Author
F. G. Caballero
Bio: F. G. Caballero is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Bainite & Ferrite (iron). The author has an hindex of 19, co-authored 32 publications receiving 1981 citations.
Papers
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TL;DR: A steel with an ultimate tensile strength of 2500 MPa, a hardness at 600-670 HV and toughness in excess of 30-40 MPa/m 1/2 is the result of exciting new developments with bainite as discussed by the authors.
Abstract: Steel with an ultimate tensile strength of 2500 MPa, a hardness at 600–670 HV and toughness in excess of 30–40 MPa m 1/2 is the result of exciting new developments with bainite. The simple process route involved avoids rapid cooling so that residual stresses can in principle be avoided even in large pieces. The microstructure is generated at temperatures which are so low that the diffusion of iron is inconceivable during the course of the transformation to bainite. As a result, slender plates of ferrite, just 20–40 nm thick are generated, giving rise to the extraordinary properties.
555 citations
TL;DR: In this paper, it was demonstrated that in a high-carbon steel where carbide precipitation is suppressed, bainite can be obtained by isothermal transformation at temperatures as low as 200°C.
Abstract: It is demonstrated that in a high-carbon steel where carbide precipitation is suppressed, bainite can be obtained by isothermal transformation at temperatures as low as 200°C. The time taken for nucleation at this temperature can be many days, but the transformation results in the growth of extremely thin platelets of bainite, so thin that the hardness of the resulting steel can be greater than 600 HV.
342 citations
TL;DR: The extremely slow transformation kinetics of a nanocrystalline bainitic steel allows the carbon content of the bainite ferrite away from any carbon-enriched regions such as dislocations and boundaries to be determined by atom probe tomography as mentioned in this paper.
162 citations
TL;DR: In this paper, the carbon distribution in austenite during isothermal bainite formation and the incomplete reaction phenomenon was analyzed by means of X-ray diffraction and atom-probe tomography in high-silicon, manganese-alloyed steels.
125 citations
TL;DR: In this article, a nanocrystalline steel consisting of a mixture of lower bainitic ferrite and carbon-enriched retained austenite has been analyzed by atom probe tomography.
121 citations
Cited by
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TL;DR: In this paper, the structure and properties of bearing steels prior to the point of service are first assessed and described in the context of steelmaking, manufacturing and engineering requirements, followed by a thorough critique of the damage mechanisms that operate during service and in accelerated tests.
729 citations
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TL;DR: A steel with an ultimate tensile strength of 2500 MPa, a hardness at 600-670 HV and toughness in excess of 30-40 MPa/m 1/2 is the result of exciting new developments with bainite as discussed by the authors.
Abstract: Steel with an ultimate tensile strength of 2500 MPa, a hardness at 600–670 HV and toughness in excess of 30–40 MPa m 1/2 is the result of exciting new developments with bainite. The simple process route involved avoids rapid cooling so that residual stresses can in principle be avoided even in large pieces. The microstructure is generated at temperatures which are so low that the diffusion of iron is inconceivable during the course of the transformation to bainite. As a result, slender plates of ferrite, just 20–40 nm thick are generated, giving rise to the extraordinary properties.
555 citations
TL;DR: In this paper, a fine-scale bainitic microstructure with high strength and high toughness has been achieved by transforming austenite at 200°C. X-ray diffraction analysis showed the carbon concentration of these bainite ferrite plates to be higher than expected from para-equilibrium.
314 citations
TL;DR: In this paper, the authors acknowledge financial support from the Spanish Ministerio de Educacion y Ciencia for the financial support in the form of Ramon y Cajal contracts (RyC 2002 and 2004 respectively).
Abstract: The authors acknowledge financial support from the
Spanish Ministerio de Educacion y Ciencia for the financial
support in the form of Ramon y Cajal contracts (RyC 2002
and 2004 respectively). Some of this work was carried out
under the auspices of an EPSRC/MOD sponsored project
on bainitic steels at the University of Cambridge; we are
extremely grateful for this support over a period of three
years. The authors are extremely grateful to Prof. H. K. D.
257 citations
25 Nov 2013
TL;DR: It is demonstrated how this can be achieved using an approach that combines the accuracy of structural characterization in transmission electron microscopy with the 3D chemical sensitivity of atom probe tomography, which indicates that ω is the most influential crystallographic parameter in this regime.
Abstract: Grain boundary segregation leads to nanoscale chemical variations that can alter a material's performance by orders of magnitude (e.g., embrittlement). To understand this phenomenon, a large number of grain boundaries must be characterized in terms of both their five crystallographic interface parameters and their atomic-scale chemical composition. We demonstrate how this can be achieved using an approach that combines the accuracy of structural characterization in transmission electron microscopy with the 3D chemical sensitivity of atom probe tomography. We find a linear trend between carbon segregation and the misorientation angle ω for low-angle grain boundaries in ferrite, which indicates that ω is the most influential crystallographic parameter in this regime. However, there are significant deviations from this linear trend indicating an additional strong influence of other crystallographic parameters (grain boundary plane, rotation axis). For high-angle grain boundaries, no general trend between carbon excess and ω is observed; i.e., the grain boundary plane and rotation axis have an even higher influence on the segregation behavior in this regime. Slight deviations from special grain boundary configurations are shown to lead to unexpectedly high levels of segregation.
253 citations