Advanced Multiphase Steels

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 21172

Special Issue Editor


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Guest Editor
Thermomechanical Processing Group, Materials and Manufacturing Division, Universidad de Navarra and Ceit-BRTA, 20018 Donostia-San Sebastián, Spain
Interests: steels; thermomechanical treatments; complex microstructures; mechanical behavior; microstructure physical and numerical modelling; electron microscopy
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Dear Colleagues,

We are currently experiencing an increasingly fast development of new steel grades with complex multiphasic microstructures that are attempting to give tailored answers to the industrial demands. The combination of the dissimilar mechanical properties of the phases gives rise to a great variety of mechanical responses, which draws the attention of the academia and industrial communities. Those mechanical properties can be tuned with the help of ad-hoc alloying and processing strategies. However, the state of the art on the relationships among properties/processing/microstructure reveals that our knowledge is far from being complete when two or more phases are involved. The need for improved microstructural/mechanical characterization techniques, simulations, and models to characterize, understand, and predict the phase transformation and the mechanical behavior of multiphase steels, under either monotonous strain conditions or complex stress states, is of key significance to achieve optimized solutions.

For this Special Issue on “Advanced Multiphase Steels”, I would like to cordially invite all researchers from the steel industry and research groups to submit their latest developments and achievements in this field with the aim of casting more light on the abovementioned aspects related to these challenging and fascinating steels. Works that focus on physical metallurgy, new characterization techniques, and mechanical performance are especially encouraged

Dr. Denis Jorge-Badiola
Guest Editor

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Keywords

  • mechanical properties
  • phase transformation
  • alloy design
  • microstructural characterization and optimization
  • processing optimization
  • physical and numerical simulations
  • damage

Published Papers (8 papers)

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Editorial

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2 pages, 179 KiB  
Editorial
Advanced Multiphase Steels
by Denis Jorge-Badiola
Metals 2023, 13(11), 1871; https://doi.org/10.3390/met13111871 - 10 Nov 2023
Viewed by 714
Abstract
We are currently experiencing an increasingly fast development of new steel grades with complex multiphase microstructures attempting to give tailored answers to industrial demands [...] Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)

Research

Jump to: Editorial

14 pages, 4863 KiB  
Article
The Significance of Optimizing Mn-Content in Tuning the Microstructure and Mechanical Properties of δ-TRIP Steels
by Baoyu Xu, Peng Chen, Zhengxian Li, Di Wu, Guodong Wang, Jinyu Guo, Rendong Liu, R. D. K. Misra and Hongliang Yi
Metals 2021, 11(3), 523; https://doi.org/10.3390/met11030523 - 23 Mar 2021
Cited by 4 | Viewed by 2138
Abstract
The δ-TRIP steel has attracted a lot of attention for its potential application in automotive components, owing to the low density, good combination of strength, and ductility. As the difficulty in yield strength further increasement is caused by large fraction ferrite, the work [...] Read more.
The δ-TRIP steel has attracted a lot of attention for its potential application in automotive components, owing to the low density, good combination of strength, and ductility. As the difficulty in yield strength further increasement is caused by large fraction ferrite, the work hardening ability was enhanced by optimizing the manganese (Mn)-content in this study. Three δ-TRIP steels with different manganese (Mn)-content were designed to explore the significant effect of Mn content on the work hardening behavior in order to develop high strength steel suitable for the industrial continuous annealing process. The detailed effect of Mn on microstructure evolution and deformation behavior was studied by scanning electron microscope (SEM), interrupted tensile tests, X-ray diffraction (XRD), and in-situ electron backscattered diffraction (EBSD). The study suggested that 2 Mn steel has the lowest degree of bainitic transformation, as a result of fine grain size of prior austenite. The large TRIP effect and dislocation strengthening improve the work hardening rate, resulting in 2 Mn steel exhibiting comparable mechanical properties with the QP980 steels. The retained austenite in 1.5 Mn steel progressively transformed into martensite and sustained the strain to a high strain value of 0.40, showing a good strength-ductility balance. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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14 pages, 13282 KiB  
Article
Effect of Mn Addition on Hot-Working Behavior and Microstructure of Hot-Rolled Medium-Mn Steels
by Adam Skowronek, Dariusz Woźniak and Adam Grajcar
Metals 2021, 11(2), 354; https://doi.org/10.3390/met11020354 - 19 Feb 2021
Cited by 2 | Viewed by 1948
Abstract
Hot plastic working behavior and microstructure evolution were investigated during a production process of four medium-Mn steels, which differed in Mn (3 and 5%) and Nb contents. The production process started with casting, followed by hot forging, rough hot-rolling and concluded with final [...] Read more.
Hot plastic working behavior and microstructure evolution were investigated during a production process of four medium-Mn steels, which differed in Mn (3 and 5%) and Nb contents. The production process started with casting, followed by hot forging, rough hot-rolling and concluded with final thermomechanical processing, which was performed to obtain multiphase bainite-based alloys with some fractions of retained austenite. The rough rolling was composed of four passes with total true strain of 0.99 and finishing rolling temperature of 850 °C, whereas thermomechanical processing contained five passes and total true strain of 0.95 at a finishing rolling temperature of 750 °C. During the process, the force parameters were recorded, which showed that the rolling forces for steels containing 3% Mn are higher compared to the 5% Mn alloys. There was no significant influence of Nb on the rolling parameters. The produced as-cast microstructures were composed of dendritic bainitic-martensitic phases. A positive effect of Nb micro-addition on a refinement of the as-cast structure was noticed. The thermomechanical processed steels showed fine multiphase microstructures with some fractions of retained austenite, the fraction of which depended on the Mn content in steel. The steels containing 3% Mn generated higher forces both during rough and thermomechanical rolling, which is related to slower recrystallization softening in these alloys compared to the steels containing 5% Mn. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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14 pages, 2024 KiB  
Article
In Situ Determination of Phase Stress States in an Unstable Medium Manganese Duplex Steel Studied by High-Energy X-ray Diffraction
by Mathias Lamari, Sébastien Y. P. Allain, Guillaume Geandier, Jean-Christophe Hell, Astrid Perlade and Kangying Zhu
Metals 2020, 10(10), 1335; https://doi.org/10.3390/met10101335 - 6 Oct 2020
Cited by 10 | Viewed by 2105
Abstract
Duplex medium Mn steels are high-potential advanced high-strength steels (AHSS) for automotive construction. Their excellent forming properties stem from the specific stress partitioning between their constituting phases during deformation, namely the ferritic matrix, unstable retained austenite, and strain-induced fresh martensite. The stability of [...] Read more.
Duplex medium Mn steels are high-potential advanced high-strength steels (AHSS) for automotive construction. Their excellent forming properties stem from the specific stress partitioning between their constituting phases during deformation, namely the ferritic matrix, unstable retained austenite, and strain-induced fresh martensite. The stability of the retained austenite and the 3D stress tensors of each phase are determined simultaneously in this work by in situ high energy X-ray diffraction on synchrotron beamline during a tensile test. The role of internal stresses inherited from the manufacturing stage are highlighted for the first time as well as new insights to understand the origin of the serrations shown by these alloys. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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9 pages, 3567 KiB  
Article
Compositional Optimization of High-Performance Ferritic (HiperFer) Steels—Effect of Niobium and Tungsten Content
by Xiuru Fan, Bernd Kuhn, Jana Pöpperlová, Wolfgang Bleck and Ulrich Krupp
Metals 2020, 10(10), 1300; https://doi.org/10.3390/met10101300 - 29 Sep 2020
Cited by 16 | Viewed by 1767
Abstract
The combined addition of Nb and W provides increased solid solution and precipitation strengthening by (Fe,Cr,Si)2(Nb,W)-Laves phase particles of ferritic, 17 wt.% Cr stainless high-performance ferritic (HiperFer) steel. Based on alloy modifications and the obtained hardness, tensile, and creep testing results; [...] Read more.
The combined addition of Nb and W provides increased solid solution and precipitation strengthening by (Fe,Cr,Si)2(Nb,W)-Laves phase particles of ferritic, 17 wt.% Cr stainless high-performance ferritic (HiperFer) steel. Based on alloy modifications and the obtained hardness, tensile, and creep testing results; a new high alloying variant is proposed as a candidate steel for future structural application up to approximately 680 °C in power engineering and the process industry. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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14 pages, 4334 KiB  
Article
Microstructural and Mechanical Characterization of a Nanostructured Bainitic Cast Steel
by Andrés Felipe Santacruz-Londoño, Oscar Rios-Diez, José A. Jiménez, Carlos Garcia-Mateo and Ricardo Aristizábal-Sierra
Metals 2020, 10(5), 612; https://doi.org/10.3390/met10050612 - 8 May 2020
Cited by 9 | Viewed by 3631
Abstract
Nanoscale bainite is a remarkable microstructure that exhibits a very promising combination of high strength with good ductility and toughness. The development of these types of microstructures has been focused on wrought materials, and very little information is available for steel castings. In [...] Read more.
Nanoscale bainite is a remarkable microstructure that exhibits a very promising combination of high strength with good ductility and toughness. The development of these types of microstructures has been focused on wrought materials, and very little information is available for steel castings. In this work, a specially designed cast steel with 0.76 wt % C was fabricated, and the heat treatment cycles to develop bainitic nanostructures were determined by studying the kinetics of the bainitic transformation using high-resolution dilatometry. The effects of isothermal holding temperature and time on the final microstructure and mechanical properties were thoroughly characterized in order to evaluate a future industrial implementation of the process in an effort to contribute to enhance and widen the potential applications for cast steels. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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17 pages, 7418 KiB  
Article
Metallurgical Effects of Niobium in Dual Phase Steel
by Hardy Mohrbacher, Jer-Ren Yang, Yu-Wen Chen, Johannes Rehrl and Thomas Hebesberger
Metals 2020, 10(4), 504; https://doi.org/10.3390/met10040504 - 12 Apr 2020
Cited by 16 | Viewed by 4695
Abstract
Dual phase (DP) steels are widely applied in today’s automotive body design. The favorable combination of strength and ductility in such steels is in first place related to the share of ferrite and martensite. The pronounced work hardening behavior prevents localized thinning and [...] Read more.
Dual phase (DP) steels are widely applied in today’s automotive body design. The favorable combination of strength and ductility in such steels is in first place related to the share of ferrite and martensite. The pronounced work hardening behavior prevents localized thinning and allows excellent stretch forming. Niobium microalloying was originally introduced to dual phase steel for improving bendability by refining the microstructure. More recently developed “high ductility” (HD) DP steel variants provide increased drawability aided by a small share of austenite retained in the microstructure. In this variant niobium microalloying produces grain refinement and produces a dispersion of nanometer-sized carbide precipitates in the steel matrix which additionally contributes to strength. This study investigates the microstructural evolution and progress of niobium precipitation during industrial processing of high-ductility DP 980. The observations are interpreted considering the solubility and precipitation kinetics of niobium. The influences of niobium on microstructural characteristics and its contributions to strength and formability are discussed. Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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18 pages, 5074 KiB  
Article
Substructure Development and Damage Initiation in a Carbide-Free Bainitic Steel upon Tensile Test
by Mari Carmen Taboada, Amaia Iza-Mendia, Isabel Gutiérrez and Denis Jorge-Badiola
Metals 2019, 9(12), 1261; https://doi.org/10.3390/met9121261 - 26 Nov 2019
Cited by 6 | Viewed by 2974
Abstract
Carbide-free bainitic (CFB) steels belong to the family of advanced high strength steels (AHSS) that are struggling to become part of the third-generation steels to be marketed for the automotive industry. The combined effects of the bainitic matrix and the retained austenite confers [...] Read more.
Carbide-free bainitic (CFB) steels belong to the family of advanced high strength steels (AHSS) that are struggling to become part of the third-generation steels to be marketed for the automotive industry. The combined effects of the bainitic matrix and the retained austenite confers a significant strength with a remarkable ductility to these steels. However, CFB steels usually show much more complex microstructures that also contain MA (Martensite–Austenite) phase and auto-tempered martensite (ATM). These phases may compromise the ductility of CFB steels. The present work analyzes the substructure evolution during tensile tests in the necking zone, and deepens into the void and crack formation mechanisms and their relationship with the local microstructure. The combination of FEG-SEM imaging, EBSD, and X-ray diffraction has been necessary to characterize the substructure development and damage initiation. The bainite matrix has shown great ductility through the generation of high angle grain boundaries and/or large orientation gradients around voids, which are usually found close to the bainite and MA/auto-tempered martensite interfaces or fragmenting the MA phase. Special attention has been paid to the stability of the retained austenite (RA) during the test, which may eventually be transformed into martensite (Transformation Induced Plasticity, or TRIP effect). Full article
(This article belongs to the Special Issue Advanced Multiphase Steels)
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