John G. Speer,et al.  Analysis of Microstructure Evolution in Quenching and Partitioning Automotive Sheet Steel , 2011 .

[29]  S. Allain,et al.  Microstructure – Properties Relationships in Carbide-free Bainitic Steels , 2011 .

[30]  Chun Ming Liu,et al.  Mechanical properties and hot-rolled microstructures of a low carbon bainitic steel with Cu-P alloying , 2011 .

[31]  H. Bhadeshia,et al.  Mechanical stabilisation of retained austenite in δ-TRIP steel , 2011 .

[32]  D. Suh,et al.  Influence of Al on the Microstructural Evolution and Mechanical Behavior of Low-Carbon, Manganese Transformation-Induced-Plasticity Steel , 2010 .

[33]  H. K. D. H. Bhadeshia,et al.  Austenite grain size and the martensite-start temperature , 2009 .

[34]  H. Lee,et al.  Microstructure and tensile properties of hot-rolled Fe–C–Mn–Si–Cu multiphase steel , 2008 .

[35]  H. Bhadeshia,et al.  Properties of Fine-Grained Steels Generated by Displacive Transformation , 2008 .

[36]  H. K. D. H. Bhadeshia,et al.  δ TRIP steel , 2007 .

[37]  F. Delannay,et al.  Multiscale mechanics of TRIP-assisted multiphase steels: I. Characterization and mechanical testing , 2007 .

[38]  H. Bhadeshia,et al.  Bimodal size-distribution of bainite plates , 2006 .

[39]  Sir Robert Honeycombe,et al.  The Effects of Alloying Elements on Iron-Carbon Alloys , 2006 .

[40]  Jonathan P. Wright,et al.  Thermal stability of retained austenite in TRIP steels studied by synchrotron X-ray diffraction during cooling , 2005 .

[41]  Mitsuyuki Kobayashi,et al.  Effects of Volume Fraction and Stability of Retained Austenite on Ductility of TRIP-aided Dual-phase Steels , 1992 .